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58 Cards in this Set
- Front
- Back
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pure breeding
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homozygous
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epistasis
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masking of effects of one gene by an allele of another
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pleiotropy
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production of superficially unrelated effects by a single allele
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penetrance
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percentage of individuals carrying allele that are affected by it
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expressivity
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degree to which the phenotype is altered in affected individual
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prophase
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-chromatin condensation occurs into units called chromosomes
-nuclear envelope forms -spindle forms -microtubules form from tubulin |
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homologs
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chromosomes in morphologically identical pairs
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karyotype
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chromosome sets as seen at end of prophase
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metaphase
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-chromosomes attach to spindle fibers by their centromeres
-line up at equator |
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anaphase
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centromeres divide at same time
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telophase
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-spindle breaks down
-nuclear envelopes reform -cell divides -chromosomes decondense |
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chromosome theory
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genes are on chromosomes
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sex chromosome
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chromosome that differs in number between sexes
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matroclinons
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like mother in phenotype
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patroclinons
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like father in phenotype
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nondisjunction
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chromosomes move toward the same pole during anaphase
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autosome
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chromosome other than sex chromosome
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sex linked
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located on sex chromosome
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hemizygous
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present in only one copy
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Turner's syndrome
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XO, 1/5000 females
-females -underdeveloped sexual characteristics -sterile, short, webbing of skin on neck |
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Klinefelter's Syndrome
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XXY, 1/1000 males
-feminized -sterile, tall/long limbs -mental abnormality |
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XXX
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1/700
-tall, basically normal |
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primary sex determination
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Y determines gonad
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secondary sex determination
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sex of genetalia
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tertiary sex determination
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events at puberty
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cis/coupling
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alleles are together on the same homolog
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trans/repulsion
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alleles are on different homologs
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linkage
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association of genes together on same chromosome
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recombination
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process of generating new gametic types
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recombination frequency
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nonparental gametes/total gametes
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leptotene
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chromatin condensation begins
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zygotene
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homologs pair with each other
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synapsis
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precise pairing of 2 homologs
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pachylene
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-condensation continues, synaptinemal complex forms
-where crossing over occurs |
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diplotene
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-becomes clear that each homolog has 2 chromatids
-homologs seem to repel one another -forms chiasma where crossing over occurred |
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locus
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position of a gene on a chromosome
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auxotroph
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requires nutritional supplementation not required by wild type
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prototroph
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wild type with respect to nutritional requirements
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chromatid interference
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influence of one crossover on the chromatids selected for a second
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allele
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alternate form of a gene
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gamete
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sex cell, sperm or egg, pollen or ova
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zygote
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fusion of two gametes
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homozygote
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carries identical alleles of a gene
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heterozygote
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carries different alleles of a gene
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genotype
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genetic makeup, description of alleles carried by an individual
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phenotype
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character determined by genotype
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law of segregation
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each trait is controlled by particular factors that occur in pairs. during gamete formation the members of a pair segregate from one another so each gamete receives only one
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test cross
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cross to pure breeding recessive
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law of independent assortment
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the segregation of each gene pair during gamete formation is independent of all others
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blocking step
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prevents nonspecific bonding of probe
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anticipation
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increase in severity from one generation to the next
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1:2:1
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ration of 2 strand: 3 strand: 4 strand double crossovers
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PD=NDP
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genes on non-homologous chromosomes
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PD >> NPD
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linkage
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essential genes
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about 1/3 of all genes, required for survival
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trait rare
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assume unrelated individuals homozygous or hemizygous for normal allele
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SNP (single nucleotide polymorphism)
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due to a base pair substitution
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coefficient of coincidence
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fraction of double crossovers expected that actually occur
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