Ch 11: Mendel and the Gene Idea

Question 1

Who is Gregor Mendel?

Answer 1

He was a mathematician and a botanist, who was born in 1822. He was also an Austrian monk who became the father of genetics. Studied pea plants and laid the mathematical foundation for the science of genetics.

Question 2

Why were pea plants beneficial for genetic studies?

Answer 2

They are easy to grow, and have true-breeding strains, meaning they have observable characteristics with 2 distinct forms (i.e. dwarf and tall).

Question 3

The law of independent assortment applies only to genes on different, non-homologous chromosomes or those far apart on the same chromosome.

Question 4

Another variation on dominance relationships between alleles is called ___________; in this variation, the two alleles each affect the phenotype in separate, distinguishable ways.

Answer 4

codominance

Question 5

You can deduce the genotype of an individual in a pedigree based on two types of information: the individual’s phenotype (affected or unaffected) and the phenotypes of his or her parents and/or children.

For autosomal dominant conditions:
Unaffected individuals are homozygous for the recessive, wild-type allele.
Affected individuals with only one affected parent are heterozygous.
Affected individuals with any unaffected children are heterozygous.
Affected individuals with two affected parents may be homozygous dominant or heterozygous.

Question 6

You can deduce the genotype of an individual in a pedigree based on two types of information: the individual’s phenotype (affected or unaffected) and the phenotypes of his or her parents and/or children.

For autosomal recessive conditions:

Affected individuals are always homozygous recessive.
Unaffected children of an affected parent are always carriers (heterozygous).
Both parents of affected individuals must have at least one recessive allele.
If both parents are carriers, their unaffected children may be carriers or homozygous for the dominant, wild-type allele.
For rare conditions, you can assume that individuals marrying into a family do not carry the recessive allele if there is no evidence that they are carriers.