Introduction to molecular biology

Question 1

What is the structure of DNA?

Answer 1

• adenine forms two hydrogen bonds with thymine

- guanine forms three hydrogen bonds with cytosine

Question 2

What is the structure of the double helix?

Answer 2

made of a sugar-phosphate backbone with bases on the inside of the structure

Question 3

How are the DNA strands arranged?

Answer 3

anti-parallel - each strand is of the opposite polarity with one in the 5’3’ direction and the other in the 3’5’ direction

Question 4

What are the two types of repetitive DNA?

Answer 4

interspersed repeats

tandem repeats

Question 5

What are the three types of DNA replication?

Answer 5

semiconservative model
conservative model
dispersive model

Question 6

What happpens in a polymerase chain reaction?

Answer 6

• the strands are separated
• primers are bound to the strands
• new DNA synthesised
• multiple copies made

Question 7

What is the function of DNA sequencing?

Answer 7

determines precise order of nucleotides in DNA molecule

Question 8

What is electrophoresis?

Answer 8

used to separate pieces of DNA that differ in length by only one base

Question 9

What are the uses of PCR?

Answer 9

genotyping
mutation detecting
paternity testing

Question 10

What are the main differences between DNA and RNA?

Answer 10

• uracil is used in RNA and thymine in DNA
• RNA has more complex secondary and tertiary structure
• DNA only involved in information storage but RNA is a catalyst, guide, message

Question 11

What is an intron?

Answer 11

non coding section of RNA transcript

Question 12

What is an exon?

Answer 12

coding section of RNA transcript

Question 13

What is a splice site?

Answer 13

a genetic mutation in the specific site at which RNA splicing takes place

Question 14

What is a promoter?

Answer 14

the region of DNA that initiates transcription of a particular gene

Question 15

What is an enhancer?

Answer 15

short region of DNA that can be bound with proteins to activate transcription of a gene

Question 16

What is mRNA?

Answer 16

carries genetic info from DNA to the ribosome

Question 17

What are the two domains of transcription factors?

Answer 17

DNA binding domain

activation domain

Question 18

How does RNA splicing take place?

Answer 18

through two esterification reactions

Question 19

What is the function of alternative RNA splicing?

Answer 19

allows more than one protein to be produced from a gene

Question 20

What is the significance of triplets?

Answer 20

more than one triplet can code for the same amino acid

Question 21

How is information read from DNA code?

Answer 21

• the starting point is the initiation codon

- the ending point is the stop codon

Question 22

What are the three stages of protein translation?

Answer 22

initiation
elongation
termination

Question 23

What are the four main types of mutations?

Answer 23

deletion
insertion
substitution
point

Question 24

What are frameshift mutations?

Answer 24

affect the whole amino acid chain

Question 25

What are silent mutations?

Answer 25

change a single letter without affecting any of the amino acids

Question 26

What is a polymorphism?

Answer 26

minor change in DNA that is present in less than 1% of the population

Question 27

What are transfer RNAs?

Answer 27

'adaptor' between the codon and the specific amino acid

Question 28

What happens after translation?

Answer 28

- translocation to the relevant part of the protein - protein folding - post-translational modification

Question 29

What effects can mutations in a cell have?

Answer 29

- no transcription - protein incorrectly processed - inappropriately regulated