BI306 Exams 1 Chapter 3 monohybrid cross/dihybrid cross

Gene

a genetic factor (region of DNA) that helps determine a characteristic

Allele

one of the two or more alternate forms of a gene

locus

specific place on a chromosome occupied by an allele

genotype

genetic makeup of an organism

heterozygote

organism that inherits two different alleles for a given gene

Homozygote

organism that inherits two alleles of the same type for a given gene

Phenotype

physical characteristics of an organism

monohybrid cross

A cross between two individuals, concentrating on only one definable trait

principal of segregation (Mendel's first law)

each individual organism possesses two alleles that can encode a characteristic. these alleles separate when gametes are formed, and one allele goes into each gamete

concept of dominance

when the two alleles of a genotype are different, only the trait encoded by the dominant allele is observed in the phenotype

Punnett Square

a shorthand mehtod of predicting the genotypic and phenotypic ratios from a genetic cross

probability=

number of ways for something to happen/total number of possible outcomes

testcross

cross between an organism with an unknown genotype and an organism with a recessive phenotype

Dihybrid cross

Cross or mating between organisms involving two pairs of contrasting traits

principal of independent assortment

genes encoding different characteristics separate independently from one another

Probability Multiplication Rule

Probability that two more independent events will occur together, use multiplication

(AND)

probability addition rule

Probability that any one of two or more mutually exclusive events will occur, add their individual probabilities

(OR)