genetics
The scientific study of heredity
Gregor Mendel Augustinian monk and botanist whose experiments in breeding garden peas led to
his eventual recognition as founder of the science of genetics (1822-1884)
trait
specific characteristic that varies from one individual to another
gene
sequence of DNA that codes for a protein and thus determines a trait
hybrid offspring of crosses between parents with different traits
allele
one of a number of different forms of a gene
principle of dominance Mendel's second conclusion, which states that some alleles are dominant
and others are recessive
law of segregation
gametes are formed
first law of heredity stating that pairs of alleles for a trait separate when
gamete specialized cell involved in sexual reproduction
fertilization
process in sexual reproduction in which male and female reproductive cells join to
form a new cell
"true breeding" term used to describe organisms that produce offspring identical to themselves if
allowed to self-pollinate
P generation
parental generation, the first two individuals that mate in a genetic cross
F1 generation the first generation of offspring obtained from an experimental cross of two
organisms
F2 generation the second generation of offspring, obtained from an experimental cross of two
organisms; the offspring of the F1 generation
probability
The likelihood that a particular event will occur
Punnett square a chart that shows all the possible combinations of alleles that can result from a
genetic cross
genotype
genetic makeup of an organism
phenotype
The physical traits that appear in an individual as a result of its gentic make up.
heterozygous
Having two different alleles for a trait
homozygous
Having two identical alleles for a trait
homozygous dominant having two dominant alleles for a trait
homozygous recessive having two recessive alleles for a trait
monohybrid cross
a cross between individuals that involves one pair of contrasting traits
dihybrid cross A cross between two individuals, concentrating on two definable traits
principle of independent assortment states that genes for different traits can segregate
independently during the formation of gametes
incomplete dominance creates a blended phenotype; one allele is not completely dominant over
the other
codominance
organism
situation in which both alleles of a gene contribute to the phenotype of the
polygenic traits Characteristics that are influenced by more than one pair of genes
multiple alleles genes with three or more alleles
meiosis (genetics) cell division that produces reproductive cells in sexually reproducing organisms
diploid term used to refer to a cell that contains both sets of homologous chromosomes
haploid an organism or cell having only one complete set of chromosomes
homologous term used to refer to chromosomes that each have a corresponding chromosome
from the opposite-sex parent
tetrad the four chromatids in a pair of homologous chromosomes that come together as a result of
synapsis during meiosis
crossing over
of meiosis
exchange of genetic material between homologous chromosomes during prophase I
zygote fertilized egg
spindle fanlike microtubule structure that helps separate the chromosomes during mitosis
gene linkage
their genes
traits that tend to be inherited together as a consequence of an association between
gene map
chromosome
Diagram showing the relative locations of each known gene ona particular