Chapter III-V: Mendelian Genetics - Linkage

Question 0

P1

Answer 0

Parental generation: original parents

Question 1

Selling

Answer 1

Self fertilization of the first generation

Question 2

F1

Answer 2

Filial gen: offspring of original parents

Question 3

Mendel’s first 3 postulates

Answer 3

1. Unit factors in pairs (each individual has 2 u.f.= alleles)
2. Dominance/Recessiveness
3. Segregation (principle of ransoms segregation and independent assortment)
   
   • an individual will contribute only 1 unit factor

Question 4

Independent assortment

Answer 4

Random segregation for both will occur simultaneously and independently

Question 5

Patterns of Inheritance

Answer 5

1. Simple dominance
2. Codominance
3. Multiallelic
4. Mutation

Question 6

Simple dominance

Answer 6

Monohybrid: 3:1
Dihybrid: 9:3:3:1
Trihybrid: 27:9:9:9:3:3:3:1

Question 7

Codominance

Answer 7

Equal expression of both alleles and exhibits blending pattern:
1 locus
2 alleles
3 phenotypes
Ratio: 1:2:1
If geno=pheno: codominance

Question 8

Multiallelic

Answer 8

Contains more than 2 alleles, ex: ABO

Question 9

Mutation

Answer 9

Leads to test cross (1:1 ratio)

Question 10

Testcross

Answer 10

A cross between an individual whose genotype at 1 or more loci maybe unknown and an individual who is homologous recessive

Question 11

Epistasis

Answer 11

Phenomenon when alleles of 1 locus will either alter or mask the expression at a second locus

Question 12

Recessive lethal condition

Answer 12

Dominant phenotype but recessive lethality: 2:1

Question 13

Simple recessive epistasis

Answer 13

9:3:4
Ex: Ag x Ag
A_ and B_ = Agouti
bb = black
aa = no color/white

Question 14

How to know parental and recombinant combinations using frequency of crossing over between 2 loci?

Answer 14

Recombinants: multiply freq. by 2 and # of meiocytes
Parentals: 4x#of meiocytes - recombinants

Question 15

Double recessive epistasis

Answer 15

9: 7
9: A_B_
7: the rest (3+3+1)

Question 16

Simple dominance epistasis

Answer 16

12:3:1

Question 17

Double dominance epistasis

Answer 17

15:1

Question 18

Pleiotropy

Answer 18

Condition in which one mutation causes multiple phenotypic effects

Question 19

Autosomes

Answer 19

Chromosomes other than sex chromosomes

Question 20

Sex influenced

Answer 20

Shows dominance reversal between sexes

Phenotypic expression conditioned by the sex of the individual

Question 21

Sex limited

Answer 21

A trait is expressed but only in one sex even though the trait may not be x-linked

Question 22

Sex linked

Answer 22

A gene is only carried on one sex chromosome and not the other
Restricted to organisms with heteromorphisms

Question 23

X-linked

Answer 23

Pattern of inheritance resulting from genes located at the x-chromosome

Question 24

Dihybrid cross

Answer 24

Individuals with 2 loci that are heterozygous are crossed

Question 25

Heteromorphisms

Answer 25

Contains sex determining chromosomes

Question 26

Polygenic

Answer 26

Transmission of a phenotypic trait whose expressions depends on the additive effect of other genes

Question 27

Reciprocal test cross

Answer 27

A pair of crosses in which the genotype of the female in one is present as the genotype of the male in the other, and vice versa.
Used to test for sex linkage

Question 28

Autosomal linkage

Answer 28

Represents linkage group where all loci are on 1 chromosome and is inherited as a unit

Question 29

Types of linkage groups

Answer 29

Complete
Incomplete
De-linked

Question 30

Complete linkage

Answer 30

Always separates the chromosomes and no cross over occurs; parentals = 100%

Question 31

Incomplete linkage

Answer 31

Crossing over occurs some of the time; parentals > 50%, recombinants < 50 %

Question 32

De-linked

Answer 32

Cross over occurs all the time

Question 33

2 point linkage

Answer 33

80:20

Question 34

3 point linkage

Answer 34

72:18:8:2