MISCELLANEOUS HUMAN BIO REVISION

stuff i got wrong in the mock

what are the 3 causes of mutations?

1. errors in DNA replication

2. exposure to mutagens

3. errors in cell division

what are some symptoms of sickle cell anemia?

fatigue, jaundice, organ damage, increased blood pressure, heart failure

blood glucose homeostasis- too low (negative feedback response)

• STIMULUS

• blood glucose decreases below homeostatic levels

• RECEPTOR

• chemoreceptors in the pancreas detect decrease in blood glucose below homeostatic levels

• MODULATOR

• the pancreas receives the signal from the chemoreceptors

• alpha cells in the islets of langerhans in the pancreas are stimulated to secrete glucagon

• EFFECTORS

• glucagon stimulates the process of glycogenolysis (glycogen → glucose)

• glycogenolysis uses glycogen stores from the liver and muscle cells 

• glucagon stimulates the process of gluconeogenesis (new glucose)

• amino acids and fats are broken down to produce glucose in the liver

• glucagon stimulates lipolysis

• fatty acids are broken down into glucose

• RESPONSE

• blood glucose increases by…

• glycogenolysis (glycogen → glucose)

• gluconeogenesis (new glucose)

• lipolysis

• the response opposes the stimulus

• negative feedback to the pancreas

• return to homeostatic levels (normal blood glucose levels)

thirst reflex

• water is lost= reduction in plasma volume

• results in increased concentration of extracellular fluid

• STIMULUS:

• osmoreceptors in hypothalamus detect increase in osmotic pressure above homeostatic levels

• dry mouth

• RESPONSE

• stimulation of thirst centre → person feels thirsty → stimulates person to drink

• fluid enters the alimentary canal

• its absorbed in the plasma

• blood circulates the body

• water moves via osmosis into intercellular and intracellular fluids

• osmotic concentrations are restored

• thirst centre no longer stimulated

shallow water blackout

• HYPERVENTILATION

• occurs before diving and artificially lowers CO2 levels

• OXYGEN DROPS

• as breath hold begins, O2 is metabolised and CO2 levels increase

• as breath hold continues, body is starved of O2

• UNCONSCIOUSNESS

• increased CO2 levels in body usually forces a breath

• because CO2 levels were low on submersion, there is not enough to initiate a breath and swimmer loses consciousness

• DROWNING

• once swimmer is unconscious, the body reacts to force a breath

• causes lungs to fill with water

steps in recombinant DNA

1. identify and isolate the desired gene in human DNA

2. use a restriction enzyme to cut the gene at recognition sites (at sticky ends)

3. select a vector (bacterial plasmid) and extract it from the bacterial cell

4. cut the bacterial plasmid using the same restriction enzyme

5. insert the gene into the plasmid (splicing)

6. DNA ligase glues in the inserted gene (now recombinant plasmid)

7. put recombinant plasmid back into vector

8. bacteria will clone to make multiple copies

9. extract genes for use

what is PCR used for

used to amplify (make copies of) DNA samples of interest

Process of PCR

• DENATURING

• buffer containing DNA sample, nucleotides and taq polymerase heated heated (approx 94-98 degrees)

• this breaks the hydrogen bonds between double stranded DNA molecules (creating single strands)

• ANNEALING

• sample is now cooled (approx 50-60 degrees)

• allows primers to bind to complementary base sequence on DNA

• primers are small single strands of DNA that allows taq polymerase to attach to DNA

• EXTENSION

• heated again (68-72 degrees)

• Taq polymerase performs complementary base pairing, building new strands of DNA

• thermocycling occurs

what is gel electrophoresis used for?

• aims to produce the DNA profile of the individual

• can then determine how similar 2 samples of DNA are

process of gel electrophoresis

• use restriction enzymes to cut DNA into small sections at recognition sites

• DNA samples of individuals placed within different wells at end of negative electrode

• electric current run through agar gel

• negatively charged DNA will move through the gel towards the positive electrode

• smaller pieces of DNA move faster and further than larger pieces

• DNA profile can now be compared to the DNA ladder to determine the lengths of the strands in the sample

steps involved in inflammatory response

• mechanical damage occurs

• mast cells are activated

• mast cells release histamine and heparin into tissue fluid

• histamine causes vasodilation= increased blood flow to the area of injury

• this causes the symptoms of heat and redness

• walls of capillaries become more permeable/leaky

• increased amount of fluid moves from blood into tissue, causing swelling

• histamines attract phagocytes to the area to actively consume microorganisms and cell debris (will form part of pus when they die)

• heparin prevents blood clotting in the immediate area of injury

• clots form in tissue around damaged area to slow the spread of the pathogen into the surrounding tissue

4 signs of inflammation

• redness

• heat

• swelling

• pain

stages of a fever

1. pyrogens are released by white blood cells into blood following infections e.g. interleukin 1

2. pyrogens cause the hypothalamus to increase the body’s set point temperature

3. the body then feels cold (thermoreceptors detect low body temp) and induces shivering

4. this increases body temp along with vasoconstriction to prevent heat loss

5. fever can ‘break’

6. this causes sweating and vasodilation which brings the body temperature back to normal/homeostatic levels

structural features of bacteria

• no nucleus

what is validity and how to increase

ensuring the experiment tests what its supposed to test

control more variables, introduce a placebo

what is reliability and how to increase

how well the experiments results are able to be replicated

conduct multiple trials to produce an average, larger sample size