Biological Molecules

Question 1

what is the use of carbohydrates in the body?

Answer 1

• used by cells for respiratory substances

- also forms structural components in plasma membranes and cell walls

Question 2

What are some things lipids can form in the body?

Answer 2

• form the bilayer of plasma membranes
• as respiratory substrates
• certain hormones

Question 3

what is the use of proteins in the body?

Answer 3

• forms many cell structures

- forms enzymes, chemical messengers and components of the blood

Question 4

what is the use of nucleic acids in the body?

Answer 4

-carries the genetic code for production of proteins

Question 5

what is a monomer?

Answer 5

the smaller units which form larger molecules

Question 6

what is a polymer?

Answer 6

molecules which are made from a large number of monomers joined together

Question 7

what does a condensation reaction do?

Answer 7

a condensation reaction joins together two molecules with the formation of a chemical bond that involves eliminating water

Question 8

what does a hydrolysis reaction do?

Answer 8

it breaks a chemical bond between two molecules and involves a water molecule

Question 9

what is a monosaccharide?

Answer 9

monomers which form larger carbohydrates- e.g fructose, glucose and galactose

Question 10

what bond is formed between two monosaccharides?

Answer 10

glycosidic bond

Question 11

what is a disaccharide?

Answer 11

formed by the condensation reaction of two monosaccharides

Question 12

3 examples of disaccharides

Answer 12

maltose- formed by 2 glucose molecules
sucrose- formed by glucose and fructose
lactose- formed glucose and galactose

Question 13

name the two isomers of glucose

Answer 13

alpha- where the H bond is at the top

beta- where the OH bond is at the top

Question 14

what are polysaccharides?

Answer 14

formed by the condensation reaction of many glucose units

Question 15

examples of polysaccharides?

Answer 15

glycogen and starch- formed by condensation of alpha

cellulose- formed by condensation of beta glucose

Question 16

What is the test for reducing sugars and method?

Answer 16

1. You add benedict’s and then heat to 90 degrees roughly

2. if you get a brick red/orange colour, reducing sugar is present

Question 17

name the structure of triglycerides?

Answer 17

-formed by condensation reaction of glycerol and 3 fatty acids

Question 18

what bond does the condensation reaction of fatty acids and glycerol form?

Answer 18

ester bond

Question 19

what is the structure of phospholipids?

Answer 19

glycerol, 2 fatty acids and a phosphate group

Question 20

properties of phospholipids

Answer 20

-phosphate head is hydrophilic whilst tail is hydrophobic which is good for membranes to prevent water soluble substances for getting through

Question 21

what is the structure of ATP (adenosine triphosphate)

Answer 21

it contains adenine, ribose and three phosphate groups

Question 22

the equation for the hydrolysis reaction of ADP

Answer 22

ATP—————–>ADP +Pi

enzyme ATP hydrolase

Question 23

the purpose of the phosphate ‘Pi’

Answer 23

to phosphorylate other compounds- make them more reactive

Question 24

condensation reaction of ATP equation

Answer 24

ADP + Pi———————-> ATP

enzyme: ATP synthase

Question 25

Emulsion test for lipids

Answer 25

1. Dissolve sample in alcohol and then add water | 2. If you get a white cloudy colour, a lipid is present

Question 26

Describe the structure of proteins

Answer 26

1 structure- polymer of amino acids joined by peptide bonds formed by condensation reactions 2 structure- folding of polypeptide chains of H bonding (alpha helixes/ beta pleated sheets) 3 structure- 3D folding due to H bond and ionic/disulphide bridges 4 structure- 2 or more polypeptide chains

Question 27

Describe the process of mRNA production (4)

Answer 27

DNA helicase breaks H bonds between two strands One strand acts as template RNA nucleotides are attracted to exposed bases according to base pair ruling RNA polymerase joins RNA nucleotides together pre-mRNA is spliced to remove introns

Question 28

Compare structures of DNA and mRNA

Answer 28

DNA has thymine base whilst mRNA has uracil DNA has base pairing or H bonding DNA has non coding DNA, mRNA doesn't DNA has deoxyribose, mRNA has ribose

Question 29

Use of hydrolysis of ATP in cells

Answer 29

Used to provide energy for reactions | To make other molecules reactive

Question 30

Describe the induced-fit model of enzymes

Answer 30

Active site isn't originally complementary to a substrate Shape of active site changes as substrate binds Stressing/distorting/bending bonds leads to reactio

Question 31

How does formation of enzyme substrate complexes increases rate of reaction?

Answer 31

the bonds are bent | this reduces activation energy of reaction

Question 32

Structure of starch and how they are adapted for their function? (3)

Answer 32

Helical so they are compact Insoluble so they do not affect water potential Large molecule so they cannot leave the cell

Question 33

How is cellulose adapted for their function in plant cells?

Answer 33

Forms long straight chains They become linked by forming hydrogen bonds to form fibrils Provide strength to a plant

Question 34

similarities between cellulose and starch

Answer 34

contains glyosidic linkage both polysaccharides both have hydrogen bonding

Question 35

differences between cellulose and starch

Answer 35

starch is alpha glucose, cellulose is beta starch is branched starch doesn't form microfibrils

Question 36

describe what a competitive inhibitor is

Answer 36

prevents formation of enzyme-substrate complexes has a similar shape to the substrate binds to active site of enzyme preventing substrate from doing so inhibition can be overcome by more substrate

Question 37

describe what a non competitive inhibitor is

Answer 37

prevents enzyme from binding to the substrate binds to site away from active site causes active site to change shape this type of inhibition cannot be overcome by adding more substrate

Question 38

Structure and properties of triglycerides

Answer 38

Large non polar molecules~> insoluble in water High H:O~> releases water when oxidised Low mass:energy~> good storage, more energy in a smaller volume High C:H~> energy source

Question 39

Properties of water

Answer 39

High specific heat capacity Good solvent Good metabolite