Topic 1A- Biological molecules

Question 1

what are polymers?

Answer 1

large complex molecules composed of long chain of monomers joined together

Question 2

what are examples of polymers?

Answer 2

carbohydrates
proteins
nucleic acid

Question 3

what are monomers?

Answer 3

small basic molecular units that can form polymers

Question 4

what are examples of monomers?

Answer 4

monosaccharides
amino acids
nucleotides

Question 5

what is a condensation reaction?

Answer 5

formation of a chemical bond between monomers releasing a molecule of water

Question 6

what is a hydrolysis reaction?

Answer 6

breaking of a chemical bond between monomers using a molecule of water

Question 7

what are monosaccharides?

Answer 7

monomers of which large carbohydrates are made
- glucose
- fructose
- galactose

Question 8

what is a hexose sugar?

Answer 8

a monosaccharide with six carbon atoms to each molecule

Question 9

what is an isomer?

Answer 9

molecules with the same molecular formula but atoms are connected a different way

Question 10

what is a disaccharide?

Answer 10

when two monosaccharides join together via a condensation reaction
- a glycosidic bond is formed and water is released

Question 11

what are examples of disaccharides?

Answer 11

• sucrose from glucose and fructose
• maltose from glucose and glucose
• lactose from glucose and galactose

Question 12

what is a polysaccharide?

Answer 12

when two or more monosaccharides are joined together by condensation reactions
- they can be broken down into their constituent parts via a hydrolysis reaction

Question 13

what is starch?

Answer 13

• plants store excess glucose as starch
• cells get energy from glucose

Question 14

what are the characteristics of amylose?

Answer 14

• long unbranched chain of alpha glucose
• coiled structure due to angles of glycosidic bonds
• compact so good for storage (more can fit in a small space)

Question 15

what are the characteristics of amylopectin?

Answer 15

• long branched chain of alpha glucose
• side branches allow enzymes to break down the molecule and get glycosidic bond (glucose can be released quickly)

Question 16

what makes starch good for storage?

Answer 16

it is insoluble in water and doesn’t affect water potential
- water won’t enter the cell via osmosis and make it swell

Question 17

what is glycogen?

Answer 17

• excess glucose in humans and animals is stored as glycogen
• lots of side branches
• glucose can be released quickly
• compact so good for storage

Question 18

what is cellulose?

Answer 18

• long unbranched chains of beta glucose
• straight cellulose chains
• chains linked by weak hydrogen bonds forming strong fibres called microfibrils

Question 19

how are triglycerides formed?

Answer 19

condensation of one molecule of glycerol and three molecules of fatty acid
- hydrophobic tail making lipids insoluble in water

Question 20

what can the R-group be?

Answer 20

saturated or unsaturated
- unsaturated have double bonds between carbon atoms causing the chain to kink

Question 21

what bond is formed between fatty acids and glycerol?

Answer 21

ester bond
condensation reaction
releasing water
x2

Question 22

what is the structure of phospholipids?

Answer 22

1 phosphate group ‘hydrophilic head’
1 glycerol molecule
2 fatty acids ‘hydrophobic tail’

Question 23

what are the properties of triglycerides?

Answer 23

• energy storage molecules
• long hydrocarbon fatty acid tail contains lots of chemical energy
• insoluble in water so does not affect the water potential causing water to diffuse via osmosis and cell to swell
• form an insoluble droplet

Question 24

what are the properties of phospholipids?

Answer 24

• bilayer of a cell membrane
• control what enters of leaves the cell
• hydrophilic head and hydrophobic tail
• centre is hydrophobic so water-soluble substances can’t pass through (barrier)

Question 25

what are amino acids?

Answer 25

monomers of proteins

Question 26

what is a dipeptide?

Answer 26

when two or more amino acids join together

Question 27

what is a polypeptide?

Answer 27

when two or more amino acids join together - proteins are made up of one or more polypeptides

Question 28

what do all living things share?

Answer 28

a bank of 20 amino acids - only difference is what makes up their carbon containing R-group

Question 29

what bonds are formed between amino acids?

Answer 29

peptide bonds condensation reaction release water

Question 30

what is the primary structure?

Answer 30

sequence of amino acids in the polypeptide chain

Question 31

what is the secondary structure?

Answer 31

- hydrogen bonds form between the amino acids in the chain - coil into alpha helix or beta pleated sheet

Question 32

what is the tertiary structure?

Answer 32

- coiled/folded further - hydrogen and ionic bonds form - disulfide bridges form when two cysteine come close together (sulfur) - proteins made of a singular polypeptide chain this is their final 3D structure

Question 33

what is the quaternary structure?

Answer 33

- several polypeptide chains held together by bonds - the way they are assembled - proteins with more than one polypeptide chain this is their final 3D structure

Question 33

what does a proteins shape determine?

Answer 33

their function ie. haemoglobin - compact soluble protein - easy to transport - good for carry oxygen around the body - specialised

Question 34

what is an enzyme?

Answer 34

a biological catalyst - lower the activation energy - wide range of intracellular and extracellular reactions that determine structures and functions

Question 35

what is the lock and key model?

Answer 35

enzymes active site and substrate are complementary forming an enzyme substrate complex - enzyme remains unchanged after the reaction

Question 36

what is the induced fit model?

Answer 36

as the substrate binds the enzymes active site changes slightly to form enzyme substrate complex

Question 37

what is the enzymes active site determined by?

Answer 37

its tertiary structure (which is determined by primary structure) - if substrate is not complementary to active site they won't bind and form an enzyme-substrate complex and the reaction will not be catalysed

Question 38

what could alter a tertiary structure?

Answer 38

- change in pH or temperature - primary structure is determined by a gene so if a mutation occurred tertiary structure may be altered

Question 39

how do you measure enzyme activity?

Answer 39

- how fast the product is made - how fast the substrate is broken down