Chromosomal Theory of Inheritance

Question 1

Describe genetic linkage

Answer 1

The condition in which two genes on the same chromosome tend to be inherited together, rather than independently assorted.

Question 2

Principle of segregation

Answer 2

Alleles of the same gene separate during meiosis.

Question 3

Independent assortment

Answer 3

Alleles at one locus sort independently from alleles at another locus.

Question 4

F2 generation ratio of a dihybrid cross with non-linked genes

Answer 4

9:3:3:1

Question 5

Nonrecombinants

Answer 5

Unchanged chromosomes

Question 6

How can linkage be revealed?

Answer 6

Linkage can be revealed through a testcross between a double heterozygote individual and a completely recessive individual.

Question 7

How many recombinant progeny after independent assortment?

Answer 7

Half

Question 8

Sign of linked genes

Answer 8

Parental alleles very similar to progeny instead of having a 9:3:3:1 ratio.

Question 9

For any linked pair of genes, parental gametes will ALWAYS be ____ numerous than recombinant gametes.

Answer 9

more

Question 10

For single crossovers, the frequency of
recombinant gametes is half the
frequency of crossing over because

Answer 10

each crossover takes place between only two of the four chromatids of a homologous pair

Question 11

Calculating recombination frequency

Answer 11

recombinant progeny/total progeny x 100

Question 12

Coupling (cis configuration)

Answer 12

One chromosome contains both wild-type alleles, one chromosome contains both mutant alleles

Question 13

Repulsion (trans configuration)

Answer 13

Wild-type allele and mutant-allele found on the same chromosome