Final Terms Part 4 Flashcards
sister chromatid
replica of chromosome - attached at centromere
homologous chromosomes
chromosomes that code for the same traits, but can be different
-one from each parent
monohybrid cross
cross to study one trait
gave raise to law of segregation
dihybrid cross
cross to study two traits
gave raise to law of independent assortment
law of segregation
two alleles segregate from each other during the formation of the gametes in anaphase I of meiosis
half gametes have one allele, thus union of gametes is random
law of independent assortment
pairs of alleles for genes on different chromosomes segregate independently in the formation of gametes during meiosis
testcross
used to determine genotype of an organism displaying dominant phenotype by mating it with a homozygous recessive
codominance
gene products are equally expressed
AB blood type
incomplete dominance
homozygous dominant gives two gene products (ie dark red)
homozygous recessive gives no product
hets give intermediate (ie light red/pink)
epistatis
form of gene interactino in which one gene interferes with the expression of another gene
haplosufficiency
one gene product is sufficieny for life
x-linked
trait is found on the x chromosome
hemizygosity
males are hemizygous-have one x and one y
SRY in humans
sex-determining region
becomes active in embryo
encodes testes determining factor
Barr bodies
inactive X chromosome in females- used to set gene dosage
gene dosage
the amount of gene product expressed
pleiotropy
one gene is responsible for multiple phenotypes
penetrance
the % of people with the genotype that express the phenotype
expressivity
the range of phenotypes
phenotypic variation
influenced by environment
epigenetics
modifier genes
maternal effect
phenotype of offspring is determined by the nuclear genotype of mother
extranuclear inheritance
typically maternal inheritance
DNA found in mitochondria and chloroplasts
polygenetic
many genes
multifactorial
many environmental factors
