A population is composed of numerous individuals, each carrying a common set of genes with a unique combination of genetic alleles. The gene pool is the sum of all of these alleles.

Mitochondria and chloroplasts are believed to have evolved from prokaryotic cells over 1.5 million years ago. This is known as the endosymbiotic hypothesis. Mitochondria, chloroplasts, and prokaryotes all contain circular DNA and reproduce via binary fission. Mitosis involves the separation of chromosomes during the cell cycle, which is only seen in the somatic cells of eukaryotes. Meiosis is not seen in prokaryotes.

The allele frequency for any given gene is the relative proportion of each allele of that gene in a population. This value can be found by dividing the number of a specific allele by the total number of alleles in a population.

Genetic drift is a change in the allele frequencies of a small population purely by chance.

The bottleneck effect occurs when allele frequencies are affected by a cataclysmic event. Evolution refers to a change in allele frequency, but is not limited to small populations or random chance. Natural selection refers to changes in allele frequency due to specific conditions, as opposed to random chance.

The Hardy-Weinberg principle is a mathematical model that states that, under certain conditions, the allele frequencies and genotype frequencies in a sexually reproducing population will remain constant over generations. This consistency means that evolution is not occurring, as evolution (by definition) requires a change in allele frequency.

Requirements for Hardy-Weinberg equilibrium include: large population size, no mutation, no migration, random mating, and no natural selection.

Evolution is any change in the proportions of different genotypes in a population from one generation to the next. Mutation, geneflow, nonrandom mating, and natural selection all contribute toward favoring certain alleles over others within a population. This leads to changes in allele frequency, and subsequent evolution.

Thomas Malthus was a political/economic theorist who observed that the human population would eventually overpopulate the world, overwhelming food and natural resources.

An adaptation is a characteristic of an organism that helps it survive and reproduce in a particular environment. Adaptations are the result of random mutations that have favorable outcomes. The favorability of these traits enables offspring that inherit them to thrive, thus increasing their prevalence in the population.

Chargaff was able to show the diversity of DNA through patterns within base pairs. While studying DNA, he noticed that the concentration of adenine was equal to the concentration of thymine, and the concentration of cytosine was equal to that of guanine. This led him to establish Chargaff’s rules, which state that the base composition of DNA varies between species, and for each species the percentages of adenine and thymine bases are roughly equal and the percentages of cytosine and guanine are also roughly equal.