Theory of Endosymbiosis

en•do•sym•bio•sis (noun)
a particular form of symbiosis wherein one of the symbionts resides within the thallus of the other symbiont. In other words, a very close relationship between two living organisms that benefit from each other that live side by side where one of the organisms actually lives inside the body of the other organism.
Origin: Latin (endo = inside, symbiosis = beneficial relationship)

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Lol so we switch from all the chemistry from last week's esterification and move to biology, for a change.

The Theory of Endosymbiosis is a very interesting one, and data has provided that strongly supports this theory. It is a theory that tries to explain the evolution of Mitochondria in all plants and animals, and Chloroplasts in plants and algae.

Mitochondria are organelles within cells that perform respiration, meaning that this is the organelle that is responsible for using oxygen to burn fats and sugars to create the energy that cells need to move, make proteins, and perform cellular functions. Chloroplasts are organelles in plants that perform photosynthesis, the process that allows plants to take light energy, carbon dioxide, and water to make sugar and oxygen.

Scientists noticed that mitochondria and chloroplasts share characteristics that are very peculiar: they both have more than one membrane (unlike the nucleus or other membrane-bound organelles, which only have one membrane), and they both divide independently from the cell (meaning that they divide and multiply without direction from the nucleus; they do it whenever they want to). This led scientists to realize that mitochondria and chloroplasts are very similar to bacteria: mitochondria are like obligate aerobic bacteria (no, that doesn't mean they do aerobic exercises; it means that they can only live in the presence of oxygen and they use oxygen to release energy from sugars) and chloroplasts are like photosynthetic bacteria.

The Theory of Endosymbiosis postulates that ancient eukarotic cells once formed a symbiotic relationship with aerobic bacteria, which eventually came to live inside the host cell, and after millions of years of evolution, the aerobic bacteria lost its ability to live by itself, and became incorporated into the host cell and evolved into an organelle. The theory is similar for chloroplasts.

The amazing thing the evidence that research has found supporting this theory. Not only do chloroplasts and mitochondria divide independently to the cell, they have their own DNA! Mitochondrial DNA is circular, exactly like bacterial DNA, and not at all like eukaryotic DNA, which is linear. Mitochondria and chloroplasts are also capable of making their own ribosomes (organelles that make proteins), and these ribosomes resemble bacterial ribosomes more than eukaryotic ribosomes! Furthermore, these ribosomes inside the mitochondria and chloroplasts allow these two organelles to make their own proteins!

Finally, the theory of endosymbiosis also neatly explains why these organelles have more than one cell membrane, explained in this diagram:

This diagram illustrates how the bacteria enters the host cell: via Phagocytosis, which creates a new membrane

Because of these and many more data, the Theory of Endosymbiosis is widely accepted as the explanation for the evolution of mitochondria and chloroplasts.

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Hey Clay, so this week I've been feeling rather lethargic; I've lost a bit of my motivation to study, but then again, I think I may just be going through a phase. I'm not depressed or anything, I think I'm just feeling tired of studying all the time without any real relaxation; because I don't see anyone as often as I'd like, I don't have many reasons to laugh, and laughing, I think, is one of the things that really drives away the loneliness.

Anyways, I really haven't done a meme in a while, so I though I should do this one I found recently =P

The Fear Meme
If you get more than 30, get some counseling. If you get more than 20, you’re paranoid. If you get 11-20, you are normal. If you get 10 or less, you’re fearless. People who don’t have any are full of crap
  
I fear ...
[] the dark
[x] staying single forever
[] being a parent
[x] being myself in front of others
[] open spaces
[] closed spaces
[] heights
[] dogs
[] birds
[] fish
[x] spiders
[] flowers or other plants
 
Total so far:3
 
[] being touched
[] fire
[x] deep water
[] snakes
[] silk
[] the ocean
[x] failure
[] success
[] thunder/lightning
[] frogs/toads
[] my boyfriends/girlfriends dad
[] my boyfriends/girlfriends mom
[] rats
[] jumping from high places
[] snow

 Total so far: 5
 
[] rain
[] wind
[] crossing hanging bridges
[] death
[] heaven
[x] being robbed/mugged
[x] falling
[] clowns
[] dolls
[] large crowds of people
[] men
[] women
[x] having great responsibilities
[] doctors
[] tornadoes
  
Total so far: 8

[] hurricanes
[x] incurable diseases
[x] sharks
[] Friday the 13th
[] ghosts
[] poverty
[] Halloween
[] school
[] trains
[] odd numbers
[] even numbers
[x] being alone
[] becoming blind
[x] becoming deaf
[] growing up, old

Total so far: 12
 
[] creepy noises in the night
[x] not accomplishing my dreams/goals
[] needles
[x] blood
 
Total:14

I am afraid of 14 out of 70 things.

Lol random meme thing. I was bored. Anyways, I hope everything is going well for you; we're in the final stretch! Only a month left of classes! It's slightly frightening yet slightly relieving...

Chat soon,
~Tim~


PS - I'm not posting the correct answers to last post's exercise until you post next with your own answers, just so you can't cheat =P