Quiz 2

zygote :: fertilized egg

mitosis :: simple division of one cell into two

meiosis :: genetic material halved so that diploid complement is reformed by fertilization

poultry :: most amount of chromosomes

swine :: least amount of chromosomes

gametes (male) :: sperm

gametes (female) :: eggs

fertilization :: the union of sperm and ovum along with the establishment of the paired condition of the chromosomes

diploid :: double or paired chromosomes

haploid :: single or unpaired chromosomes

gene :: basic unit of inheritance, segment of DNA

DNA :: contains deoxyribose sugar, phosphate, and one of four bases

(DNA) Adenine pairs with :: Thymine

(DNA) Guanine pairs with :: Cytosine

poultry sex chromosomes :: female determines the gender (X & Y)

homozygous :: correspond

heterozygous :: differ

alleles :: genes that occupy the same loci but affect the character in different ways (black or red color)

identical alleles :: genes that occupy the same loci and affect the character in the same way

dominant gene :: always expressed gene (uppercase letter)

recessive gene :: rarely expressed gene (lowercase letter)

genotype :: the genetic makeup

phenotype :: the physical appearance

linear interaction :: hormones, nutrition, temperature (doesn’t occur in farm animals)

allelic interaction :: dominant gene is always expressed

lack of dominance :: heterozygous animal shows a different trait than the homozygous

additive gene action :: each gene has an expressed phenotypic effect

overdominance (hybrid vigor) :: heterozygous animals are superior to either homozygous conditions

epistatic interaction :: when a gene alters/masks the expression of genes on another chromosome

most important interaction between genes & environment :: feed supply (ability to survive on low supply)

superovulation :: greater production of eggs (remove and give to other females)

somatotropin :: protein hormone produced in anterior pituitary gene to stimulate growth

205 Adjusted Weaning Weight Cattle :: [(actual ww - birth weight)/weaning age] x 205 + birth weight + additive factor

Quantitative :: objectively measured (growth traits, skeletal size, speed), many pairs affecting 1 trait

Qualitative :: descriptive, subjective (hair color, horned v polled), environment play little role, 1-4 pairs of genes

pleiotropy :: some genes may have an effect on more than one trait

Phenotype = :: Genotype + Environment

contemporary group :: a group of animals with the same herd, sex, breed, birth season, weigh dates, management

environmental differences :: nutrition, health, weather, injury, fertility of dam & sire, season of the year

Expected Progeny Differences (EPDs) :: a prediction of future progeny performance relative to some standard within a breed

heritability :: the portion of the phenotypic variation in a trait which can be attributed to transmissible genetic effects

reproductive heritability :: <0.20

growth heritability :: 0.20 - 0.40

carcass heritability :: >0.40

correlated responses :: can be postive or negative, genetic change seen in traits not directly selected for