LECTURE 24 GENETICS II: GENOTYPES, PHENOTYPES, DOMINANTS, RECESSIVES, SEGREGATION AND THE ONE FACTOR CROSS

Define the terms genotype and phenotype.

Genotype: The combination of alleles (genetic makeup) in an organism.

Phenotype: Observable traits of an organism.

Explain the terms dominant, recessive, co-dominant, homozygous, heterozygous.

Dominant: In the case that an organism possesses two different alleles at a locus, the allele that determines the genotype of the organism is the dominant allele.

Recessive: The recessive allele determines the phenotype of the organism only in the case that two recessive alleles are present at that locus.

Co-dominant: Two different alleles both affect the phenotype in separate, indistinguishable ways. Example: the human MN blood group.

Homozygous: Two of the same allele (two dominant or two recessive alleles).

Heterozygous: Two different alleles (one dominant and one recessive allele, or two co-dominant alleles).

Understand the terms gamete, F1, F2, one-factor cross.

Gamete: Sex cells (sperm and egg)

F1: First generation after the parental generation; parents are true-breeding varieties.

F2: Second generation after the parental generation, offspring of the F1 generation.

One-factor cross: A genetic cross using only one trait.

State Mendel's first law and understand how it relates to meiosis.

Mendel's first law = the law of segregation: The two alleles for a heritable characteristic segregate during gamete formation and end up in different gametes.

Use a Punnett square to predict the genotypes of offspring from parental gametes for a one factor cross.

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Lectures 23-28 of Biology 1B

Genetics