Molecular Biology

Question 1

What does DNA stand for?

Answer 1

Deoxyribonucleic acid

Question 2

What is a gene?

Answer 2

An inheritable unit that is a sequence of DNA

Question 3

What is a genome?

Answer 3

The entire genetic makeup of an orgamism

Question 4

DNA can contain 4 different kinds of bases. What are these 4 bases?

Answer 4

Adenosine, Thymine, Guanine, Cytosine

Question 5

Explain basic DNA structure in terms of sugars, phosphates and bases

Answer 5

DNA has a sugar phosphate backbone. The bases attach to the sugar and to a complimentary base which then attaches to the other sugar phosphate backbone.

Question 6

Explain the ‘central dogma’ of molecular biology

Answer 6

DNA makes DNA. DNA makes RNA. RNA makes protein

Question 7

BRIEFLY explain the statement ‘the information for making a new strand of DNA comes from an old strand of DNA’

Answer 7

The DNA splits to form 2 new DNA molecules which are identical due to the complimentary bases.

Question 8

What is transcription?

Answer 8

DNA is transcribed to create RNA. RNA synthesis

Question 9

What is translation?

Answer 9

RNA is translated into proteins. Protein synthesis

Question 10

In one short sentence explain what an Intron is

Answer 10

A segment of DNA or RNA that does not code for proteins and interrupts the sequence of genes

Question 11

In one short sentence explain what an Exon is

Answer 11

A segment of DNA or RNA that codes for proteins or peptide sequences

Question 12

What is a codon?

Answer 12

A sequence of 3 nucleotides which together form a unit of genetic code in DNA or RNA molecule

Question 13

What is meant by the term ‘Genetic Code’?

Answer 13

A set of rules in which the living cells translate information in the genetic material into proteins

Question 14

What are two differences between RNA Polymerases and DNA polymerases?

Answer 14

RNA does not require a primer

DNA uses thymine not uracil

Question 15

BRIEFLY explain what a restriction enzyme is

Answer 15

a restriction enzyme cuts DNA at a specific site, depending on the enzyme

Question 16

BRIEFLY explain what a ligase enzyme is

Answer 16

Ligase enzyme is the molecular glue that holds together nucleotides in DNA

Question 17

Explain how PCR could be used for sex determination

Answer 17

DNA samples can be taken, amplified and analysed to determine the SRY protein (the protein which determines sex)

Question 18

State 3 additional applications PCR could be used for

Answer 18

Genetic engineering
Producing human insulin from bacteria
Detecting viruses

Question 19

What are the steps of a PCR reaction? Describe what happens at each step

Answer 19

Denaturation
- The DNA is split into 2 ssDNA

Annealing
- Primer is annealed to the strands

Extension
- The DNA is rebuilt from where the primers attached

Question 20

Are there any infectious, disease-causing agents that can not be detected using a PCR-type reaction? If so, name one such agent or disease.

Answer 20

Prions are a protein based infectious agent which do not have nucleic acid. Therefore they are not detected with a PCR test.

Question 21

Describe an application of electrophoresis

Answer 21

Analyse and purify proteins, DNA and RNA

Question 22

When electrophoresed over a given period of time, will a small DNA molecule usually migrate a shorter distance or a further/longer distance through an agarose gel, compared to a large DNA molecule?

Answer 22

A smaller DNA molecule will travel a longer distance than a larger molecule

Question 23

True or False. Electrophoresis can separate molecules based on both size and charge?

Answer 23

True

Question 24

What types of molecules can be separated using electrophoresis?

Answer 24

DNA, RNA and proteins

Question 25

A certain type of PAGE can be used to separate denatured proteins. What are denatured proteins?

Answer 25

Denatured proteins are proteins that have broken the weak bonds (hydrogen bonds) and have lost their native state.