cellular biology

"the mitochondria is the powerhouse of the cell"

but why???? how the fuck did this little bean shaped nubbin of a thing wind up being this all-important piece of cell that we learn about in once sentence and then completely forget about until it’s time to take an exam?

tumblr, sit down and let me learn you a thing

back in the waaaaaaaaaaaaay back early days of life, when there were just like, bacteria and random assed algae and shit floating around in the primordial soup, before there was oxygen in the atmosphere, all cells got their energy from anaerobic respiration

which basically means they used no oxygen, just kinda fermented stuff and nibbled at nutrient bits here and there, but it was suuuuuuuper inefficient

like, imagine trying to run through your day on only two sips of coffee.  that’s literally all you can make each day is two sips of coffee, and you HAVE to work with it in order to do your whole life and living thing.  that is literally all you are allowed

you’d be pretty fuckin sluggish, amirite

well, along the way, these new kinds of bacteria start forming.  they have these weird greenish pigments.  they can use the sun to make a jillion times more energy than most other cells.  like, by an enormous margin.  like, instead of starting their day with two sips of coffee, they start their day with three and a half cups.

and the byproduct of their energy conversion is oxygen

suddenly they just start breeding, since they can outperform everything else in the primordial soup

and this oxygen keeps filling the air, changing the composition of the atmosphere from methane, ammonia, nitrogen, and CO2, to something a little more oxygen rich.  the skies turn blue.  the oceans go from olive to reddish to blue as the iron in them oxidizes and falls to the seafloor.  suddenly it starts looking like what we’re used to.

these little green bacteria start making some pretty sweet deals.  some of them sneak into larger cells, trading their energy output for not having to hunt down nutrients for their own survival.  the cells they live inside stop trying to make energy on their own and rely on the bacteria, now basically functioning as chloroplasts.

but now that there’s oxygen in the atmosphere, a NEW kind of bacteria emerge.  these little guys are purple.

these guys use sunlight and oxygen to produce even MORE energy than just chloroplasts on their own.  They’re mega efficient, but they don’t produce oxygen at the end of their little processes.  instead they make sulfates and phosphates.

these little guys start hanging around inside larger cells, some of which have chloroplasts, and some of which instead consume other cells to create energy

they give up photosynthesis, instead getting their energy from either the chloroplasts or the “food” from the larger cells, and in return the bigger cells get an enormous amount of energy, which lets them compete on a much higher level than before.

that’s where mitochondria come from.

but the thing is, mitochondrial DNA doesn’t change much over time.  It was already pretty solid when it first entered the early, larger cells.

what they’ve found is that plants, fungi, and animals all have different mitochondrial DNA bases

and protists have basically a FRILLION different types of mitochondrial DNA

this means that this happened multiple times, each using slightly different kinds of little purple bacteria

in fact, fungi’s are SO different that some of the codons in the DNA, that in every other organism on earth mean “stop coding for anything, this is the end of the sequence” in fact produce a completely different result and make amino acids instead like tryptophan

which means this has to be an ancient, crazy lineage that happened before DNA was really set in stone, before the different codons became universal for different kinds of amino acids

it’s a window into the very beginning of DNA.

and if that’s not exciting shit, idk what even is

Adenosine triphosphate (ATP)

Referred to by my biology teacher in high school as a “cellular workhorse” this molecule is constantly being used and reused in the living cell to facilitate energy transfer for a wide range of metabolic processes. Cells break down the ATP to release energy for vital processes and also reform the molecule in order to transfer energy onwards, hence ATP’s nickname as the “energy currency” in cells. The breakdown process involves the removal of the phosphate group on the end (top-left in the diagram) to convert the molecule into ADP (adenosine diphosphate).

The phosphorus design is based on the 5-petal Woodland Star flower, each petal having 3 lobes.

Piece requested by @myceliumman.

Polar bears face an ironic dilemma. They are surrounded by water they cannot use; ice and snow are too cold and seawater is too salty. They produce all the water they need from the metabolism of fat. Interestingly, adult polar bears consume only fat from the seals they catch. By not consuming protein (and merely recycling their own proteins into new ones), they have no need to urinate or defecate and go for months without doing so, thus saving previous body water. 

remember when snsd rhymed “supersonic” and “hypertonic” in their songs…… that was so iconic. queens of rhyming. queens of cellular biology

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|10-10-15| “Don’t give up. Not ever. Not for one single day. Be safe, if you can be. But always be amazing.” ~Clara Oswald

Might as well include a Doctor who quote since my screensaver is the Tardis. However, here are my revised Biology notes. I quite like to make my notes kinda like a comic book, it makes studying easier for me.  

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Mycoplasma mycoides:

A painting of an entire Mycoplasma mycoides cell. The cell shown is about 250 nanometers in diameter, which is at the small end of the range of observed sizes. The macromolecules were shownat reasonable locations and concentrations, and with the actual shapes and sizes.

Key

Protein synthesis (labels in black)

1. DNA
2. DNA polymerase
3. single-stranded-DNA binding protein (protects single-stranded portions during replication)
4. RNA polymerase
5. messenger RNA
6. ribosome
7. transfer RNA (in pink) and elongation factor Tu (in blue)
8. elongation factor Tu and Ts
9. elongation factor G
10. aminoacyl-tRNA synthetases
11. topoisomerases
12. Rec system for DNA repair: a) RecA, b) RecBC
13. chaperonin GroEL (helps folding of new proteins)
14. proteasome ClpA (destroys old proteins)

Enzymes for energy production (labels in red)

15. glycolytic enymes
16. pyruvate dehydrogenase complex

Membrane proteins (labels in blue)

17. ATP synthase
18. secretory proteins
19. sodium pump
20. zinc transporter
21. magnesium transporter
22. ABC transporter (different ABC transporters transport different types of molecules-ABC is short for “ATP-binding cassette”)
23. magnesium transporter
24. lypoglycan (long carbohydrate chains connected to lipid in the membrane)

(Credit: David Goodsell)

The Golgi Apparatus is a membrane-bound organelle in the cell that receives proteins and lipids from the rough endoplasmic reticulum. It modifies some of them and sorts, concentrates and packs them into sealed droplets called vesicles. This organelle can be seen using an electron micrograph. 

youtube

Electron Transport Chain for your viewing pleasure

On the Endosymbiotic Theory of Mitochondria and Chloroplasts

(The following is a paper did for school that I find interesting.)

            The endosymbiotic theory states that many different organelles of eukaryotes started as prokaryotic organisms. The main two organelles included in this theory are the chloroplast and the mitochondria. There is a lot of evidence supporting this theory, and I believe it to be true. In this paper I will pass on the evidence and try to deconstruct the arguments against it.

            One of the main agreements for this theory is that mitochondria and some plastids (including chloroplasts) contain circular DNA. Most bacteria also contain circular DNA. From this we can infer that, perhaps, mitochondria and chloroplasts were once their own organisms. The DNA contained within them has the instructions for carrying out most of the organelles’ functions. There are some functions of the organelles, however, that must receive supplement from the rest of the cell to work properly.

            One argument against this theory is that which was stated at the end of the last paragraph; the organelles aren’t completely self-sufficient. The reason that proprietors for this argument give is that the organelles were developed through the natural evolution of the cells. The correct reason why the organelles are completely self-sufficient, I believe, is that it is either more efficient or more feasible for the rest of the cell to create some materials that these organelles need to function.  This must of developed over time as both the cell and the new organelles co-evolved.

     As you can see from the evidence shown above, the endosymbiotic theory is our best guess at where mitochondria and chloroplasts came from. It must be remembered, however, that it is still a guess. However well informed it is, it has not, and most likely cannot, be proven or disproven.

God Must Be An Engineer

by  Saṃsāran

If you watch any documentary on evolution you cannot help but note one crucial thing. Evolution is all about solving engineering problems. The development of the backbone, the gill, the lung, skin, the jaw, the hip, grasping digits and the eye are all engineering advances.

You have all kinds of mechanical devices being used. The lever, the gear, the buttress, scaffolding, the ball and socket, bushings, flanges, pivots, hinges, O rings, I beams, filters, pumps even tiny engines complete with propellers. 

If this doesn’t amaze you then you are far harder to impress than I am.

Actual SEM Image of a cellular engine which propels a human sperm.

Diagram of the cellular engine pictured in the previous illustration.