1 Foundations of Genetics and Mendelian Inheritance Free Online FlashCards

What does genetics study?

Genetics is the study of inheritance and of how genetic variation interacts with the environment.

What is a gene?

A gene is a DNA sequence that contributes to a biological function or trait.

What are alleles?

Alleles are different versions of the same gene.

How do genotype and phenotype differ?

Genotype is an organism’s genetic makeup for a gene or set of genes. Phenotype is its observable characteristics, which can reflect both genotype and environment.

What does homozygous mean?

An individual is homozygous for a gene when it has two matching alleles.

What does heterozygous mean?

An individual is heterozygous for a gene when it has two different alleles.

How does complete dominance affect a heterozygote’s phenotype?

With complete dominance, the dominant allele determines a heterozygote’s phenotype; the recessive phenotype appears only when both alleles are recessive.

What does dominance not tell you about an allele?

Dominance describes how alleles affect a particular phenotype; it does not mean an allele is more common or better.

What approach did Mendel use to study inheritance?

Mendel bred garden pea plants, chose clear contrasting traits, used true-breeding plants, controlled crosses, and compared offspring across generations.

What did the alternate trait’s return in F₂ suggest?

The reappearance of the alternate trait in F₂ suggested that inherited information passes in discrete units, rather than permanently blending.

What does Mendel’s law of segregation state?

The two alleles an individual carries for a gene separate during gamete formation, so each gamete receives one. Fertilization brings alleles from two gametes together.

For $\mathrm{Yy} \times \mathrm{Yy}$, what genotypic ratio is expected?

The expected genotypic ratio is $1\,\mathrm{YY} : 2\,\mathrm{Yy} : 1\,\mathrm{yy}$.