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biology year 2 - exam q > Mutations and Gene Expression > Flashcards

Flashcards in Mutations and Gene Expression Deck (41)
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1
Q

what are identical twin studies useful for?

A

determin whats due to enviro factors and whats due to genetic factors

2
Q

if twins are identical, what must any difference in phenotype be due to?

A

enviro factors

3
Q

TF are important in the synthesis of particular proteins.

describe how?

A
  • bind to promotor regions
  • stimulate gene expression by helping RNA polymerase to bind
4
Q

explain what causes siRNA to attach only to one sort of mRNA molecule?

A

has complementory base sequence

5
Q

describe and explain how expression of target gene is affected by siRNA?

A
  • no longer able to make specific protein
  • because mRNA been cut into pieces
6
Q

scientists have suggested that siRNA may be useful in treating some diseases.

suggest why siRNA may be useful in treating disease?

A
  • prevents gene expression by cutting up mRNA before translated
  • siRNA stops product of that gene
7
Q

explain how activated oestrogen receptor affects target cell?

A
  • receptor binds to promotor
  • stimulates RNA polymerase
  • transcribes gene
8
Q

how does endoxifen reduce the growth rate of these breast tumours?

A
  • similar shape to oestrogen
  • binds to receptor - prevents oestrogen binding
  • no transcription
9
Q

the black mambas toxin kills prey by preventing their breathing.

it does this by inhibiting the enzyme acetylcholinesterase at neuromuscular junctions.

explain how this prevents breathing?

A
  • acetylcholine not broken down
  • Na+ continue to enter
  • ICM cannot relax
10
Q

what is meant by epigenetics?

A
  • heritable changes in gene function
  • without changes to the base sequence of DNA
11
Q

explain how increased methylation could lead to cancer?

A
  • methyl groups added to TSG
  • transcription of TSG inhibited
  • leading to uncontrolled cell division
12
Q

a mutation of a TSG can result in the formation of tumour.

how?

A
  • gene incactivated
  • uncontrolled rate of cell division
13
Q

some cancer cells have a receptor protein in their cell surface membrane that binds to a hormone called growth factor.

this stimulates the cancer cells to divide.

scientists have produced a monoclonal antibody that stops this stimulation.

use your knowledge of monoclonal antibodies to suggest how this antibody stops growth of tumour?

A
  • antibody has specific TS
  • comp shape to receptor protein
  • prevents growth factor from binding to receptor
14
Q

how would you explain evidence from a table that cells from a stem tip are totipotent?

A
  • gives rise to new plants
  • must be able to develop into diff tissues
15
Q

papaya plants reproduce sexually by means of seeds.

papaya plants grown from seeds are variable in their yield.

why?

A
  • meiosis/crossing over/independent assortment
  • random fertilisation
16
Q

explain the advantages of growing papaya plants from tissue culture rather than from seeds?

A

will be genetically identical

17
Q

suggest why the plasmids were injected into the eggs of silkworm, rather than into the silkworms?

A
  • gene gets into most cells of silkworm
  • gets into cells that make silk
18
Q

suggest why scientists used a marker gene and why they used the EGFP gene?

A
  • not all eggs will successfully take up plasmid
  • silkworms that will have taken up gene glow
19
Q

suggest TWO reasons why it was important that the spider gene was expressed only in the silk glands of the silkworms?

A
  • so protein can be harvested
  • fibres in other cells could cause harm
20
Q

give 2 characteristic features of stem cells?

A
  • can differentiate into any type of cell
  • keep dividing
21
Q

SCID is a severe inherited disease. people who are affected have no immunity. doctors carried out a trial using gene therapy to treat children with SCID. the doctors who carried out the trial obtained stem cells from each childs umbilical cord.

some of the children in a trial developed cancer.

how might the insertion of DNA have caused cancer?

A
  • inactivates TSG
  • tumour cells divide uncontrollably
22
Q
A
  • attaches to DNA
  • to stimulate RNA polymerase
23
Q

using all the info provided, evaluate the use of iPS cells to treat type 1 diabetes in humans?

A
  • results of group A similar to group C
  • glucose levels of group A lower than glucose levels of group B
  • investigation tested on mice not humans
  • short time - only 12 week period - long term effects unknown
24
Q

why does the antibody bind to TF?

A
  • has comp shape to TF
  • has specific TS
25
Q

what does precipitated DNA consist of?

A

DNA, TF and antibody

26
Q

how can single stranded cDNA prevent transcription of p34 gene?

A

binds to p34 gene

27
Q

describe role of 2 names types of enzymes used to insert DNA fragments into plasmids?

A
  • DNA LIGASE
  • joins DNA to plasmid vector
  • RESTRICTION ENDONUCLEASE
  • cut plasmid
28
Q

2 features of structure of diff proteins that enable them to be separated by gel electrophoresis?

A
  • charge
  • R groups
  • diff length polypeptides
29
Q

how ips cells could correct red-green colour blindness?

A
  • ips cells divide
  • ips cells differentiate into cones
30
Q

advantage of ips over gene therapy?

A
  • long term uses of ips
  • less risk of rejection
  • single treatment
  • harm/side effects from using viruses in gene therapy
31
Q

use all info to suggest how the mutation of NOTCH1 led to the difference in percentage of B cells destroyed by Rituximab?

A
  • changes tertiary structure of protein (TF)
  • TF not comp to CD20 gene
  • little mRNA for CD20 produced
32
Q
A
  • few faulty mitochondria

OR

  • has mostly lots of normal mitochondria
  • egg has genes of affected woman
33
Q
A
  • siRNA binds to mRNA for CENP-W
  • prevents translation of CENP-W
  • CENP-W reduces so does tubulin production
34
Q

the scientists put the same number of skin tumour cells in each dish at the start of this investigation.

explain why it was important to put the same number of cells in each dish

A

ensure colour at start = same

35
Q

an article in a newspaper claimed that these data show that bromelain can be used to treat cancer.

give reasons why we should be careful about accepting this claim?

A
  • only tests on one type of cancer
  • use of mice cells rather than human
  • not possible to predict effect on humans as no data collected
36
Q

rate of cell division is important in investigations into cancer

suggest why

A
  • faster rate of cell division, faster cancer grows
  • by measuring rate of cell division, you could see ow effective treatment was
37
Q

scientists have investigated the effects of bromelain on cancer growth in humans

suggest why they gave bromelain in addition to, rather than instead of, usual treatment

A
  • not ethical to replace conventional treatment
  • as life of patient at risk
38
Q
A
  • no cadmium
  • other conditions same as cadmium treated groups
39
Q
A
40
Q
A
  • RNA polymerase cannot bind to dna
  • no transcription of p16 gene
41
Q
A
  • cadmium causes expression of methyl transferase enzyme
  • methyl groups onto p16 gene
  • p16 normally suppresses tumour growth
  • p16 expression falls afer 4 weeks
  • tumour formation occurs after 10 weeks AFTER p16 falls