Genetics 2

Question 1

Phenotype

Answer 1

physical characteristics, can be seen or measured, influenced by environment, genotype+enviroment=phenotype

Question 2

Genotype

Answer 2

: Genetic potential of an animal, inherited, the pair of alleles at the loci

Question 3

Polypetide

Answer 3

inheritance of more than 2 full sets of chromosomes
-uncommon in vertebrates

Question 4

Aneuploidy

Answer 4

chromosome number is not an exact multiple of the haploid number
-due to nondisjunction

Question 5

Monosomy

Answer 5

only one chromosome from a pair is present in cells rather than the two copies usually found in diploid cells.

Question 6

Trisomy

Answer 6

an extra chromosome

Question 7

Mendel’s law of independent assortment

Answer 7

-Seperation of gene pairs is independent of other gene pairs
-no pair of gene has influence on other genes

Question 8

Linkage

Answer 8

when 2 genes are found on the same chromosome they are considered to be linked

Question 9

Incomplete Linkage

Answer 9

when 2 genes on the same chromosomes are split over due to crossing over during meiosis

Question 10

Mendel’s law of segreatation

Answer 10

Alleles will separate during meiosis so that only 1 allele is found in any gamete and chromosomal pairs must separate during gametogenesis (making of sperm/egg cells)

Question 11

Inheritance

Answer 11

-Pattern of allele transfer from parent to offspring
-dependent upon Mendel’s laws of inheritance

Question 12

Epistasis

Answer 12

-another gene action
-expression of one gene is dependent on the expression of another gene
-ex. Labrador retrievers
-2 genes: black gene B and extension of pigment gene E
-E controls what is seen at B
-B_E_-black lab
-bbE_-chocolate lab
-_ _ee- yellow lab

Question 13

Deleterious Recessive traits

Answer 13

-some recessive alleles can lead to certain diseases/disorders/conditions
-heterozygous individuals are carriers
-only homozygous recessive inheritance allows the trait to be expressed
-can cause economic damages to herd or flock
-usually traced back to a popular sire that carried the recessive allele

Question 14

Spider leg syndrome in sheep

Answer 14

Deleterious recessive trait
-ovine hereditary chondroplasia
-inheritance leads to incorrect bone and cartilage formation
-do not live past 6 months
-carriers undetected

Question 15

Epidermolysis bullosa

Answer 15

Deleterious Recessive trait
-fragile skin syndrome, blistering and slouching of skin

Question 16

Dwarfism

Answer 16

deleterious recessive trait
-specifically in Hereford cattle
-short-faced animals with difficulty breathing

Question 17

Lethal Dominant Genes

Answer 17

Animal with homozyogus domiant genes is lethal and will not survive

Question 18

Manx Cats:

Answer 18

Lethal Dominant Genes
-homozygous recessive (tt)-long tails
-heterozygous (Tt)-bobtails
-homozygous dominant (TT)- LETHAL (not included in genotype ratio)

Question 19

Dexter Cattle

Answer 19

-homozygous recessive (dd)-normal stature
-heterozygous (Dd)-chondrodysplasia dwarfism
-homozygous dominant (DD)-LETHAL

Question 20

Semi-Lethal Traits

Answer 20

-controlled by several genes
-linked to desirable traits

Question 21

consumer demand lean pork-selected for less fat

Answer 21

-pigs can now produce PSE pork
-pale, soft, exudative pork-watery and flavorless but very lean
-undesirable pork
-up to 40% of the market

Question 22

extreme leanness linked to

Answer 22

porcine stress syndrome (PSS)
-even small amounts of stress can lead to death
-pigs can live to marketable age but death rates can be high during marketing
-testable through halothane susceptibility test
-semi lethal because they could make it to market but could die in travel

Question 23

Sex-Influenced traits

Answer 23

-reciprocal expression of the trait in males and females
-ex.
-horned dorset sheep
-males P=horned, p=polled
-females: P=polled, p=horned
-in the heterozygous state, males are horned and females are polled

Question 24

Sex-Limited Traits

Answer 24

-both sexes carry the genes but only one sex will express it
-ex. Milk production in females
-cryptorchidism in males- only one testicle will descend

Question 25

Sex-Linked Traits

Answer 25

genes found on the X or Y chromosomes -genes on Y chromosome will code for male sex characteristics -do not contribute to sex-linked inheritance -genes on x chromosome can contribute to sex-linked characteristics -any deleterious trait found on the x chromosome will be expressed -a female carrier of an x-linked trait will not express it -her male offspring will have a 50% chance of inheriting it

Question 26

-inante factors affecting genetics improvement of quantitative traits:

Answer 26

-heritability of the trait -selection differential -generation interval