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43 Cards in this Set

  • Front
  • Back
a heritable feature that varies among individuals (flower color)
each variant for a character (purple vs. white)
when the plants self-pollinate, all their offsrping are of the same variety.
mating or crossing of two varieties
monohybrid cross
a cross that tracks the inheritance of a single character (i.e. flower color)
P generation
true breeding parents
F1 generation
hybrid offspring (F for first fillial). all show the dominant trait these self pollinate to create F2
F2 Generation
this generation led to Mendel's discovery of the law of seg. and the law of ind. assortment. ratio 3:1
1. Alternative versions of genes (different alleles) account for variations in inherited characters
each gene resides at a specific locus on a specific chromsome, but DNA can very somewhat in its sequence of nucleotides
alternative versions of genes
2. For each character, an organism inherits two alleles, one from each parent
one chromsomes, allele etc. is inherited from each parent
3. If the two alleles differ, then the dominant allele shows above the recessive allele
dominant-fully expressed in the organism's appearence
recessive- no noticable effect on the organism's appearence
4. The two alleles for each character segregate during gamete production
an ovum and a sperm each get only one of the two aleles that are present in the somatic cells of the organism
law of segregation
allele pairs separate during gamete formation and then randomly re-form pairs during the fusion of gametes at fertilization
law of independent assortment
each allele pair segregates independently during gamete formation, applies when genes for two traits are located on different pairs of homologous chromosomes
having a pair of identical alleles for a character. true breeding
having two different alleles for a gene. can produce either
appearence (PP and Pp are the same)
genetic makeup (PP and Pp are different)
test cross
breeding of a recessive homozygote with an organism of dominant phenotype but unknown genotype
dihybrid cross
mating of parental varieties differeing in two characters
the rule of multiplication
to compute the probability that two independent events will occur in some specific combination, multiply the individual probabilities. (.5 x .5=.25)
the rule of addition
the probability of an event that can occur in two or more different ways is the sum of the separate probabilities of those ways (.25+.25=.5)
incomplete dominance
F1 hybrids have an appearence somewhere in between the phenotypes of the two parental varieties. (written in subscript)
complete dominance
the phenotypes of the heterozygote and dominant homozygote are indistinguishable
both alleles are separately manifest in the phenotype
important points about dominant and recessive
1. they range from complete dominance, through various degrees of incomplete dominance, to codominance
2. they reflect the mechanisms by which specific alleles are expressed in phenotype and do not involve the ability of one allele to subdue another at the level of the DNA
3. they do not determine the relative abundance of alleles in a population
multiple alleles
like blood type
the ability of a gene to affect an organism in many ways
a gene at one locus alters the phenotypic expression of a gene at a second locus
dihybrid cross ratio
quantitative characters
characters vary in a population along a continuum
polygenic inheritance
additive effect of two or more genes on a single phenotype character
norm of reaction
a range of phenotypic possibilities over which there may be variation due to environmental influence. broadest for polygenic traits
many genetic and environmental factors influence the phenotype
family tree describing the interrelationships of parents and children across the generations
phenotypically normal people who transmit the recessive allele of a disorder to their offspring
cystic fibrosis
hits those of euro descent. abnormally high concentration of extracellular chloride do to lack of chloride channels, which leads to mucus/bacter.
Tay-Sachs disease
hits ashkenazic jews. dysfunctional enzyme cant break down brain lipids of a certain class
sickle cell disease
hits blacks. substitution of a single amino acid in the hemoglobin protein of red blood cells. when oxygen in the blood is low, cells are deformed. one allele of it helps ward of malaria.
huntingtons disease
degenerative disease of the nervous system is caused by allele that has no effect until age 35-45
inserts a needle into the uterus, extracts amniotic fluid, tests it for chemicals and then cultures cells for karyotyping
chorionic villus sampling
suctions of a small amount of fetal tissue from placenta. can do in 8th week of pregnancy, and know results sooner.