BIOLOGICAL MOLECULES

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A level Biology Flashcards on BIOLOGICAL MOLECULES, created by liv harvey on 11/06/2017.
liv harvey
Flashcards by liv harvey, updated more than 1 year ago
liv harvey
Created by liv harvey almost 7 years ago
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CHARACTERISTICS OF WATER High boiling point due to hydrogen bonding, becomes less dense in solid state, cohesive & adhesive, polar so acts as a solvent in which solutes can be dissolved, efficient transport medium
CARBOHYDRATES - GLUCOSE C6H12O6 Six carbons- hexose monosaccharide. Alpha- OH at bottom, Beta- OH at top Polar & soluble in water Glycosidic bonds formed between carbons 1 & 4 by condensation reactions, produces water
CARBOHYDRATES - STARCH Energy store in plants. Many alpha glucose molecules joined to form 2 slightly different polysaccharides known collectively as starch. Amylose- joined by 1-4 bonds, helical, compact and less soluble. Amylopectin- joined by 1-4 & 1-6 bonds, branched structure.
CARBOHYDRATES - GLYCOGEN Energy store in animals and fungi. Branched structure, compact so less room needed for storage. Many free ends where glucose can be added or removed.
CARBOHYDRATES - CELLULOSE Beta glucose molecule joined in straight chain. Beta molecules can only join together if alternate molecules are turned upside town. Cellulose molecules make hydrogen bonds with each other forming microfibrils, joined to make macrofibrils which combine to produce fibres. These are strong and insoluble and used to make cell walls.
TESTING FOR CARBOHYDRATES Benedicts for reducing sugars: >equal amount of sample and Benedict's reagent >Heat gently for five minutes > Brick red precipitate shows positive result
LIPIDS - TRIGLYCERIDES 1 glycerol (alcohol) & 3 fatty acids (carboxylic acids) Both molecules contain hydroxyl groups which interact leading to formation of 3 water molecules and bonds between fatty acids and glycerol (ester bonds)
LIPIDS - PHOSPHOLIPIDS Modified triglycerides containing phosphorus. Found in the cytoplasm of every cell. Phosphate ions have extra electrons- negatively charged, soluble in water. One of the fatty acid chains in triglyceride molecule replaced with a phosphate group
LIPIDS - STEROLS Complex alcohol molecules based on a four carbon ring structure with a hydroxyl group at one end. Dual hydrophobic/ hydrophilic. e.g. Cholesterol.
ROLES OF LIPIDS >membrane formation & creation of hydrophobic barriers >hormone production >electrical insulation >waterproofing >thermal insulation >cushioning to protect vital organs
STRUCTURE OF PROTEINS Primary - sequence of amino acids Secondary - oxygen, hydrogen and nitrogen atoms interact pulling it into alpha helix/ parallel polypeptide chains form sheet-like structures Tertiary- folding of protein into final shape Quaternary - association of two or more individual proteins called subunits
PROTEINS - GLOBULAR Compact, water soluble and roughly spherical in shape. Hydrophobic R-groups kept away from aqueous environment e.g. Insulin
PROTEINS - CONJUGATED Globular proteins that contain an non-protein component called a prosthetic group e.g. Haemoglobin & catalase
PROTEINS - FIBROUS Formed from long, insoluble molecules. High proportions of amino acids with hydrophobic R-groups. Repetitive amino acid sequence. Make strong, long molecules. e.g. Keratin & elastin & collagen
NUCLEOTIDES & NUCLEIC ACIDS Nucleotides: pentose monosaccharide, phosphate group & nitrogenous base. Linked together to form polynucleotide. Phosphate group at fifth carbon of pentose sugar forms phosphodiester bond with hydroxyl group at third carbon of adjacent nucleotide.
DNA Nucleotides have one of four bases. Pyrimidines- smaller, single carbon ring structures - cytosine and thymine Purines- larger, double carbon ring structures- adenine & guanine
ATP Nitrogenous base (adenine), pentose sugar and three phosphate groups. Small, soluble & easily regenerated. Required for synthesis, transport and movement. Hydrolysis removes phosphate group, forming adenosine diphosphate and a phosphate ion, releasing energy.
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