Patterns of Inheritance

Question 1

One chromosome is inherited from the _________ and one is inherited from the _________.

Answer 1

mother
father

Question 2

Males have two ____________ sex chromosomes: ___

Females have two __ chromosomes: ____

Answer 2

different
XY

X
XX

Question 3

Homozygous:

Heterozygous:

Answer 3

Two same alleles.

Two different alleles.

Question 4

What 2 things does the inherited disorder; cystic fibrosis, mainly affect?

Answer 4

Lungs
Digestive system

Question 5

When inheriting cystic fibrosis, the lungs and digestive system _________________________.

So they become __________ with mucus.

Answer 5

produce too much mucus

clogged

Question 6

Cystic fibrosis is caused by a ______________________ on chromosome 7.

The child must inherit ___________ of this faulty gene; one each from each of their parents.

Answer 6

faulty recessive allele

two copies

Question 7

Polydactyl is caused by a ________________ of a gene.

Answer 7

dominant allele

Question 8

Parents that do not have any alleles for polydactyly produced a child with polydactyly.
Explain how polydactyly suddenly occurred in this family:

Caused by a mutation during __________.

Causing a __________ in ______________________.

Causing a _______________________ to be produced.

Answer 8

meiosis

change
amino acid sequence

different specific protein

Question 9

Antenatal testing analyses an individual’s DNA _____________________.

Answer 9

before they are born

Question 10

What is neonatal testing?

Answer 10

A new born blood spot test where a sample of blood is taken from pricking a baby’s heel.

Question 11

Pre-implantation genetic diagnosis (PGD) is used on embryos before implantation.

__________________ are used to stimulate the release of ___________________.

The eggs are ______________________ in a Petri dish. This is known as IVF.

Later, the cells are tested for the _________________________. Embryos that don’t contain the disorder allele are _________________________.

Answer 11

Fertility drugs
several eggs

collected and fertilised

disorder-causing alleles
implanted into the uterus

Question 12

What is a false positive?

Answer 12

A genetic test that wrongly detected a certain allele or faulty chromosome.

Question 13

What is a false negative?

Answer 13

A genetic test that has failed to detect a certain allele or faulty chromosome.

Question 14

The steps of gene therapy:

1. ___________ the gene involved in the genetic disorder.
2. Use __________________ to cut out the normal allele
3. ________________ of the normal allele are made.
4. Copies of the _______________________ are put into the _______ of the person who has the genetic disorder.

Answer 14

Identify

restriction enzymes

Many copies

normal working allele
cells

Question 15

What are 3 problems with gene therapy?

1. Alleles may not go into ____________________.
2. The alleles may be inserted into the chromosomes at ________________.
3. Some treated cells may be __________________ by the patient’s own untreated cells through ______________.

Answer 15

every target cell

random places

replaced naturally
mitosis

Question 16

What are 2 alternatives to gene therapy?
1.
2.

Answer 16

Cold viruses as vectors.
Nose sprays.