ANS 42 Lecture Notes - Lecture 18: Agouti Gene, Neutral Mutation, Wild Type
13 Jan 2017
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Genetics
1. Genes are composed of DNA sequences
a. Coalesce together to form a trait
2. Talk about diversity and the ability to have differences upon which we can select
a. Can happen in any species that can sexually reproduce
3. Phenotype: what an animal looks like, the physical appearance
a. Easy to distinguish
4. Genotype: genetic make up, genetic directions
a. More difficult to distinguish and identify
b. There may be an environmental component
c. Chromosomes: units of DNA
i. Paired
ii. When paired, referred to as diploid
1. 2 in a set
2. If one is defective, one can compensate
3. Also can offer variety in selection
iii. When no pair, haploid
5. In sexual reproduction, there is DNA from mom and dad
a. Meiosis is the process of going from diploid to haploid in gamete production
b. Egg and sperm are haploid and then combine
c. Fertilization makes it diploid again
d. Forms a zygote
6. Chromosomes have genes on them
a. On regions of the chromosomes
b. Genes come in different versions, represent differences in DNA sequence: called alleles
c. Changes in DNA sequences are called mutations
d. Genes represent the region of the chromosome that carry the genotype for that trait
e. Allele is the specific DNA sequence that codes for that gene
7. Allele that fully compensates is referred to as Dominant
a. The allele that is compensated for is the recessive allele
b. Homozygous: two of the same allele
c. Heterozygous: two different alleles: one dominant, one recessive
8. Mutations: changes in DNA that form alleles for a given gene
a. Natural selection: there can be positive mutations
i. Benefits them and improves its survival
ii. Negative mutation: decreases the survival, eliminated from the population as
soon as possible
iii. Neutral mutation: no change to survival ability
iv. Affects domesticating selection
1. We at positie, ot egatie ad e do’t ko about the neutral
9. Allelic series: reflects the dominance of alleles relative to one another
a. Agouti gene in dog
i. ay: fawn/sable color
ii. a: aded oat, olf allele, ild tpe allele
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