Lecture 10 - Comparative Genetics

How do eukaryotic genome sizes compare with prokaryotes?

eukaryotic genomes are larger

Does a larger genome mean greater complexity?

no

What is gene density?

number of genes relative to amount of dna

Why do humans have more proteins than genes?

alternative rna splicing allows one gene to produce different proteins

How do small regulatory RNAs contribute to complexity?

regulate gene expression

What are exons?

gene regions that encode proteins or functional rna

What are introns?

gene regions removed from rna during splicing

What are transposable elements?

dna sequences that move to different genome locations

How can transposable elements cause mutations?

insert into genes or cause dna rearrangements

What are the two classes of transposable elements?

dna transposons, retrotransposons

What is a retrotransposon?

mobile element that uses rna intermediate to make new dna copy

What does reverse transcriptase do?

makes dna using an rna template

What is gene duplication?

production of an extra copy of a gene

How can unequal crossing over cause gene duplication?

misaligned chromosomes exchange dna, duplicating a gene in one copy

What is a multigene family?

group of identical or similar genes formed largely through duplication

What is a pseudogene?

gene copy that has become nonfunctional

Why can duplicated genes evolve different functions?

mutations can change functions and sequences over time

What are the human globin gene families?

alpha globin on chromosome 16, beta globin on chromosome 11

Why are different globin genes expressed at different stages?

different globin forms needed during development

What is a tandem gene family?

repeated gene copies arranged next to one another

Why are rRNA genes repeated many times?

produce enough rRNA to build more ribosomes

Why do humans have fewer chromosomes than chimpanzees?

two ape chromosomes fused to form human chromosome 2

What is comparative genomics?

comparing genomes to study similarities, differences and evolution

What does the FOXP2 gene regulate?

genes involved in vocalisation

What happens when FOXP2 is disrupted in mice?

brain structure and vocalisation affected

What does the Neanderthal FOXP2 protein sequence suggest?

matches humans, neanderthals may have speech ability

What is one limitation of comparing FOXP2 sequences?

sequence similarity alone cannot prove complex speech ability