Genetic variation and Mutations Flashcards
What causes genetic variation?
Mutations and Gene flow are the only two ways to cause genetic variation
What is a Mutation?
A Mutation is any change in the DNA sequence of a cell. Although the term often has a negative connotation, mutations can be harmful, beneficial, or neutral in their effect on cell function.
What are the different types of mutations and what are their effects
1) Frameshift: This is a mutation in a gene that refers to the insertion of extra nucleotide bases or the deletion of nucleotides. The effects of this form of mutation are that the entire gene sequence following the mutation will be incorrectly read. This can result in the addition of the wrong amino acids to the protein and/or the creation of a codon that stops the protein from growing longer
2) Nonsense: This is a mutation that results in a premature stop codon. This can cause a protein to terminate or end its translation earlier than expected. This is a common form of mutation in humans and in other animals that causes a shortened or nonfunctional protein to be expressed.
3) Substitution: This is a type of mutation where one or more nucleotides are replaced with different nucleotides. This can result in entirely new proteins being created but they do not cause frameshift mutations. Substitution mutations can be good, bad, or have no effect. They cause three specific types of point mutations: silent, missense, and nonsense mutations.
4) Missense: This is when a substitution results in a different polypeptide being created. A missense mutation can be lethal or; alternatively, it can be mildly deleterious, effectively neutral, or beneficial
5) Silent: This is when a substitution occurs (Mostly in the 3rd position) that does not end up affecting the final protein product.
how do mutations relate to alleles and genetic diversity in a population?
Mutations can cause small and sometimes quite big changes in the alleles of an individual. These small differences in a DNA sequence make every individual unique. They account for the variation we see in human hair color, skin color, height, shape, behavior, and susceptibility to disease.
What are some of our natural mechanisms that stop mutations from occurring?
1) During DNA synthesis, most DNA polymerases “check their work,” fixing the majority of mispaired bases in a process called proofreading.
2) The replication errors that have escaped from proofreading are removed by the strand-directed mismatch repair. This system detects distortion potential in the DNA helix that is due to mismatched base pairs
what is gene flow?
Gene flow: is any movement of individuals, and/or the genetic material they carry, from one population to another. Gene flow includes lots of different kinds of events, such as pollen being blown to a new destination or people moving to new cities or countries.
