Chapter 8: Genetics Flashcards

Question

Law of Segregation

Answer 1

alleles separate so only one per gamete

Answer 2

separation of a pair of genes is independent of separation of other pairs

Answer 3

Dominant alleles mask recessive alleles and are expressed over them, signify dominant allele with capital letter EE colored coat, ee white, Ee colored EE is the genotype, colored is the phenotype

Answer 4

Used to predict the results of a genetic cross In a genetic cross, two parents (P generation) are crossed to produce offspring (F1 generation). The simplest Punnett square follows one character in a monohybrid cross.

Answer 5

Can’t always tell genotype by looking at phenotype Can test cross individual with homozygous recessive to see what offspring are If some recessive, then parent is heterozygous

Answer 6

neither allele masks the other, both are expressed Red coat (RR) + white coat (WW) = roan (RW)

Answer 7

heterozygous individual is intermediate

Answer 8

expression of one gene is influenced by the presence of another Defies classical Mendelian genetics Horse hair color black is E at E locus, but whether black all over or just points is controlled by another locus Ea is black, EA is bay with black points

Answer 9

only 2 alleles on each locus, but population could have many alleles A-B-O blood types in humans

Answer 10

is the effect of many genes on a single character. In humans, height and skin color are each affected by several genes. Size and growth rates common in animals

Answer 11

Some genes only found on X or Y, homologous in some regions, not in others X-linked genes can be inherited by males and females Y-linked only in males Found on autosomes, phenotypes are not expressed the same way for the sexes In male sheep horns (H) is dominant to polled (no horns(h)), in females h is dominant So heterozygous male has horns, hetero female doesn’t

Answer 12

Traits unique to a single sex Milk production, egg production Both have genes, but only one sexes expresses them

Answer 13

proportion of a particular allele in a population

Answer 14

how often a genotype occurs in a population

Answer 15

how often a phenotype occurs in a population

Answer 16

uses pop genetics to improve livestock

Answer 17

changes in the composition of a gene that alter DNA, producing new alleles Mutations that affect phenotype are rare Beneficial ones spread through natural selection

Answer 18

change in gene frequency due to chance, affected by population size Big problem for small populations

Answer 19

wild animals migrating or bringing new breeding stock into a population Can make large changes in gene frequencies quickly this way Works best when new sire is very different from herd

Answer 20

allowing some animals to breed more than others

Answer 21

some individuals are better adapted and will therefore breed more Happens in managed herds with multiple bulls Wild populations

Answer 22

breeding controlled by manager, culling less desirable animals Affected by rate of reproduction and generation time

Answer 23

In a large, randomly mating population without natural selection, migration, or mutation, gene frequencies will remain stable Rare in the wild, common in managed herds Once desired genes are achieved in a large herd, they will remain constant

Answer 24

phenotypes classified into groups Coat color, horn presence

Answer 25

numerically measured, usually polygenic Growth rate Additive gene action- no dominance at locus, each gene increases the effect A+ gene makes calves 2lbs heavier at birth, AA is norm, A+A+ is 4lbs heavier

Answer 26

Genes determine your potential, but environment determines if live up to that potential Climate, management practices, health

Answer 27

How much phenotypic variability among individuals that is due to genetics and can be passed down Ranges from 0-1 First calculate a selection differential- difference between the population and desired trait, multiply by heritability value Need to be considered before breeding Pig litter size- norm is 7, breed parents from litters of 11 Differential is 11-7= 4 Heritability value is .1, so 4x.1= .4 So litter will be 7.4 piglets larger Some traits are more heritable than others

Answer 28

Measures how closely related individuals are, also important before breeding. Ranges from 0-1 Parent-offspring- 0.5 Siblings- 0.5 Half-Siblings- 0.25 Grandparent-offspring- 0.25

Answer 29

mating closely related individuals Increases homozygosity, decreases genetic variation Can increase incidence of detrimental recessive traits Causes decline in quality called inbreeding depression

Answer 30

inbreeding to concentrate genes of an outstanding ancestor Genetic evaluations have eliminated need for this in livestock, but still practiced in companion animals

Answer 31

mating less closely related individuals Increases heterozygosity, genetic diversity Increases vigor, known as heterosis Lowly heritable traits show more heterosis

Answer 32

mating animals of different breeds Most successful if parent genetics complement each other Strengthen good traits, depress bad ones Great for reproductive traits Often breed crossbred mothers with purebred sires Tend to be more vigorous, fertile, and healthy

Answer 33

Tools that use living organisms to make improvements or modifications for specific uses

Answer 34

altering an animals genes

Answer 35

Bacteria that produce human insulin Before used pig and cattle insulin, slightly different Cows, sheep, goats can produce proteins in milk to treat disease Can produce large quantities Chickens can produce proteins in eggs Animal models for human diseases Animals to produce organs for human transplant

Chapter 8: Genetics Flashcards

(59 cards)