Control of Gene Expression

Question 1

define mutation

Answer 1

a change to the nucleotide sequence of DNA

Question 2

what does a Mutogenic Agent do?

Answer 2

increases the rate of mutation

Question 3

What is a Base Analogue?

Answer 3

a chemical that can substitute for a normal nucleotide base —-> substition mutation

Question 4

what does radiation cause?

Answer 4

change to the structur of DNA eg) UV

Question 5

describe substitution

Answer 5

one base swapped for another one

Question 6

describe addition, and what it causes

Answer 6

one base added this causes frame shift

Question 7

describe deletion

Answer 7

one base is removed

Question 8

decribe inversion and what it can cause

Answer 8

sequence of bases are reversed, can cause no change (degenerate) ,change a few, doesn’t cause frame shift

Question 9

describe duplication

Answer 9

one or more bases are repeated

Question 10

describe translocation

Answer 10

DNA is moved from one part of a genome to another part of a genome

Question 11

what could be the impact of the alteration of one AA?

Answer 11

changes primary structure, changing H bonds, changing tertiary structure (could have negligable change)

Question 12

what does change to many AA cause?

Answer 12

frame shift= change to primary/H bonds —> tertiary

Question 13

describe stem cells

Answer 13

capable of diffferentiating into specialised cells, can divide for the organisms lifetime (no apoptosis)

Question 14

what is a totipotent stem cell?

Answer 14

can differentiate into any specialised cell, found in early mammalian embryos

Question 15

describe a pluripotent cell

Answer 15

can differentiate into many types of cells, but cannot make placental cells

Question 16

describe a multipotent stem cell

Answer 16

can differentiate into a few types of specialised cells

Question 17

describe a unipotent stem cell

Answer 17

stem cells that can differentiate into one type of cell

Question 18

what happens when a cell becomes specialised?

Answer 18

conditions inside the cell control which genes are expressed (eg) transcription factors) cells become irreversibly specialised

Question 19

How can we obtain induced pluripotent stem cells (iPS)

Answer 19

use a modified virus as a vector, virus inserts transcription factors from pluripotent —-> unipotent, transcription factors are expressed

Question 20

how can we obtain embryonic stem cells?

Answer 20

IVF embryos, pluripotent stem cells are removed after a few days, pluripotent cells can differentiate into all types of body cell

Question 21

how can we obtain Adult Stem Cells?

Answer 21

taken by consenting adults in an operation (eg) bone marrow) Adult stem cells are multipotent

Question 22

how can bone marrow be used in medicine?

Answer 22

contain multipotent stem cells, can differentiate into WBCs and RBCs, donor bone marrow can be used to treat leukemia

Question 23

how can stem cell grown organs be used in medicine?

Answer 23

no donor required, use iPS cells, no rejection

Question 24

what are the advantages of stem cells in medicine?

Answer 24

improve quality of life, prevent suffering, save lives

Question 25

what are the disadvantages of stem cells in medicine? (how can some of these be combatted)

Answer 25

embryos could develop into a foetus, fertalised ---> right to life ( use an unfertalised egg that has been triggered to multiply, or develop iPS cells)

Question 26

define transcription factor

Answer 26

proteins that control the rate of transcription by switching genes on and off

Question 27

define promotor region

Answer 27

short sequence of DNA at the start of the gene that the ribosome attaches to

Question 28

decribe the process of a transcription factor

Answer 28

TF moves from the cytoplasm to the nucleus, binds to the promotor region, activate/ repress transcription by helping/ preventing RNA ploymerase binding to DNA

Question 29

describe using the example of oestrogen how transcription factors can be controlled

Answer 29

steriod hormone, binds to receptor, foring oestrogen - oestrogen receptor complex, alters shape to make transcription factor

Question 30

define cancer

Answer 30

uncontrolled cell division resulting in a tumour

Question 31

what is the role of a tumour suppressor gene?

Answer 31

make genes which slow down mitosis or trigger apoptosis

Question 32

what may result from a mutation of a tumour suppressor gene?

Answer 32

a non functional protein

Question 33

what is the role of a proto-oncogene?

Answer 33

speed up mitosis

Question 34

what is a proto-oncogene called if it mutates?

Answer 34

oncogene

Question 35

how does mutation of a proto -oncogene cause cancer?

Answer 35

oncogene can be over expressed, over increasing the rate of mitosis, resulting in a tumour

Question 36

define epigenetics

Answer 36

changes to gene expression caused by the environment (without changing the base sequence of DNA)

Question 37

can epigenetics be inherited?

Answer 37

yes

Question 38

how does epigenetics control gene expression?

Answer 38

by preventing transcription

Question 39

Methylation?

Answer 39

More Methylation ----> Terminates Transcription

Question 40

describe methylation

Answer 40

methyl group attaches to cytosine (CpG site) and prevents transcription, methylated CpG sites prevent transcription enzymes

Question 41

Acetylation?

Answer 41

Less Acetylation -----> Terminates Transcription

Question 42

describe acetylation

Answer 42

acetyl group make histones space out, and DNA less tightly coiled, allows transcription enzymes to attach

Question 43

How does RNA interferance control gene expression?

Answer 43

prevents translation

Question 44

describe siRNA

Answer 44

short, double stranded

Question 45

describe how siRNA prevents translation

Answer 45

combines with protein to form siRNA - protein complex, becomes single stranded, unpaired bases are complementary to target mRNA, siRNA protein complex breaks down mRNA, preventing translation

Question 46

what is formed when microRNA joins with protein?

Answer 46

microRNA-protein complex

Question 47

how does microRNA prevent translation?

Answer 47

binds to mRNA by complementary base pairing, prevents translation by stooping the ribosome attaching

Question 48

Describe hypermethylation

Answer 48

affects tumour suppressor genes (think why), proteins are not transcribed, leading to uncontrolled cell division (cancer)

Question 49

describe hypomethylation

Answer 49

affects proto-oncogenes (think why?), more proteins are transcribed, leading to uncontrolles cell division

Question 50

how can we uses mitosis to identify a tumour?

Answer 50

more cells dividing

Question 51

how can we use nuclei to identify a tumour?

Answer 51

appear large, irregular, multiple per cell

Question 52

how can we use the shape of cells to identify a tumour?

Answer 52

irregular appearance

Question 53

how would the arrangement of cells in a tumour appear?

Answer 53

disorganised

Question 54

what is a benign tumour?

Answer 54

non cancerous

Question 55

describe a benign tumour

Answer 55

slow growing, harmless, can become malignant

Question 56

what is a malignant tumour?

Answer 56

cancerous

Question 57

describe a malignant tumour

Answer 57

fast growing, harmful, can spread

Question 58

what hormone may cause breast cancer?

Answer 58

oestrogen

Question 59

how may oestrogen cause cancer?

Answer 59

oestrogen- oestrogen receptor complex acts as a transcription factor to increase rate of cell division, increasing cell divisin increases risk of mutations, leading to cancer

Question 60

why has the chain termination method of gene sequencing been replaced with high throughpat pyrosequencing?

Answer 60

automated, faster, cheaper

Question 61

why is it easier to sequence the genome of simple organisms such as prokaryotes?

Answer 61

few regulatory genes, little non coding DNA

Question 62

how is the genome project used?

Answer 62

understand evolutionary relatedness (phylogeny), medicine applications such as finding antigens for vaccines