CH 14 Flashcards
character
-a heritable feature that varies among individuals
trait
-each variant for a character
-EX purple or white flowers
True-Breeding
-plants that produce offspring of the same variety when they self pollinate
Hybridization
-a process where two contrasting, true breeding varieties are mated
P generation
-the true breeding parents
F1 generation
-hybrid offspring of the P generation
F2 generation
-When F1 individuals self-pollinate or cross-pollinate with other F1 hybrids
alleles
alternative versions of a gene
Dominant allele
-determines the organism’s appearance
recessive allele
-no noticeable effect on appearance
Law of segregation
-the two alleles for a heritable character separate during gamete formation and end up in different gametes
Punnett square
-diagram that predicts the possible outcomes from a cross
Homozygote
-An organism with two identical alleles for a character
-true breeding
homozygous
-having two identical alleles for a given gene
heterozygote
-An organism with two different alleles for a gene
-not true breeding
heterozygous
-having two different alleles for a given gene
Genotype
-genetic makeup
-EX GG, gg, Gg
Phenotype
-physical appearance
-EX purple flowers
Test cross
-breeding a mystery individual with a homozygous recessive individual
Monohybrids
-heterozygous for one character
monohybrid cross
A cross between monohybrids
Dihybrids
-individuals heterozygous for the two characters in the cross
-EX parents—AABB, aabb product—AaBb
Dihybrid cross
-a cross between F1 dihybrids
-can determine whether two characters are transmitted to offspring as a package or independently
Law of independent assortment
-states that each pair of alleles segregates independently of any other pair of alleles during gamete formation
Multiplication rule
-states that the probability that two or more independent events will occur together is the product of their individual probabilities
Addition rule
-states that the probability that any one of two or more mutually exclusive events will occur is calculated by adding together their individual probabilities
Complete dominance
-occurs when phenotypes of the heterozygote and dominant homozygote are identical
incomplete dominance
-the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties
codominance
-two dominant alleles affect the phenotype in separate, distinguishable ways
Tay-Sachs disease
-a dysfunctional enzyme causes an accumulation of lipids in the brain
-fatal
Pleiotropy
-multiple phenotypic effects
epistasis
-expression of a gene at one locus alters the phenotypic expression of a gene at a second locus
Quantitative characters
-those that vary in the population along a continuum
polygenic inheritance
-an additive effect of two or more genes on a single phenotype
multifactorial
-Traits that depend on multiple genes combined with environmental influences
pedigree
-a family tree that describes the interrelationships of parents and children across generations
Carriers
-heterozygous individuals who carry the recessive allele but are phenotypically normal
Cystic fibrosis
-lethal genetic disease
-results in defective or absent chloride transport channels in plasma membranes, leading to a buildup of chloride ions outside the cell
Sickle-cell disease
-caused by the substitution of a single amino acid in the hemoglobin protein in red blood cells
Huntington’s disease
-a degenerative disease of the nervous system
amniocentesis
-the liquid that bathes the fetus is removed and tested
chorionic villus sampling (CVS)
-a sample of the placenta is removed and tested
