U2T4 - Keywords Flashcards
Gene Technology Up to GM Microorganisms (5.4.7)
PCR
Polymerase Chain Reaction. Used to create multiple copies of same DNA section, allowing for meaningful analysis. e.g. forensic science. Carried out in thermocycler PCR machine. Machine loaded with DNA sample, DNA primers, thermostable DNA polymerase enzyme + dNTPs. Set for 20+ cycles for genetic profiling + medical research.
dNTPs
Free DNA nucleotides.
Thermostable DNA Polymerase
Most commonly used = Taq polymerase. Obtained from Thermo Aquaticus bacteria in hot springs so enzyme optimum temp is higher.
Primer
Short sequence (20 bases) of DNA complementary to sections at ends of target sequence to be amplified. All Allows DNA polymerase to add more comp bases to DNA sequence + stops strands rejoining.
Anneal
Bind
Restriction Endonuclease Enzymes
Enzymes that cut DNA into fragments by hydrolysis, extracted from diff bacteria + produced as defence mechanism against viruses to stop them reproducing.
Recognition Sequence
Complementary sequence of DNA bases in restriction enzyme.
Sticky Ends
Short sequence of unpaired bases which are free to anneal to other DNA fragments produced through action of same restriction enzyme.
Palindrome
Same backwards as forwards. e.g. Anna, racecar
Coding DNA
Sections of DNA expressed as proteins.
MRSs
Microsatellite Repeat Sequences. Occur in introns. Short sequences of 2/3 bases which repeat many times. Num repeats varies between individuals, unique. Forms basis of DNA profiling/genetic fingerprinting.
SNPs
Single Nucleotide Polymorphisms. Changes in DNA sequences which don’t make individuals of same species different. Change in 1 nucleotide results in alleles which can result in disease.
Allele
Different form of a gene. Only some genes have these, most have only one form.
Gel Electrophoresis
Sample of DNA treated with restriction enzymes, creating DNA fragments with diff lengths, this method separates them. Nowadays, membrane stage bypassed as gel subjected to UV light, probes added earlier + target sequences visible in situ. Shorter travel further (closer to negative)
Southern Blotting Technique + Incubation
Blot DNA onto membrane (Nylon). Moisture from gel absorbed and DNA fragments transferred onto membrane, replica of OG DNA. Incubation happens + DNA probes tagged with dye/radioactive substance added + anneal to DNA.
DNA Probes
Single stranded DNA of known, complementary base sequence to DNA being investigated. Used as markers. Carries part of base sequences of gene being investigated. Labelled with radioactive/fluorescent markers.
kBP
Thousands of base pairs. Used as units for length of DNA molecules.
Hybridise
Attach
Reverse Transcriptase
Catalyses reversal of normal transcription, makes cDNA.
cDNA
Complementary/Copy DNA
Vector
Gene carrier. Molecule of DNA used to carry foreign (human) gene into host cell (bacteria) to make human protein. Commonly used are bacterial plasmids + phage viruses.
Plasmids
Circular pieces of double stranded DNA found naturally in bacteria. In addition to main bacterial DNA. May contain genes useful to bacterium. (Genes which provide resistance to antibiotics)
Ligation
Sticky ends of cut genes + plasmids join together.
Incubated
Mixed
Screened
Identified + separated.
Replica Plating
Process which allows exact location of diff colonies of bacteria to be known + retained. Blot membrane on colonies grown on initial ampicillin plates.
R-Plasmid
Plasmids with genes for antibiotic resistance, used as vectors. Contains 2 antibiotic resistance genes. 1 for tetracycline, other for ampicillin.
Ampicillin Resistance Gene
Allows identification of cells that have taken up plasmids being worked with.
Downstream Processing
Insulin produced by bacteria secreted into culture solution. Extracted + purified so safe for human use by diabetics.
Transgenic Organisms
Organisms that have had genes transferred to them from another organism.
Liposomes
Lipid vesicles that can fuse with cell membrane to deliver donor DNA into cell. Lipid coating protects against degradation + helps DNA bind to target cells. Aided using markers like monoclonal antibodies.
Electroporation
Applying electrical voltage to cell membrane to make it more permeable.
Gene Therapy
Uses knowledge of defective genes linked to disease development. Replace defective form of gene with fully functional form. Conditions treated this way caused by defective recessive gene.
DNA Chips/Microarrays
Mini spotting tile. In each well of chip, num of DNA probes attached, each well has slightly diff sequence on probes. Probes added robotically + sequences stored on comp. Some probes contain DNA sequences spec for gene sequences linked to patient ability to respond correctly to certain drug.
Oncogenes
Genes that act to switch off genes that should be operating. Cancer causing genes.
Pharmacogenetics
Stratified/personalised medicine. Reduces likelihood of side effects, ensures effective treatment + reduces costs as ineffective drugs not prescribed.
Genome Sequencing Projects
Aim to determine order of ATGC bases in genome. In viruses, strand of DNA/RNA. For prokaryotes, single circular chromosome. For eukaroytes, complete sequence of haploid chromosomes set.
Human Genome Project
To sequence entire human genome. 1990 - 2003. Slow to complete at first but as progressed, tech improved and more rapid. Cost $2.7 billion and took 13 years. Not takes a couple weeks + $1000. Genome contains 3 billion nucleotides + 21,000 genes.
Knock Out Technology
Determine what gene controls. Inactivate/remove single gene in model organism (mouse). Studied to understand genetic diseases like Huntington’s + muscular dystrophy. Mouse as similar to humans + rapid life cycle so study of development can be done faster.
Knock In Technology
Add defective gene to organism to understand disease progression.
Germ Line Gene Therapy
Replace defective genes if heritable disease known in family history. ‘Designer Babies’ Gene doesn’t pass to future offspring also as gametes won’t contain defective gene. Not currently carried out.
Transgene
Donor gene in transgenic organisms.
Somatic Cell Gene Therapy
Gene therapy targets affected tissues. Used when caused by defective gene that affects specific + easily reached body parts (lungs). Done at any stage in life.
Adenoviruses
Cause resp infections. Ideal for lung gene therapy. Must first have harmful disease causing genes removed + DNA spliced in. Difficult to remove the disease genes without dismantling genes for entering cells. May cause infection + some immune to them so can’t penetrate.
Retroviruses
Target host cells. Its RNA + donor RNA converted by reverse transcriptase into DNA in host cell.
Episomes
Can function as independent DNA units in nucleus not incorporated into main nuclear DNA. Occur when donor DNA inserted.
Cystic Fibrosis
Malfunction of trans-membrane-conductance regulator protein which keeps epithelial membranes in good conditions. 2 recessive alleles for this. Membranes covered in thick sticky mucus, affecting lungs (higher lung infection risk + lower gas exchange) + pancreatic duct (pancreatic enzymes can’t reach duodenum). Gene therapy helps lungs but not pancreatic duct + adenoviruses may cause infections, immune responses + allergies. Those with G551D (Celtic) mutation can be treated with Ivacaftor. If homozygous for delta F508 mutation, Lumacaftor + Ivacaftor.
Haemophilia B
Variant of haemophilia. Gene for clotting factor 9 mutated.
Genetic Mapping
Identifying where genes are on chromosomes. Location of defective or useful genes.
Chemiluminescent Tag
Involves emission of light due to reaction (e.g. hybridisation)
HapMap Project
International consortium analysing genomes of 300 people to map location of SNPs. Identify set of genetic markers to screen genetic data.
Biobanks
Where genetic data generated by genome sequencing projects is stored.
Gene Knockout
Transgenic organism that has had gene removed or made inoperative. Help to understand genetic diseases.
Gene Knockin
Gene added. Deliberately add defective gene to study disease progression.
Superweeds
GM crops + GEMs could spread their resistance to herbicides + pests to weeds, creating these. Also possible by way of natural selection.
Genetic Screening
Before or after birth. Can screen for Down’s but if positive, is abortion ok? After birth has fewer ethical implications. All newborns in Britain tested for PKU, given diet of low phylalanine so PKU doesn’t develop.
PKU
Phenylketonuria. Recessive inherited condition affecting 1 in 10k people. Lack enzyme so AA phenylalanine accumulates in blood, causing severe mental handicap if left to continue.
Huntington’s Disease
Caused by defective allele. CAG repeated more times than it should. Causes progressive brain deterioration in middle age with complete neurological dysfunction + death. Unusual as allele is dominant, not recessive so no carries. If 1 parent is heterozygous for it, child has 50% chance of getting it.
Pre-Implantation Genetic Diagnosis (PGD)
Screening at embryo stage for parents in at risk groups. Conception by IVF + embryos screened for genetic abnormality. Only healthy embryos implanted. In UK, 60 inherited conditions licensed for PGD.
SCID
Severe Combined Immunodeficiency Disease
Genetically Modified
Containing genetic material that has been artificially altered so as to produce a desired characteristic.
Defective Alleles
Different versions of a gene which are faulty and therefore cause a person to have a particular disease or disability.
Personalised Medicine
Type of medical care in which treatment is customised for each patient.
Designer Drugs
Synthetic type of a legally restricted/prohibited drug, as a loophole for drug laws.
Suicide Genes
Gene whose expression in a cell is lethal for that cell.
Containment Mechanisms
Ways to contain genetically modified organisms. Legal requirement.