PPT 17 Genetics Flashcards
T or F. More has been accomplished by the application of genetics to poultry than any other livestock.
True
what are the 3 objectives that commercial breeders are trying to accomplish?
- increase output per bird
- increase efficiency of production
- improved quality of the product and disease resistance.
what is a chromosome?
Cel that contains DNA and associated proteins in its nucleus that carry genetic information.
how many pair of chromosomes do chickens have?
39, 38 are autosome pair and 1 sex chromosome.
what is a gene?
unit of heredity DNA sequence that codes for specific protein products(thousands per chromosomes)
what is a locus?
location on a chromosome where a specific gene resides.
what is an allele?
it is the genetic form of a trait at a specific locus.
what is a somatic cell? what do they contain?
all cells in the body except sex cells.
contains full complement of DNA.
what are sex cells? What do they contain?
sperm or egg cells
1/2 complement of DNA
how many pairs of large chromosomes do chickens have?
5 or 6
what are qualitative traits? give examples.
simplest of inheritance. single gene trait determines comb type, feather color, etc.
what are quantitative traits? give examples.
multiple genes interact to determine traits. body weight, # of eggs layer, etc.
T or F. Environment can effect gene traits.
True
what cell replication to somatic cells undergo? sex cells?
mitosis(full complement)
meiosis(1/2 complement)
define dominance.
ability of one gene to mask the expression of its allele.
define recessive.
an allele that is not expressed
define incomplete dominance.
the production of an intermediate phenotype in heterozygotes.
Phenotypic expression means what?
traits that are visible
genotypic expressions mean what?
allelic makeup responsible for traits
male sex genes are _______?
homogametiic (ZZ)
female sex genes are ______?
heterogametic (ZW)
phenotypes of sex linked genes are only associated with what gene?
Z gene
if we want to increase breast meat yield genetic heredity will yield a bird with decreased _________?
hatchability, egg #’s, and disease resistance
If we want to increase growth rate the quantitative results cause what?
increased fatness and leg problems, but decreases livability and hatchability
