PROCESSES IN PAPER 1

processes and practicals you could be asked six markers on

genetic engineering

• process in which the genes of an organism are modified in order to introduce desirable traits, directly introduces new genes to that genome not seen in species

• find desired gene in organism

• cut it out using restriction enzymes leaving sticky ends (unpaired bases at ends)

• extract plasmid dna from bacteria

• cut open plasmid dna leaving sticky ends also using restriction enzyme

• insert desired gene into gap in plasmid dna

• connect sticky ends using ligase and you now have recombinant DNA

• recombinant dna goes back into bacteria, acts as vector as it has transported foreign dna

• when bacteria divides it will copy modified dna

evolution by natural selection

1. genetic variation exists within a species due to sexual reproduction and mutations

2. change in environment cause increased competition for resources

3. SOME VARIATIONS OF A GENE MAKE organisms HAVE traits THAT ARE better adapted to changed environment

4. these organisms are more likely to survive and reproduce, and pass on variation to offspring

5. over many generations evolution will have occurred as species will be better adapted to cope with environments

tissue culture

• process of growing cells or tissues in liquid containing nutrients (agar)

• advantages in medicine (growing organs that wont be rejected, study how cells communicate w eo, study viruses, study how cells respond to different medicines)

• advantages in plant breeding (clone plants, grow plants near extinction, grow plants that are difficult to grow)

  1. piece of plant placed in bleach solution to sterilize

  2. small piece of plant put in nutrient agar to grow

     2. few cells put in nutrient agar to grow into callus (group of undifferentiated cells)

  3. piece of plant treated with hormones to grow roots and shoots

     3. callus treated with hormones so that it grows roots and shoots

     4. plantlets are separated and grown on nutrient medium in sterile conditions

  4. when large enough planted into the soil

protein synthesis

• sections of dna are called genes

• genes code for are particular trait

• alleles are variations of a gene (you have two alleles for each gene)

  1. rna polymerase binds to non coding region of dna in nucleus, unzipping the two strands of dna

  2. complementary mrna bonds to the dna bases. (dna bases can be a,t,c,g but mrna is aucg)

  3. mrna strand leaves the nucleus by nuclear membranes and travels to the ribosomes

  4. in the ribosome complementary anticodons of rna bind to codons of mrna.

  5. each anticodon of rna brings along a specific amino acid, the amino acid forms a chain of protein

  6. ergo the order of bases in dna codes for a particular protein

     • note: steps 1-3 were transcription, steps 4-6 were translation

genetic engineering

virus pathways

lyctic and lysogenic pathway

food tests

look at one note maty

microscopy

• take a thin slice of specimen.

• pipette a drop of water onto clean slide.

• use tweezers to place specimen on slide.

• if the specimen is colourless, put a drop of stain on it such as iodine.

• place a coverslip over the specimen, lowering it gently so there are no air bubbles.

• select the lowest objective lens, and use the coarse adjustment knob to focus the image

• adjust focus with fine focus knob, until you see a clear image, and place a ruler to find your field of view.

investigating osmosis

investigating energy in food

• weigh a small amount of dry food

• add a set volume of water to a boiling tube which will later on be used to see how much energy the food has released

• measure the temp of the water then set fire to the food using a bunsen burner

• hold the burning food directly under the boiling tube, and keep relighting until the food doesn’t catch fire again

• measure the temperature of the water again

• mass of water x temp rise in water x 4.2 = total energy in food (J)

WHO definition of health

the state of complete physical and social wellbeing and not merely the absence of disease or infirmity

immune response

1. pathogens have molecules on their surface called antigens, which vary from molecules on human cells

2. b-lymphocytes produce antibodies

3. when a b-lymphocyte produces a complementary antibody for an antigen on a pathogen, it becomes activated

4. an activated lymphocyte rapidly divides by mitosis and releases lots of antibodies into the blood

5. antibodies bind to antigens and pathogens are killed

6. some lymphocytes remain in the blood as memory lymphocytes to ensure a fast and strong second wave response

making monoclonal antibodies

• monoclonal antibodies are antibodies that are specific to one antigen

  1. inject a rat with a particular pathogen, which has particular antigens on

  2. remove lymphocyte which produces the complementary antibody

  3. fuse the lymphocyte with tumour cell called MYELOMA cell (this means the lymphocyte will divide rapidly)

  4. this fusion of lymphocyte and myeloma cell makes a hybridoma cell.

  5. hybridoma cells divide rapidly and produce monoclonal antibodies

uses of monoclonal antibodies

• pregnancy tests

  • more on next flashcard

• diagnosing/ monitoring cancer cells

  • antibodies labelled with radioactive substance and injected into body by drip

• delivering drugs to cancer cells

  • drug attached to ma, ma binds to cancer cell and deliver drug to specific cell

• detecting blood clots

  • antibodies are labelled by radioactive substance and enter body by drip, blood clots have proteins on them which monoclonal as can bind to

pregnancy test (the deets)

• only pregnant women’s urine contains hormone HCG, the antibodies in pregnancy test sticks are complementary to this hormone

  1. the bit of the stick you wee on has antibodies with blue beads attached

  2. the hormone hcg bonds to these antibodies also

  3. the antibody flows along the stick with the flow of urine

  4. some antibodies are stuck to the stick on the test line and cant move

  5. hcg attaches to these antibodies on the test line, bringing the blue bead with it and turning the test line blue = pregnant!

development of new drugs

• preclinical testing

  • first on human cells and tissues in labs

  • then test drugs on animals to see the effects on whole body, and the ideal dosage

• clinical testing

  • test on healthy volunteers first to see if the drug has side effects

  • test on unhealthy volunteers. half the group is given the drug and half the group is not to allow for the placebo affect. (this tests one what affect the drug actually has)

effects of different antibiotics and antiseptics (can be plant extracts)

• prepare bacteria culture on petri dish with nutrient agar or in nutrient broth solution

• to prepare agar, agar jelly is poured into a petri dish and with in an inoculating loop bacteria is transferred onto agar jelly. leave bacteria to multiply.

• add paper discs soaked in different types of antibiotics/antiseptics/plant extracts, to agar.

• as the antibiotic diffuses into the agar, it should kill bacteria around it leaving a zone of inhibition. the larger the zone the more effective the antibiotic. use pir²

aseptic techniques in practical above

• whole practical needs to be carried out with aseptic technique so no microorganisms cannot get on equipment and interfere with experiment / result

  1. petri dish put in autoclave to kill any microorganisms

  2. inoculating loop passed through hot part of bunsen flame (blue bit)

  3. bacteria cultures should be kept in a container with a lid to stop air of microorganisms getting in

  4. petri dish kept upside down so condensation cannot drip on bacteria culture

treatments for cardiovascular disease

1. improve lifestyle (less fatty diet, more exercise, no smoking, lose weight)

2. drug treatment to thin blood, reduce cholesterol and lower blood pressure

   • statins reduce the amount of cholesterol in the blood

   • anticoagulants reduce the chance of blood clotting

   • antihypertensives reduce blood pressure

3. surgery to add stent to artery (widen artery, reduce blood pressure,) bypass blocked artery with healthy artery or heart transplant

   • surgery always comes with the risk of infection, and in the heart, rejection, blood clots, and internal bleeding

how does smoking cause cardiovascular disease

• nicotine in smoke fumes increases heart rate

• this increases blood pressure

• this damages arteries

• this increases cholesterol build up

• this causes blockages in arteries

• this causes strokes or heart attacks (cardiovascular disease.)

meiosis

• is a reduction division that results in four non genetically identical haploid cells, the process involves two divisions

cholera

bacteria

tuberculosis

bacteria

coughing and lung damage

stomach ulcers

bacteria (helicobacter pylori)

ebola

virus

is spread through bodily fluids

causes haemorrhagic fever

HIV

virus

this is the virus that kills white blood cells and leads to the onset of aids

can be spread through sexual contact, sharing needles, or from mother to unborn child

malaria

protist

damages red blood cells and can damage the liver

chalara

fungus