Chapter 10 Flashcards
What are the advantages of the pig model?
They are non-primates, non-rodent mammalian animal models. They more closely resemble humans. Also:
- Similar enviromental conditions
- Detailed phenotypic characterization (between breeds: muscle and fat mass, growth rate, metabolism etc.)
- High translation potentiel (commparable to humans?)
- Less heterogeneity -> reduced complexity (because they are domesticated, selective breeeding)
- Amenable for intervention studies (meaning?)
Why are domesticated dogs interesting animal models?
Less heterogeneity than humans
Been artificially selected more than any other animal for their apperance, behaviour and inherited diseasees this is interesting
Why are animal models interesting in terms of functional genomics?
Tehy provide an unique resource for understanding the genetic basis of phenotypic variation
+ This is something that is hard in biological sciences to elucidate the individual gene/genomic elements function an functional relationship
What is comparative genomics?
How does it work?
Its the comprehensive systematic comparison of genome sequences.
Usually begins with a computer program the identifies homologous regions within the genomes under comparison. Then the homologous sequences are grouped and aligned at basepair level.
what comparisons can be made between species? (5)
- Phenotypes
- Chromosomes
- Gene order
- Gene sequences
- Genomic sequences
What is the heterozygous advantage
In some cases new mutations only provide an advantage in the heterozygote and not the homo. The heterozygote has an fitness advantage over both mutant homo and normal homo
what principles affect population frequency?
Natural selecetion:
- capacity to engage in reproduction (mortality, healt and mating succes)
- to produce healthy offspring (fertility and viability of offspring)
- > overall the fitness of the organism
Random genetic drift:
- changes in allele frquency simple by chance. The effects of RGD are more pronounce in smalle populations, because a smaller amount of gametes are passed on to next generation. But some RGD will always occur.
Interlocus sequence exchange/interlocus gene conversion:
due to unequal corssover and gene conversion, sequence exchange between “the different repoeats” results in sequence homogenization
What is purifying selection
Negative selection:
A sequence with and important function is manitained through the phylogeny because deleterious mutations areselected against. The mutations are asaid tho be evolutionaryly constrained
Explain positive selection
also called darwinian selection.
Mutations that benefit the organism is selectively retained. They can be identified in coding DNA as repidly evolving codons within af backround of evolutionaryily constrained sequence.
What information can comparative genomics provide? (3)
- amount of noncoding DNA
- validate predicted genes and indentify novel ones
- identify regulatory sequences
Three methods can be used for elucidating gene order, which?
FISH (forstå)
Linkage mapping
Sequencing
How can exon duplication occur and what might an advantage be?
Due to unequal crossover can result in intragenic duplication so that a segment of genomic DNA spanning one or more exons is duplicated
advantage: it can result in exstension of structural domain
alternative splicing can produce different isoforms by selecting one exon sequence from a group of duplicated exons that have diverged in sequence
What are th twon ways eexon shuffeling can occur?
By non-allelic recombination
or (more importantly) by transposons, in particular retrotransposons can copy-paste
What are orthologs
Genes present in the genomes of different species that are directly related through descent from a common ancestor
What are paralogs?
Paralogs are closely related genes present in a single genome as result of gene duplication
