Animal genetics part 1

What are haplotypes?

Different combinations of alleles along the chromosomes

What is menders first law?

Principle of segregation

for any trait during gamete formation the two alleles in each parent separate and only one allele is passed on, 50/50

How can we test wether observed phenotypes are different to expected?

Use chi squared test

calculate expected number and obtain observed

(observed-expected)²/expected + other phenotype

find degrees of freedom and if value is lower then non-significant difference

What is mendels second law?

principle of independent assortment

alleles for each gene locus are passed to offspring independently

combination of phenotypes will be produced in offspring not present in parents

only applies to genes far apart of on the same chromosome

What are the three types of allele mutations?

Loss of function

Gain of function

Isoalleles

What is loss of function alleles?

Gene product has reduced activity compared to wild type

less mRNA/protein, less protein function

often recessive to wild type, needs both allies mutant

What are Gain of function alleles?

Gene product has increased or misexpressed activity

increased gene expression/protein activity, protein with new function, expressed in wrong tissue

Often dominant, mutant product may oppose effect of wild type

What is a Isoallele?

different alleles that produce the same or similar phenotype

observed effect is the same/molecular changes may differ

nucleotide/amino acid substitutions that don’t alter protein

mutant allele has same observable effect to wild type

What are examples of modes of inheritance?

Autosomal dominant

autosomal recessive

X-linked recessive

sex limited inheritance

polygenic

What is meant by autosomal dominant?

Genes on autosome, only one copy of allele needed, passes from one generation to next

a condition may be autosomal dominant if common ancestor of all affected individuals

strong correlation with specific breeds/lines

affected offspring may have one affected parent

What is meant by autosomal recessive?

Two copies needed

most common mode of inheritance of single gene disorders

may skip generations, increases with inbreeding

What is incomplete penetrance?

Penetrance is proportion of individuals with particular genotype that expresses associated trait

incomplete if genotype doesn't equal phenotype

Variable expressivity-same genotype may exhibit different degrees of severity