Fundamentals 4

Question 1

What is the chromosomal theory of inheritance?

Answer 1

Morgan conducted experiments using fruit flies (Drosophilia melanogaster).
This provided evidence that genes are located on chromosomes and that chromosomes are the basis for inheritance.

Question 2

Describe Morgan’s experiments

Answer 2

1. He crossed white eyes males with red eyed females.
   All F1 offspring has red eyes- suggesting red is dominant.
2. Red eyed males crossed with red eyes females.
   All females has red eyes. 50% of males had red eyes, 50% had white eyes.

Question 3

What is a hybrid chromosome ?

Answer 3

Formed through the recombination between homologous chromosomes

Question 4

What is the equation for recombination frequency?

Answer 4

Recombination frequency = (number of recombinat progeny / total number of progeny) x 100
Result is in map units or centiMorgans (cM)

Question 5

What is recombination frequency?

Answer 5

The percentage of offspring in which a crossover event has occurred between 2 genes in meiosis.
It is used to estimate genetic distance between genes on a chromosome.
Eg. 10.7% cM indicated that the loci are 10.7cM apart.

Question 6

What is linkage ?

Answer 6

The tendency of genes located close together on the same chromosome to be inherited together.
Reduces the number of recombinant offspring.