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Biological Molecules - Coggle Diagram
Biological Molecules
Proteins
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Functions: structural, enzymes, transport, hormones, antibodies
Amino acid general structure:
Each has a different R-group (20 different)
Biuret’s Test: sample of solution in test tube + add equal volume of NaOH then a few drops of dilute CuSO4 + mix, positive result goes purple
Globular proteins: spherical, soluble in water, interact with other molecules, enzymes/hormones/haemoglobin
Fibrous proteins: elongated, insoluble, structural roles, keratin/collagen/myosin/actin
Primary structure: polypeptide chain, only contains peptide bonds , sequence of amino acid determine shape + function of protein
Secondary structure: hydrogen bonding causes polypeptide chain to twist into 3D shape, alpha helix/beta pleated sheet
Tertiary structure: twisting + folding of secondary, 3D specific structure, ionic, covalent + hydrogen bonds
Quaternary structure: linking of numerous polypeptide chains, may also contain prosthetic groups
Enzymes
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Lock + Key Model: enzyme is rigid but scientists observed that other molecules could attach to enzyme + alter activity
Induced Fit Model: enzyme is more flexible, active site alters in presence of substrate putting a strain on substrate molecules, distorting bonds + lowering activation energy
Effect of Temperature:
- increase in temp increases kinetic energy so more successful collisions so more enzyme substrate complexes are formed
- hydrogen bonds can break changing shape of active site (45°C)
- optimum temp is when substrates are converted into products at their fastest rate (40°C)
- 60°C, enzyme is so disrupted it denatures
Effect of pH:
- measure of a solution’s hydrogen ion concentration
- small change from optimum alters charges on amino acids changing shape of active site
- significant change can cause hydrogen + ionic bonds to break resulting in denaturation
- -log10[H+]
Effect of Enzyme Concentration: as long as there’s an excess of substrate, an increase in the amount of enzyme leads to a proportionate increase in the rate of reaction up until a certain point (shown by Vmax)
Effect of Substrate Concentration: if the conc of enzyme is fixed + substrate conc is increased slowly, rate of reaction will increase in proportion
Competitive Inhibitors: molecules that have similar shape to the substrate so compete for the AS
Non-Competitive Inhibitors: molecules that attach themselves to an allosteric site
Carbohydrates
Monosaccharide: basic monomer unit of a polysaccharide, sweet-tasting, soluble, CH2On
Alpha Glucose: C6H12O6, hexose sugar
Beta Glucose: isomer, H + OH group switched on Carbon 1
Benedict’s Test: 2cm³ liquid food sample, equal vol of Benedict’s, heat in water bath, positive result goes red
Disaccharide: resulting molecule when a pair of monosaccharides are joined by a condensation reaction, glycosidic bond forms
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Starch: amylose/amylopectin, in plants, energy store + source, large, insoluble, chains of a-glucose
Test: iodine, positive goes blue/black
Glycogen: chains of a-glucose, in animals + bacteria, energy store + source, in muscles + liver, highly branched
Cellulose: in plant cell walls for structure, long straight chains of b-glucose, form cross-links
Nucleic Acids
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DNA Structure: 2 nucleotides chains twisted forming double helix, one phosphate group, deoxyribose, adenine, thymine, cytosine + guanine
bases held together by hydrogen bonds, contain nitrogen
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RNA Structure: single polynucleotide chain, ribose, uracil instead of thymine
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DNA Replication: starts at replication origin
DNA helicase breaks hydrogen bonds
4 different nucleotides in nucleoplasm attach to original strand
DNA polymerase joins nucleotides together by phosphodiester bonds
strands wind into double helix
2 new identical DNA molecules formed
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Water
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High specific heat capacity + boiling point, acts as a buffer to temp changes
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Used in hydrolysis + condensation reactions, photosynthesis + site of chemical reactions
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Lipids
Contain C, H and O, insoluble in water but soluble in other solvents
Triglycerides: 3 fatty acids bonded to 1 glycerol molecule, saturated/unsaturated, high ratio of C-H bonds, high H:O ratio of atoms
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Phospholipids: 2 fatty acids bonded to 1 phosphate molecule, polar molecule
Emulsion Test: 2cm³ sample + 5cm³ ethanol into grease-free, dry test tube + shake, add 5cm³ water + shake, positive result shown by cloudy white emulsion
Functions: cell membrane, energy source, waterproofing, insulation, protection
ATP
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Structure: adenine, ribose + 3 phosphate groups
Unstable bonds between phosphate groups with low Ea
in cells, end phosphate is removed
Hydrolysis of ATP: ATP + H2O -> ADP + Pi + E
adenosine triphosphate + water -> adenosine diphosphate + inorganic phosphate + energy
catalysed by ATPase
Synthesis of ATP: reversible reaction, energy can be used to add a phosphate group to ADP to reform ATP (phosphorylation)
Immediate energy source, releases energy in small, manageable amounts
Roles of ATP
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Phosphate molecule released from breakdown of ATP can be used to phosphyrlate another molecule (more reactive)
Inorganic Ions
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Phosphate: structural roles in DNA + RNA, releases energy in ATP when hydrolysed
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monomers are small, repeating units that combine to form polymers
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condensation reaction is when a bond is formed when 2 smaller molecules join to form a larger one by removing a molecule of water
hydrolysis reaction is when a bond is broken when a large molecule is split into 2 smaller molecules using a molecule of water