genetics 2

Question 1

incomplete dominance

Answer 1

this occurs when both alleles are expressed resulting in a blending of the alleles
ex. Red snapdragons, X White snapdragons resulting in pink snapdragons.

Question 2

codominance

Answer 2

this occurs when both alleles are expressed but not blended.

Ex. blood type AB in humans.

Question 3

X-linked genes

Answer 3

this gene is located on the X chromosome.

Question 4

multiple alleles

Answer 4

there are more than two possible alleles

Ex. four blood types

Question 5

polygenic inheritance

Answer 5

sometimes two or more genes affect a single characteristic.

ex. skin pigment is controlled by 3 genes at least

Question 6

sex-linked genes

Answer 6

a gene located on the sex chromosome is said to be sex-linked.

Question 7

crossing over

Answer 7

crossing over the process in which the genetic information between two non-sister chromatids during prophase 1 of meiosis.

Question 8

linkage map

Answer 8

a genetic map based on the frequency of recombination between genes due to crossing over

Question 9

nondisjunction

Answer 9

during meiosis, there is an error that prevents the sister chromatids to separate properly resulting in one gamete having two copies of the same chromosome and the other gamete receives no copy.

Question 10

sex nondisjunction

Answer 10

nondisjunction of the sex chromosomes. when egg or sperm has an abnormal number of X or Y chromosomes.
eg Klinefelter’s XXY.

Question 11

aneuploidy

Answer 11

the condition of possessing an abnormal chromosome number.

Question 12

X-inactivation

Answer 12

in females, one of the x chromosomes becomes inactive forming a Barr body. females might have two types of cells.