Week 2 DNA mutation & molecular biology techniques

Question 1

What is mutation

Answer 1

Permanent change in DNA sequence

Causes: Errors in DNA rep/repair or by induced mutations e.g chemicals, radiation or viruses

e.g cystic fibrosis CFTHR gene

Sig: Evolution disorders can study gene function

Question 2

Haploinsufficiency

Answer 2

Motor loss

Question 3

Gain of function explained

Answer 3

Chromosome rearranged, new function but may not respond to negative effects

Question 4

DNA glycosylase

Answer 4

Removes damaged base

Question 5

AP endonuclease

Answer 5

Identifies damaged location of strand

Question 6

DNA polymerase

Answer 6

Inserts new base to the strand

Question 7

DNA ligase

Answer 7

Seals the nick

Question 8

Base excision repair

Answer 8

Fixes singular base

DNA glycolase removes the base, AP endonuclease cuts DNA , DNA polymerase adds new base, Ligase seals the gap

Question 9

Nucleotide excision repair mechanism enzymes

Answer 9

uvra,b,c,d and helicase 2 uvrD

Fixes distortions caused by dimers

Proteins detect distortions, damaged strands excised by endonuclease, DNA polymerase fils gap ligase seals

Question 10

Homologous recombination

Answer 10

Repairs a split in DNA strand

New single strand DNA is produced, new strand joins old one, DNA polymerase fils the gap and ligase seals

Question 11

Stop codon

Answer 11

Sequence of nucleotides, shows the end of translation

Question 12

Missense mutation

Answer 12

Single nucleotide change, causes different AA in the protein

Question 13

Frame shift

Answer 13

Add/del of nucleotide

Question 14

Silent mutation

Answer 14

Doesn’t affect AA being encoded, only changes the nucleotide sequence

Question 15

What is electrophoersis?

Answer 15

Movement of a charged molecule in an electrical field

Question 16

The role of a pcr amplifier

Answer 16

To study a gene and to get many copies of it, to detect cancer, micro-organisms

Question 17

Restriction enzyme

Answer 17

recognises a particular set of sequences which then cuts them

Question 18

Maxam gilbert method

Answer 18

Cleaves dna strand at different bases use gel elctrophoerisis to separate strand to be then viewed

Question 19

Cloning

Answer 19

Exact replication of DNA by DNA polymerase

Question 20

What direction is mRNA synthesised

Answer 20

5-3

Question 21

Describe southern blotting

Answer 21

1. DNA extracted, digestion of product using restriction enzyme, separate DNA using gel electrophoreseis, denature protein, incubate, use fluoro imaging
2. detects specific genes, identifies mutations, identifies clones
3. specific but time consuming and large amounts of DNA needed

Question 22

Northern blotting

Answer 22

1. Extract RNA, denature, run on gel electrophoresis, incubate, use fluorescnce imaging
2. Shows what gene is being expressed, detects mutations, diagnostics study gene expression
3. Specific but time consuming, less sensitive and rna unstable

Used to detect specific RNA samples, allows for the usage of different splicing techniques

Produces info on RNA but is time consuming and low sensitivity

Question 23

Microarray

Answer 23

1. Used in gene expression detects mutations, diagnostics
2. Analyse many genes but low sensitivity and possible to get false results

Question 24

PCR analysis in DNA analysis

Answer 24

1. Denaturation, annealing, DNA polymerase creates a new strand of DNA repeated 20x to amplify
2. Used in forensics, analyse DNA, diagnostics and identify gene mutations
3. High sensitivity, specific and fast but contamination and errors may occur

Question 25

Western blotting

Answer 25

Used to analyse specific proteins in a sample

Isolate proteins, separate using gel, incubate, 1st AB to detect protein, 2nd to lavel part, use immunofluruoescence

Used in protein expression and modifications

Specific but time consuming

Question 26

DNA damaging agents

Answer 26

External: UV - produces dimers that distort DNA (sun)
Ionising - X-rays, breaks DS (nuc radiation)
Chemicals, viruses integrates with host gene

Internal: Oxidative stress, rep errors and deamination

Question 27

Non-homologous recombination

Answer 27

Repairs DS breaks

Recognised by specific proteins, DNA end that aren’t broken are extended, DNA ligase seals

Question 28

small scale mutations

Answer 28

Point mutation, only affects a few nucleotides

Question 29

nonsense mutation

Answer 29

Converts a codon to a stop codon halting the protein production

Question 30

large scale mutations