Genes and Behaviour Flashcards
What do genes produce
protein
What are genes
Genes are located on chromosomes (DNA coiled around histones) located in the cell nucleus
Genes are expressed through two linked processes
what is gene expression
nscription (RNA transmitted to a protein) + translation
Most of the vertebrate genome does not…
code for proteins
What animals have more genes than a human
lots including pufferfis
what animals have more chromosomes than a human
lots including chicken
What % of DNA is shared by human
99.8%
What % of human genes are shared w chimpanzees
98%
Humans and mice share what % of genes
92%
How are eye colours decided
As they are on the same chromosome, they are inherited together.
what are diploid organisms
Humans are diploid organisms. This means we have two copies of each chromosome (one from father and one from mother). All vertebrates are diploid.
what is homozygous
same alleles. no conflict in gene expression
what is heterozygous
different alleles. Brown allele is dominant
what is an agouti gene
- involved in coat pattern and shading of mammals
- produces a greyish-brown coat colour
- when upregulated, hair follicle melanocytes switch from making black to yellow pigment
what are lethal allels
Lethal alleles lead to death of homozygous recessive offspring.
Homozygous yellow-coated mice die as embryos.
Individuals that have two yellow coat genes will die as embryos.
What did Weber et al find
Captive-reared mice placed in sand-filled arena for first time
builds species-typical burrow
F1 offspring of maniculatus × polionotus hybrid
100% escape tunnels
Backcrossed F1 × maniculatus
~50% escape tunnels
A crossbreed of the two mice would build the escape tunnels (100% of the time).
The hybrid was backcrossed against the deer mice. These ¾ deermouse ¼ oldfield, 50% created an escape tunnel.
The simplest explanation of this is that the behaviour is controlled by a gene.
The allele for building an escape tunnel is dominant. In the back cross, half will be homozygous and the other heterozygous which explains why half build the escap tunnel.
single, dominant locus controls building of escape tunnel
What does fosB mutation in mice cause
disruption of maternal behaviour: creating a nest, cleaning the pups, retrieving them to the nest, crouching over them for warmth and nursing
what effect do mutations have
Most mutations are harmful or neutral in their effects; only rarely are mutations beneficial
what percent of alleles are wild type
Alleles at >1% frequency termed wild-type
what percent of alleles are mutant
Alleles at <1% frequency termed mutant
what is Gene with one wild-type allele
monomorphic
what is Gene with >1 wild-type allele
polymorphic
what increases mutation rate above spontaneous level
Mutagens and radiation
