Genetics Review

1. Describe Mendel’s experiments and know terms relating to the experiment

(P, F1, F2, cross pollination, true-breeding)

2. Explain the three principles that Mendel developed.

3. Know the relationship between alleles, genes and chromosomes.

4. Use punnett squares to do genetic crosses. There are different types of crosses. You should know how to do each

-- basic crosses that involve dominance and recessiveness (Tt x Tt)

-- crosses that involve codominant or incomplete dominance (red, blue and purple flowers)

-- crosses that involve two traits – dihybrid crosses (AaBb x aabb)

5. Know basic genetic terms

-- genotype/phenotype

-- heteroygous/homozygous

-- dominant/recessive

-- monohybrid/dihybrid

-- polygenic trait

-- heredity

-- genetics

-- allele/gene

-- true-breeding

-- probability

--segregation

-- independent assortment

--fertilization

-- multiple alleles

-- gametes

-- hybrids (Tt)

Practice Problems:

1. In fruit flies, short wings is a recessive trait. Show the cross between a normal fly (WW) and a short-winged fly (ww). List the phenotypic ratios.

WW = normal
Ww = normal
ww = short wings

2. Two heterozygous flies are crossed. Show the cross and list the phenotypic ratios.

3. A short-winged fly is crossed with a heterozygous fly. Show the cross and list the phenotypic ratios.

4. Also in fruit flies, gray bodies are dominant to black bodies. What phenotypes are expected from this cross: GgWw x ggww

5. If you cross a gray bodied fly (GG) that is also short winged (ww) with one that has a black body and short wings, what percentage of the offspring do you expect to be grey bodied and short winged?

In a certain plant, flowers can be red, white, or pink.

1. Is this an example of codominance or incomplete dominance? Show the letters you would use to represent each color.

2. Show the cross between a red flower and a white flower. List the phenotypic ratios.

3. Show the cross between two pink flowers. List the phenotypic ratios.

4. Show a cross between a red and a pink flower? What percentage of the offspring would you expect to be red?