Overview of unit 1 biology aqa

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  • Created by: mariam
  • Created on: 08-01-13 22:53

Pathogens cause disease by-producing toxins and damaging host cells
Tests- buirette-enzymes-purple indication=present
Reducing sugar-benedicts reagent- water bath-red=present

past paper notes

Antibodies in test must be monoclonal antibodies because they all have the same shape.
Antigens are reffered to as monoclonal because they are produced form a single clone of B cells

When starch is hydrolysed it forms glucose and maltose

 Subrate wont bind elswhere very common reasons on markschemes-
Only fits in that active site
complementary shape to active site, only binds to that enzyme and form Enzyme Substrate complexes.


ice cold- redce enzyme activity

isotonic-net movement 0 prevents osmosis-cell doesnt shrivel or burst.

Buffered-mantain constant PH- repirationin cells produces carbon- carbonic acid

What is a HPV antigen?- protein that causes immune response.

Lactase breake down to glucose and galactose

digestion of starch-

Amylase hydrolyses starch to maltose.
Maltase breaks down maltose to alpha glucose
Hydrolysis of glycosidic bond takes place.

Competetive inhibitor-reason- complementary shape to enzymes active site and binds to it so less enzyme substrate complexes are formed.

Co-transport of glucose uses facilliated diffusion

Induced fit model- substrate does not have complementary shape to active site. The substrate binds to active site and alters its shape as its flexible.

Antibodies only affect one antigen as they have a specific shape and fit to a certain antigen-complentary shape-forns E-S complexes.

Lock and Key model-

Substrate binds to active site which is complementary. Forms enxyme substrate complexes.

Facilliated diffusion- some cant pass due to their shape and size.

Small water soluble molecule diffuse rapidly through the membrane.

Lung disease-

Reduced efficiency of gas exchange alveoli walls are thickened-longer diffusion pathway-fibrous tissues in lungs so less intake of oxygen- reduces surface are afor gaseous exchange.

TB-Caused by bactrium spreads in upper regions of lungs where there is pentifull suplly of oxygen.

Pulmonary fibrosis-

Scars form on epethelium of lungs. air space in lungs contain fibrous tissues so less intake of oxygen. Alveoi walls are thickened- reduced surface area and longer diffusion pathway. Loss of elasticity in lungs.

Asthma-example of an allergic recation-lining of the airways become inflammed.
cells of the epethelium lining release larger quantities than normal. Fluid leaves capillarie sinto airways. Muscles surrounding bronchi and bronchioles contract.

Emphysema- loss of elastin. Impossible to diagnose untill lugs have become irreversibly thickened. Break down of the alveoli causes increase in diffusion pathway and decrease of surface are so less diffusion. Less elastina so reduced flow rate.


If reduced elasticity- diffusion gradient reduced and lungs will not inflate.
To mantain a difference in oxygen alveoli bring in air containing higher oxygen concentration and removes lower concentrations.

Alveoli walls folded- increases surface area so faster rate of diffusion.

Prtimary structure determined by sequence of amino acids.

Quarternary structure-More than one polypeptide chain.
Ttertairy structure- disulfide, ionic and hydrogen bonds.- 3D shape bending and twisting of the polypeptide helix.


If more than one injection given- increase production of memory cells and antibodiesaccination-

contains dead antigens which stimulate productionof antibodies which destroy…


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