生物学101:Genetics and Evolution.

[Duke Guilmon]

よこそう 生物学 学生。 私はエゼキエル。 私は生物学先生。


As it should be know genetics is a major part of understanding evolutionary biology. Here I will give a summary of how evolution ties with genetics.

1.Mutations:

A fan favorite. Mutations in short are errors in the sequence of DNA. These happen in ways like deletion or replacement. Mutations can add new traits to an organism and they come in at random. Whether they benefit or harm comes down to the environment of said organism. Mutations have some controversy within biology as there are two different methods of it. The first one is called direct mutation. This is when said mutation is already in the population and they appear once members of a population. For example, if long and fluffy coats where always in yak, but the mutation did not show until they yak with short and thin coats began to die. The other form of mutation is sporadic, appearing in a out of no where state, even if the population is fine.

2.Reproduction:

Yup, sex is major in genetics(as DLJ should know already). Reproduction is what not only helps separate good and bad genes, it guaranties there will be more genes to pass in the species. There are two major forms of reproduction. Sexual (the way organisms like humans do it) is when it requires two of said organism to make off spring. The two come in the form of a male and a female. The benefit of sexual reproduction is that genetic variation is easier, as males and females can pass on traits they have that they other does not. The down fall is that it requires two, mating and the process of find a mate is tedious, and there might be a chance of rejection meaning an organism can go its life without mating. Asexual reproduction is when an organisms can reproduce on its own. There are many forms of asexual reproduction. Budding,spores,vegetative, and parthenogenesis. Asexual reproduction comes with the benefit of it being a one woman/it job, meaning that even if there is only one left, many asexual organisms can still reproduce and start anew. The down fall is the lack of genetic variation that can happen in the species, making every child of their parent a clone, and leaving mutations to be the only saving grace for genetic variation. Either way sex still plays an important part in passing on genes to offspring so that the species can hopefully and eventually adapt to the new environment.

3. RNA:

DNA is not the only thing that gets to have fun with evolution. RNA, its protein building son, helps in the process of evolution. During central dogma, the code from DNA is transferred to Adenine, Guanine,Uracil, and Cytosine. When DNA has a mutation, this may end up changing the proteins during said central dogma. Sure some amino acids come from different codes but still end up the same, but many don't. Let us take a look at a RNA chart to see:



Now looking at this chart let us say the a usual code for amino acid in the is something like UCG,CGC, and GGA. Now if a mutation happens in the DNA that will effect the RNA. Now let say this mutation turned CGC into GUC. That would turn arginine to valine. This shows a major connection between evolution and RNA.

RNA also shows how related animals can be to each other. Take for example and human and a chimpanzee vs a human and a horse on this chart.



As you can see the human and the chimp have the same in this short chain than that of the human and the horse, and the horse has more in common with the zebra than the apes. This is used to determine common ancestry and relations between organisms in taxonomy, something very important in evolution

4.Genetic drift:

Death occurs in all species(well except immortal jelly fish, and maybe someday one day humans, but we will see how that works out). With death comes life, and a change in a species. Genetic drift is the scientific understanding on how genes are passed. If natural selection is master hand, then genetic drift is crazy hand. It is random, and whatever population survives, survives even if it is weaker. For example if there were a population of strong cows vs normal cows. Then something bad happens and only one strong cow is left but the normal cows still have a strong number. This means the normal cows will be the dominate population, though the strong cow can still breed with the normal ones, the normal ones will still be the main population and the strong ones will not.

5.Molecular clocks:

A complex subject, but this helps humans determine splits between species. However it is also still an kind of ehh part of it, as it can still be improved upon( but what science doesn't, it is a learning process). Using Cytochrome C, scientist determine the time in which populations between different species once shared a common ancestor. There is a pattern in cytochrome C is dependent of when animals split. For example, birds and mammals share the equal amount of differences with fishes in their Cytochrome C.

Genetics is a fine away of discovering evolution and seeing how they connect is nothing but enchanting.

ありがと ございます and keep learning.

Also quick japanese lesseon

生物学=seibutsugaku(biology)

学生=gakusei(student)

先生=sensei(teacher)

よこそう=yokosoo(welcome)

私=watashi(I am)

ありがとう=arigato(thank you). Gozaimasu makes it polite.
Sources:

http://en.wikipedia.org/wiki/RNA-based_evolution

http://evolution.berkeley.edu/evolibrary...tations_01

http://www.ncbi.nlm.nih.gov/books/NBK22508/

http://www.nature.com/scitable/topicpage...ence-41971

http://evolution.berkeley.edu/evolibrary/article/evo_24

[Jenny A]

Thank you ZeKe.

I've been fascinated by a subset of genetic drift, i.e. founders effect. Founder's Effect is the result of a small subset of a population becoming separated from the main population either by naturally forming barrier or migration. The effects on the separated group are the same as the effects genetic drift on a natural disaster thinned population would be on the whole group.

I find it interesting because there are so many well documented cases of founders effect in people, such as the Amish population in Pennsylvania, or island populations where recessive genes for particular traits are much more highly represented (for good or ill) than in the general human population.

[Dystopia]

As a noob who knows only the basics about evolution, this was useful. I'm needing a 101 class. Thanks!