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  • Created on: 31-05-13 21:02


Monomer: amino acid. Polymer: Polypeptide/protein.

Primary Structure: The unique sequence of amino acids.

Secondary Structure: The coiling or folding of a polypeptide chain into alpha helices or beta pleated sheets. Held in place by hydrogen bonds.

Tertiary Structure: The 3D shape of a protein. Ionic, hydrogen bonds, disulphide bridges, hydrophobic and hydrophilic interactions.

Quaternary Structure: Several polypeptide chains.

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Monosacharides are joined in a condensation reaction with glycosidic bonds.

Polysacharides include: coiled chains in amylose, straight in cellulose and branched in glycogen

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Mainly triglycerides: glycerol and three fatty acid molecules. 

Insoluble, good insulator, used for membranes.

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Food Tests

Lipids: Emulsion test. Mix thoroughly with ethanol, then pour into water.

Reducing sugars: Benedicts' test. Heat with Benedicts' solution. Orange/green precipitate.

Non-Reducing sugars: Boil with HCl, then neutralise with sodium hydrogencarbonate. Complete Benedicts' test.

Proteins: Add biuret reagent blue to purple.

Starch: add iodine, turns blue/black.

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Nucleic acids

Monomer: Nucleotides. Polymer: polynucleotides.

DNA nucleotide: deoxyribose (pentose sugar), nitrogenous base (A,C,G,T), phosphate group.

A gene codes for a protein.

Replicates semi-conservatively.

DNA is needed to make all the proteins/enzymes needed to control cell activities.

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Lower activation energy and speed up metabolic reactions. Biological catalysts.

Intracellular or extracellular.

Globular proteins.

Lock and Key hypothesis.

Induced fit hypothesis: Active site changes shape to fit more closely to the substrate.

ESC forms, bonds made/broken EPC formed. Product released.

Increasing substrate or enzyme concentration speeds up a reaction until the maximum.

Competitive inhibitors are similar shape to substrate, fit into active site non permantently.

Non-competitive inhibitors change the shape of an active site permanently.

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Diet and Nutrition

A balanced diet has 7 components, if these are unbalanced, malnutrition.

All food chains start with plants.

Too much saturated fat can lead to CHD.

LDLs deposit cholesterol in the artery walls, this may cause bloackages.

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Food Production

Selective breeding to acheive desired characteristics.

Fertilisers to improve crop growth.

Pesticides improve yield by decreasing disease.

Antibiotics stop the spread of disease.

Microorganisms can be made for food.

Food spoilage prevented by freezing, heating, irradiation, pickling, adding sugar/salt.

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Health and Disease

Parasite: lives on or in its' host, gaining nutrition from its host and causing it harm.

Pathogen: a disease causing organism.

Malaria affects over 200 million. TB and HIV are spreading.

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Smoking and Disease

Tar: a combination of chemicals that settle in the airways and on the alveoli increasing diffusion distance in gaseous exchange.

Paralyses cilia and stimulates goblet cells. Pathogens are not moved out and can block bronchioles. bronchitis.

Alveoli lose elasticity and burst. emphysema.

Tar contains carcinogens. Lung cancer.

Nicotine releases adrenaline and makes platelets sticky increasing risk of thrombosis and strokes.

CO causes atherosclerosis and CHD.

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B cells create antibodies. T cells attack pathogens directly.

Phagocytes engulf and digest.

Artificial Immunity: injection

Natural Immunity: Breastfeeding, across placenta

Passive: antibodies

Active: Antigens.

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Classification: sorting organsims into groups.

Taxonomy: Studying characteristics of organisms so they can be classified.

Phylogeny: Studying the evolutionary relationship between organisms.

Prokaryotes: single celled, no nucleus, naked DNA

Protoctista: Organisms that don't fit anywhere else

Animals: Multicellular, eukaryotic, heterotrophic, can move.

Plants: Multicellular, autotrophic, cellulose cell wall.

Fungi: Hyphae from a mycellium, multinucleate, chitin cell walls.

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Variation is either continuous or discontinuous.

Darwin observed: offspring are similar to parents, overproduce, variation, population size stays constant.

Darwin concluded: There is a struggle to survive, those better adapted survive to pass on characteristics.

The frequency of these characteristics increase as they have been selected.

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It is imprtant to conserve species due to aesthetics, ethics, ecological reasons and economical reasons.

Climate change will affect agriculture and will allow tropical diseases to spread worldwide.

In situ: national parks. conflict over land use.

Ex situ: zoos and seed banks. difficult to breed in captivity and hard to reintroduce to wild.

CITES monitors trade.

Rio Convention encourages protection of biodiversity in many countries.

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