Biology Unit 1 summary notes

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  • Created by: Marms
  • Created on: 16-03-12 11:10
  • Risk: a measure of the probability that damage to health will occur as a result of given hazard.

lifestyle aspects that CONTRIBUTE to cancer:

  • smoking-l ung cancer
  • diet- low-fat, high fibre reduces risk
  • obesity- increase chances
  • physical activity- less exercise has higher risk
  • sunlight- more exposed to sunlight/sunbed, the higher chances of developing skin cancer.

Enzymes and Digestive system (in order)

  • oesophagus carries food to stomach
  • stomach- muscular sac, inner layer secretes enzymes. Also has a layer of mucus to stop digesting itself
  • Small intestines- muscular tube, walls secrete enzymes, inner walls are folded into villi for large surface area that increases rate of absorption.
  • Large intestine- absorbes water
  • Rectum- stores faeces
  •  Salivary glands- secrete enzymes such as amylase, breaks down starch into maltose.
  • Pancrease- large gland secretes pancreatic juice containing protease, lipase, amylase.

Digestion is: 1) physical break down 2) chemical digestion

when bigger molecules are broken down into smaller ones by enzymes via HYDROLYSIS. (BY ADDING WATER)

Monosaccarides- (CH2O)n, sweet tasting best know is Glucose ( hexose sugar). when many monosaccarides join together via condensation to make Polysaccarides. they are held together by glycosidic bonds.

test for reducing sugars- add benedict's reagent, if present will turn from blue to orange/brick red.


  • glucose and glucose-maltose
  • glucose and fructose-sucrose
  • glucose and galactose-lactose

hydrolysis breaks the glycosidic bonds!

Test for non-reducing sugars:

add benedict's reagents-no change

add sample to hyrochloric acid (breaks glycosidic bonds)

then add siodium hydrogencarbonate to neutralise

retest, if changes colour then ur test was positive.

Lactose intolerance

person Can't produce lactase. when lactose reaches large intestine it's broken down by microorganism, releasing gas that causes cramps, diarrohea,bloating.

bonds that joins two amino acids called peptide bond, forms during condensation and breaks in hydrolysis.( primary structure-making a chain of them)

secondary- when they twist into a-helix.

tertiary-helix twists and fold further and held together by: disulfide bonds (strongest), ionicbonds and hyrogen bonds (weak) this is a typical 3D shape that enzymes consist of.

Quaternary- 4 polypeptides twisted and folded and an inorganic group e.g. haem group in haemaglobin (quaternary).

test for proteins: add sodium hydroxide, then drops of copper sulphate, purple colorations indicates protein presence.

Enzymes have specific 3D shape that can attatch to substrate to make enzyme-substrate complex.

Lock and key theory- idea that substrate (key) fits into enzyme's active site (lock) like lock and key.

Induced fit- idea that enzyme is flexible and active site moulds itself around sustrate like a hand fits a glove.

higher temperates that enzyme's optimum temp will denature it. (not kill)

any other factos like pH thats above optimum will denature enzyme.

Competitive inhibitor-inhibitor  molecule   has similar shape to substrate so occupies active sit (not permanantly) preventing enzyme-substrate complex being formed. Increasing concentration of sub will increase rate of reaction.

Non-competitive- a molecule that bind to enzyme (not active site) but changes theshape of active site so the substrate doesn't fit. Increasing conc of sub has no effect.


MAGNIFICATION= size of image/ actual…



Brilliant, thank you so much for these!

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