Flashcard #6 - Genetics & Punnett Squares

Front

What is a genotype?

Back

A genotype is the genetic makeup of an organism, represented by the alleles it possesses (e.g., BB, Bb, bb).

Front

What is the difference between homozygous and heterozygous?

Back

Homozygous means having two identical alleles for a trait (e.g., BB or bb), while heterozygous means having two different alleles (e.g., Bb).

Front

What does it mean for an allele to be dominant?

Back

A dominant allele is one that expresses its trait even when only one copy is present (e.g., T in Tt).

Front

What does it mean for an allele to be recessive?

Back

A recessive allele is one that only expresses its trait when two copies are present (e.g., tt).

Front

How do you set up a Punnett square?

Back

A Punnett square is set up by placing one parent's alleles along the top and the other parent's alleles along the side, then filling in the squares to show possible offspring genotypes.

Front

What is the probability of producing a homozygous recessive offspring from a Tt x Tt cross?

Back

The probability is 25%.

Front

What are the possible genotypes from a Tt x Tt cross?

Back

TT = 25%, Tt = 50%, tt = 25%.

Front

What is the phenotype ratio for a Tt x Tt cross?

Back

The phenotype ratio is 3 tall (T) to 1 short (t).

Front

What is the genotype of a green pea plant that is heterozygous?

Back

The genotype is Gg.

Front

What is the result of crossing a heterozygous green pea plant (Gg) with a homozygous recessive yellow pea plant (gg)?

Back

The offspring will be 50% heterozygous (Gg) and 50% homozygous recessive (gg).