Biochemistry🧪 Flashcards
Magnesium function
- Used to form chlorophyll
* Present bone and teeth
Iron function
Component of haemoglobin
Calcium function
- Used to strengthen bones and teeth
- Used to strength cell walls in plants - major part of middle lamellae
- Important role in blood clotting and muscle contraction
Phosphate function
- Used to form phospholipids
- In many biological compounds such as ATP and nucleic acid
- Needed for root growth
Why is water polar?💧
The hydrogen atoms are slightly positive and the oxygen atom is slightly negative
What does the polar nature of water allow to form?💧
Hydrogen bonds form between a hydrogen atom of one water molecule and the oxygen atom of another - this creates cohesion
What is water cohesion?💧
- Hydrogen bonds between water molecules creates cohesion
* Molecules stick together in a strong lattice structure - long water columns don’t break, e.g. transpiration stream
What is surface tension of water?💧
- At the air/water interface, cohesion produces surface tension
- Some insects can exploit this property - body is supported by surface tension
Why is water’s solvent properties important?💧
- Known as a universal solvent
- Chemical reactions can occur in a solution - chemicals are free to move about
- Makes transport easier - solutes are able to dissolve, e.g. in the blood, and then be carried around the organism
Why is water a metabolite?💧
Used up in many reactions
Why is water a good transport medium?💧
- Good solvent
- Viscous
- Lubricant
Why is water’s high specific heat capacity important?💧
- Takes large amount of energy to raise the temperature of a body of water
- Important to cells - large amount of energy to raise a cell’s temperature, so cell can maintain stable internal temperature which is important for actions of enzymes
- Important In bodies of water - provides a relatively stable environment for aquatic animals
Water’s high latent heat of evaporation💧
- Relatively large amount of energy required to turn water from a liquid to a gas
- Important for organisms as evaporation of water takes energy away from skin, causing a cooling effect
Density changes in water💧
- Solid water has a lower density than liquid water - ice floats
- Important as ice provides an insulating layer on top of a body of water - liquid below ice has higher temperature than air above it - organisms survive
Water’s transparency💧
Light can travel through water, meaning organisms such as plants and algae are able to photosynthesise underwater
Water as a buoyancy aid💧
Water provides support and buoyancy for aquatic organisms
What is a polymer?
Large molecules made up of repeating units of monomers
What is a condensation reaction?
A chemical reaction involving the joining together of two molecules and the removal of a molecule of water
What is a hydrolysis reaction?
The splitting of a large molecule into smaller molecules by the addition of water
What are carbohydrates?🍞
- Source of energy in all living organisms
* All contain carbon - forms 4 bonds, hydrogen - forms 1 bond and oxygen - forms 2 bonds
What is a monosaccharide?🍞
- CnH2nOn
- Classified by number of carbon atoms: triose (3), pentose (5), hexose (6)
- Provides building blocks for larger carbohydrate molecules
- Act as a respiratory substrate
Glucose🍞 (monosaccharide)
- Used in respiration to produce ATP
- Monomer for many different polysaccharides
- Has two isomers: alpha and beta - differ in arrangement of H and OH on carbon 1
What is an isomer?
Molecules with the same chemical formula but different structure
What is a disaccharide?🍞
- Two monosaccharides joined by a glycosidic bond - condensation reaction (produces a molecule of water)
- Can be broken back into monosaccharides (hydrolysis)
- Small and water soluble - suitable for transport
What are reducing sugars?🍞 (disaccharide)
- Monosaccharides and some disaccharides
- Have carbonyl groups which can be oxidised to carboxylic acids
- Reduce other compounds, forming a precipitate
What is a polysaccharide?🍞
- Three or more monosaccharides joined by condensation reactions
- Either have a structural or storage function
- Large size - insoluble
- Osmotically inactive - stored without being affected by osmosis
What is starch? (Storage polysaccharide)🍞
- Store of glucose - made up of many alpha glucose molecules
- Two components - amylose and amylopectin
What is amylose?🍞(Starch)
Chain of glucose monomers joined by 1,4 glycosidic bonds and formed into a helix - unbranched
What is amylopectin?🍞(starch)
Has 1,4 and 1,6 glycosidic bonds, giving it a branched structure
What makes starch a good good store?🍞(Storage polysaccharide)
- Compact - pack lots of energy into a smaller space than glucose
- Insoluble - has little effect on osmotic pressure, doesn’t get transported from storage areas by water
- Readily converted to sugars -easily converted into transportable molecules
What is glycogen?🍞(storage polysaccharide)
- Polymer made up of many alpha glucose monomers
- Similar to amylopectin - 1,4 and 1,6 glycosidic bonds - branched structure
- Store glucose in animals
Why does glucose’s structure indicate animals’ higher metabolic requirements?🍞
More branched structure - broken down more rapidly
What is cellulose?(structural polysaccharide)🍞
- Polysaccharide made up of beta glucose monomers joined by 1,4 glycosidic bonds - forms long straight (unbranched) chains - strength
- Each beta glucose molecule is rotated 180’ from the previous molecule - enables hydrogen bonds to form between OH groups in adjacent chains
- Many cellulose chains form a microfibril, many microfibrils form a cellulose fibre, cellulose fibres make up cell walls of plants
What gives cellulose its strength?🍞(structural polysaccharide)
Many hydrogen bonds and unbranched structure
What is chitin?(structural polysaccharide)🍞
- Made up of chains of beta glucose monomers, rotated 180’ from previous monomer, with hydrogen bonds between chains forming microfibrils
- Amino acids added to form a mucopolysaccharide
- Contains nitrogen
- Strong and lightweight
- Forms exoskeletons of insects and cell walls of fungi
What is used to test starch?🍞
- Several drops of iodine added to sample
* If present, sample turns blue/black
What is used to test for reducing sugar?🍞
- Benedict’s reagent is added to sample
- Solution is boiled
- If present, change from blue to brick red precipitate
What is used to test for non-reducing sugar?🍞
- If reducing sugar test shows a negative result, this test can be carried out
- Hydrolysing glycosidic bond by heating with hydrochloric acid - forms two monosaccharides
- Neutralised by adding sodium hydrogen carbonate
- Boiled with Benedict’s reagent
- If present, brick red precipitate
What are lipids?🍔
- Made up of carbon, hydrogen and oxygen
- Made up of glycerol and fatty acids
- Non-polar, insoluble
What are fatty acids?🍔
- Consist of a methyl group, a variable length hydrocarbon chain and a carboxyl group
- Hydrocarbon chains contain an even number of carbon atoms - between 14 and 22
- Either saturated or unsaturated
- Vary - length of hydrocarbon tail or how saturated the molecule is
- Fatty acids affect the lipids’ properties
Difference between saturated and unsaturated fatty acids🍔
- Saturated - no carbon-carbon double bonds in the hydrocarbon chain
- Unsaturated - carbon-carbon double bonds in the hydrocarbon chain
Difference between monounsaturated fatty acids and polyunsaturated fatty acids🍔
- Monounsaturated - one carbon-carbon double bond
* Polyunsaturated - two or more carbon-carbon double bonds
What are triglycerides?🍔
- 1 glycerol and 3 fatty acids
- 3 condensation reactions which form 3 ester bonds
- When oxidised, releases more energy than carbohydrates and produces metabolic water
What are phospholipids?🍔
•2 fatty acids and a phosphate group combine with a glycerol molecule
Functions of lipids in living organisms🍔
- Energy storage - 2x more than same mass of carbohydrate
- Protection of delicate organs
- Thermal insulation
- Buoyancy
- Source of metabolic water for organisms such as camels
- Waterproofing
Why is a high intake of saturated fats a contributory factor in heart disease?🍔
Raises LDL cholesterol level, increasing the risk of atheroma in coronary and other arteries
What are waxes?🍔
- Long chained fatty acids linked to a long chained alcohol
* Insoluble and form a waterproof layer
What are steroids?🍔
- Four-ring structure with various side chains
- Insoluble in water but soluble in organic solvents
- Important as hormones
- Synthesised from cholesterol
What is cholesterol?🍔
- Important constituent of body cells, especially cell membrane
- Too much cholesterol and saturated fat can produce atheroma deposits - reduce blood flow in arteries
What are proteins?🥩
Polypeptides made up of carbon, hydrogen, oxygen, nitrogen and sometimes sulphur
What is a polypeptide?🥩
- A polymer consisting of a chain of amino acid molecules
- Joined by peptide bonds formed by condensation
- One or more polypeptides form a protein
What is used to test for lipids?🍔
- Emulsion test
- Ethanol added to sample and shaken thoroughly
- Distilled water is added
- If present, a layer of cloudy white suspension will form
Roles of proteins🥩
- Enzymes
- Carrier proteins
- Antibodies
- Structural proteins
- Hormones
- Transport - haemoglobin
- Contractile proteins
What are amino acids?🥩
- Made up of a amino group (NH2) and a carboxyl group (COOH) and a variable residual (R) group
- Amino end - base - positive amino acid ion
- Carboxyl end - acid - negative amino acid ion
- They are amphoteric - act as base and acid, so can act as a pH buffer
How many R groups are there?🥩
20 different R groups, so 20 different amino acids
How is a dipeptide Formed?🥩
- Two amino acids combine in a condensation reaction to form a dipeptide - a molecule of water is also formed
- Peptide bond forms between carboxyl group of one amino acid and the amino group of the other amino acid
What is a protein’s primary structure?🥩
The type, number and sequence of amino acids in a protein
Peptide bonds
What is a protein’s secondary structure?🥩
- Polypeptide can twist to form either an alpha helix or a beta pleated sheet
- Shape is held together by hydrogen bonds between the peptide bonds
What is a protein’s tertiary structure?🥩
- Polypeptide helix twists and folds into specific complex 3D shapes
- Specific structure is maintained by hydrogen bonds, ionic bonds and disulphide bonds between the R groups of the amino acids
What is a protein’s quaternary structure?🥩
- Only some proteins have a quaternary structure
* Two or more polypeptides with a tertiary structure can combine to form a quaternary structure
What is the hydrophobic effect?🥩
- Helps some proteins maintain their structure
- When globular proteins are in solution, the hydrophobic groups point inwards, away from the water
- Allows molecule to be soluble in water
Stability of proteins🥩
- Increases in temperature/changes in pH or presence of heavy metal ions or organic solvents cause the atoms to vibrate
- Bonds break - 3D structure changes
- Affects tertiary and quaternary structure - denatures
Globular proteins🥩
- Tertiary and quaternary structure
- Compact molecules
- Highly twisted polypeptide chains roll up into a ball - specific in shape
- Hydrophobic R groups point out - water soluble
- Tend to be less stable and are involved in metabolic reactions
- Includes enzymes, antibodies and hormones
What is haemoglobin?🥩(globular)
- Globular protein
- Consists of 4 polypeptide chains - disulphide bridges hold them together
- At the centre of each polypeptide is a haem group
Fibrous proteins🥩
- Secondary structure
- Insoluble, strong, stable and flexible
- Polypeptides Laos sown in parallel chains, linked together to form long fibres or sheets
- E.g. keratin or collagen
What is collagen?🥩(fibrous)
- Fibrous protein
- Provides the tough properties needed in tendons and bones
- Consists of 3 alpha helix chains formed into long strands - wind around each other held together by hydrogen bonds
What is used to test for proteins?🥩
- Biuret test
- Biruet reagent is added to sample
- If present, change from blue to lilac/purple
Number of bonds formed by Carbon, oxygen and hydrogen🍞🍔
- Carbon - 4
- Oxygen - 2
- Hydrogen - 1
Monosaccharides and the disaccharides they form🍞
- Glucose + glucose = maltose
- Glucose + fructose = sucrose
- Glucose + galactose = lactose
