Topic 1 - Biological Molecules Flashcards
what is a monomer
smaller repeating molecules from which larger molecules/polymers are made
what is a polymer
molecule made up of many identical/similar molecules/monomers
what happens in a condensation reaction
2 molecules join together, forming a chemical bond, releasing a water molecule
wwhat happens in hydrolysis reactions
2 molecules separated, breaking a chemical bond using a water molecule
give 3 examples of polymers and the monomers from which they’re made
nucleotide - polynucleotide (DNA or RNA)
monosaccharide e.g. glucose - polysaccharide e.g starch
amino acid - polypeptide (protein)
what are monosaccharides
monomers from which larger carbohydrates are made
give 3 examples of monosaccharides
glucose, fructose, galactose
what is the difference btwn the structure of alpha and beta glucose
OH is below carbon-1 in alpha glucose but above carbon- 1 in beta glucose
they are isomers
what are disaccharides
2 monosaccharies joined together with a glycosidic bond
list 3 common disaccharides and monosaccharides from which they are made
maltose - glucose, glucose
lactose - glucose, galactose
sucrose - glucose, fructose
what are polysaccharides
many monosaccharides joined together with glycosidic bonds
describe the basic function of starch
energy store in plants
describe the structure of starch
- polysaccharide of alpha glucose
- amylose has 1-4 glyocisidic bonds, unbranched
- amylopectin has 1-4 + 1-6 glycosidic bonds, branched
explain how the structures of starch relates to its function
helical - compact for storage in cell
large, insoluble plysaccharide molecule - can’t leave cell, cross cell membrane
insoluble in water, water potential of cell isn’t affected
describe the basic function of glycogen
energy store in animals
describe the structure of glycogen
polysaccharide made of alpha glucose
1-4 + 1-6 glycosidic bonds, branched
explain how the strucutre of glycogen relates to its function
branched - compact so can fit more moelcules in a small area, more ends faster for hydrolysis (release glucose for respiration to make ATP for energy relase)
large, insoluble plysaccharide molecule - can’t leave cell, cross cell membrane
insoluble in water, water potential of cell isn’t affected
describe the basic function of cellulose
provides strength and structural support to plant/algal cell walls
describe the structure of cellulose
polysaccharide of beta glucose
1-4 glycosidic bonds, straight unbranched chains
chains linked in parallel by hydrogen bonds to form microfibrils
explain how the structure of cellulose relates to its function
every other beta glucose molecule is inverted in a long, striaght, unbrnached chain
many hydyrogen bonds linked in parallel by hydrogen bonds to form microfibrils
hydrogen bonds are strong in high numbers so provides strength to plant cell walls
name 3 reducing sugars
monosaccharides, maltose, lactose
describe the test for reducing sugars
- add Benedict’s solution (blue) to sample
- heat in a boiling water bath
- positive result = green,yellow,orange, red precipitate
name a non-reducing sugar
sucrose
describe the test for non-reducing sugars
- Benedict’s test and stays blue
- heat in a boiling water bath with acid (hydrolyses into reducing sugars
- neutralise with alkali e.g. sodium bicarbonate
- heat in a boiling water bath with Benedict’s solution
- positive result = green,yellow,orange,red precipitate
suggest a method to measure the quantity of sugar in a solution
- carry out Benedict’s test for non reducing sugars, filter and dry precipitate. weigh to find mass
- make sugar solutions of known concenttrations, heat set volume of each sample with a set volume of Benedict’s for the same time, use colorimeter to measure absorbance of each known conc, plot calibration curve conc x, absorb y, repeat with unkown sample and measure absorbance, read conc off graph
describe the biochemical test for starch
addd iodine dissolved in potassium iodide, shake and stir. positive = blue/black
name 2 groups of lipids
triglycerides and phospholipids
describe the structure of a fatty acid (RCOOH)
variable R-group - hydrocarbon chain (saturated or unsaturated)
- COOH is the carboxyl group
describe the difference btwn saturated and unstaturated fatty acids
saturated - non C=C bonds in hydrocarbon chain, all carbons are fully saturated with hydrocarbon
unsaturated - one or more C=C bond in hydrocarbon chain creating kinks
describe how triglycerides form
1 glycerol molecule and 3 fatty acids, condensation reaction, removing 3 water molecule, forming 3 ester bonds
what is the function of a triglyceride
energy storage
explain how the properties of triglycerides relate to their structure
- high ratio of C-H bonds to C atoms in hydrocarbon chain, so used in respiratio tto release more energy than same mass of carbohydrates
- hydrophobic/non polar fatty acids soinsoluble in water (clump together in droplets) , no effect on water potential of cell
describe the difference btwn the structure of triglycerides and phospholipids
triglyceride - glycerol, 3 fatty acids
phospholipid - glycerol, 2 fatty acids, phosphate group
what is the function of phospholipids
forms a bilayer in cell membrane, allowing diffusion of lipid-soluble (non polar) or very small substances and restricting movement of water soluble (polar) or larger substances
describe how the properties of phospholipids relates to its structure
- phospholipid heads are hydrophillic, attracted to water so point to water either side of membrane
- fatty acid tails are hydrophobic, repelled by water so point awat from water