Biological Molecules

Question 1

Whats a polymer

Answer 1

A long compex chain made up of monomers

Question 2

What is a monomer

Answer 2

A small basic molecule

Question 3

What are examples of monomers

Answer 3

glucose, fructose, galactose

Question 4

Whats a hexose sugar

Answer 4

monosaccharideccontaining 6 carbon atoms

Question 5

Whats an isomer

Answer 5

molecules with same chemical formula but atoms connected in different ways

Question 6

Whats a condensation reaction

Answer 6

Two molecules being joined by forming a new bond and release of water

Question 7

What are maltose, sucrose and lactose made of

Answer 7

alpha glucose+ alpha glucose
glucose + fructose
glucose + galactose

Question 8

Whats a hydrolysis reaction

Answer 8

separation of molecules by breaking chemical bond using a water molecule

Question 9

What is reducing sugars test

Answer 9

Add benedicts solution to test sample
add to water bath brought to boil
if positive will go from blue to green to yellow or orange or brick red

Question 10

Whats a more accurate way to compare amount of reducing sugars

Answer 10

filter and weight the precipitate

Question 11

What is the non reducing sugars test

Answer 11

obtain more of sample
add dilute hcl and heat in water bath brought to boil
neutralise it with sodium hydrocarbonate
repeat benedicts test

Question 12

Whats a polysaccharide

Answer 12

Two or more monosaccharides joined via glycosidic bonds from condensation reaction

Question 13

What is starch and its structure

Answer 13

Starch is what plants store excess glucose as
Made up of two polysaccharides of alpha glucose amylose and amylopectin

Question 14

Function of statch

Answer 14

Amylose- long unbranched chains of alpha glucose which angles of glycosidic bonds allow it to coil making it compact so good for storage
Amylopectin- long branches chains of alpha glucose which provide large sa for enzymes to hydrolyse it back into glucose quickly
Insoluble so doesnt affect water potential of cells and cause swelling

Question 15

What is iodine test for starch

Answer 15

add iodine dissolved in potassium iodine solution if positive will go from browny orange to blue black

Question 16

What is glycogen

Answer 16

How animals store excess glucose and is chains of alpha glucose

Question 17

Functions of glycogen

Answer 17

is compact and insoluble
has more branches than amylose allowing quick release of glucose

Question 18

Structure and function of cellulose

Answer 18

long unbranched chains of beta glucose that are joined by hydrogen bonds between parallel chains forming microfibrils providing structural support

Question 19

What are structure of triglycerides

Answer 19

Three fatty acid chain joined by three ester bonds to glycerol molecule

Question 20

What is a saturated fatty acid

Answer 20

A fatty acid that is saturated with hydrogen and so has no double bonds between carbons

Question 21

What is an unsaturated fatty acid

Answer 21

Fatty acids containing at least one double bond between carbon atoms and cause chain to kink

Question 22

Phospholipid structure

Answer 22

Two fatty acid chains bound to glycerol and phosphate head

Question 23

What parts of phospholipid are hydrophobic and hydrophillic

Answer 23

Hydrophobic- fatty acid tails
Hydrophilic- Phosphate head

Question 24

What is triglycerides structure related to its function

Answer 24

Good at energy storage due to
high chemical energy in fatty acid hydrocarbons that when broken down release it
Insoluble so don’t affect water potential of cells and form insoluble droplets as fatty acid tails clump together facing inwards shielding themselves from water with glycerol heads

Question 25

Emulsion test

Answer 25

add ethanol to substance being tested and shake for a minute until its dissolved pout into water and if milky emulsion is produced lipid is present

Question 26

Phospholipid structure related to function

Answer 26

Fatty acid tails face inwards and phosphate head face out on either side towards water leaving double layer Centre of bilayer is hydrophobic so acts as a barrier to water soluble molecules

Question 27

What is a dipeptide

Answer 27

Two amino acids joined via condensation reaction forming peptide bond

Question 28

What is polypeptide

Answer 28

Two or more amino acids joined together

Question 29

What do all amino acids vary due to

Answer 29

Their R group

Question 30

What do all amino acids have in common

Answer 30

All have carboxyl, amine and r group

Question 31

What does peptide bond form between

Answer 31

carboxyl and amino group of amino acids

Question 32

What is primary and Secondary structures of proteins

Answer 32

1. Sequence of amino acids that are in polypeptide chain 2. Hydrogen bonds form between amino acids in polypeptide chains causing it to coil into alpha helixes or fold into beta pleated sheets

Question 33

What is tertiary and quaternary structure of proteins

Answer 33

3. further coils or folds as more hydrogen bonds form or ionic bonds form between positive and negative parts of molecule , disulphide bridge may form between two amino acids of cysteine as sulphur atoms bind. This final 3d structure of single polypeptide chain 4. Two or more polypeptide chains bonded together

Question 34

Structural proteins structure

Answer 34

long chains of polypeptides arranged in parallel with cross links between them

Question 35

What is biuret test

Answer 35

must be alkaline so add sodium hydroxide and copper (II) sulfate solution and if present will go from blue to purple

Question 36

How do enzymes work

Answer 36

lower activation energy required for reaction to occur

Question 37

How does it make energy lower for joining molecules

Answer 37

when attached in enzyme substrates held closer together and reduces repulsion so bond between molecules form

Question 38

How does it lower energy for breaking bonds

Answer 38

when fitted into active site strain is put on bonds in substrate so are easy to break bonds

Question 39

Describe induced fit model

Answer 39

complimentary substrate binds to active site forming enzyme substrate complex and active site slightly changes shape providing better fit and substrate is broken down or joined together

Question 40

How can change in amino acid sequence affect enzyme function

Answer 40

Sequence of amino acids make up primary structure of amino acids which determine tertiary structure which can change shape of active site so substrate will no longer fit and form enzyme substrate complex

Question 41

How are enzymes specific

Answer 41

Very specific as usually only catalyse one reaction as only one complimentary substrate will fit into active site which is determined by tertiary structure Each different enzyme has different tertiary structure and so different active site if substrate doesnt match active site no enzyme substrate complex form If tertiary structure altered shape of active site will change so substrate wont fit anymore

Question 42

How does temperature increase rate of reaction

Answer 42

increase kinetic energy so more collisions between enzymes and substrates so more enzyme substrate molecules can form and energy of collisions also increases so more likely to result in reaction

Question 43

How can temp denature enzymes

Answer 43

Vibrations can break bonds holding enzyme in shape so active site can change shape so is denatured

Question 44

How does ph affect enzyme activity

Answer 44

each enzyme has own optimum ph such as pepsin in stomach acid H+ and OH- can break bonds in enzyme causing ut to denature

Question 45

Enzyme concentration effect on rate of reaction

Answer 45

Will increase rate of reaction as more collisions but if substrate concentration is limited there will be more than enough enzymes for substrates to point where no further effect

Question 46

Substrate concentration effect on rate of reaction

Answer 46

collisions again up to saturation point where all enzymes active sites are occupied substate concentration decreases over time so rate of reaction fastest at start and decreases

Question 47

How do competitive inhibitors work

Answer 47

have similar shapes to substrates and so compete for active sites with substrate so no substrate can fit into If substrate concentration increased however there will be higher chance of enzyme substrate complexes form before inhibitor so increases rate of reaction to a poiny

Question 48

Non compeitive inhibitors

Answer 48

Bound elsewhere on enzymes not active sites and cause active site to change shape and so substrate can no longer fit and form enzyme substrate complex no imcrease of substrate concentration can change effect