Chapter 12 - Alleles

Question 1

What is an allele?

Answer 1

Two or more versions of a gene that arise by mutation, from the same place on a chromosome

Question 2

What are alleles responsible for?

Answer 2

Genetic variation

Question 3

What are homozygous alleles?

Answer 3

Alleles that are the same

Question 4

What are heterozygous alleles?

Answer 4

Alleles that are different.

Question 5

What is a recessive allele?

Answer 5

An allele that will not be expressed unless it is paired with the same recessive allele.

Question 6

What is a dominant allele?

Answer 6

An allele that takes priority over a recessive allele.

Question 7

How many alleles are there in a blood group gene?

Answer 7

3

Question 8

What does a blood group gene do?

Answer 8

Makes an enzyme

Question 9

Which type sugars are present on the surface of red blood cells when the blood type is A?

Answer 9

A type.

Question 10

Which type sugars are present on the surface of red blood cells when the blood type is B?

Answer 10

B

Question 11

Which type sugars are present on the surface of red blood cells when the blood type is AB?

Answer 11

A and B type

Question 12

Which type sugars are present on the surface of red blood cells when the blood type is O?

Answer 12

None.

Question 13

What does the enzyme produced by the blood group gene do?

Answer 13

Attaches a sugar to the red blood cell

Question 14

Where is the gene for blood group alleles located?

Answer 14

On chromosome 9

Question 15

What are blood group alleles represented by?

Answer 15

IA, IB, and io

Question 16

What is a phenotype?

Answer 16

A blood group

Question 17

What is a genotype?

Answer 17

A combination of alleles (there are 6 possible combinations)

Question 18

How many chances do female people have of getting a good allele?

Answer 18

2

Question 19

How many chances do male people have of getting a good allele?

Answer 19

1

Question 20

What are mutations that take place outside of genetic code called, and what do they do?

Answer 20

Silent mutations that do nothing.

Question 21

What effect do mutations to the DNA in front of a gene have on RNA polymerase?

Answer 21

How it binds to DNA. This can cause more, less, or no protein to be produced.

Question 22

Which allele for a blood group is recessive?

Answer 22

io

Question 23

Which genotype shows co-dominance?

Answer 23

AB

Question 24

What is co-dominance?

Answer 24

Dominant alleles that contribute equally to the phenotype.

Question 25

The ABO gene is said to have multiple alleles. State what this means.

Answer 25

More than two alleles for that gene.

Question 26

What do stop triplets do?

Answer 26

Tell ribosomes to stop adding amino acids.

Question 27

Which chromosome carries sex-linked traits?

Answer 27

X

Question 28

The sex that always passes their chromosome alleles to their offspring is…

Answer 28

Male.

Question 29

What is haemophilia?

Answer 29

A disorder in which blood clotting after injury is defective.

Question 30

What is the most common cause of haemophilia?

Answer 30

A mutation in the gene on the X chromosome that produces clotting factor VIII.

Question 31

When was the Human Genome Project completed?

Answer 31

In 2003.

Question 32

How many base pairs are there in the human genome?

Answer 32

3.3 billion.

Question 33

What percentage of bases are the same between individuals?

Answer 33

99%

Question 34

What percentage if differentiation in base pairs is responsible for all genetic variation?

Answer 34

1%

Question 35

What benefit is there to having knowledge of a person’s genome?

Answer 35

We can predict what diseases they are more likely to develop, or how they are likely to respond to certain medications.

Question 36

How many alleles are in the polypeptide that combines to make haemoglobin?

Answer 36

4.

Question 37

What happens when a mutation occurs in part of the DNA that does not code for amino acids?

Answer 37

Nothing.

Question 38

What is the effect of a gene mutation?

Answer 38

More or less protein being made.

Question 39

Characteristics that are caused completely by environmental factors are called…..

Answer 39

Acquired characteristics

Question 40

Can acquired characteristics be passed on to offspring?

Answer 40

No.