Aos 1 sac

Question 1

Polymerase

Answer 1

An enzyme involved in synthesising nucleic acids, which is then able to accurately copy a DNA template strand
- The double helix needs to be unzipped and made single stranded

Question 2

Polymerase Chain Reaction (PCR)

Answer 2

the technique used to amplify a segment of DNA

Question 3

Reverse Transcription

Answer 3

1. mRNA isolated from specific cell
2. Poly-A-tail add to the mRNA
3. Primer is added and binds to the mRNA poly-A-tail. Reverse transcriptase enzyme added. DNA lengthens in addition to nucleotides
4. When the DNA is complete, the mRNA chain is removed by the alkali treatment
5. Polymerase enzyme added
6. DNA double-strand is completed

Question 4

Reverse transcriptase

Answer 4

an enzyme used to generate complementary DNA (cDNA) from an RNA template

Question 5

Endonuclease

Answer 5

• Enzyme (restriction enzyme)
• which cut at specific sits within DNA molecules
• Splitting DNA into smaller fragments

Question 6

Blunt ends

Answer 6

Ends of DNA fragments with no overhanging bases after being cut by the endonuclease

Question 7

Ligase

Answer 7

• An enzyme that catalyses the joining of two double-stranded DNA fragments

Question 8

Sticky ends

Answer 8

Ends of a DNA fragment with overhanging bases after being cut by an endonuclease

Question 9

Primary structure

Answer 9

Specific linear sequence of amino acids in the protein

Question 10

Secondary structure

Answer 10

folding of some portion of the amino acid chain.

folds occur depending on the R groups of different amino acids

Hydrogen bonds form between segments of the folded chain to help stabiles the three-dimensional shape of protein

Question 11

Tertiary

Answer 11

• Hydrogen bonds
• Ionic attraction between R groups
• Interactions between hydrophobic R groups in the protein interior
• Covalent disulfide cross-links

Question 12

Quanternary

Question 13

Messenger RNA (mRNA)

Answer 13

• Carries genetic information from the nucleus to the ribosomes for protein synthesis

Question 14

Ribosomal RNA (rRNA)

Answer 14

• Serves as the main structural component of ribosomes within cells

Question 15

Transfer RNA (tRNA)

Answer 15

• Delivers specific amino acids to the ribosome after recognising specific codons on mRNA
  (Anticodon is complementary to codon)

Question 16

Transcription

Answer 16

• DNA unwinds/unzips
• RNA polymerase catalyses transcription (moving from a 3’ to a 5’ direction) through the joining of complementary RNA-free nucleotides to the pre-mRNA 3’ end
• Transcription of the DNA template strand into pre-mRNA occurs
• Pre-mRNA is complementary to the DNA template strand
• In the pre-mRNA, a pairs with u, not with t

Question 17

Capping

Answer 17

A methyl G cap is added to the 5’ end of pre-mRNA
- protects pre-mRNA from enzyme attack
- Provides stability
- Helps to attach to ribosome

Question 18

Adding a tail

Answer 18

A is added to the 3’ end of the pre-mRNA
- Provides stability
- Facilites mRNA export from the nucleus

Question 19

Splicing

Answer 19

Introns are removed and exons are joined together
- Complex molecules ‘spliceosomes’ recognise introns sequences and remove them

Question 20

Translation

Answer 20

• Ribosomes bind to and read the mRNA molecule
• tRNA anticodons are complementary to the mRNA codons
• tRNA brings the corresponding amino acids to the ribosome
• Adjacent amino acids are joined together into a polypeptide chain via a condensation reaction

Question 21

Promotor

Answer 21

• 5’ end (upstream) = binding site for RNA polymerase

Question 22

Termination sequence

Answer 22

• DNA sequence that signals the end of transcription

Question 23

Operator

Answer 23

• Serves as a binding site for repressor proteins to inhibit gene expression

Question 24

Leader

Answer 24

• Upstream of coding region, yet downstream of the promoter and operator

Question 25

Trp LOW

Answer 25

• Repressor cannot bind to operator (inactive)
• RNA polymerase can bind to the promotor
• Transcription of structural genes does occur
• Operon is turned on

Question 26

Trp HIGH

Answer 26

• tryptophan binds to the repressor protein
  Causes a conformational change -> active
  repressor
• Active repressor binds to the operator
• RNA polymerase cannot bind to the promoter
• Transcription does not occur
• Operon is turned off