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Biological Molecules - Coggle Diagram
Biological Molecules
Water is a polar molecule. Unevenly distributed charge due to the fact that the oxygen is slightly negative attracts the hydrogen atoms that are slighly positive of other oxygen molecules
- metaobolite - removed in condensation reactions, water is added to break a bond in hydrolysis reactions
- solvent - as water is a polar molecule, allows chemical reactions to occur within cells, metabolites can be transported efficiently
- High specific heat capacity - 4200 J/Kg°C measure of the energy required to raise the temperature of 1kg of a substance by 1°C Many hydrogen bonds, so it buffers temperature chages
- Large latent heat of vaporisation - energy required to change its state without a change in its temperature (liquid to gas) to break hydrogen bonds absorbs this energy as heat providing a cooling effect with loss of water through evaporation (for example sweating)
- Strong cohesion between water molecules because of hydrogen bonds between water molecules -Allows columns of water to move through the xylem of plants & blood vessels (adhesion -to other molecules- to cellulose) -Surface tension, supports small organisms like pond skaters that rely on surface tension (habitat for small organisms)
- Transparent - essential for aquatic plants because it allows light to penetrate through the water. Rely on sunlight to carry out phootysynthesis
- Decreased density, makes it float. Surface freezing because of hydrogen bonds works as an insulator to prevent the water from freezing
Definitions
Monomer smaller units from which larger molecules are made
Polymer larger molecules from many repeating units joined together
Condensation reaction joins 2 monomers together with the formation of a covalent bond and the elimination of a water molecule Hydrolysis reaction breaks the covalent bond between 2 monomers using a water molecule
Triglycerides A glycerol molecule and three fatty acid chains - NON-POLAR ester bond formed by condensation reaction between each of the 3 OH groups on the glycerol & the OH group of each fatty acid chain.
- energy storage, large ratio of energy-storing carbon-hydrogen bonds 2. high ratio of hydrogen to oxygen atoms- metabolic water source 3. hydrophobic/ non-polar fatty acids so insoluble in water (do not affect water potential)
Phospholipids A glycerol molecule, a phosphate group & 2 fatty acid chains 2 condensation reactions to form 2 ester bonds
hydrophilic 'head' can interact with water as it is charged, face outwards towards water & the fatty acid tails are hydrophobic face inward, away from the water repelled by water so point away from water Forms phospholipid bilayer make up plasma membrane,allowing lipid-soluble (non-polar)/small substances forms a barrier
Saturated fatty acids- the hydrocarbon chain has ONLY single bonds between carbons Unsaturated fatty acids- the hydrocarbon chain has one or more double bonds between carbon atoms
Dipeptide: joining of two amino acids by a condensation reaction Polypeptides: condensation of many amino acids Amino acids join together by a condensation reaction, removing a water molecule between a carboxyl group of one and an amine group of anotjer, forming a peptide bond
Proteins
PRIMARY STRUCTURE - the number and sequence of the amino acids in a polypeptide chain -held by peptide bonds
SECONDARY STRUCTURE 1. The sequence of amino acids causes parts a protein molecule to coil into alpha helix or fold into beta-pleated sheets. 2. Many hydrogen bonds hold the secondary structure, between NH and C=O
TERTIARY STRUCTURE Folding to form unique 3D shape of the polypeptide chain Hydrogen bonds, ionic bonds and disulphide bridges form between R groups. A change to the amino acid sequence would affect the secondary & tertiary structure as these bonds would form in different places.
QUATERNARY STRUCTURE - more than one polypeptide chain - formed by interactions between polyppetides eg. Antibodies, haemoglobin
If even one amino acid in the sequence is different, causes ionic/hydrogen/disulphide bonds to form in a different location. This results in a different 3D shape.
Enzymes - (a bilogical catalyst) proteins with a 3D structure, an active site which has a specific shape that can only bind to a certain substrate. -Each enzyme lowers activation energy -to speed up the reaction
Lock & Key Model - Shape of the active site (lock) is exactly complementary to the speciifc substrate molecule (key) - the enzyme active site is a fixed shape. The substrate fits in exactly, can collide and attach to the enzyme. This forms an enzyme-substrate complex.
Infuced Fit Model - Substrate binds to the active site of the enzyme. Causing active site to change shape so it is complementary to its substrate. So enzyme-substrate complex forms. Causing bonds in substrate to bend/distort, lowering the activation energy
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Tests
Tests for starch: 1. add iodine solution 2. turns from roange to blue-black Test for reducing agent: 1. Add Benedict's reagent 2. Heat in a boiling water bath 3. blue to brick red
Test for non-reducing sugars (sucrose) 1. Do Benedict's test and & stays blue 2. Heat in a boiling water bath with acid (to hydrolyse into reducing sugars) 3. Cool the solution then add an alkali to neutralise. 4. Add Benedict's reagent & heat. 5. blue to red precipitate
Test for lipids 1. Mix/Shake the sample in ethanol 2. Then, add distilled water. 3. Milky white emulsion
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Inorganic Ions does not contain carbon -found in solution in the cytoplasm & body fluids -used in cell signalling & neuronal transmission
Hydrogen Ions are protons, inverse realationship, the more H+ ions present, the lower the pH (the more acidic the solution) Changes in pH can affect enzyme structure
Iron ions (ferrous Fe2+, ferric Fe3+, oxidation states), haemoglobin transports oxygen around the body contains Fe2+, binds to oxygen
Sodium ions are required for the transport of glucose and amino acids across the cell-surface membranes by co-transport & transmission of nerve impulses
Phosphate ions (PO4 3-) attach to other molecules to form phosphate group, component of DNA, RNA & ATP -In DNA & RNA, allow indivudal nucleotides to bond to form polynucleotides -in ATP bonds between phosphate groups store energy when broken release a large amount of energy used for cellular processes -Phospholipid bilayer
Carbodyrates
Starch - alpha glucose - 1-4 glycosdic bonds in amylose. 1-4 & 1-6 in amylopectin -made of 2 polymers: Amylose (unbranched helix), Amylopectin (branched molecule, increased surface area for rapid hydrolysis back to glucose for AEROBIC respiration) -helical (compact), large & insoluble (won't affect water potential)
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Cellulose -beta glucose -1-4 glycosidic bonds -structure strength for cell wall -Polymer forms long, straight chains, held in parallel by many hydorgen bonds to form thicker fibres called microfibrils (very strong, still flexible)
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Glycogen -alpha glucose -1-4, 1-6 glycosidic bond -highly branched molecule -branched structure increases surface area for rapid hydrolysis back to flucose for respiration -glucose is an energy store as it can be hydrolysed to release glucose quickly when needed respiration, insoluble (won't affect water potential)
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Nucleic Acids
DNA: holds genetic information, RNA: transfers genetic information from DNA to ribosomers -both are polymers of nucleotides - information-carrying molecules -RIBOSOMES formed from RNA & proteins
DNA Nucleotide: Pentose sugar (deoxyribose, nitrogen-containing organic base (adenine, guanine, cytosine, thymine) & phosphate group
RNA Nucleotide: Pentose (ribose), nitrogen-containing base (adenine, guanine, cytosine uracil) & phosphate group
Polynucleotides, created via condensation reactions between the deoxyribose sugar & the phosphate group of different nucleotides, creating a phosphodiester bond
DNA molecule: 2 polynucleotide chains that form a double helix, held together by hydrogen bonds between speciifc complementary base pairs. An RNA molecule is a single-stranded, short polynucleotide chain
Complementary base pairs: Adenine - Thymine (2 hydrogen bonds) Cytosine - Guanine (3 hydrogen bonds)
Stable structure- phosphodiester bonds & double helix. Double stranded- replication so both strands as a template Weak hydrogen bonds for easy unzipping of the two strands in a double helix during replication A large molecule to carry lots of information, Complementary base pairing allows identical copies to be made
DNA Replication-Before cells divide (by mitosis/meiosis) all DNA must replicate to have identical copies of the entire genome. - Semi-conservative replication: in the daughter DNA, one strand is from one parental DNA and one strand is newly synthesised)
Semi-conservative Replication: 1 DNA heliase breaks the hydrogen bonds between complementary bases in the polynucleotide strands, causing the unwinding of the double helix. 2. Both strands act as templates 3. Free DNA nucleotides are attracted to exposed complimentary bases & join by specific complementary base paring. 3. DNA polymerase (5' to 3') joins adjacent nucleotides, forming a phosphodiester bond via a condensation reaction.
ATP
- ribose - adenine - 3 phosphate groups
ATP hydrolysis catalysed by enzyme ATP hydrolase ATP --> ADP + Pi ATP is synthesized by a condensation reaction between ADP & Pi catalysed by ATP synthase (Photosynthesis & Respiration) ADP + Pi (energy) --> ATP + water
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