Genetics - Guide to the Human Genome for Clinicians

Question 1

What is the structure of DNA?

Answer 1

Two strands bind in antiparallel form with a sugar backbone and bases A, T, C and G. Slide 12

Question 2

What are the four bases in an RNA molecule?

Answer 2

AUCG. Slide 12

Question 3

What is DNA normally arranged like?

Answer 3

A ball of string. Slide 16

Question 4

When does DNA take form of the chromosomal shape?

Answer 4

At metaphase. Slide 17

Question 5

How is a chromosome formed?

Answer 5

The DNA associates with proteins e.g. histones and wraps round them. Slide 20

Question 6

What is the order of the cell cycle?

Answer 6

G1 - S - G2 - M phase. Slide 23

Question 7

Which is the leading strand in DNA replication?

Answer 7

3’ to 5’. Slide 24

Question 8

What is the lagging strand in DNA replication?

Answer 8

5’ to 3’, is completed in little segments. Slide 24

Question 9

What are 3 examples of DNA damage?

Answer 9

DNA strand breaks, chemical crosslinking and mismatched base. Slide 25

Question 10

What happens if DNA cannot be repaired?

Answer 10

Risk of getting cancer. SLide 26

Question 11

What is an example of a genetic disease if DNA strands break?

Answer 11

BRCA1, BRCA2, RAD51, BR - breast cancer. Slide 26

Question 12

What is an example of a genetic disease of UV or chemical crosslinking?

Answer 12

Xeroderma Pigmentosa. Slide 26

Question 13

What is an example of a genetic disease of a mismatched base?

Answer 13

Hereditary Colorectal Cancer. Slide 26

Question 14

When does DNA replication occur?

Answer 14

S phase. Slide 27

Question 15

During mitosis what happens?

Answer 15

One diploid parent cell forms two diploid daughter cells, are NOT identical as there may be mutations. Slide 29

Question 16

What happens during meiosis?

Answer 16

One diploid parent cell becomes 4 haploid daughter cells, each one different. Slide 32

Question 17

What is the structure of RNA?

Answer 17

Single stranded, ribose in backbone (not deoxyribose) and has uracil instead of thymine. Slide 33

Question 18

What is the amount of protein produced determined by?

Answer 18

Rate of transcription
Rate of splicing to mRNA
Half life of mRNA
Rate of processing polypeptide. Slide 36

Question 19

What happens to the coded RNA in brief terms?

Answer 19

DNA is transcribed to pre mRNA. Pre mRNA is spliced to form mRNA. mRNA is translated to a protein where the protein is modified for its function. Slide 37

Question 20

What are examples of sequence variations within a gene?

Answer 20

Changes in promotor and exon sequences. Slide 41

Question 21

What are examples of sequence changes in the DNA between genes?

Answer 21

Single Nucleotide Polymorphisms (SNPs)

Larger deletions or duplications. Slide 41

Question 22

What is a polymorphism?

Answer 22

Any variation in the human genome that has a population frequency of greater than 1%
OR
Any variation in the human genome that does not cause a disease in its own right. Slide 42

Question 23

What is a mutation?

Answer 23

A gene change that causes a genetic disorder
OR
Any heritable change in the human genome. Slide 43

Question 24

Why does everyone not look the same?

Answer 24

Each copy of the genome is slightly different, as DNA replication is imperfect so new genetic variants come about. Slide 50