Module 2.2 Biological Molecules Flashcards
Calcium (Ca2+)
- Increases rigidity of bones, teeth and cartilage
- Component of the exoskeleton of crustaceans
- Clotting blood and muscle contractions
- Activator for enzymes e.g. lipase, ATPase and cholinesterase
- Stimulates muscle contractions
- Regulates transmission of nerve impulses
- Regulates permeability of cell membranes
- Important for cell wall development (in plants) and formation of middle lamellar between cell walls
Sodium (Na+)
- Helps regulate osmotic pressure
- Helps control water levels in body fluid
- Helps maintaining pH
- Affects absorption of carbohydrates in intestine
- Affects absorption of water in the kidney
- Contributes to nervous transmission and muscle contractions
- Present in vacuole which helps maintain turgidity
Potassium (K+)
- Helps control water levels in body fluid
- Helps maintain pH
- Assists active transport
- Involved in synthesis of glycogen and protein, and breakdown of glucose
- Helps keep leaves and flowers healthy
- Involved w nervous transmission and muscle contraction
- Present in vacuoles to help maintain turgidity
Hydrogen (H+)
- Involved in photosynthesis
- Involved in respiration
- Involved in transport of oxygen and carbon dioxide in the blood
- Involved in regulation of blood pH
Ammonium (NH4+)
- Component of amino acids, proteins, vitamins and chlorophyll
- Essential component of nuclei acids
- Involved in maintaining pH in the body
- Component in the nitrogen cycle
Nitrate (NO3-)
- Component of amino acids, proteins, vitamins and chlorophyll
- Essential component of nucleic acids
- Some hormones are made out of proteins which contain nitrogen e.g. insulin
- Component in nitrogen cycle
Hydrogencarbonate (HCO3-)
- Regulates blood pH
- Involved in transport of carbon dioxide in and out of the blood
Hydroxide (OH-)
-Regulates blood pH
Chloride (Cl-)
- Helps production of urine in the kidneys and maintaining water balance
- Involved in transport of carbon dioxide in and out of the blood
- Regulates affinity of haemoglobin to oxygen through allosteric effects on the haemoglobin molecule
- Involved in blood pH regulation
- Used to produce HCl in the stomach
Phosphate (PO4 3-)
- Increases rigidity of bones, teeth and cartilage
- Component of the exoskeleton of crustaceans
- Component of phospholipids, ATP, nuclei acids + several important enzymes
- Involved in blood pH regulation
- Helps roots grow in plants
Phospholipids
- Composed of glycerol and a phosphate head w 2 fatty acid tails
- Soluble head and insoluble tail in water
- Part hydrophilic, part hydrophobic
- Make up cell surface membranes
- Made up of C, H and O
- Fatty acid chains joined to glycerol w ester bonds
- Phosphate group + carbohydrate = glycolipid (used for cell signalling)
Triglycerides
- Composed of a glycerol molecule and 3 fatty acid tails
- Fatty acid chains joined to glycerol w ester bonds in a condensation reaction
- The ester bonds form at 3 OH groups on glycerol - 3 water molecules released
- Made up of C, H and O
- Hydrophobic molecule (evenly distributed charge)
- Insoluble in water (means doesn’t effect water potential of cells)
- Used as energy stores by hydrolysing ester bonds breaking down CO2 and H2O to release energy
Cholesterol
- Made up of C, H and O
- Make up cell surface membranes
- Hydrophobic molecule (evenly distributed charge)
- Insoluble in water
- Made up of a 4 carbon ring structure
- Vital to organisms - made by many cells
- Helps regulate fluidity
- Can build up causing heart disease and can clog arteries etc. It can be deposited in blood vessels causing atherosclerosis
- Produce steroid hormones e.g testosterone and oestrogen which can pass straight through membranes to target cells
Lipids
- Solid lipid = fat
- Liquid lipid = oil
- Lipids dissolve in organic solvents e.g. alcohol but not in water
Roles of lipids in organisms
- Energy source
- Energy store (lipids stored in adipose cells)
- Phospholipid bilayer
- Insulation
- Myelin sheath of neurones - electrical insulation
- Steroid hormones
- Waxy cuticle of leaves
Glycerol
- C3H8O3
- Glycerol and fatty acids are both found in 2 major groups of lipids - glycerolipids (energy store/source) and glycerophospholipids
Fatty acids
- All have an acid group at one end joined to a hydrocarbon chain (2-20 carbons long)
- Fatty acids are used to make up lipids
- An essential fatty acid is one that we can’t assemble ourselves
- 3 types - palmitic, stearic and oleic
Saturated fats
- No double bonds in the hydrocarbon chain
- Raise cholesterol
Monounsaturated fats
One C=C bond
Polyunsaturated fats
2+ C=C bonds
Are unsaturated fats more or less permeable?
More permeable
What bond joins glycerol to a fatty acid?
An ester bond
Haemoglobin
- Conjugated protein
- 4 polypeptides
- 2 alpha, 2 beta
- Prosthetic haem groups have an affinity for oxygen (each one can attract 1 oxygen molecule)
- Fe2+ ions
- Function - to carry oxygen from the lungs to tissues for aerobic respiration
- Globular - for metabolic reactions
- Primary structure - amino acids
- Secondary structure - mostly alpha helices
- Tertiary structure - alpha chains and beta chains
- Quaternary structure - 2 alpha and 2 beta chains
Collagen
- Structural protein
- Fibrous
- Quaternary structure - 3 polypeptide chains tightly wound around each other
- H bonds give strength
- Every 3rd amino acid on each peptide chain is glycine - small - tiny R group - allows close packing
- Covalent bonds across peptide chains (cross linkage) helps to form a collagen fibril - staggered cross linkage adds strength
- Many fibrils make up a fibre
Functions of collagen (protein)
- Lines arteriole walls - prevents bursting at high pressure
- Tendons allow movement
- Bones - collagen reinforced to make them hard
- Cartilage and connective tissue
- Used in cosmetic treatments
Properties of collagen (protein)
- High tensile strength
- NOT elastic
- Flexible
- Insoluble
Comparing collagen and haemoglobin (both proteins)
Collagen:
- Fibrous
- Insoluble
- No prosthetic group
- Structural
Haemoglobin:
- Globular
- Soluble
- Prosthetic haem group
- For transporting oxygen
Secondary structure of proteins
- As polypeptides form, to stabilise them, they are coiled (a-helix) or pleated (ß-pleated sheets)
- These are held in place by H bonds
Why is the secondary structure of proteins dependant on the primary structure?
- Primary structure = unique sequence of amino acids in the protein
- Different proteins have different combinations of amino acids which each have different R groups and different properties
- Different proteins have H bonds formed in different places in the pleats/coils meaning some are more or less pleated/coiled than others
Tertiary structure
- 3D shape
- When coils/sheets are folded into their final shape
- Tertiary structure is 🔑 to the protein’s function
Tertiary structure - disulfide bonds
- The amino acid cysteine contains sulfur
- Where 2 cysteines are found close to each other, a covalent bond forms
Tertiary structure - ionic bonds
- The strongest 💪🏻
- R groups sometimes carry a charge (either +ve or -ve)
- When oppositely charged amino acidsare found close to each other, an ionic bond forms
Tertiary structure - Hydrogen bonds
-Form when slightly positively charged groups are found close to slightly negatively charged groups
Tertiary structure - Hydrophilic and hydrophobic interactions
- In a water-based environment, hydrophobic amino acids are most stable if they are held together w water excluded
- Hydrophilic amino acids tend to be found on the outside in globular proteins w hydrophobic amino acids in the centre