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25 terms

Bio Ch 8

Biology
STUDY
PLAY
heredity
the passing of characteristics from parent to offspring
genetics
the branch of Biology that focuses on heredity
monohybrid cross
a cross that involves 1 pair of contrasting traits (eg: crossing purple flowers with white flowers)
true-breeding
describes organisms or genotypes that are homozygous for a specific trait and thus always produce offspring that have the same phenotype for that trait
p generation
parent generation; the first two individuals that are crossed in a breeding experiment
F1 generation
the offspring of the P generation; filial generation
F2 generation
the offspring of the F1 generation; the second filial generation
allele
one of the alternative forms of a gene that governs a characteristic (eg: hair color)
dominant
Genetic trait that is expressed when its allele is homozygous or heterozygous
recessive
an allele for a trait that will be masked unless the organism is homozygous for this trait
homozygous
when two alleles of a particular gene present in an individual are the same
heterozygous
when two alleles of a particular gene present in an individual are the different
genotype
an organism's genetic makeup, or allele combinations
phenotype
an organism's physical appearance, or visible traits
law of segregation
Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete
law of independent assortment
Mendelian principle stating that genes for different traits are inherited independently of each other
Punnett square
a diagram that predicts the outcome of a genetic cross by considering all possible combinations of gametes
test cross
the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype
probability
the likelyhood that a possible future event will occur in any given instance of the event; the mathematical ratio of the number of times one outcome of any event is likely to occur to the number of possible outcomes of the event
pedigree
a diagram that shows the occurance of a genetic trait in several generations of a family
sex-linked gene
a trait that is determined by a gene found on one of the sex chromosomes, such as the X chromosome or the Y chromosome in humans
polygenic inheritance
a characteristic of an organism that is determined by many genes
incomplete dominance
a condition in which a trait in an individual is intermediate between the phenotype of the individual's two parents because the dominant allele is unable to express itself fully
multiple alleles
more than two alleles (versions of the gene) for a genetic trait
codominance
a condition in which both alleles for a gene are fully expressed