Intro To Genetics and Punnet Squares

Question 1

Define Genetics:

Answer 1

Is the study of how the characteristics and qualities of parents are passed down to their offspring by genes.

Question 2

What is an Allele?

Answer 2

Are alternate forms of genes.
They control the contrasting characteristics of each trait.
Two alleles make up a genotype.

Question 3

Define Dominant Alleles:

Answer 3

They are represented through capital letters.
A dominant allele will always express itself.

Question 4

Define Recessive Alleles:

Answer 4

Will only express themselves in the absence of a dominant allele.
Are symbolized through lower case letters.

Question 5

What is a Genotype?

Answer 5

Is the genetic makeup of an organism.
Combination of alleles. (E.x. Bb)

Question 6

What is a Phenotype?

Answer 6

The physical appearance of an organism.
Is the expression of a genotype. (E.x. Blue Eyes)

Question 7

Define Homozygous (Pure Bred):

Answer 7

An organism has two identical alleles for a trait. (BB, bb)
BB - Homozygous Dominant
bb - Homozygous Recessive

Question 8

Define Heterozygous (Hybrid):

Answer 8

An organism has two different alleles for a trait. (Bb).
The recessive cannot be expressed in this case as the dominant allele will mask it.

Question 9

Who is the Punnet Square named after?

Answer 9

Reginald Punnet

Question 10

Why do we use Punnet Squares?

Answer 10

It is used to find the probability of a particular trait being passed on to an offspring.

Question 11

How do you set up a punnet square?

Answer 11

Step 1: Draw a 3 x 3 grid, with a cross in the top left box.

Step 2: Write the alleles of the first parent in boxes on the top row, one allele in each.

Step 3: Write the alleles of the second parent in the boxes down the left side, one allele in each.