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Description
Flashcards by joannalivesey, updated more than 1 year ago
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Created by joannalivesey
over 10 years ago
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| Question | Answer |
| factors which might increase the frequency at which a mutation in a gene occurs | • high energy radiation (e.g. X-rays) • chemical mutagens (e.g. benzene, cigarette smoke, mustard gas) • length of time of exposure to a mutagen • dosage of mutagen |
| Reasons for using a virus to transfer genes into cells | targets cells and replicates in cells |
| how do you make radioactively labelled fragments visible following electrophoresis? | transfer to a nylon membrane, then use autoradiography |
| how are stem cells able to develop into different types of cell? | • different genes are switched on/off • different enzymes/proteins produced • determined by hormones in its environment |
| why would you see an object in you peripheral view in low visual acuity? | • Higher density of rod cells in periphery, cones concentrated in fovea • Many rod cells connect to one bipolar cell, many of which connect to one ganglion cells • Rod cells send few impulses per unit area of retina |
| why is evaporation of sweat from the skin effective in reducing body temperature? | • sweat evaporates from skin which requires much heat energy • this cools the blood |
| why are males more likely to have a disease carried on sex chromosome? | • males are XY, females are XX • Y chromosome is shorter so often has no equivalent • males only need to inherit one recessive allele to have the disease |
| role of calcium ions in muscle contrations | • calcium ions bind to troponin and cause tropomyosin to twist and reveal binding site on actin • activate ATPase- ATP needed to break and form cross bridges, and move myosin head |
| why use bacteria in genetic engineering? | • Easy to insert genes into bacteria; using a plasmid as a vector • Bacteria reproduce rapidly; so many copies of the target gene are produced • Bacteria can be grown on a large scale; so lots of the target protein can be produced |
| why injected plasmids with target gene into fertilised eggs instead of adults? | • embryo divides by mitosis • gene will be present in all cells of the organism • the gene gets passed to future generations |
| role of phosphates | • ATP – energy source • Phospholipids – membranes • DNA /RNA – e.g. protein synthesis • NADP – photosynthesis |
| arguments against giving reproductive hormones to pigs | • hormones may be present in meat and ingested by humans- may affect female menstral cycle/ have unknown effects |
| why might 2 primers be needed in PCR? | because the sequences at the ends of the target sequence are different- allows both strands to be copied |
| All or nothing principal | • All action potentials are the same size • There is a threshold value that must be exceeded in order for action potential to occur |
| role of a vector? | transfer genes from one organism to another |
| how to antibodies work? | bind to antigens on pathogen, causing agglutination which makes it easier for the phagocyte to engulf the pathogen |
| what is a clone? | A group of genetically identical cells or organisms |
| what is an oncogene? | A gene that stimulates cell division; produced by mutation of a proto-oncogene |
| what are stem cells? | cells that can... divide and renew themselves over long periods are unspecialised can develop into other specialised cell types |
| advantages and disadvantages of using embryonic stem cells in organ transplants | • easier to find (e.g. lots available from IVF), easier to grow, and are pluripotent • might be rejected by immune response of recipient |
| why use yeast rather than bacteria to produce human proteins? | Yeast is eukaryote and it is able to remove introns but bacteria are not |
| why insert pesticide resistance genes into chloroplasts DNA instead of the plant's chromosomes? | Pollination is a potential source of transfer of genes between plants. As pollen grains do not contain chloroplasts, pollen transferred from transgenic plants to non-transgenic plants does not contain foreign genes |
| difference between RFLPs and STRs? | The basic unit of a RFLP is longer |
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