Topic 2 Molecular Biology 2.1-2.4 Flashcards
2.1 Name the common elements in living organisms
Carbon, hydrogen, oxygen, nitrogen
2.1 Define organic
Contains carbon/ C-H bonds
2.1 What are the 4 types of molecules
Carbohydrates, lipids, proteins and nucleic acids
2.1 Exceptions to “organic=has carbon and C-H bonds”
CO2 has carbon but inorganic, urea no C-H bonds but organic
2.1 What is anabolism and catabolism
Anabolism: from macromolecules to monomers, require ATP to build large molecules from small ones
Catabolism: from monomers to macromolecules, releases energy from breaking down larger molecules, the energy is reused in the cell
2.1 What is metabolism
Sum of all enzyme catalysed reactions in an organism
2.1 Name a substance that contains 1) nitrogen and 2) phosphorus
1) amino acids
2) nucleic acids
2.2 What is hydrogen bonding?
Bonds formed between hydrogen (partially positive) of a molecule and an electronegative atom from another- usually oxygen, nitrogen, fluorine (partially negative).
2.2 Explain what is cohesion and adhesion
Cohesion= the attraction between water molecules allowing them to stick together Adhesion= the hydrogen bonds that can form between water and other polar molecules
2.2 How are water’s cohesive and adhesive properties useful to living organisms- state example
Allows water to travel up xylem vessels in plants, keeping cell walls moist
2.2 What are water’s thermal properties? Explain them
- (High) latent heat of vaporization= the heat needed to break hydrogen bonds allowing them to change state, high meaning it doesn’t vaporize easily
- (High) specific heat capacity= heat needed to raise water temperature by 1 degree. hydrogen bonds restrict movement of water molecules so lots of energy is needed to increase temp
- (High) boiling point= highest temperature a substance can reach at liquid state. water doesn’t start to boil until high temperatures
2.2 How are water’s thermal properties significant to living organisms?
Allows water to be a stable and neutral habitat since temperature does not fluctuate easily
2.2 Explain solvent properties, surface tension and transparency of water
Solvent properties= dissolves ions and polar molecules
Surface tension= surface acts like an elastic sheet caused by intermolecuar forces, resembles a stretched membrane
Transparency= its transparent!
2.2 How are water’s solvent properties, surface tension and transparency useful to living organisms?
Solvent properties allows organisms to use water to transport substances and allows dissolved substances to react easily with one another
Surface tension allows organisms such as insects to travel on its surface without sinking
Transparency allows sunlight to pass through for photosynthesis to happen and allow animals to see
2.2 Water vs methane in terms of mp, bp, heat capacity and latent heat
Water higher mp, bp, heat capacity and latent heat than methane because of hydrogen bonds restricting movements. More energy is needed to melt it, boil it to turn it into vapour, or increase temperature.
2.2 How is sodium chloride transported in blood?
Sodium chloride is an ionic compound so its soluble in water, transported dissolved as Na+ and Cl- ions
2.2 How is oxygen transported in blood?
Oxygen is non-polar but small enough to be transported in small amounts, relies on hemoglobin in red blood cells to carry large amounts
2.2 How are glucose and amino acids transported in blood?
Glucose and amino acids are polar so they can be transported dissoled
2.2 How are cholesterol and fats transported in blood?
They are non-polar and insoluble so they have to be transported in lipoprotein complexes
2.3 What are carbohydrates?
Organic compounds made of carbon hydrogen and oxygen
2.3 What are monosaccharides, disaccharides and polysaccharides?
Monosaccharides= single sugar units with general formula CH2O Disaccharides= two monosaccharides linked together Polysaccharides= many monosaccharides
2.3 How are monosaccharides converted into polysaccharides?
Through condensation reaction (anabolic process) where the -H group from one molecule and -OH from the other joins to form H2O, allowing many monosaccharides to join together to form polysaccharide
2.3 How are disaccharides converted into monosaccharides?
Through hydrolysis reaction (catabolic process) which is the addition of water to split a molecule, reverse of the condensation reaction where water is produced
2.3 Name the polysaccharides produced by α-glucose and β-glucose (3 total)
α-glucose - starch and glycogen
β-glucose - cellulose
2.3 What are features of the structure of starch? Uses? (7 points)
Made by linking α-glucose molecules, insoluble, -OH groups pointing in same direction/ same orientation giving the polymer a helical shape- good for storage, easy to add or remove glucose molecules, used by plants to store glucose
2.3 What are features of the structure of cellulose? Uses? (7 points)
Made by linking β-glucose molecules, insoluble, unbranched, -OH groups pointing in opposite directions/ alternating orientation makes polymer straight, allows cellulose molecules to be arranged in parallel and linked by hydrogen bonds forming cellulose microfibrils- incredible tensile strength, basis of plant walls
2.3 Two forms of starch: amylose and amylopectin, which one is branched?
Amylopectin is branched, amylose unbranched
2.3 What are features of glycogen? Uses? (5 points)
Made by linking α-glucose molecules, insoluble, similar to amylopectin but more branched, -OH groups pointing in same direction/ same orientation, used by animals to store glucose in liver and muscle cells
2.3 What do the monosaccharides, glucose, fructose and galactose make?
α-glucose + α-glucose = maltose
glucose + fructose = sucrose
glucose + galactose = lactose
2.3 What are lipids?
Organic compounds made of carbon hydrogen and oxygen, long hydrocarbon chain, do not form polymers, mostly or entirely hydrophobic
2.3 What are the three main types of lipids? Describe them
Triglycerides: 3 fatty acids, 1 glycerol, formed from condensation reaction
Steroids: 4 fused rings in their molecules, eg. cholesterol and estrogen
Phospholipids: 2 fatty acids, 1 phosphate, 1 glycerol, partly hydrophobic partly hydrophilic, basis of membranes
2.3 What are the 2 parts to a fatty acid?
Carboxyl group and hydrocarbon chain
2.3 What are the different types of fatty acids? State their features
Saturated= all single bonds Unsaturated= one or more double bonds Monounsaturated= only ONE double bond in chain Polyunsaturated= MORE THAN ONE double bond Cis-unsaturated= hydrogen bonds on the same side of double bond Trans-unsaturated= hydrogen bonds on the opposite sides of double bond
2.3 Why do cis-unsaturated fats have lower melting points than trans-unsaturated fats?
There is a bend at the double bond of hydrocarbon chain of cis-unsaturated fats so the molecules don’t stack together as well, usually liquid at room temperatures- oil, trans is solid fat
2.3 Discuss health risks of a diet rich of lipids, 3 marks
Saturated fats cause high cholesterol, trans fats causes coronary heart disease, but some populations like kenyans have diets rich in lipids but CHD occurrence is rare
2.3 Name uses of lipids, 5 marks
hormone production, cushioning, protection, insulation, form membranes, energy store
2.3 How to calculate BMI?
mass in kg/ (height in meters)^2
2.3 Carbohydrates vs lipids, name some differences
- carbs stored in liver as glycogen, lipids stored as fat around body
- carbs is short term energy, lipids long term energy
- carbs easier to digest release energy quicker, lipids release more energy per gram. therefore adds less mass to body for same amount of energy stored
HOW TO IDENTIFY/DRAW: AMINO ACIDS
1) amine group -NH2 (left)
2) R group (below carbon)
3) carboxyl group -COOH (right)
4) central carbon atom (middle)
HOW TO IDENTIFY/DRAW: CARBOHYDRATES- GLUCOSE and RIBOSE
CARBOHYDRATES- arranged in a ring
α-glucose & β-glucose
1) hexagon shape
2) 1st carbon- α has H on top, β has OH on top
3) 2nd- H on top, 3rd- OH on top, 4th- H on top
4) 5th carbon- CH2OH
5) plus oxygen to complete hexagon
ribose
1) pentagon shape
2) 1st-3rd carbon all H on top
3) 4th carbon- C on top, H on bottom
4) Carbon^ connected to H on both sides + OH on top
(C on top can be written as CH2OH instead)
HOW TO IDENTIFY/DRAW: LIPIDS + GLYCEROL
- Triglyceride: 3 hydrocarbon chains
- Phospholipids: 2 hydrocarbon chains + phosphate
- Steroid: quadruple 4 ring structure
- glycerol: H-C-C-C-H with H on top of C and OH on the bottom
HOW TO IDENTIFY/DRAW: FATTY ACIDS
- Monounsaturated= only ONE double bond in chain
- Polyunsaturated= MORE THAN ONE double bond
- Cis-unsaturated= hydrogen bonds on the same side of double bond
- Trans-unsaturated= hydrogen bonds on the opposite sides of double bond
