Lecture 2 Flashcards
1
Q
Recombinant Phenotype
A
- Where the combination of phenotypes differs from parents
- Occurs through independent assortment or crossing over
2
Q
Crossing over
A
- Occurs during Pachytene phase of prophase 1
1. Synapsis pairing of homologous chromosomes
2. Synaptomal complex is a protein “zipper” that holds homologous chromosomes together in the tetrad
3. Formation of the synaptamal complex leads to crossing over
3
Q
Recombinantion frequency
A
Number of recombinents/total progeny x 100%
4
Q
Coupling vs replusion heterozygotes
A
- Affects the outcome of a testcross
- The largest phenotype will always be parental
5
Q
Chromosomal maps
A
- 1913, A.H.Strutevant relised that this information could be used to draw chromosomal maps
- Genes closer apart doesn’t have space to be seperated so it less likely
6
Q
Incomplete dominance
A
Where a dominant allele does not fully mask the efft of a recessive allele
Blending of traits and a “diluted” phenotype
7
Q
Co-dominance
A
Where each allele affects the phenotype in seperate different ways
8
Q
Pleiotrophy
A
When a single trait has multiple effects on the phenotype
9
Q
Polygenic inheritance
A
When a single trait is determined by multiple genes
10
Q
Epistasis
A
When one gene masks or modifies the expression of another gene
