unit 5 bio flashcards

Pregunta	Respuesta
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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