Genetic disorders 1

Question 1

Where are mutations causing heritable genetic diseases found?

Answer 1

The germline

Question 2

What is the main difference between germline mutations and somatic mutations?

Answer 2

in germline mutations, it will affect all the cells in the organism whereas in somatic mutations it may only affect specific areas

Question 3

Where in the genome do most disease causing mutations occur?

Answer 3

Exons

Question 4

What is polyploidy?

Answer 4

Extra set of chromosomes

Question 5

What can polyploidy be caused by?

Answer 5

nondisjunction

Question 6

What is nondisjunction?

Answer 6

Failure of chromosomes to properly separate

Question 7

What phase of mitosis/meiosis1 or 2 does nondisjunction occur during?

Answer 7

Anaphase

Question 8

What is aneuploidy?

Answer 8

One single chromosome extra or missing

Question 9

When does aneuploidy usually occur?

Answer 9

Egg production in meiosis

Question 10

What can cause aneuploidy?

Answer 10

nondisjunction

Question 11

What is a splice site mutation?

Answer 11

A change in the splice acceptor site, causing splicing to occur differently

Question 12

What is the role of the splice acceptor site?

Answer 12

It signals to the spliceosome where the cut should be made

Question 13

What is known about a disease if it needs both copies of a gene to mutate in order to manifest?

Answer 13

It is recessive

Question 14

What is known about a disease if only one copy of a gene needs to mutate in order for it to manifest?

Answer 14

it is dominant

Question 15

What is a dominant negative effect of a gene?

Answer 15

When the protein product of a mutated gene interferes with the protein product of the wild type gene

Question 16

What is mendelian inheritance?

Answer 16

The situation when the presence of mutation in a single gene is sufficient for disease manifestation

Question 17

What is locus heterogenity?

Answer 17

Mutations in one of multiple genes can cause the same phenotype

Question 18

What is incomplete penetrance?

Answer 18

A mutation not causing a disease when otherwise expected

Question 19

How could incomplete penetrance occur?

Answer 19

Although the gene has mutated, other factors that affect gene expression could come into play

Question 20

What factors that affect gene expression could cause incomplete penetrance?

Answer 20

Genetic background and environment

Question 21

What is genetic background?

Answer 21

Other genes effect on that specific gene

Question 22

Who is mtDNA inherited from?

Answer 22

Mother

Question 23

Why is mtDNA only inherited from the mother?

Answer 23

Mitochondria from the sperm doesnt enter the egg during fertilisation

Question 24

How can siblings have varying degrees of severity of a mitchondrial disease?

Answer 24

If the mother only has some mutant mitochondria, different childeren will inherit different amounts of this and so have different disease severity?

Question 25

What organs are most severely affected by mitochondrial diseases?

Answer 25

Brain and skeletal muscle

Question 26

Why is the brain and skeletal muscle most affected by mitochondrial diseases?

Answer 26

High energy organs so require mitochondria the most