DNA Function & Structure

Question 1

Give an example of DNA in physiology?

Answer 1

DNA, RNA, protein

Question 2

Give examples of DNA in pathology?

Answer 2

Genetic diseases
Viruses
Cancer

Question 3

Give an example of DNA in diagnostics?

Answer 3

Mutation analysis
Microbiology
Forensic medicine

Question 4

Give an example of DNA in therapy?

Answer 4

DNA as drug target
Gene therapy
Risk assessment

Question 5

Give an example of DNA in biotechnology?

Answer 5

Production of biomedicines
Delivery vectors
Gene products

Question 6

What are prokaryotes?

Answer 6

No nuclear membrane, DNA arranged often in a single chromosome

Question 7

What are eukaryotes?

Answer 7

DNA is in the nucleus. Bound to proteins (chromatin complex)

Question 8

What are functions of DNA?

Answer 8

•DNA as template and regulator for transcription and protein synthesis.

•DNA is the genetic material, structural basis of heredity and genetic diseases

Question 9

Why is cell cycle control and DNA repair so important in medicine?

Answer 9

Cancer

Oncogenes
Proto-oncogenes
Cell cycle control
DNA repair

Question 10

How fast is DNA replication?

Answer 10

About 700-1000 bp per second

Question 11

How much work needs to be done in DNA replication?

Answer 11

6 billion base pairs

Question 12

Prior to cell division where does DNA open at?

Answer 12

Replication fork

Question 13

DNA replication is…

Answer 13

Semi-conservative

Question 14

What enzymes are used in DNA replication?

Answer 14

Polymerases (5’ to 3’)
Helicase
Ligase
Nuclease
Primase
Topoisomerase

Question 15

What enzyme opens the DNA strands?

Answer 15

Helicase

Question 16

What keeps the DNA strands open?

Answer 16

Single stranded binding proteins (SSB)

Question 17

What enzyme unwinds the strands?

Answer 17

Topoisomerase

Question 18

What does DNA polymerase do?

Answer 18

Has editing function

Detects incorrect insertion of base and will excise and repeat

Question 19

What can damage our DNA?

Answer 19

Chemical

Radiation

Spontaneous insertion of incorrect bases during replication

Product of incomplete combustion of hydrocarbons

Barbecued food is a good source

Smoking

Question 20

What does ionising radiation do to DNA?

Answer 20

Damages bases

Causes breaks in phosphate backbone

Question 21

What does UV do to DNA?

Answer 21

Damages bases, in particular the formation of thymine dimers

Question 22

What is benzopyrene?

Answer 22

Adduct: forms chemical bonds with DNA, forms a bulky group that disrupts replication

Question 23

What happens if you break both strands of DNA?

Answer 23

Non-disjunction
Mutation

Question 24

What is p53?

Answer 24

Tumour suppressor gene

Question 25

What does p53 do?

Answer 25

Detects DNA damage and turns on repair mechanisms Can pause the cell cycle until repair is carried out Causes apoptosis

Question 26

What happens if there is a mutation in p53?

Answer 26

Cancer

Question 27

Why would we want to develop drugs that interfere with DNA replication?

Answer 27

To prevent cancer

Question 28

What do phosphodiester bonds do?

Answer 28

Hold the sugars together forming the backbone of the DNA molecule

Question 29

What is heterochromatin?

Answer 29

Condensed form of DNA, greater density then usual

Question 30

What is enchromatin?

Answer 30

Lightly packed form of chromatin, less dense

Question 31

What happens in a polymerase chain reaction (PCR)?

Answer 31

Choose your region of DNA to be amplified Heat to separate strands Cool and add primers Add heat-stable DNA polymerase Heat and cool (with primers and DNA polymerase present) Repeat heating and cooling cycle Multiple heating and cooling cycles Present in about 10^6 copies

Question 32

What happens when there is a mutation in the p53 gene?

Answer 32

Li-fraumeni syndone