{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture 3 - Next Topic Genes Within Populations Evolution...

Info icon This preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Next Topic: Genes Within Populations Evolution can result from any process that causes a change in the genetic composition of a population We cannot talk about evolution therefore without considering population genetics – the study of the properties of genes in populations.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Five Agents of Evolutionary Change 1. Mutation – ultimate source of variation 2. Gene flow – movement of alleles between populations 3. Non-random mating – can affect proportion of homozygotes vs. heterozygotes 4. Genetic drift – the effect of chance on small populations 5. Selection – some genotypes do better than others in their environment Any of these forces may bring about changes in allele frequencies. Multiple forces can act at once!
Image of page 2
All completely new genetic variation arises via mutation
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Mutation (general) = change in the genetic material carried by individual organisms Mutation (detailed) = an error in the replication of a nucleotide sequence, or any other alteration of the genome (except recombination)
Image of page 4
In a molecular context a gene mutation is an alteration of a DNA sequence, independent from whether or not it has a phenotypic effect Mutations have evolutionary consequences only if they are transmitted to succeeding generations Mutations are considered by most biologists to be errors . Thus, the process of mutation is generally thought to be not an adaptation, but a consequence of un-repaired DNA damage What are the different kinds of DNA mutations ?
Image of page 5

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Synonymous mutations – have no effect on the amino acid sequence of the protein, therefore no effect on phenotype and the mutation is ‘hidden from selection’ Non-synonymous mutations – result in an amino acid change, this change may have little or no effect on the function of the protein, and thus little phenotypic effect, or there may be substantial functional and phenotypic effects Mutations can have phenotypic effects if they occur in protein-coding regions However, even in this case, many mutations will not have phenotypic effects. Why? Redundancy of genetic code (remember neutral theory)
Image of page 6
Synonymous (‘silent’) mutations – have no effect on the amino acid sequence of the protein, therefore no effect on phenotype and the mutation is ‘hidden from selection’ Non-synonymous mutations – result in an amino acid change, this change may have little or no effect on the function of the protein, and thus little phenotypic effect, or there may be substantial functional and phenotypic effects Mutations can have phenotypic effects if they occur in protein-coding regions However, even in this case, many mutations will not have phenotypic effects. Why? Redundancy of genetic code (remember neutral theory)
Image of page 7

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Synonymous (‘silent’) mutations – have no effect on the amino acid sequence of the protein, therefore no effect on phenotype and the mutation is ‘hidden from selection’ Non-synonymous mutations – result in an amino acid change, this change may have little or no effect on the function
Image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern