1. Biological Molecules

Question 1

what is the purpose of the sugar-phophate backbone?

Answer 1

to protect bases from mutation

Question 2

describe induced fit model of enzyme

Answer 2

Before reaction active site is not complementary to substrate.
active site changes shape as bonds bend allow E-S to form

Question 3

structure of starch

Answer 3

1-4 glycosdic bonds and 1-6 therefore highly branched = large surface area for quick hydrolysis
made of alpha glucose
in plants
coiled so compact

Question 4

structure of cellulose

Answer 4

1-4 glycosdic bonds
beta glucose
long chains
forms microfibrils with hydrogen bonds providing strength
cell wall in plants

Question 5

structure of glycogen

Answer 5

1-4,1-6 glycosdic bonds
highly branched
alpha glucose
animals

Question 6

name one non reducing sugar and the test for non reducing sugars

Answer 6

sucrose
if no change in benedicts test add hcl and boil
neutralise with sodium hydrogen carbonate
heat to 95
colour change to green/yelllow/red = positive result

Question 7

test for reducing sugars

Answer 7

add benedicts
heat to 95
positive= blue to green/yellow/orange/red

Question 8

how is a peptide bond formed between 2 amino acids

Answer 8

in a condensation reaction releasing a h2o molecule
between carboxyl group and amine group

Question 9

what is an enzyme

Answer 9

a biological catalyst which speeds up the rate of reaction without being used up
made of proteins
lowers activation energy

Question 10

difference between saturated and un-saturated fats

Answer 10

unsaturated have double bonds between carbon atoms, saturated fats don’t

Question 11

adavantages of ATP releasing energy in small ammounts

Answer 11

very little energy wasted
quick and easy hydrolysis
helps with regulation of temperature

Question 12

what enzyme catalyses the hydrolysis of ATP

Answer 12

ATP Hydrolyase

Question 13

what enyme joins together ADP + Pi

Answer 13

ATP synthase

Question 14

how does the formation of an enzyme substrate complex increase the rate of reaction

Answer 14

puts strains on bonds of enzyme by bending bonds
lowers activation energy = less energy required

Question 15

DNA polymerase function

Answer 15

joins together new nucleotides to form a new strand with phospodiester bonds in a condensation reaction

Question 16

DNA helicase function

Answer 16

unzips DNA by breaking hydrogen bonds between bases

Question 17

Sucrase does not hydrolyse lactose
explain why (2)

Answer 17

lactose has a different tertiary structure to sucrase.
therefore it cannot bind to the active site of sucrase

Question 18

describe the structure of proteins (5)

Answer 18

polymer of amino acids joiin together by peptide bonds in a condensation reaction

secondary structure is folding of polypeptides into alpha helix or beta pleated sheets held together by hydrogen bonds

tertiary structure creates a 3D shape held together by either H bonds, disulphide bridges or ionic bonds

quaternary structure is when more than 1 polypeptide chain joins together.

Question 19

compare and contrast the structure and properties of triglycerides and phospholipids

Answer 19

triglycerides made of 3 fatty acids and glycerol - phospholipids 2 fatty acids and glycerol and phosphate group

both contain ester bonds

both insoluble in water

phospholipids form a bilayer triglycerides dont

triglycerides entierly hydrophobic, phospholipids have a hydrophillic phosphate head.

Question 20

describe how the structure of glycogen is related to its function

Answer 20

coiled so compact
insoluble so doesnt affect water potential
branched so faster hydolysis
polymer of glucose so easily hydrolysed