GB1: Chapter 14 Flashcards
character
heritable feature that varies among individual (ex: flower color)
trait
each variant for character (ex: purple)
true-breeding
produce same offspring of same variety over generations
hybridization
crossing of 2 true-breeding varieties
P-generation
parental gen. (true-breeding)
F1-generation
first filial gen. (P-gen. hybrid offspring)
F2-generation
2nd filial gen.
gene
sequences of nucleotides at specific place along chromosome
locus
specific physical location of gene on chromosome
allele
alternative versions of genes; variation in gene’s nucleotide sequence
phenotype
appearance/physiological trait
genotype
genetic makeup
testcross
breeding an organism of unknown genotype with recessive heterozygote
monohybrid cross
cross between 2 heterozygotes for character
dihybrids
heterozygotes for 2 characters
Law of independent assortment
2 or more genes assort independently (each pair of alleles segregates independently of any other pair of alleles) during gamete formation
multiplication rule
probability that 2 or more independent events will occur in sequence
addition rule
probability of occurrence of 1 event or other of 2 mutually exclusive events summed together
complete dominance
phenotypes of heterozygotes and homozygotes are the same
incomplete dominance
phenotype of F1 hybrids are a mix between parental phenotypes
codominance
2 dominant alleles affect phenotype in separate ways
Tay-sachs disease
- inherited disorder
- child’s brain cells cannot metabolize specific lipids due to disfunctionality of crucial enzyme
- lipids accumulate, child experiences seizures, blindness, degredation of motor/mental performance
- Need 2 alleles to have disease, so recessive disease
polydactyly
- dominant allele causes disease
- baby born with extra fingers/toes
- recessive allele is more common due to low frequency of this condition
pleiotropy
genes that have multiple phenotypic effects
epistasis
expression of a gene at one locus alters the phenotypic expression of a gene at a second locus
Quantitative characters
they vary in the population along a continuum, indicates polygenic inheritance
polygenic
additive effect of two or more genes on a single phenotype
multifactorial
Traits that depend on multiple genes combined with
environmental influences
pedigree
family tree describing
interrelationships of parents and children across
generations
carriers
heterozygous, carries
recessive allele but phenotypically normal
Albinism
- recessive condition
- lack of pigmentation in skin & hair
cystic fibrosis
- cystic fibrosis allele results in defective or absent chloride transport channels in plasma membranes, leads to buildup of chloride ions outside the cell
- symptoms: mucus buildup in internal organs, abnormal absorption of nutrients in the
small intestine
sickle-cell disease
- substitution of a single amino acid in the hemoglobin protein in red blood cells
- homozygous: all hemoglobin is abnormal (sickle-cell)
- heterozygous: usually healthy but suffer some symptoms; BUT are less susceptible to malaria parasite
- symptoms: physical weakness, pain, organ damage, paralysis
Achondroplasia
- dominant allele
- rare form of dwarfism
Huntington’s disease
- degenerative disease of
the nervous system - phenotypic effects show at 35-40 years old
- condition is irreversible & fatal
