Sheet 10--Test 3 Flashcards
What is the chromosomal theory of heredity?
Genes are located on chromosomes
Why does sex linkage prove the chromosomal theory of heredity?
traits are inherited on the X chromosome
Why are there more genes which show independent assortment than chromosomes?
crossing over and genetic recombination
what is genetic linkage? why does it occur?
- Genes on the same chromosome are usually inherited together unless they are separated during crossing over during prophase 1,
How do you know if two genes are linked ?
- Usually inherited together
Why do linked genes sometimes recombine?
crossing over
What is genetic mapping?
locating genes on a chromosome
how do geneticists measure the distance between two genes and what unit do they use
centimorgan
what is a 3 point cross
used to determine the order of genes on a chromosome, gene in middle allows one to see recombination events on either side.
why is the human genetic map useful?
its used to determine genetic disorders
also, the first step in treating genetic defect is finding the gene.
what are the two classes of human genetic disorders?
1) aheration–wrong chromosome number
2) mutations–change in DNA sequence
why does down syndrome arise
trisomy due to non-disjunction
why do women over the age of 35 have a much greater chance of having children with downsyndrome?
eggs are more likely to undergo non-disjunction
perform a trihybrid corss between two individuals heterozygous for all three genes (AaBbCc). what is the expected frequency of individuals showing all three dominant traits?
27/64
if you cross white carnations with red carnations all the F1 are pink. what is the name for this kind of interaction?
incomplete dominance
