OCR AS biology FULL revision notes unit 2

these are my revision notes that I've got and i thought i'd share them with you people 

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Revision Notes for Biochemistry
Definitions
Metabolism ­ All of the chemical reactions that happen in an organism.
Monomer ­ single small molecule, can be joined to make a polymer
Polymer ­ Many similar repeating subunits joined together
Covalent ­ bond formed from sharing electrons. Strong bond
Condensation ­ reaction links 2 molecules with a covalent bond, producing water. Enzyme catalysed
Hydrolysis ­ reaction that splits larger molecules into monomers, using water. Enzyme catalysed
Hydrogen bond ­ weak interaction between slightly negative part and slightly positive part of a
molecule
Functions of Molecules
Carbohydrates Energy storage and supply, structure in some organisms
Proteins Structure, transport, enzymes, antibodies, hormones
Lipids Membranes, energy supply, thermal and electrical insulation, hormones
Vitamins and minerals Take part in reactions, coenzymes, enzyme activators
Nucleic acids Information storage ­ instructions to make proteins
Water Takes part in reactions, support, solvent (polar), transport
Carbohydrates ­ Monomers
Monosaccharides are the monomers (simple sugars ­ sweet and soluble)
Cn(H20)n . 3C = triose, 5C = pentose, 6C = hexose.
Glucose ­ C6H12O6, Used in respiration to release energy
Alpha glucose ­ OH on Carbon 1 is below the ring
Beta glucose ­ OH on Carbon 1 is above the ring
Monosaccharides are joined together by condensation to form
glycosidic bond. Water is made and resulting molecule is a
disaccharide. Many joined together makes polysaccharides.
Carbohydrates ­ Polymers: Energy Storage
Starch: amylose + amylopectin. Amylose: many alpha glucose joined by 1-4 glycosidic bonds.
Amylopectin: Chains of alpha glucose joined 1-4 and branches joined by 1-6 links. Starch found in
plants as starch grains ­ broken down into glucose for respiration

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Glycogen: Chains of 1-4 linked alpha glucose with branches joined by 1-6 links (more 1-6 links than
amylopectin, shorter chains). More compact, more ends to break glucose off ­ energy storage in
animals.
Carbohydrates ­ Polymers: Structural
Cellulose: beta glucose joined 1-4 glycosidic bonds. Second glucose must be upside down to join to
first. Makes long straight chain.
one chain linked to other
chains by hydrogen bonds
­ bundles called
microfibrils. Microfibrils
join together by more H
bonds ­ macrofibril.…read more

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Primary structure ­ specific sequence of amino acids joined by peptide bonds. Order dictated by
order of bases in DNA.
Secondary structure ­ Folding of polypeptide chain into alpha helix or beta pleated sheet. Held
together by H bonds.
Tertiary Structure ­ Folds again to form 3D structure. Held in place by hydrogen bonds, ionic
bonds, hydrophobic interactions and disulphide bridges. Shape depends on order of amino acids and
therefore R groups. Specific shape made, e.g.…read more

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Cholesterol
4 carbon rings. Small, narrow, hydrophobic ­ sits between phospholipids to regulate
fluidity and strength of membrane.
Steroid hormones (testosterone, oestrogen) and vit D and bile made from
cholesterol.
XS cholesterol ­ sticks together in bile ­ gallstones, deposited in lining of blood vessels ­
atherosclerosis.
Water ­ Hydrogen bonding joins molecules together ­ more difficult to escape the liquid, means
water has to get to 100 before it boils.…read more

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Carry out Benedict's test on unknown solution, filter it, and find out transmission, read off graph.
Nucleic Acids ­ Monmers
DNA Nucleotides ­ phosphate group, deoxyribose and organic nitrogenous base (adenine, cytosine,
thymine or guanine)joined by covalent bonds.
RNA Nucleotides ­ phosphate, ribose, base (Adenine, cytosine, uracil or
guanine)
Nucleic Acids ­ Polymers
DNA ­ double stranded polynucleotide. Two strands held together by
Hydrogen bonding between bases ­ complementary base pairing. A-T and
C-G.…read more

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RNA brings amino acids to the ribosome in the correct order, according to the bases on mRNA
amino acids joined together by peptide bonds.…read more

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Revision Notes for Diseases and Immunity
Health = state of mental, physical and social wellbeing
Disease = Departure from good health
Parasite = An organism that lives in or on another living thing
Pathogen = Organisms that cause disease.
Infectious diseases can be cause by :
- bacteria: prokaryotes, reproduce rapidly, damage our cells and release toxins
- fungi: grow on skin, release spores.…read more

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Cause: Mycobacterium tuberculosis and Mycobacterium bovis. Usually affects lungs
Transmission: droplet infection. Some people can become immune to it, others are vaccinated
against it. Transmission increased by: overcrowding, poor ventilation, poor health, poor diet. Can be
cured by 9 months of antibiotics.
Worldwide Importance: 2005 ­ 8.8 million new cases. Most common in SE Asia, sub-Saharan Africa
and Eastern Europe (poor living conditions). Spread into new areas by people migrating. New strains
are resistant to drug treatment.
World Health Organisation
Use epidemiology, e.…read more

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Macrophages may keep the antigens and display them on their surface to initiate the specific
immune response.
Specific Response
Lymphocytes ­ made in bone marrow. B lymphocytes mature in the bone marrow, T migrate to
Thymus to mature. All have receptors on their surface.
1. Infection ­ the pathogen reproduces and infects cells and tissues.
2.…read more

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T cells, B cells and macrophages release interleukins (stimulate proliferation of B and T)
- Many cells release interferon (inhibit virus replication and stimulate T killer cells)
Vaccination
Can be whole live organisms, harmless version, dead pathogen, just antigens or toxins.
Immune system goes through immune response ­ makes antibodies and memory cells. Upon second
infection response is quicker.
Herd vaccination ­ vaccinate all. Not always possible
Ring vaccination ­ only those who have been in contact with known case.…read more

Comments

Ellen Thompson

amazing, thank you so much!

Bethany Cunningham

Nice detail and easy to read-thank you!

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