CONTOL OF GENE EXPRESSION Flashcards

Question

ACTIVATORS

Answer 1

increase rate of transcription eg. Help RNA polymerase bind

Answer 2

decrease rate of transcription eg. Bind to start of gene and prevent RNA polymerase from binding

Answer 3

initiate transcription of target genes small, hydrophobic hormone-means it is lipid soluble and can diffuse through phospholipid bilayers of membranes to all cells Only target cells contain oestrogen receptor ERα in cytoplasm ERα is also a transcription factor but is only ‘activated’ when oestrogen binds When oestrogen binds to ERα oestrogen receptor in cytoplasm, it changes shape ERα oestrogen receptor can now enter nucleus and bind to promoter region of one of its target genes, stimulating RNA polymerase to transcribe that target gene

Answer 4

formed as hair-pin bends of RNA but processed to single strands about 22 to 26 nucleotides long- single strands become incorporated to protein-based RISC

Answer 5

formed as long double-stranded molecule and then diced to smaller fragments about 21 to 25 base pairs long- One of their strands becomes incorporated to protein-based RISC

Answer 6

1.DNA produces miRNA or siRNA in nucleus 2.RNAi moves from nucleus to cytoplasm 3.RNAi unwinds to become single stranded 4.RNAi binds to protein to form RISC 5.single stranded siRNA or miRNA binds to target mRNA molecule by complementary base pairing 6.prevents mRNA from attaching to ribosome and being translated 7.Enzymes may then hydrolyse mRNA

Answer 7

.siRNAs created against viral genetic material will signal for their degradation and stop the virus from using host's cellular machinery to replicate itself .siRNAs can be used in cancer treatment by targeting oncogenes that have been expressed or unregulated reduces number of proteins produced that can lead to cancer or that maintain cancerous growth

Answer 8

heritable change in gene function without changing DNA base sequence caused by changes in environment can inhibit transcription

Answer 9

Methyl groups –CH3 are attached to gene Hypermethylation of promoter prevents transcription factors from binding RNA Polymerase is not stimulated- gene is not transcribed, and mRNA is not made + gene is not expressed

Answer 10

Acetyl groups –COCH3 are removed which condenses chromatin-Transcription factors cannot bind to promoter region- RNA Polymerase is not stimulated gene can’t be transcribed so mRNA is not made + gene is not expressed

Answer 11

drugs can be developed to switch DNA methylation off so can be used to treat cancers cause by increased methylation of tumour suppressor genes

Answer 12

group of genes which prevent cell from dividing or triggers apoptosis-programmed cell death

Answer 13

prevent transcription factors and RNA Polymerase from binding-mRNA cannot be made and therefore protein is not produced-results in cell going into mitosis when it normally would not and therefore causing uncontrollable cell division

Answer 14

group of genes which trigger cell division genes which regulate cell cycle are not expressed ‘normally’ then cell can divide uncontrollably leading to tumour

Answer 15

allows transcription factors and RNA Polymerase to bind more readily-More mRNA can be produced, leading to more of protein to be produced and causing uncontrolled cell division

Answer 16

mutated version of proto-oncogene results in constant initiation of DNA replication and mitotic cell division causes tumour formation

Answer 17

Slow growing Non-invasive Do not metastasise (spread) to other parts of body

Answer 18

Fast growing Invasive Do metastasise (spread) to other parts of body

Answer 19

Oestrogen is steroid hormone it binds to oestrogen receptor site on transcriptional factor causing change in shape + moves to nucleus so it can bind to promoter of proto-oncogene stimulating RNA Polymerase and causing mRNA to be created which initiates transcription result in uncontrolled cell division

Answer 20

.Prevention: Can screen for specific known cancer-causing mutations eg. BRCA1 for breast cancer- could have mastectomy if mutation is present .Treatment: Different mutations need treating differently .Cure: gene therapy to replace inactivated tumour suppressor genes

Answer 21

entire set of DNA including all genes of cell

Answer 22

full number of different proteins that cell is able to produce

Answer 23

Knowing which gene in genome codes for which protein allows antigen producing alleles to be identified in pathogens- allows scientists to design DNA and mRNA-based vaccines which are faster to engineer than traditional antigen based vaccines

Answer 24

Reading full genome of organisms provides opportunities to screen DNA to identify potential medical problems

Answer 25

separate DNA fragments based upon their length and size

Answer 26

1.DNA has a slight negative charge due to phosphate groups so is attracted towards positively charged electrode – so DNA moves 2.gel used in technique has small pores that smaller fragments can move easier through – causes smaller fragments to move further in given time than larger fragments

Answer 27

codon in one species code for same amino acid in another species

Answer 28

combining different organisms’ DNA enable scientists to manipulate and alter genes to improve industrial processes and medical treatment

Answer 29

convert mRNA to single stranded complementary DNA 1.Cells that create target protein are isolated from an organism as these will have lots of mRNA in cytoplasm 2.target mRNA is extracted, and reverse transcriptase added 3.Single stranded complementary DNA is created 4.DNA Polymerase is used to create complementary strand to produce double stranded DNA fragments

Answer 30

Advantages: lots of DNA fragments can be produced as there will be multiple copies of mRNA at the start creates DNA fragments that do not have introns Disadvantages: relatively slow process

Answer 31

recognise specific DNA sequences called recognition sites – bind to these sites and break bonds, cutting the gene from rest of DNA many different restriction enzymes as they are specific to one recognition site- because they are enzymes w/specific tertiary structure, resulting in specifically shaped active site, complementary to recognition sequence

Answer 32

Advantages: Many restriction enzymes naturally cut DNA in way that creates sticky ends: where one strand of DNA is longer than other w/small tail of unpaired bases sticky ends make it easier to insert desired gene to another organism's DNA or to vector as they can easily form hydrogen bonds w/complementary base sequences on other pieces of DNA that have been cut w/same restriction enzyme Disadvantages: creates DNA fragments w/ introns which could not be inserted to prokaryotic organisms maximum of 2 DNA fragments per genome could be gained Relatively slow process

Answer 33

genetic code-amino acids are required scientists use computers to generate nucleotide sequence rather than an mRNA template to produce gene

Answer 34

Advantage: Faster to use gene machine than all enzyme-catalysed reactions creates DNA fragments without introns Disadvantages: potential harm when creating new or more vigorous pests and pathogens

Answer 35

1.Denaturation: Heat to 95oC breaks hydrogen bonds to separate DNA strands which become templates for new complimentary strands 2.Annealing: Cooling to 55oC causes primers to attach to DNA template strands at complimentary sequence as hydrogen bonds reform 3.Elongation - Synthesis of new DNA: Raise temperature to 70oC optimum for DNA polymerase which attaches to primer and adds new bases complementary to template

Answer 36

.Target DNA or RNA being amplified .primers-short sequences of single-stranded DNA that have base sequences complementary to 3’ end of DNA or RNA being copied define region that is to be amplified by identifying to DNA polymerase where to begin building new strands .DNA polymerase – enzyme used to build new DNA or RNA strand- most commonly used polymerase is Taq polymerase as it does not denature at high temperature involved during first stage of PCR reaction and secondly, its optimum temperature is high enough to prevent annealing of DNA strands that have not been copied yet .Free nucleotides – used in construction of DNA or RNA strands .Buffer solution –provide optimum pH for reactions to occur in

Answer 37

1.relatively low amounts of DNA 2.DNA is doubling 3.exponential increase larger amount DNA doubling each cycle 4.ran out of primer + DNA nucleotides

Answer 38

DNA sequences indicating to RNA polymerase when to stop producing mRNA

Answer 39

DNA molecule used as vehicle to carry DNA fragment eg. plasmids/viruses

Answer 40

sequences of bases that read same forwards as they do backwards

Answer 41

Exposed staggered ends of bases palindromic base sequences created by restriction endonuclease enzymes

Answer 42

used to stick DNA fragment to create recombinant DNA

Answer 43

1. promotor + terminator region to modify fragment 2. plasmid DNA is cut using same restriction enzyme which was used to isolate DNA fragment 3. produces sticky ends on plasmid that are complementary to sticky ends of of DNA fragment 4. DNA ligase is used to ‘anneal’ donor and vector DNA-DNA is now called recombinant DNA 5. Vectors are inserted into target host cells 6. Marker genes are inserted to vectors at same time as DNA fragment

Answer 44

ensures that only transformed cells form colonies

Answer 45

.antibiotic resistance .Fluorescent proteins .Enzymes which cause colour changes

Answer 46

.Genetic engineering of microorganisms, plants and animals .Inserting gene to egg cell of female or early animal embryo means all cells of offspring will contain gene .Promotor regions will only be activated in specific cell types so it could be used to control exactly what cells produces protein could mean protein is harvested more easily and avoids damage to organism by avoiding producing protein in wrong cell .Agricultural crops could be produced to give higher yield, be resistant to pests or be more nutritious. .Used in industry e.g. cheese making .Drug production e.g. insulin .Gene therapy: inserting alleles into cells using vectors e.g. altered viruses, plasmids or liposomes

Answer 47

alters alleles of body cells e.g. epithelial cells targeted for patients w/cystic fibrosis alters alleles in sex cells, meaning all offspring cells will be affected

Answer 48

alters alleles in sex cells, meaning all offspring cells will be affected

Answer 49

.Monoculture: planting one type of transformed crop – reduced biodiversity .Transformed crops could interbreed w/wild plants forming e.g. superweeds .Organic crops could become contaminated by wind-blown seeds and pollen from transformed crops .Anti-globalisation activists oppose growth of large multi-national companies which may force smaller companies out of business .Designer babies – currently illegal

Answer 50

.drought – resistant crops could reduce risk of famine .Transformed crops could be used to make pharmaceutical products e.g. vaccines and medicines more cheaply .Gene therapy to treat disease

Answer 51

short, single, strands of DNA that have specific sequence which is complementary to part of target allele

Answer 52

1. DNA sample broken down to smaller fragments 2. DNA fragments separated by electrophoresis 3. DNA fragment treated form single strands + DNA probes added 4. DNA probes allow specific base sequences of DNA to be detected

Answer 53

two complementary single-stranded DNA molecules combine through base pairing to form double-stranded DNA molecule

Answer 54

.diagnose genetic disorders .Can also be used to identify health risks e.g. to cancer and determine how patients will respond to drugs and inform personalised drug treatment .used to inform genetic counselling: advising on treatment, prevention

Answer 55

distinguishing between individuals based on their unique DNA sequence

Answer 56

variable number tandem repeats sequences of bases in introns unique to each person + non coding sequences of DNA

Answer 57

.sample cells contain DNA is obtained eg. blood .use PCR make copies if sample of DNA is small .use restrictive enzymes to hydrolyse DNA targeted to VNTR regions .use gel electrophoresis to separate DNA fragments by size .DNA strand transferred to nylon membrane + treated to make single stranded .DNA probes specific to each targeted VNTR are added + bind to complementary base pairings .DNA fragments viewed using UV or X ray to produce pattern of bands .compare size + positions of bands

Answer 58

Individuals inherit half of their VNTRs from each parent-means that 50% of an individual’s bands in their fingerprint will match mother’s bands in their fingerprint means that remaining 50% of bands must match biological father

Answer 59

Instead of copying entirety of DNA, primers complementary to targeted VNTRs are added to sample- means that scientists can amplify specific VNTRs, allowing forensic analysis of tiny tissue samples and partially degraded DNA multiple VNTR copies are then separated and analysed using gel electrophoresis

Answer 60

type of VNTR that occurs when short sequence of DNA is repeated many times in row –eg. triplet such as CAG

Answer 61

mixture of DNA fragments of known lengths-pattern it creates can then be compared to unknown fragments to determine their lengths

Answer 62

more closely pattern of banding matches more closely related two people are Determining genetic variability in population-more number of repeats vary, greater genetic variability could inform and prevent inbreeding between animals and plants involved in breeding programmes which could lead to genetic disorders Medical diagnosis of genetic disorders: STR testing is used to diagnose conditions that are predominantly caused by expansions in length of specific region of genome

CONTOL OF GENE EXPRESSION Flashcards

TOPIC 8 (86 cards)