1.A – Mickie Wilkinson

This week in AP Biology we learned about what factors influence evolution, as well as how he can calculate the expected traits of a population using the Hardy-Weinberg theorem.

There are many factors that change how an organism evolves, but first you need to understand that populations evolve, not individuals. This is also stated in Big Idea 1.A; change in the genetic makeup of a population over time is evolution. Here are the five sources of evolution:

Mutation: A change in DNA sequence that changes traits but may or may not affect fitness.
Gene Flow: The movement of individuals and alleles in and out of a population.
Genetic Drift: The effect of chance events on a population- if many individuals die out, the ones that survive will create a new population with similar traits.
Non-Random Mating: Sexual selection- stronger individuals will have offspring, giving those offspring the best traits possible.
Natural Selection: Different survival and reproduction rates due to changing environment.

When we learned these sources of evolution, I thought that gene flow and genetic drift would stop evolution, but I realized that they all work together to change populations over time.

The Hardy-Weinberg theorem is a way to calculate the expected physical or genetic traits of a population. We used this theorem to find the heterozygous, homozygous dominant, and homozygous recessive allele frequencies of a population.

Sources:

https://prezi.com/wypg7zbawzez/ap-bio-evolution-4-measuring-evolution/

https://i.ytimg.com/vi/1inA6ZLAgM4/maxresdefault.jpg

This week in AP Biology we learned more about evolution, and also some theories of how life started.

Evolution was first theorized by Charles Darwin while he was on board the HMS Beagle. As he circumnavigated the globe he collected specimens and other evidence to prove his ideas (1.A.4). After he went home, it took him 20 years to publish his theory of evolution. I thought this was an absurd amount of time to wait, but in that time period many people did not believe him, so he wanted to be sure he could prove it.

We also read some theories on how life was created on earth. One of them was the Replication-First (or Gene-First) Hypothesis, which explains how RNA most likely created the original form of life on Earth. When I read this, I wondered how the RNA could be created in the first place. I then learned that this hypothesis is dependent on the idea that organic molecules formed on Earth, including the nucleobases in RNA. RNA can store information, as well as carry out functions, something that DNA cannot do. Then the RNA bonds with random amino acids, and the good combinations survive to pass on their order of acids. They eventually form lipid layers around the RNA, creating the first cell, then DNA and proteins replace the RNA to carry out more complex functions of life. This relates to one of our big ideas, 1.D.1, which says “There are several hypotheses about the natural origin of life on earth, each with supporting evidence.”