Chapter 12.1.3 (Exam 3) Mendel's Laws

Question 1

What is Mendel’s first law?

Answer 1

The law of segregation: The two copies of each gene separate during gamete formation; each gamete receives only one copy

Question 2

What is the function of a Punnett square?

Answer 2

All possible allele combinations can be predicted using a Punnett square

Question 3

What are the inheritable, discrete units known as genes made of?

Answer 3

Genes are now known to be short sequences of DNA; a DNA molecule makes up a chromosome

Question 4

How do alleles of a gene segregate?

Answer 4

Alleles of a gene segregate as chromosomes separate during meiosis I

Question 5

What do genes determine and how?

Answer 5

Genes determine phenotypes through the proteins they encode

Question 6

If only dominant alleles are expressed, then what are recessive alleles used for?

Answer 6

Recessive alleles may be mutated and no longer expressed, or encode non-functional proteins

For example, wrinkled seed phenotype is due to absence of starch branching enzyme (SBE1)

Question 7

What are the two possible allele combinations for round seeds?

Answer 7

RR or Rr

Question 8

How did Mendel test for the two possible allele combinations that can produce round seeds?

Answer 8

Mendel tested this by doing test crosses: F1 individuals are crossed with homozygous recessive individuals (rr)