MENDEL’S EXPERIMENTS

Question 1

What did Mendel notice about traits in the 1st and 2nd generation of pea plant offspring?

Answer 1

Some traits would disappear in the 1st generation but reappear in the 2nd generation

This observation was crucial in the development of Mendelian genetics.

Question 2

Define expression in genetics.

Answer 2

When a gene is translated into a functional protein

This process is essential for the manifestation of traits.

Question 3

What is a Dominant Allele?

Answer 3

Always expressed if at least one copy is present, usually indicated by a Capital Letter

Dominant alleles mask the effect of recessive alleles.

Question 4

What is a recessive allele?

Answer 4

Only expressed when there is no dominant allele present, usually indicated by a lowercase letter

An organism needs 2 copies of a recessive allele for that trait to show.

Question 5

How many copies of a recessive allele does an organism need for that trait to show?

Answer 5

2 copies

Each organism inherits one allele from each parent for every gene.

Question 6

What does homozygous mean?

Answer 6

Having two copies of the same alleles (ex. BB or bb)

This condition can affect the expression of traits.

Question 7

What does heterozygous mean?

Answer 7

Having two different alleles (ex. Bb)

This can result in the expression of the dominant trait.

Question 8

Define genotype.

Answer 8

The genetic makeup of the alleles inherited (the ‘letters’)

Genotype determines potential traits but not necessarily their expression.

Question 9

Define phenotype.

Answer 9

The physical traits or characteristics expressed (the ‘look’)

Phenotype is influenced by genotype and environmental factors.

Question 10

What are Punnett Squares used for?

Answer 10

Tools used to predict probabilities of genotypes and phenotypes of offspring

Alleles from parents are placed on the outside of the grid.

Question 11

What does a monohybrid cross predict?

Answer 11

The inheritance of only one specific trait

Example: In pea plants, round peas (R) are dominant over wrinkled peas (r).

Question 12

What is the Law of Segregation?

Answer 12

States that only one of the two alleles for any one trait in a parent organism will be distributed into each gamete

This distribution is random and begins in anaphase I of meiosis.

Question 13

When does the distribution into each gamete begin and finish?

Answer 13

Begins in anaphase I of meiosis and finishes after anaphase II

This explains why individual traits do not blend or dilute over generations.