control of gene expression Flashcards

Question

cancer is…

Answer 1

result of mutations in genes that control mitosis/ cell cycle results in the uncontrollable division of cells and therefore the formation of a tumour tumours can be benign or malignant

Answer 2

can grow large but at a slow rate non-malignant, so can’t spread/metastasis surrounded by a capsule and contain adhesion molecules, so remain compact and can be removed by surgery

Answer 3

grow large rapidly have the ability to spread to tiger parts of the body- metastasis develop their own blood supply can be life threatening and often need supplementary treatment (chemotherapy+radiotherapy)

Answer 4

oncogenes, tumour suppressor genes increased oestrogen concentration

Answer 5

mutated version of porto-oncogenes encodes proteins involved in DNA replication + mitosis can be permanently switched on, causing excessive cell division + tumour formation hypo methylation increased expression as chromatin will be less condensed

Answer 6

encode proteins that inhibit cell division + cause apoptosis (programmed cell death) if a mutation occurs, apoptosis is inhibited and cell division is stimulated, leading to u controllable cell division + tumour formation hyper methylation leads to increased expression as chromatin is more condensed, so the genes transcription is limited

Answer 7

oestrogen production by ovaries stops at menopause fat cells in breast tissues produce oestrogen can cause cancer as oestrogen activates transcription factors + consequently the transcription of genes e.g oncogenes formation of tumour results in even more oestrogen production, increasing tumour size + attracting white blood cells

Answer 8

full set of genes in each cell genome can be sequenced

Answer 9

reading the genomes of a variety of organisms determining genome of simple organisms allows the sequence of the proteins that are encoded applications= identification of potential antigens to use in vaccines in more complex organisms, the presence of introns means that knowledge of the genome can’t be translated into the proteome proteome= full range if proteins that can be encoded by the genome allows genome-wide comparison between different species, allowing the determination of evolutionary relationships beneficial to medical research as genome comparisons between individuals can allow the development of personalised medications

Answer 10

deteniendo the sequence of bases in a human genome applications= screening for abnormal/ mutated sequences, allowing identification of disorders before symptoms arise, pre implantation screening however, ethical issues as misuse and discrimination if genetic info/data is possible

Answer 11

are constantly developing + becoming faster/ more efficient to use have become more computer based human genome took 15 years to sequence, but nowadays it can take as little as 26 hours

Answer 12

involves transfer of fragments of DNA from one organism, or species, to another genetic code, transcription + translation machinery are universal, so transferred DNA fragments can be translated within cells of the recipient organism- transgenic

Answer 13

reverse transcriptase restriction endonuclease gene machine

Answer 14

make DNA copies from mRNA naturally occurs in retrovirus cell that produces the protein that scientists want is chosen, should have a large amount of mRNA for the protein reverse transcriptase can align + join the complementary DNA based to the mRNA bases this is single stranded and called complementary DNA (cDNA) DNA polymerase makes the cDNA double-stranded cDNA doesn’t have introns

Answer 15

enzymes that ‘cut’ DNA at restriction sites to form DNA fragments complementary to a base sequence at a specific restriction site some cut through the same location in the double-stranded DNA to produce a blunt end some create staggered (sticky) ends with exposed bases, these are palindromic, can join to como lenta tu base pairs

Answer 16

DNA fragments can be created using computerised methods 1. scientists identify amino acid sequence of the protein of interest and the mRNA + DNA sequence from that 2. DNA sequence entered into a computer, which has to pass bio safety and bio security checks 3. computer creates small sections of overlapping DNA strands called oligonucleotides 4. oligonucleotides can then be joined to form the DNA sequence of the entire gene

Answer 17

in vitro, pcr (polymerase chain reaction) in vivo, transformation

Answer 18

1. DNA fragment heated to 95°c so hydrogen bonds between base paris break, producing 2 singles DNA strands 2. cooled to 55°c to allow primers to anneal to the DNA fragments, primers are short sequences that allow the attachments of DNA polymerase 3. heated to 72°c as this is optimum temp of DNA polymerase, DNA polymerase nucleotides together to form 2 new double-stranded DNA fragments number of DNA fragments produced by a given number of cycles can calculated 2^x x= number of cycles

Answer 19

1. DNA is cut using restriction endonucleases to create fragments with sticky ends 2. a promotor + terminator region are added to allow transcription 3. same restriction endonucleases are used to cut open the plasmid (DNA loop in bacteria, act as vector) to allow complementary sticky ends 4. enzymes DNA ligase is used to incorporate the DNA fragment into the plasmid- recombinant DNA is formed 5. recombinant plasmid is the then transferred into bacteria via heat shock or Ca2+ to increase membrane permeability not all plasmids take up the foreign DBA fragments not all recombinant plasmids will be taken up by the bacteria cell we can identify which bacterial cells have taken up the recombinant plasmids through marker genes

Answer 20

plasmids contain antibiotic resistance genes bacteria are given and agar plate containing antibodies if bacteria have taken up the plasmids, they will survive as they will contain antibiotic resistance genes

Answer 21

1. DNA fragment is inserted directly in the middle of a marker gene e.g GFP gene, encode fluorescence 2. GFP no longer be made, so plasmids that don’t fluoresce are recombinant and those do are no -recombinant, so haven’t taken up the foreign DNA fragment 3. can be done in antibiotic resistant genes too, as recombinant plasmids wouldn’t survive on agar plates with antibodies

Answer 22

mechanism by which genetic disorders can be cured or treated by masking the effect of the faulty allele with the insertion of the functional allele 1. healthy allele isolated into cells using vectors 2. if mutant allele is recessive, a dominant allele is inserted, and if the mutant allele is dominant, DNA with the insertion into the middle of it to silence it 2 main types= somatic- alleles in body cells are altered, and is not passed on to offspring germline= alleles in sex cells altered, and are passed on to offspring but is considered unethical due to concern over designer babies or safety of gene therapy

Answer 23

short sections of DNA that are complementary to a known DNA sequence e.g a mutated allied labelled with fluorescent or radioactive tags mainly used for genetic screening- study if individuals DNA to identify whether they possess a mutated allele that causes a particular gene

Answer 24

1. labelled DNA probe is mixed with denatured DNA samples from and individual 2. if the individual has the mitigated allele, the probe will bind to the complementary base sequence in on DNA stranded-hybridisation 3. hybridised DNA is detected using radiation and fluorescence

Answer 25

DNA sequences from different species that have complementary base pairs are mixed together and therefore hybridise the more closely related the species are, the higher temperature it takes to break the hydrogen bonds between the 2 strands

Answer 26

genetic screening to see if an individual is the carrier of a recessive mutation or to evaluate their risk of developing diseases such as cancer allow for personalised medicine specifically tailored to an individual genotype individual may have genetic counselling after screening, which provided info + support about the results of the screening + how you can lower your risk of getting a particular disease

Answer 27

method used to produce a specific pattern of DNA bands from an individual genome

Answer 28

variable number tandem repeat short repeating sequences of DNA in non-coding regions in every individual, they vary in length + in the no. of repeats, so the probability of 2 individuals having the same VNTR’s is very low

Answer 29

1. extraction of the DNA of interest + amplification by PCR 2. digestion using specific restriction endonucleases into DNA fragments 3. separation of DNA fragments by gel electrophoresis -DNA fragments move towards the positive electrode -smaller fragments move further down the gel -different sized fragments are separated into bonds 4. VNTR’s are hybridised at specific complementary base sequences with DNA probes 5. gel is developed- pattern of bands can be visualised by placing the gel on an X-ray film as the probes can emit radiation 6. reveals the positions

Answer 30

determine genetic relationships by looking at how similar the binding patterns are forensics=comparing DNA profile with those founds at the crime scene medical diagnosis=identify individuals at risk of developing particular diseases plant+animal breeding=used to prevent inbreeding by not breeding individuals with similar banding patterns.