Chapter 24

Chapter 24 - Chapter 24: Evolution of Genes and Genomes...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 24: Evolution of Genes and Genomes 24.1 – How are genomes used to study evolution? o A genome is the full set of genes an organism contains o Mutations supply the raw material for evolutionary change o The capacity to cooperate with other genes increases if a gene is stable in a population o Genes of an organism are like interacting members of a group o Molecular evolution investigates mechanisms and consequences of the evolution of macromolecules o Evolution of nucleic acids and proteins depend on genetic variations o One form of variation is called nucleotide substitutions o Nucleotide substitutions sometimes lead to an amino acid substitution that may lead to a phenotypic difference o The longer two sequences have been evolving have been evolving separately, the more different they will be o Homologous features are shared by homologous proteins which are represented by their nucleotide sequences o Therefore to determine similarities, we can look at the sequences o Sequence alignment techniques help us compare protein sequences to determine homologous traits o Gaps can occur too in addition to substitutions o A similarity matrix tells us the minimum amounts of changes that had to have occurred between the organisms o There are several reasons why the similarity matrix isn’t the correct number of changes that occurred Multiple substitution – more than one change occurs at the same locus Coincident substitution – diff substitutions occur at same locus in two organisms Parallel substitution – same substitution occurs at same locus in two organisms Back substitution – substitution occurs and goes back to original sequence
Background image of page 1

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

View Full DocumentRight Arrow Icon
o To track these changes effectively, biologists have created models that describe how DNA typically evolves o These models take into account the rate of transitions (changes between two purines or two pyramidines)and transversion (changes between a purine and a pyramidine) o Using these models, we cane estimate the total number of substitutions that occurred
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

Chapter 24 - Chapter 24: Evolution of Genes and Genomes...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online