Gene Linkage Flashcards
What are genes located on the same chromosome called?
Linked genes
Linked genes do not assort independently during meiosis.
What is the term for the location of a gene on a chromosome?
Locus
The locus indicates where a specific gene is found on a chromosome.
What is the result of linked genes in dihybrid crosses?
Deviations from Mendelian ratios
For example, the expected 9:3:3:1 ratio is not observed.
How do crossovers during meiosis affect linked genes?
They can separate linked genes
Genes farther apart are more likely to undergo crossovers.
What is the relationship between gene distance and recombination frequency?
Genes farther apart exhibit higher recombination frequency
Leading to more recombinant gametes.
What is used to map the relative distances between genes?
Recombination Frequency
Measured in centimorgans or map units.
How is 1% recombination expressed in mapping?
1 map unit
Indicates the genetic distance between genes.
What ratio do unlinked genes show in a test cross?
1:1:1:1
This indicates equal segregation ratios.
What is the expected ratio for linked genes in a test cross?
Deviations from 1:1:1:1
Linked genes do not segregate evenly.
What can recombination data from multiple crosses help determine?
Gene order and distances on chromosomes
This aids in genetic mapping.
What are genes located on sex chromosomes called?
Sex-linked genes
Typically associated with the X chromosome.
What is the sex determination system in humans?
Females: XX; Males: XY
This defines the genetic sex of an individual.
Why are X-linked traits more common in males?
Males have only one X chromosome
Conditions like colorblindness and hemophilia are more prevalent.
What phenomenon occurs in females regarding X chromosomes?
X-Inactivation
One X chromosome is randomly inactivated for dosage compensation.
What is an example of a trait resulting from X-inactivation?
Calico coat patterns in cats
Different X chromosomes are active in different cells.
