Genetic Variation and Disease II

Question 1

What is the central dogma?

Answer 1

The process of transcription and translation

Question 2

What is a mutation?

Answer 2

A genetic variation that causes a disease

Question 3

What is polymorphism?

Answer 3

A genetic variation that is prevalent in the population but not disease causing itself

Question 4

What is the result of a promotor mutation?

Answer 4

No, or reduced, transcription = no, or reduced, protein

Question 5

What happens if the splice consensus is altered?

Answer 5

At translation there is mRNA decay and so an abnormal or absent protein

Question 6

What happens if the base change makes a new stop (nonsense mutation)?

Answer 6

mRNA decay and a short or absent protein

Question 7

What happens if the base change alters the amino acid sequence?

Answer 7

Results in a differing or non-functioning protein

Question 8

What is a missense mutation?

Answer 8

When the base change results in the same amino acid and so no affect on protein

Question 9

What is an in frame mutation?

Answer 9

When a whole triplet is inserted or removed, all amino acids remain the same there are just less or extra

Question 10

What is an out of frame mutation?

Answer 10

When there is only 1/2 or 4/5 etc bases inserted or deleted ie all amino acids after that point are affected

Question 11

What is a triplet expansion?

Answer 11

When a whole triplet of bases is repeated ie a repeat amino acid

Question 12

How are mutations described?

Answer 12

Standard nomenclature - c. what base number it is, the base letter it was and what it is now (eg 12A>G), p. original amino acid, number of amino acid in sequence, new amino acid (eg His3Gln) - or del(etion), Ins(ertion) also fs = frameshift

Question 13

What does the c and p stand for in standard nomenclature?

Answer 13

c stands for Effect on mRNA sequence (cDNA) and the p is effect on the Peptide sequence

Question 14

How is a stop codon represented by standard nomenclature?

Answer 14

Ter(mination) or *

Question 15

What 3 things could any genetic change be?

Answer 15

A disease causing mutation, a polymorphism or a variant of unknown significance

Question 16

What is penetrance?

Answer 16

The likelihood of having a disease if you have a gene mutation - 100% penetrance means you will always get the disease if you have the mutation

Question 17

What is a Mendelian disorder?

Answer 17

Diseases that segregate in families in a manner predicted by Mendel’s Laws ie a disease that is predominantly caused by a change in a single gene (high penetrance)

Question 18

What is autosomal dominance?

Answer 18

When 1 faulty copy of a gene causes disease. This disease is seen in all generations, if a parent is affected then their child has 50% chance of being affected. Severity of disease can be variable and males and females are equally likely to be affected.