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Topic 1 -ID - Coggle Diagram
Topic 1 -ID
Nucleic acids DNA & RNA
DNA
Deoxyribonucleic Acid codes for the sequence of amino acid in the primary structure of a protein, which in turn determines the final 3D structure and function of a protein.
it is essential that cells contain a copy of this genetic code.
The DNA polymer forms a double helix
DNA Nucleotide
The monomer that makes up DNA is called a nucleotide. It is made up of deoxyribose (pentose sugar), a nitrogenous base and one phosphate group.
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PolynucleotidesThe polymer of nucleotides is called a polynucleotide.Created via condensation reactions between the deoxyribose sugar and the phosphate group, creating a phosphodiester bond.The DNA polymer occurs in pairs joined by hydrogen bonds between bases. This creates the double helix.Hydrogen bonds an only form between complementary base pairs
- Cytosine & Guanine
- Adenine & Thymine.
RNA
RNA is a polymer of a nucleotide formed of ribose, a nitrogenous base and a phosphate group.
The nitrogenous bases in RNA are adenine, guanine, cytosine and uracil.
RNA has the base uracil instead of thymine. In comparison to the DNA polymer, the RNA polymer is a relatively short polynucleotide chain and it is single stranded.
The function of RNA is to transfer the genetic code from DNA in the nucleus to the ribosomes. Some RNA (rRNA) is also combined with proteins to create ribosomes.
RIBOSE INSTEAD OF DEOXYRIBOSE
Semi-conservative replication
- Double Helix unwinds - DNA helicase breaks the hydrogen bonds between complementary bases.
- Free floating nucleotides bind - attracted to complimentary base pairs on the template strands.
- Phosphodiester bonds form between adjacent nucleotides by a condensation reaction - catalysed by DNA Polymerase.
- Two sets of daughter DNA - both with one strand of parental DNA.
Evidence for this model
Watson & Crick discovered the structure of DNA in 1953 helped by Rosalind Franklin's research on X-ray diffraction.
Meselson and Stahl conducted an experiment with heavy and light chains which proved the model.
Biochemical Tests
Test for Starch
- Add iodine
- A positive test observation = solution turns from orange to blue/black
Test for reducing sugars
- Add Benedicts reagent and heat
- A positive test observation = solution turns from blue to green, yellow, orange or red
- the more red the more concentrated
Test for non-reducing sugars
- Following a negative Benedict's test, where the reagent remains blue.
- Add acid and boil - (this is acid hydrolysis).
- Cool the solution then add and alkali to neutralise.
- A positive test observation = solution turns from blue to orange or red
Test for Proteins
- Add Biuret.
- A positive test observation = solution turns from blue to purple.
Test for lipids
- Dissolve the sample in ethanol
- Then, add distilled water.
- A positive test observation = a white emulsion forms.
Carbohydrates
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Polysaccharides
Starch
Monomers - Alpha Glucose
Bonds - 1,4 + 1,6 glycosidic
Function - Store of glucose
Location - Plant cells (e.g chloroplasts)
Structure - Amylose (unbranched helix) + Amylopectin (branched molecule)
Structural benefit - Helix can compact. Branched structure increases SFA for rapid hydrolysis. Insoluble will not affect water potential.
Celluose
Monomers - Beta Glucose
Bonds - 1,4 glycosidic
Function - strength for cell wall
Location - Plants - cell wall
Structure - Long straight chains. Held in parrallel forming Fibrils (hydrogen bonds)
Structural Benefits - many bonds provide strength. Insoluble, does not affect water Potential
Glycogen
Monomers - Alpha Glucose
Bonds - 1,4 & 1,6 Glycosidic
Function - store of glucose
Location - Animals, mainly in muscle and Liver cells.
Structure - Highly branched molecule.
Structural benefits - Branched structure increases SFA for rapid hydrolysis. Insoluble, no affect on water potential.
Lipids
Triglycerides
Formed from the condensation reaction between a glycerol molecule and three molecules of fatty acids.
3 Water Molecules produced
Properties of Triglycerides
- Energy Store - Large ratio of energy-storing carbon hydrogen bonds to carbon atoms, a lot of energy is stored.
- Metabolic water Source - due to the high ratio of hydrogen to oxygen atoms. Can release water if oxidised.
- Do not affect water Potential or osmosis - because they are large and hydrophobic, making them insoluble.
- Low mass - lots can be stored without increasing mass and preventing movement.
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Phospholipids
Properties
Hydrophobic head - negative charge on phosphate group. Causing attraction of water and repel fats.
Hydrophobic tail - uncharged fatty acid chains, repels water and mixes with fats.
Polar - two charged regions.
Bilayer - positioned so that heads are exposed to water and the tails are not.
Structure
- 1 Glycerol molecule.
- 2 Fatty acid chains - bound to glycerol through condensation reaction (ester bond)
- 1 Phosphate group - bound to glycerol as well.
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Proteins
Enzymes
Structure & Function
Enzymes are tertiary structure proteins which lower activation energy of the reactions they catalyse.
The active site is specific and unique in shape due to the specific bonding in the tertiary structure of the Protein. The Location of the bonds is determined by the primary structure.
Due to this specific active site, enzymes can only attach to substrates that are complementary in shape
Models of Enzyme Action
The induced fit model is more widely accepted than the lock and key model.
Induced fit is when the enzyme active site is induced to mould around the substrate.
When the enzyme-substrate complex occurs, due to the enzyme moulding around the substrate it puts a strain on the bonds and therefore lowers the activation energy.
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Inhibitors
Competitive Inhibitors
- Same shape as the substrate
- Bind to the active site
- Prevents enzyme-substrate complexes.
If you add more substrate it will out-compete the inhibitor, knocking them out the active site.
Non-competitive inhibitors
- Bind to the allosteric site.
- Causes the active site to change shape.
- No enzyme-substrate complexes.
The substrate can no longer bind, regardless of how much substrate is added.
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Water
Five Key Properties of WaterHyrdrogen bonds form between different water molecules between the oxygen and hydrogen atom.THESE BONDS GIVE PROPERTIES OF:
- Metabolite - (Condensation and hydrolysis)
- Important solvent in reactions.
- High heat capacity - buffers temperature.
- Large latent heat of Vaporisation - provides a cooling effect with loss of water through evaporation.
- Strong Cohesion between water molecules; supports transpiration.
ATP
ATP is a nucleotide derivative. It is and immediate source of energy for biological processes. Metabolic reactions in cells must have constant supply of ATP.
ATP is made during respiration from ADP + Pi using ATP synthase.
ATP can be hydrolyzed into ATP + Pi using ATP hydrolase. This releases a small amount of energy.
ATP can also transfer energy to other compounds. The inorganic phosphate released during the hydrolysis of ATP cann be bonded onto different compounds to make them more reactive.This is known as phosphorylation.
Inorganic Ions
- Inorganic ions occur in solution in the cytoplasm and body fluids of organisms, some high in concentrations and others very low.
EXAMPLES:
- Hydrogen Ions - Lower pH of solutions and impact enzyme function and haemoglobin function.
- Iron ions - component of haemoglobin in oxygen transport.
- Sodium Ions - involved in co-transport and generating of action potentials.
- Phosphate ions - component of DNA and ATP.
