Genetics
Key Words
Replication of DNA #
genotype = individual's alleles
phenotype = expression of alleles
alleles = multiple forms of a gene
genetics = inheritance
nucleosome structure remains intact
DNA = double helix, seperates
chromatin becomes less compact
replicon =small bubble in DNA
primer RNA = substrates
DNA polymerase = DNA synthesizing enzyme
semiconservative replication = DNA strand is a template
Okazaki = new fragments
replication fork = uncoiled DNA
ligated = attached w covalent bonds
Mutations #
point mutation = single base conversion
deletion = DNA lost
mutation = change
insertion = extra DNA
inversion = backwards
Causes of Mutations
chemicals
radiation
mutagen = cause mutation
nitrous acid = C ---> U
insertion = enzymes
transposable elements = change their positions
insertion sequences = code for enzymes
transposons = code for proteins
mutations used for genetic analysis
Effects of Mutations
almost always harmful
majority are deletions
may have no effect
natural selection
Somatic Mutations = autosomal cell mutations
DNA Repair Processes
DNA polymerase = not 100% accurate
mutations also occur in gene repair genes
advantageous
DNA repair mechanism = not perfect
Monohybrid Crosses #
monohybrid cross = single character analyzed
parental generation
cross = sexual reproduction
F1 = first filial generation
F1 x F1 = F2
homozygous = two identical alleles
heterozygous = differing alleles
incomplete dominance = two alleles phenotypes combined to one
selfing = fertilize with own pollen
Punnett square = used to predict genotype and phenotype of progeny
Mendel = peas ; 1:2:1 ratio
dominant = allele that is expressed over recessive
complete dominance = hard to predict genotype
test cross = reveal genotype
pure bred = selfed; "pure"
Dihybrid Cross
independent assortment = separate chromosome & separate movement
crossing over
two genes analyzed at same time
part of one chromosome switch spots with another
linked no independent assortment
recombinant chromosomes = after crossing over
parental type chromosome = no crossing over
map unit = centimorgan
Inheritance
quantitative trait loci phenotype and gene
pleiotropic effects = multiple phemotypes
epistasis = multiple genes for each trait
uniparental inheritance = one parent
biparental inheritance = both parents equal
maternal inheritance = mom
pollen parent vs. ovule parent
variegation = spots instead of green
Lethal Allele/Gene Families
difficult to detect
polypoid = more than two sets of chromosomes
lethal = deadly
nondisjunction = chromatids do not separate #
paralogs = originated as duplicates
gene family = multiple copies for a gene