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Thursday, January 20, 2011

Bioplasten and Henrietta Lacks

In 1890 german biologist Richard Altmann observed mitochondria in cells and named them the “Bioplasten.”  Mitochondria are everyone’s favorite cell organelle.  Unfortunately we never have enough time in class to discuss thoroughly these fascinating cells.  Wait a minute, ….these are cells?  Well I am going to go out on a limb and say that these are obligate endocytobiotic  bacteria.  However this phenomena is not that unusual because more and more endocytobiotic bacteria are being described. 
So I thought we would use this blog to collect information about these interesting creatures.  Lets start with their abundance.  If these are intracellular bacteria then they are perhaps the most numerous bacteria on earth with estimates of  1026.  This may represent a  good portion of all bacteria on earth.  In fact we could estimate that the mitochondria from one person, Henrietta Lacks,  may be one of the most abundant bacteria on earth, with estimates of 1017.  (Pallen, Trends in Microbiology, 2011)
Who was Henrietta Lacks?
From WikiPedia:
Henrietta Lacks (August 18, 1920 – October 4, 1951) was an African American woman who was the unwitting source of cells from her cancerous tumor, which were cultured by George Otto Gey to create an immortal cell line for medical research. This is now known as the HeLa cell line.

The story of Henrietta Lacks is a fascinating one and was published in a book last year.  Many many researchers have grown her cells and used them in research, thus her mitochondria are very abundant on earth;  some suspended in a timeless state in freezers all over the world.
One scientist suggests that we name the mitochondrian bacteria as Mitochondrian lacksi.
So here is the first set of questions about mitochondria.
1 What are the current theories regarding the origin of mitochondria?
2 What is the structure of the mitochondrial membrane?
3 Mitochondria provide several functions in cells, what are they?
4 What bacteria do mitochondria resemble the most?
5 Do all cells have mitochondria?
6 Why do mitochondria have DNA? 

40 comments:

  1. After losing my comment information 3 times now, I'ved decided to post my response to the questions seperately ;)
    1) The websites I've visited point to endosymbiosis of the bacterial cell (mitochondria) into the host cell or eukaryotic cell. One website in particular argues that the mitochondria was once a bacterial cell because it seems to reproduce independently and it carries its own DNA. Also, its size relative to the other organelles resembles that of bacteria. My question then, since the Bible would not point to evolutionary means to achieve this process, how then would mitochondria go from an independent bacteria to a cell organelle? Did God create the bacteria inside the cell already or could the mitochondria simply be a complex organelle..?

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  2. 2) This was from the same website I used primarily to answer question 1 and I liked the clarity of its explanation..(minus the few words I had to look up on dictionary.com of course ;) ) "The outer membrane is a relatively simple phospholipid bilayer, containing protein structures called porins which render it permeable to molecules of about 10 kilodaltons or less (the size of the smallest proteins). Ions, nutrient molecules, ATP, ADP, etc. can pass through the outer membrane with ease.

    The inner membrane is freely permeable only to oxygen, carbon dioxide, and water. Its structure is highly complex, including all of the complexes of the electron transport system, the ATP synthetase complex, and transport proteins. The wrinkles, or folds, are organized into lamillae (layers), called the cristae (singlular: crista). The cristae greatly increase the total surface area of the inner membrane. The larger surface area makes room for many more of the above-named structures than if the inner membrane were shaped like the outer membrane.

    The membranes create two compartments. The intermembrane space, as implied, is the region between the inner and outer membranes. It has an important role in the primary function of mitochondria, which is oxidative phosphorylation."

    http://www.ruf.rice.edu/~bioslabs/studies/mitochondria/mitotheory.html

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  3. 3) The main functions mitochondria perform are the production of energy in synthesizing ATP. The mitochondria is also known as the cell's respiration because of it's role in oxidation during the synthesis of ATP. Another function I found particularly fascinating was it's role in programmed cell death to prune away excess cells. According to epilepsy.com this form of cell pruning has also been used in cancer treatments. That same website provided these other functions that I found simple enough not to restate in my own words: "Other functions of mitochondria are related to the cell type in which they are found. Mitochondria are involved in building, breaking down, and recycling products needed for proper cell functioning. For example, some of the building blocks of DNA and RNA occur within the mitochondria. Mitochondria are also involved in making parts of blood and hormones such as estrogen and testosterone. They are required for cholesterol metabolism, neurotransmitter metabolism, and detoxification of ammonia in the urea cycle. Thus, if mitochondria do not function properly, not only energy production but also cell-specific products needed for normal cell functioning will be affected."

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  4. 5) Only eukaryotic cells have mitochondria.

    6) I would say, because the mtDNA seem to be specific to the mitochondria's function within the cell, the the mtDNA is there to help the mitochondria funtion properly and smoothly. I'm basing that off of this quote: "Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function. Thirteen of these genes provide instructions for making enzymes involved in oxidative phosphorylation. Oxidative phosphorylation is a process that uses oxygen and simple sugars to create adenosine triphosphate (ATP), the cell's main energy source. The remaining genes provide instructions for making molecules called transfer RNA (tRNA) and ribosomal RNA (rRNA), which are chemical cousins of DNA. These types of RNA help assemble protein building blocks (amino acids) into functioning proteins"
    http://ghr.nlm.nih.gov/chromosome/MT

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  5. Kaylin asked, "My question then, since the Bible would not point to evolutionary means to achieve this process, how then would mitochondria go from an independent bacteria to a cell organelle?"

    Is there a difference between an independent bacterium and a cell organelle? Or is it more of a continuum? Can you really draw a line between the two?

    Just thinking out loud...

    I shall now return to lurking.

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  6. Good work Kaylin, Dr Wood (he is a friend of mine) has a good question and here is my question. If the cell has DNA, and it can make mitochondrial proteins, why does a mitochondria need DNA? Can anyone help Kaylin with these questions?

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  7. Maybe mtDNA helps regulate other functions in the mitochondria that DNA wasn’t designed to. mtDNA and DNA have some different properties. Most mitochondrial DNA is inherited from the mother. Nuclear DNA is inherited from both parents. There are thirty seven genes of mitochondrial DNA. The two strands of mitochondrial DNA are separated into a “heavy” strand and a “light” strand. The differentiation refers to each strand’s nucleotides. The heavy strand has more guanine, and the light strand has more cytosine. The heavy strand is responsible for the encoding of twenty eight of the genes, and the light strand is responsible for the encoding of nine of the genes. So, these are some of the differences between mtDNA and DNA.
    Also,Thirteen of the thirty seven genes of mitochondrial DNA are vital for the process of oxidative phosphorylation. The process of oxidative phosphorylation is the metabolic pathway in which energy released during the oxidation of nutrients is used to produce. Maybe it is more efficient for the mitochondria to have their own mtDNA because this is a regular process.

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  8. Nice work Kaylin!

    I've been thinking about Dr. Wood's question. According to Wikipedia, "an organelle is a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer." So, it sounds like organelles are inside of the cells. This makes it even more interesting if there really is DNA in both. Maybe it just looks like it could have come from bacteria, but God in his creativeness (if that's a word) made the organelles to look like bacteria but do not have any more resemblance. Erik's idea sounds plausible as well.

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  9. 1)

    The Endosymbiotic Hypothesis:

    “The endosymbiotic hypothesis for the origin of mitochondria (and chloroplasts) suggests that mitochondria are descended from specialized bacteria (probably purple nonsulfur bacteria) that somehow survived endocytosis by another species of prokaryote or some other cell type, and became incorporated into the cytoplasm.” From http://www.ruf.rice.edu/~bioslabs/studies/mitochondria/mitorigin.html. Basically, mitochondria are a result of prokaryotes engulfing bacteria.

    The Endosymbiont Hypothesis:

    “...the theory that [chloroplasts and mitochondria] are direct descendants of prokaryotes that entered primitive nucleated cells. Among billions of such events, a few could have led to the development of stable, symbiotic associations between nucleated hosts and prokaryotic parasites. The hosts would provide the parasites with a stable osmotic environment and easy access to nutrients, and the parasites would repay the hosts by providing an oxidative ATP-producing system or a photosynthetic energy-producing reaction.” From http://www.britannica.com/EBchecked/topic/101396/cell/37425/The-endosymbiont-hypothesis?anchor=ref313791. Basically, mitochondria are the result of prokaryotes parasitizing other cells.

    The Episome-Hypothesis:

    “This hypothesis assumes that mitochondria have developed from protomitochondria, that were derived from the proto-eukaryote inner membrane, and which contained genes for (mt) ribosomal components, t-RNA’s and several components of the respiratory chain.” From “The Origin of Mitochondria” by L Reijnders. Basically, mitochondria developed from the early membranes of eukaryotic cells.

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  10. 2)

    The mitochondrial membrane is actually composed of an outer and inner membrane.

    Outer:
    About half lipids by weight
    Full of various enzymes
    Contains porins, making it permeable

    Inner:
    3:1 protein to lipids by weight
    Impermeable


    3)

    Production of ATP and the “synthesis of numerous substances, including certain amino acids and the heme groups... Mitochondria also play a vital role in the uptake and release of calcium ions. Calcium ions are essential triggers for cellular activities, and mitochondria (along with the endoplasmic reticulum) play an important role in regulating the [calcium ion] concentration of the cytosol. The process of cell death, which plays and enormous role in the life of all multicellular animals, is also regulated to a large extent by events that occur within mitochondria.” From “Cell and Molecular Biology” by Gerald Karp.

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  11. 4)

    Mitochondria resemble aerobic bacteria. Some examples of aerobic bacteria are Staphylococcus, Neisseria, Pseudomonas aeruginosa, Mycobacterium tuberculosis, and Nocardia.

    5)

    No. Prokaryotes do not have mitochondria. Mature erythrocytes, which are a type of eukaryotic cells, also do not have mitochondria. I’m sure there are also other eukaryotic cells that I am unaware of that also do not have them.

    6)

    The answer to this question is two-part. If they were to have come from aerobic bacteria, mitochondria would have DNA because the bacteria they engulfed had DNA. In terms of what function mitochondrial DNA serves, it codes for rRNA, tRNA, and polypeptides.

    To answer the question posed to Kaylin, perhaps the mitochondrial DNA is a type of “safety net.” If the DNA of the nucleus was to experience harmful mutation, the unaltered mitochondria could continue to function and produce crucial ATP.

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  12. Safety net hypothesis. Interesting. However there seems to be a lot of dependence between the cell nucleus and mitochondrial nucleus...but I like the way you are thinking!!

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  13. hmm..I'll definitely have to look into this later Dr. Francis. ;) This is interesting.

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  14. 1. The most commonly accepted theory for the origin of mitochondria in the cell is the endosymbiotic hypothesis, which states that early cells incorporated aerobic bacteria for the energy they would gain from respiration. This would be an advantage over cells without these bacteria because they would only be able to gain their energy from fermentation and glycolysis.

    2. The mitochondria has two membranes. The outer membrane is similar in composition to cellular membranes and has proteins interspersed throughout it. The inner membrane is where the metabolic processes occur, and it folds into cristae to increase its surface area, and thus its capacity for ATP synthesis.
    3. Aside from producing ATP during cellular respiration, the mitochondria is also involved in producing heat, regulating cellular metabolism, performing cellular apoptosis, and synthesizing some steroids.

    4. Mitochondria closely resemble rickettsiales, which is a type of proteobacteria commonly seen living inside other cells, much like mitochondria. They can also be responsible for disease in humans.
    5. There are some unicellular eukaryotes that don’t have mitochondria, and these tend to be either parasitic or symbiotic. Bacteria also don’t have mitochondria but use photosynthesis, chemosynthesis, glycolysis, and a number of other processes to get their energy.
    6. Mitochondria have DNA so that they can create proteins from ribosomes, much like the nucleus. An interesting difference between mitochondrial DNA and nuclear DNA is that the DNA in the mitochondria is only inherited from the mother in humans, and the paternal mitochondrial DNA is rarely if ever used.

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  15. 1. This is what one website said the mitochondria came from:"mitochondria appear to originate only from other mitochondria. They contain their own DNA, which is circular as is true with bacteria, along with their own transcriptional and translational machinery. Mitochondrial ribosomes and transfer RNA molecules are similar to those of bacteria, as are components of their membrane.These and related observations led Dr. Lynn Margulis, in the 1970s, to propose an extracellular origin for mitochondria."
    This website says that through the endosymbiotis theory, the mitochondria DID come from a bacteria:Endosymbiotis theory:
    " > This is the most popular scientific theory was first attributed to Lynn Margulis, though related concepts by others (i.e. Mereschkowsky) have been around for years.
    > It is theorized that a larger anaerobic prokaryotic cell “swallowed” a smaller aerobic one, and the aerobic prokaryote became an organelle ... a mitochondrion ... of the larger cell. "
    Another theory, the autogenous theory, says this:" 3. According to the autogenous hypothesis, mitochondria and chloroplasts have evolved within the protoeukaryote cell by compartmentalizing plasmids or vesicles of DNA within a pinched off invagination of the cell membrane."
    And then here are multiple other ones that I found:" - Ox-tox model: the ancestor of mitochondria was an aerobic proteobacterium; the host was an anaerobic, primitively amitochondriate eukaryote; addresses the origin of mitochondria, not the complete eukaryote cell
    - Panspermia (or Cosmozoan): cells came from somewhere else (outer space) and seeded Earth
    - Biblical (or Scientific Creationism): both types of cells came from a Creator".

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  16. 1. THe origin of mitochondria appears to orginate from the theory endosymbiotic hypothesis, where they come from a free-living bacteria.
    2. The mitochondria membrane contain a double membrane. The outer membrande being fairly smooth and the inner contains cristae.
    3. The main function of mitochondria is to produce energy in ATP. Also helps control levels of water and other materials in a cell. It recycles and decomposes proteins, fats, and carbohydrates, forming urea.
    5. Eukaryotic cells only contain mitochondria.
    6. They have DNA because then it can know the specifics of that cell heling with a proper function. And for the other things needed for the nucleus.

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  17. 2. The structure of the Mitochondria is "The double-membraned mitochondrion can be loosely described as a large wrinkled bag packed inside of a smaller, unwrinkled bag. The two membranes create distinct compartments within the organelle, and are themselves very different in structure and in function." according to one website. The outer membrane is made up of a phospholipid bilayer that contains protein structures which make it hard to get through, only allowing certain things to pass such as ATP and ADP.
    The inner membrane is much more permeable, allowing more things such as C2O, oxygen, and water to go through.
    There's also a matrix which contain enzymes.

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  18. 1. The current theories that I have found so far all start with the endosymbiotic theory, which is the theory that suggests that mitochondria descended from bacteria that survived endocytosis by another cell, and became incorporated into the cytoplasm. However, this still doesn’t describe ho mitochondria came about.
    2. The structure consists of an inner and outer membrane (similar to the paramecium) with a phospholipid bilayers and proteins. There are five major components to the structure of mitochondria: the outer mitochondrial membrane, the intermembrane space, the inner mitochondrial membrane, the cristae space-which is formed by the inner membrane foldings, and the matrix.
    3. There are many functions of mitochondria, the main one being the production of ATP for the cell. Another main function is to regulate cellular metabolism. Other functions consist of regulation of the membrane protein, calcium signaling, steroid synthesis, and the list goes on. However, the main function is to produce ATP.
    4. From what I can find, Mitochondria resemble aerobic bacteria which are bacteria that can survive and produce in oxygenated environments.
    5. No, all cells do not have mitochondria. Only eukaryotes do-animal cells. However, I did find that these few groups of unicellular eukaryotes lack mitochondria. The microsporidians(spore forming parasites), metamonads(flagellate protozoa) and archamoebae(a kind of amoeba) do not contain mitochondria. Not sure how accurate this information is though-wikipedia.
    6. Mitochondria have DNA because they are essential for the production of mature mRNA’s.

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  19. 3. The mitochondria produces energy. Here is interesting information that I found on the functions of a mitochondria:"The most important function of the mitochondria is to produce energy. The food that we eat is broken into simpler molecules like carbohydrates, fats, etc., in our bodies. These are sent to the mitochondrion where they are further precessed to produce charged molecules that combine with oxygen and produce ATP molecules. This entire process is known as oxidative phosphorylation.
    It is important to maintain proper concentration of calcium ions within the various compartments of the cell. Mitochondria help the cells to achieve this goal by serving as storage tanks of calcium ions.
    Mitochondria helps in the building of certain parts of the blood, and hormones like testosterone and estrogen.
    Mitochondria in the liver cells have enzymes that detoxify ammonia."

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  20. 4. I would definitely have to say that mitochondria are most like the aerobic bacteria. According to a website, they both contain their own DNA and they both make their own proteins.
    5. All eukaryotic cells have mitochondria, but no prokaryotic and no single celled organisms. Actually, not all eukaryotic cells have mitochondria either. Erythrocytes (red blood cells) lack mitochondria when they are first starting out.
    6. evolutionists believe that "they have separate DNA because they originally evolved as distinct organisms."
    Another person said this:"To help it to replicate to aid respiration."

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  21. 1. The evolutionary origin of mitochondria states that mitochondria is a true bacteria which survives and incorporated into the cytoplasm.

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  22. 1. after looking at a few different website for the origin of mitochondria, one stood out to me and that was from the Experimental Biosciences website. They said that endosymbiotic hypothesis for the origin of mitochondria suggests that mitochondria are descended from specialized bacteria that somehow survived endocytosis by another species of prokaryote and then became incorporated in the cytoplasm with all the other organelles.
    2.the inner membrane is permeable only to oxygen, carbon dioxide and water, which i dont know why but i find very interesting!! the outer membrane has almost the same amount of phospholipids as proteins. It has a large number of special proteins called porins, that allow molecules of 5000 daltons or less in weight to pass through it. The outer membrane is completely permeable to nutrient molecules, ions, ATP and ADP molecules.

    3. the functions of the mitochondria include Cell-specific functions such as building, breaking down, and recycling products needed for proper cell functioning. They also are involved in cell-program death, and Energy production.

    4.one website that i found said that it resembled a specialized bacteria and i would guess an aerobic bacteria.
    5. Mitochondria are only present in eukaryotic cells.
    6.I think they have their own DNA because mitochondria serves so many different functions so the DNA is there to aid the cell in the specificity of its functions.

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  23. 1) according to sources from the Rice University, Dr. Lynn Margulis, in the 1970s, proposed an extra-cellular origin for the mitochondria. There are other instances of symbiotic life where bacteria live inside another cell, thus this theory is not without some basis (but we know that God Himself put the mitochondria in the cell upon creation). The theory states that the mitochondria were incorporated into the early prokaryotic cells."The ability of symbiont bacteria to conduct cellular respiration in host cells that relied on glycosis and fermentation would have provided a considerable evolutionary advantage". -David R. Caprette (caprette@rice.edu), Rice University 19 Jun 2000. Thus because of this ability for the mitochondria to have a good environment to live in, they were able to more greatly able to find suitable environments (the cells). But this theory has some flaws. The mitochondria (bacteria cells) does not have enough DNA to produce all of its needed proteins. The argument (a not very convincing one) is that over the billions of years of it living in the cell, that it progressively lost its complexity and independency.

    2) The mitochondrial general structure of its membrane consists of an outer membrane, and an inner membrane with and intermembrane space in between. The outer membrane is a simple phospholipid bilayer with protein structures that let small molecules in such as: ions, nutrient molecules, ATP, ADP, and many other molecules. Basically its a pretty simple membrane. The inner membrane, on the other hand, is more complex because it is where the synthesis of ATP takes place. It has all of the complexes of the electron transport system, the ATP synthetase complex, and transport proteins. It has some folds in its design, folding it in and out, creating more surface area for the above mentioned structures. These folds are called cristae.

    3) Mitochondria in cells have many functions besides oxidative phosphorylation (a metabolic pathway that uses energy released by the oxidation of nutrients to produce adenosine triphosphate (ATP) - wikipedia). Apparently they have DNA , mRNA, tRNA, and ribosomes! so they have the ability to produce proteins as well as ATP. Also the cell uses mitochondria to hold a bunch of calcium ions. Strange how the text books usually only say stuff like "they are the 'powerhouse' of the cell", not mentioning the vast responsibilities of these strange organelles. Also they are "involved in building, breaking down, and recycling products needed for proper cell functioning", depending on the specific purpose of the cell. -By Russell P. Saneto, D.O., Ph.D., Children’s Hospital and Regional Medical Center/University of Washington School of Medicine, Seattle, WA.
    "RECENT STUDIES SUGGEST that mitochondria do much more than generate energy. They are intimately involved in cell signaling, raising a red flag during times of cellular stress, such as when viruses invade or oxygen levels drop. It now appears that subtle abnormalities in mitochondria contribute not only to rare metabolic disorders but also to many common diseases, including chronic hepatitis, cancer, and certain aging-related diseases, such as type 2 diabetes." - Howard Hughes Medical Institute This is very interesting seeing the many different areas that biologist are starting to research.

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  24. 4) source after source claims that the mitochondria must have been introduced into the cell as a type of aerobic bacteria (cells that require oxygen to synthesize energy). Mycobacterium Tuberculosis (TB), the Staphylococcus species, and the Streptcoccus species.

    5) Eukaryotes have mitochondria (except plant cells which contain the green with envy chloroplasts which wish they were mitochondria). Prokaryotes do not have mitochondria.

    6) "Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function. Thirteen of these genes provide instructions for making enzymes involved in oxidative phosphorylation. The remaining genes provide instructions for making molecules called transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), which are chemical cousins of DNA. These types of RNA help assemble protein building blocks (amino acids) into functioning proteins." -

    Also the DNA in mitochondria seem to be of maternal descent. They rarely, if ever, receive their DNA from the father of the cell (the sperm cell in humans), thus their DNA is less shuffled and changed every generation. This slower rate of change of DNA then the Cell's DNA allows for some interesting information for geneticists

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  25. 2)Mitochodria has outer mitochodrial membrane, intermembrane space,inner membrane,cristae space and matrix. The outer and inner membrance are make of phospholipid bilayers and proteins.

    3) Mitochodria generate ATP to supply enery for the cell, it control the cell cycle and cell growth. It also involves in the aging process, signaling and cell death.

    4)Mitochondria has similar genome with bacteria's genomes

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  26. One of the most popular theories on the origin of mitochondria suggests that mitochondria are actually bacteria that were engulfed by a cell at some point during the evolutionary process. The mitochondrial membrane is a phospholipid membrane with two compartments: the inner and outer membranes. Mitochondria are responsible for energy production in the cell as well as the synthesis of various amino acids. Mitochondria most resemble alpha-proteobacteria and the endosymbiont that created mitochondria (from an evolutionary standpoint) was most likely one of these. Mitochondria are not present in all cells as some unicellular eukaryotes and prokaryotes have no mitochondria. Mitochondria have DNA because they are also responsible for amino acid production. They need DNA in order to create these amino acids.

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  27. 1.Endosymbiotic theory: Protists are eukaryotes, of course, meaning that their genetic material is organized into a compartment, the nucleus, that is surrounded by membrane, and that they have membrane-delineated organelles. In the warm seas of the ancient earth, the first living things would have been prokaryotes. The endosymbiotic hypothesis for the origin of mitochondria (and chloroplasts) suggests that mitochondria are descended from specialized bacteria (probably purple nonsulfur bacteria) that somehow survived endocytosis by another species of prokaryote or some other cell type, and became incorporated into the cytoplasm. The ability of symbiont bacteria to conduct cellular respiration in host cells that relied on glycosis and fermentation would have provided a considerable evolutionary advantage. Similarly, host cells with symbiont bacteria capable of photosynthesis would also have an advantage. In both cases, the number of environments in which the cells could survive would have been greatly expanded.

    2.The outer mitochondrial membrane, which encloses the entire organelle, has a protein-to-phospholipid ratio similar to that of the eukaryotic plasma membrane (about 1:1 by weight). It contains large numbers of integral proteins called porins. It contains more than 151 different polypeptides, and has a very high protein-to-phospholipid ratio (more than 3:1 by weight, which is about 1 protein for 15 phospholipids).

    3.-Production of ATP in two series of reactions: Citric Acid Cycle or Kreb’s Cycle and the Electron Transport Chain.
    -Production of heat
    -Storage of calcium ions
    -Regulation of membrane potential, cell proliferation, and cell metabolism
    -Initiation of apoptosis or programmed cell death
    -Calcium signaling
    -Biosynthesis of heme and steroids
    -Metabolic detoxification

    4. The circular structure is also found in prokaryotes, and the similarity is extended by the fact that mitochondrial DNA is organized with a variant genetic code similar to that of Proteobacteria.

    5. Mitchondria are only found in eukaryotic cells.

    6. Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function. Thirteen of these genes provide instructions for making enzymes involved in oxidative phosphorylation. The remaining genes provide instructions for making molecules called transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), which are chemical cousins of DNA. These types of RNA help assemble protein building blocks (amino acids) into functioning proteins.

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  28. 1. Because of their many similarities with that of prokaryotes, they are theorized to have been originally derived from endosymbiotic prokaryotes.

    2. The mitochondria have two membranes (the outer and the inner one), the space between those membranes, a certain substance that divides the inner membrane into different compartments called the cristae, and the matrix, which is the enclosed space in the inner membrane.

    3. Mitochondria proved the necessary energy for cells to move about, for the production of secretory products, contraction, and cell division. They, in a sense, act as the cells battery, powering them with energy required for these functions.

    Also, 5. Eukaryotes have mitochondria, but prokaryotes, and such lack them. I guess it would be safe to say that mitochondria are strictly found in eukaryotic cells.

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  29. The endosymbiotic hypothesis states that mitochondria descended from bacteria.

    The mitochondria contain two membranes that create distinct compartments within the organelle. The outer membrane is like the phospholipid bilayer, and the inner membrane has folds organized into layers called cristae. These layers increase the surface area of the inner membrane.

    The mitochondria functions to provide energy for the cell. It recycles and decomposes proteins, fats and carbs and also controls the level of water and other materials in the cell.

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  30. 1. Currently the main theory regarding mitochondria origin is the endosymbiotic theory (should be called endocytobiotic theory). This theory says that cells phagocytized bacterial cells. These new phagocytized cells then began to act as energy factories, eventually evolving into mitochondria.
    2. The mitochondria has two membranes, and inner and outer membrane.
    3. The outer membrane has a protein-to-phospholipid ratio of about 1:1 by weight. This membrane has integral proteins called porins and allows the passage of proteins into the space between the two membranes. The inner mitochondrial membrane and its protein’s functions include oxidative phosphorylation, ATP synthesis, metabolite transport, protein import, and mitochondria fusion and fission.
    4. Alpha-proteobacteria resemble mitochondria. This relationship was found by doing phylogenetic analyses of both protein-coding genes and ribosomal RNA genes specified by mitochondrial DNA.
    5. Eukaryotes are the only cells with mitochondria; however, there are some eukaryotes that do not have mitochondria. These eukaryotes include diplomonads (Giardia), microspordia (Encephalitozoon), parabasalids (Trichomonas).
    6. Mitochondria might have their own DNA because it gives another layer of control in the cell. Since mitochondria have their own ribosomes it is easier to stop mitochondria function while continuing the other functions of the cell. Maybe mitochondria having their DNA also acts as a way to prevent mtDNA mutation. This would be important in the case of apoptosis. If mitochondrial DNA was mutated and as a result mitochondria lost the ability to apoptosize then there could be major problems in the cell and cancer could spread much more easily. Also because mitochondria self replicate it may require other proteins to be coded by their DNA.

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  31. 1. The endosymbiotic theory states that the mitochondria was a free living cell and was taken up by another cell that formed a symbiotic relationship, this was first theorized by Konstantin Mereschkowski.
    2. The membrane is a double membrane. The outer layer is a phospholipid bilayer that can take in proteins with its porins. The inner layer is freely permeable to only O, CO2, and H2O.
    3. The mitochondria produces energy, controls levels of particles in the cell and recycles.
    4. Neither bacteria or mitochondria have a nucleus but both have their own DNA.
    5. No they do not, only eukaryotic cells have them.
    im not to sure about number six.

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  32. 1 What are the current theories regarding the origin of mitochondria?

    the origin of mitochondria seems to come from only from other mitochondria it has its own DNA and it seems to live on its own without outside help. Mitochondrial ribosomes and transfer RNA molecules are similar to those of bacteria these only seem to be found in endosymbiotic hypothesis

    2 What is the structure of the mitochondrial membrane?

    it contains a cytoplasm, an outer membrane inner membrane, and intermembrane structure, and it also has a matrix. it also has a spce between the two membranes.

    3 Mitochondria provide several functions in cells, what are they?

    they are considered to be cellular power plants
    they do all of these things, signaling,cellular differentiation, cell death.

    4 What bacteria do mitochondria resemble the most?

    blue-green algae,because this algae, also does produce oxygen. it also does because it also has two membranes as do most algae's it also has enzymes segregated according to use, as do bacteria.

    5 Do all cells have mitochondria?

    All living cells have mitochondria, all living things need energy.

    6 Why do mitochondria have DNA?

    there are 37 dna strands which are all are essential for normal mitochondrial function. 13 of these are like the instruction manual for the mitochondria/if it has its own dna then that might prevent the DNA from mutating although it probly still could mutate ever through it has its own complete set.

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  33. 3 Mitochondria provide several functions in cells, what are they?
    they keep DNA from mutating, they also provide the nucleus with energy.
    4 What bacteria do mitochondria resemble the most?
    they resemble algae, algae as we know doesnt produce oxygen thus it acts as a bacteria.
    5 Do all cells have mitochondria? yes everything living has it, they have no choice.

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  34. 1 What are the current theories regarding the origin of mitochondria?
    The current theory regarding mitochondria is the endosymbiotic theory. This theory was originally dismissed, but has become more popular in recent years. It is that mitochondria came from specialized bacteria that were released from another bacteria through exocytosis and were then brought into another cell by endocytosis and survived that them became incorporated into the cytoplasm. "The ability of symbiont bacteria to conduct cellular respiration in host cells that relied on glycosis and fermentation would have provided a considerable evolutionary advantage."
    2 What is the structure of the mitochondrial membrane?
    There is an outer membrane is a simple phospholipid bilayer which is straight just like normal cell membranes are, then there is an inner membrane which is curved and these curves are called crista. The membranes contain two compartments: the intermembrane space and the matrix.
    3 Mitochondria provide several functions in cells, what are they?
    Mitochondria is an energy provider for the cell. It is known by many are the powerhouse of the cell. It produces energy in the form of adenine triphosphate. Mitochondria also control the level of water and other materials in the cell. It also recycles and decomposes proteins, fats, and carbohydrates. It also forms urea.
    4 What bacteria do mitochondria resemble the most?
    I already know that mitochondria resemble aerobic bacteria the most. I have been looking and can only find different similarities between mitochondria and bacteria and not actual specific types of bacteria which the mitochondria resemble.
    5 Do all cells have mitochondria?
    No, mitochondria are only found in eukaryotic cells. They are not found in single celled organisms or fungi. Just all animal cells.
    6 Why do mitochondria have DNA?
    There is obviously a reason that mitochondria have DNA because there can be genetic illnesses that are caused by a mutation in mitochondrial DNA but I really cannot find why. I'll keep searching... I found this is in article "In humans, mitochondrial DNA spans 16,569 DNA building blocks (base pairs),representing a fraction of the total DNA in cells. Unlike nuclear DNA, which is inherited from both parents and in which genes are rearranged in the process of recombination, there is usually no change in mtDNA from parent to offspring. Although mtDNA also recombines, it does so with copies of itself within the same mitochondrion. Because of this and because the mutation rate of animal mtDNA is higher than that of nuclear DNA, mtDNA is a powerful tool for tracking ancestry through females (matrilineage) and has been used in this role to track the ancestry of many species back hundreds of generations."

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  35. 1. Right now the popular theory is that anaerobic cells engulfed a small aerobic prokaryote that began produce energy for then and reproduced within them becoming an organelle. This is supported by the fact that mitochondria contain their own DNA and divide like separate entities within the cell.

    2. There is an outer membrane that strongly resembles a plasma membrane and an innermembrane that is folded inside the mitochondria and is the site of cellular respiration.

    3. They primarily trun glucose into ATP. They also are one of the main mechanisms used for a quick apostasis. The mitochondria also recycle molecules and probuce chaperone proteins that repair unfolded proteins from the cell.

    4. They closely resemble aerobic bacteria. technically I guess they could be called bacteria since they posess all the components of many prokaryotic cells.

    5. No- Giardia lamblia is a eukaryote that does not have mitochondria. Instead, they have mitosomes, and they are anaerobic.

    6. Mitochondria need to work fast. They have to constanly be pumping out enormous amounts of ATP and need to be able to shut down the cell quickly if they need to apostate. Having their own DNA could possibly help them operate with greater speed and efficiency.

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  36. The origin of mitochondria is to be originally derived from endosymiotic prokaryotes. The endosymbiotic hypothesis states that mitochondria descended from bacteria, and became incorporated into the cytoplasm. Functions of mitochondria are to provide energy for the cell in the form of ATP through respiration, and also to regulate cellular metabolism. Because the mitochondria provide energy for the cell, it is also known as the “powerhouse”. Other functions of the mitochondria is controlling the level of water and other materials in the cell; and recycling and decomposing proteins, fats, and carbohydrates.
    The mitochondira contains an outer and inner membrane. The structure of the mitochondria membrane is composed of phospholipid bilayers and proteins. The outer membrane is composed of lipids and enzymes. And the inner membrane of contains polypeptides.
    All cells don’t have mitochondria. Prokaryotic cells don’t have mitochondria.
    Mitochondria DNA contains 37 genes. Thirteen of these genes provide instructions for making enzymes involved in oxidative phosphorylation, and the rest of the genes provide instructions for making tRNA and rRNA.

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  37. 1 Its is believed that mitochondria where "eaten" by a cell in the past vie endosytitosis but instead of processing it like most food it somehow started a beneficiary relationship with this cell much like how holospora contribute to paramecium but what is odd about this relationship is that it happened out of nowhere and the mitochondria somehow already had all the chemical pathways to be able to communicate with the cell an produce the energy that mitochondria do in normal eukariotic cells.
    2 It reassembles a jelly bean but instead it is folded multiple times this has been attributed to processing energy in slower steps so as not to have all the energy released at once which could kill the cell.
    3 Their primary function is the production of energy and the processing of substances useful for the cells energy.

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  38. 1. The endosymbiotic theory is the leading theory on the origin of mitochondria. I do not agree with it. Other than the fact that it is part of the evolutionary model, I was unable to find anything about mitochondrial survival independent of a host. If the mitochondria truly were bacteria, they may have survived on their own for a short period of time and then died as they are dependent symbionts. However, this does not appear to be the case. The speculation around this has to do with the loss of some DNA which supposedly migrated to the nucleus. Extracting DNA from another organism sounds like something a prokaryote would do. Another thing I noticed is that mitochondria only replicate when signalled to do so. Despite having some of the features of an independent cell, mitochondria are totally dependent. Perhaps it could be argued that they surrendered their control to their host, however this is completely self-sacrifical and does not benefit mitochondria as it is non-living on its own. The endosymbiotic theory is mostly backed up by the presupposition that eukaryotes evolved from prokaryotes, but simultaneouly provd false by the lack of benefit for the mitochondria. Also, my theory on obligate symbionts could be totally wrong.

    2. Mitochondria have a phospholipid bilayer membrane. The outer layer is smooth on both sides, while the inner layer has structures on its inner side called cristae protuding into the mitochondrial plasma.

    3. Mitochondrial functions:
    Energy production
    Cell Apoptosis
    Production of Metabolic products
    Metabolic Recycling and Waste disposal
    Steroid and Hormone Synthesis
    Homeostasis in Membrane
    Neural Cell Signalling
    Oversees maintenance of Cell Lineage
    http://www.buzzle.com/articles/mitochondrial-function.html

    4. Mitochondria resemble aerobic bacteria.

    5. Only eukaryotes have mitochondria.

    6. Mitochondria may have DNA as they are safe place to keep a self-destruct sequence should the cell's genetic functions become dysfunctional. I think it is a pretty cool design feature. In the evolutionary model, it would be because the bacteria had DNA of its own to begin with, some of which it may have lost.

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  39. The outer membrane is a phospholipid bilayer containing protein structures called porins. The inner membrane is freely permeable only to oxygen, carbon dioxide, and water. Its structure is highly complex because of the electron transport system, the ATP synthetase complex, and transport proteins.
    The most prominent function of the mitochondria is to produce ATP through respiratin and to regulate cellular metabolism.

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  40. 1 What are the current theories regarding the origin of mitochondria?
    some theories state that the mitochondria came from a different cell, probably some kind of bacteria, it doesn't really make sense though, how could something take on a foreign body and then make it apart of it. for the most part when that happens in other cells it kills them, it doesn't benefit them. also, how would cells get energy before the mitochondria?

    2 What is the structure of the mitochondrial membrane?
    it has a double membrane, including an inner and outer membrane. in-between these is extracellular matrix. They are both made of phospholipid bilayers.

    3 Mitochondria provide several functions in cells, what are they?
    mitochondria produce energy, they break down substances that are put in the body to retrieve the energy. they are involved in the suicide function of the cell and recycling. they help build ad break down as well in cell function.

    4 What bacteria do mitochondria resemble the most?
    the few that i could find were the genomes of bacteria, aerobic bacterias (aka: Mycobacterium Tuberculousis, and some of the Staphylococcus species.) there is still a lot of variation.
    5 Do all cells have mitochondria?
    the giardia lamblia doesn't have a full mitochondria, it is able to convert energy in its own way, but it is a variation of a mitochondria, it isn't missing it altogether. prokaryotes don't have them either.

    6 Why do mitochondria have DNA?
    the DNA in mitochondria is essential probably to save the mitochondria's butt in case of a mutation. because this is how the story goes: mitochondria is producing energy --> mutation --> it doesn't work --> no energy for cell --> cell dies. --> cell R.I.P  its a sad ending. it has to protect against that.

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