The Chromosomal Basis of Inheritance Flashcards
Why did Morgan choose to study the Drosophilia melanogaster?
- They produce many offspring
- A generation can be bred every two weeks
- They have one four pairs of chromosomes
For a recessive X-linked trait to be expressed, a female needs ___ copies of the allele (homozygous), a male needs __ copy of the allele (hemizygous)
two ; one
What are linked genes?
Genes that are located on the dame chromosome tend to be inherited together
What is genetic recombination?
The production of offspring with combinations of traits differing from either parent
What is an offspring with a phenotype matching one of the parental (P) phenotypes called?
Parental types
Offspring with nonparental phenotypes (new combinations of traits) are called?
Recombinant types, or recombinants
___ ___ increases the number of variant combinations
Random fertilization
What is the raw material upon which natural selection works?
Genetic variation
What is a linkage map?
A genetic map of a chromosome based on recombination frequencies
Distances between genes can be expressed as what?
Map units
One map unit represents a ___ recombination frequency
1%
Genes that are far apart on the same chromosome can have a recombination frequency near ___
50%
What is nondisjunction?
When pairs of homologous chromosomes do not separate normally during meiosis
What results from a nondisjunction?
One gamete receives two of the same type of chromosome, and another gamete receives no copy
____ results from the fertilization of gametes in which nondisjunction occured
Aneuploidy
