Ch. 5 Genetics

Question 1

What is an allele?

Answer 1

Different expressions of a gene which leads to changes in phenotype such as different eye color.

Question 2

What is Phenotype?

Answer 2

Someone’s observable characteristics.

Question 3

What is a genotype?

Answer 3

Genetic makeup of an organisms genes coding for things such as Pp or Ww.

Question 4

What does homozygous mean?

Answer 4

An organism with two do the same alleles such as PP or pp.

Question 5

What does herteozygous mean?

Answer 5

An organism with two different alleles for a gene.

Question 6

What is a punnett square?

Answer 6

A diagram which shows all the possible combinations for offsprings genotype.

Question 7

What is a dominant allele

Answer 7

An allele that only needs to be in the genotype once to be expressed in the phenotype.
Capital is dominant (eg. A) and lowercase is recessive (eg. a). Aa would express A.

Question 8

What is a recessive allele

Answer 8

And allele that can be masked completely if a more dominant allele is present.

Question 9

What would be an example of a heterozygous individual using the letter T.

Answer 9

Tt

Question 10

What would be an example of a homozygous recessive individual using the letter T

Answer 10

tt

Question 11

What would be an example of a homozygous dominant individual using the letter T?

Answer 11

TT

Question 12

What would be a carrier of a recessive gene’s genotype using the letter T?

Answer 12

Tt

Question 13

What are the three types of gene dominance?

Answer 13

Complete dominance, co-dominance, and incomplete dominance.

Question 14

What is co-dominance?

Answer 14

When a gene has alleles that can both be expressed at the same time in the phenotype. This could be something such as spots on a cow. It expresses both the black and white alleles at the same time.

Question 15

What is incomplete dominance?

Answer 15

When neither allele fully covers the other. This means both mix together to make a new phenotype. This could be a red and a white flower producing pink offspring.

Question 16

Which blood type alleles are more dominant over another? Use I(a) I(b) and i to represent the three possible alleles for blood.

Answer 16

I(a) and I(b) are dominant over type i.

Question 17

What do the different blood type alleles actually mean?

Answer 17

The difference is the type of antigen (an antibody generator) that is carried on the surface of the red blood cells (erythrocytes).

Question 18

AB type blood is an example of ___dominance. Which two alleles does it carry?

Answer 18

Co-dominance
I^a and I^b

Question 19

What is sex linked inheritance?

Answer 19

A trait who gene is located on the x or y chromosome

Question 20

What does wild type mean?

Answer 20

An individual who carries the most common trait in the population. For example, a tiger with orange fur with white stripes is a wild type because most tigers have that phenotype.

Question 21

What is discontinuous variation?

Answer 21

When there are limited number of phenotypes a population can have. Not a range.
Eg. Blood type- A, B, AB, or O
Ability to roll tongue- yes or no

Question 22

What is continuous variation?

Answer 22

When there are not set groups/phenotypes of variation. Phenotype is a spectrum-usually controlled by multiple genes.
Eg. Human skin colour
Height
Weight

Question 23

What is gene linkage?

Answer 23

When two genes are very close together on a chromosome, they are unlikely to be separated during chromosome crossover in prophase I.

Question 24

What is a barr body

Answer 24

Each cell only has one active x chromosome. A barr body is the inactive x chromosome in healthy females or males with Klinefelter’s syndrome (XXY). Genes on the x chromosome can be expressed differently throughout the body (Eg. Cat fur colour)

Question 25

What is epistasis?

Answer 25

When the expression of one gene can have an impact on the expression of another.
Eg. One gene could code for red or brown hair
Another could code for being bald, masking the colour gene

Question 26

What is Mendel’s law of independent assortment?

Answer 26

Any two genes which are located on different chromosomes will be inherited independently of each other. ie the allele passed down have no correlation to another allele