B1 - You and Your Genes

Question 1

What are the two types of Variation factors?

Answer 1

• Genetic factors e.g) Dimples, eye colour.
• Environmental factors e.g) Scars, hair style.

Question 2

What are the two types of proteins and a name an example of each one.

Answer 2

• Structural proteins (For cell growth or repair) e.g) Collagen.
• Functional proteins e.g) Enzymes (To speed up chemical reactions) such as amylase.

Question 3

How do cells carry out DNA instructions?

Answer 3

By producing proteins.

Question 4

How many chromosomes does a human cell have?

Answer 4

2 pairs of 23, making 46 in total.

Question 5

If you inherit two alleles that are the same, this is called _________.

Therefore, if you inherit two alleles that are different, this is called _________.

Answer 5

If you inherit two alleles that are the same, this is called homozygous.

Therefore, if you inherit two alleles that are different, this is called heterozygous.

Question 6

What is your genotype?

Answer 6

The combination of alleles you have.

Question 7

What is an allele?

Answer 7

A variant form of a gene.

Question 8

In a punnett square, a capital letter shows a dominant/recessive allele.

Answer 8

A capital letter shows a dominant allele. Therefore, a lower case letter shows a recessive allele.

Question 9

Huntington’s disease (HD) is dominant/recessive.

Answer 9

Huntington’s disease (HD) is dominant.

Question 10

What is the name of the fluid that can be tested for faulty alleles?

Answer 10

Amniotic fluid.

Question 11

Explain the process of in vitro fertilisation (IVF).

Answer 11

1. Ova are harvested from the mother and fertilised.
2. The embryos are tested for the faulty allele.
3. Healthy embryos are implanted into the uterus. The pregnancy proceeds as normal.

Question 12

Explain the process of Pre-implantation Genetic Diagnosis (PGD).

Answer 12

1. After fertilisation, the embryos are allowed to divide into eight cells before a single cell is removed from each embryo.
2. The cells are tested to see if they carry the alleles for a specific genetic disorder.
3. The unaffected embryo(s) are transferred into the uterus.

Question 13

How can animal clones be produced artificially?

Answer 13

By transferring the nucleus from an adult body cell into an empty (nucleus removed), unfertilised egg cell.

Question 14

Most plants produce clones naturally and asexually, how do they do this?

Answer 14

By forming bulbs or runners.

Question 15

What is the difference between the sex chromosomes in males and females?

Answer 15

In males, half the sperm carry X chromosomes and half carry Y chromosomes.

In females, all the eggs carry X chromosomes.

Question 16

In a dominant disorder, you need ___ ________ allele(s) to cause the disease.

Answer 16

In a dominant disorder, you need 1 dominant allele to cause the disease.

So, the following genotypes would cause the disease:

Gg, GG.

Question 17

In a recessive disorder, you need ___ ________ allele(s) to cause the disease.

Answer 17

In a recessive disorder, you need 2 recessive alleles to cause the disease.

So, the following genotypes would cause the disease:

gg.

Question 18

What are the implications of Genetic Testing?

Answer 18

For the individual

• Would have to go on health records.
• Could hinder future employment.
• Increase insurance premium.

For the parents

• Knowledge would allow you to make life choices.
• May not want to know the result - put your mind at rest or know the extent of the problem.
• Whether or not to tell family.
• Can they get treatment for their condition?
• Counselling / stress.
• Whether or not to have children.
• Reliability of tests (False positive/negative results).
• Risk of miscarridge from tests.
• Whether or not to have IVF.
• Whether or not to have an abortion.
• Adoption.

For society

• Idea of freedom of information.
• Idea of misuse of information.
• Is it ethically / morally the right thing to do?

Implications of not or after testing:

• Financial implications of having a disabled child.
• Care issues/quality of life for baby.
• Stress on family if they have a disabled child.
• Test result could reveal other information e.g) Paternity issues and other disorders.
• Problems re-employment.
• Problems re-insurance.

(Note: Allow overlap of points)

Question 19

What is a fertilised egg cell called?

Answer 19

A zygote.

Question 20

How do identical twins develop?

Answer 20

The blastocyst spontantuously splits into 2 blastocysts, each undergoing mitosis.

Question 21

All stem cells are __________.

Answer 21

All stem cells are unspecialised.

Embryonic stem cells after the first couple of cell divisions are totipotent (Can make any cells, including plactenal cells).

They then become pluripotent (Can make up all cells of the body).

Adult stem cells are multipotent.

Specialisation occurs at an early stage.