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Flashcards in Errors Involving DNA Deck (94)
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1

What are oncogenes?

Genes that increase growth, promotes survival and inhibit apoptosis

2

Why might oncogenes have an increase in activity?

Due to mutation (either in the gene itself, in other involved signalling proteins or in the transcription factor binding region).

3

What are tumour suppressing genes?

Genes that inhibit proliferation, reduce growth or promote apoptosis

4

What is the p53 gene?

A tumour suppressing gene that is commonly mutated

5

What is slippage in DNA replication?

Where a newly synthesised nucleotide/strand can slip out and so there are extra nucleotides on the strand. Or nucleotides can slip out on the template strand, shortening the DNA strand.

6

What is mis-match pairing?

When DNA polymerase inserts the wrong nucleotide

7

How can a mismatch be easily repaired?

There can be a base excision repair from the exonuclease domain of the DNA polymerase.

8

What results from an increase of p53 activity?

Tumours

9

What is DNA replication stress?

Inefficient replication that leads to the replication fork slowing, stalling or breaking

10

What happens when the replication fork meets a single strand break?

A double strand break occurs

11

What disease results from a trinucleotide repeat?

Huntingtons

12

What is dysplasia?

Features of abnormal cell growth

13

Errors in what 4 areas lead to genomic instability?

1. Errors in oncogenes
2. Errors in tumour suppressing genes
3. Errors in chromosome structure
4. Errors in chromosome number

14

Increasing the activity of which genes results in dysplasia

Oncogenes

15

What is mismatch repair?

When DNA polymerase finds a mistake and so the exonuclease domain cuts out the mistake for polymerase to fix

16

Outline nucleotide excision repair

A stretch of damaged DNA is removed by endonuclease and replaced by DNA polymerase and joined together by DNA ligase, using a variety of proteins which are produced in the genes controlling this repair

17

What does UV light do to cells?

It initiates a reaction between 2 thymine molecule to form a pyrimidine dimer.

18

Why can some DNA synthesis inhibitors be used as antibiotics?

They may only inhibit bacterial DNA synthesis not human

19

What is non-homologous end joining used to repair

Double stranded breaks

20

Outline non-homologous end joining

The ends are directly lighted. This is done by proteins binding onto the ends of the breaks, which then recruit other proteins which removed damaged strands and then DNA ligase brings the strands together

21

What are chromosomal translocations?

When part of a chromosome attaches to another. It can be balanced or unbalanced

22

What is chromosomal inversion?

When a segment of DNA is reversed end to end.

23

What type of disease can be caused by translocations

Leukaemia

24

What is a mutation

An alteration in a gene or chromosome

25

What is a bulky addict

When chemicals bind to areas of DNA and prevent it replicating

26

When do mutations occur

When DNA repair mechanisms are defective

27

State exogenous sources of mutation

Ionising radiation, free radical, mutagenic chemicals

28

What are free radicals

Molecules with an extra electron

29

State endogenous sources of mutation

DNA replication defects and transposable elements

30

What are transposable elements

When DNA has no fixed position and move around the genome