The Chromosomal Basis of Inheritance

Flashcards reviewing key concepts from the lecture on the chromosomal basis of inheritance.

Who was Marie Černá?

Studied the chromosomal basis of inheritance.

Who was Thomas Hunt Morgan?

Conducted experiments with fruit flies (Drosophila melanogaster) in the 1910s-1920s.

Why were fruit flies (Drosophila melanogaster) ideal for Morgan's experiments?

Prolific breeders with hundreds of offspring every 2 weeks, and have 4 pairs of chromosomes (8, XY; 8, XX).

What are Morgan's Laws about linked genes?

Genes located on the same chromosome that tend to be inherited together because they are located linearly in the gene loci.

What contributes to genetic recombination?

Independent assortment of chromosomes (unlinked genes) with a 50% frequency and crossing over (linked genes).

How does the distance between genes affect crossing over?

The greater the distance between two genes, the more points there are between them where crossing over can occur; 1 centimorgan = 1% recombination frequency.

What is a linkage map?

Based on recombination frequencies.

What is a cytological map?

Based on stained bands of chromosomes seen under a microscope.

What is a genetic map?

Based on DNA nucleotide sequences.

What organisms use the X-Y sex-determination system?

Mammals(humans) and some insects (fruit files).

What organisms use the X-0 sex-determination system?

Grasshoppers, crickets, and roaches

What organisms use the Z-W sex-determination system?

Birds, some fishes, and some insects (butterflies, moths).

What organisms use the haplo-diploid sex-determination system?

Bees and ants.