Biological Molecules

Question 1

What does ATP stand for and what is it?

Answer 1

Adenosine Tri Phosphate. It is the energy currency of a cell

Question 2

what is ATP made up from?

Answer 2

Adenine
Ribose (sugar)
Phosphate

Question 3

where is ATP made?

Answer 3

in photosynthesis and in respiration

Question 4

Why is ATP not a long term energy store?

Answer 4

ATP is broken almost as soon as it is made as the bonds are unstable, so therefore it has a low activation energy

Question 5

Formula for ATP formation

Answer 5

ADP + Pi + ATP synthase –> ATP +Water

Question 6

Formula for hydrolysis of ATP

Answer 6

ATP + Water —> ADP + Pi + Energy

Question 7

examples of energy from the hydrolysis of ATP

Answer 7

muscle contraction
cell division
active transport

Question 8

what is phosphorylation?

Answer 8

adding a phosphate to a molecule

Question 9

What happens to a molecule if it has undergone phosphorylation?

Answer 9

The molecule is more reactive as adding a phosphate has lowered the molecules activation energy

Question 10

what are amino acids and what do they form?

Answer 10

they are monomers. lots of them form polypeptides

Question 11

how does a peptide bond form?

Answer 11

when a condensation reaction occurs between 2 amino acids. between the amine and the carboxylic acid

Question 12

how to test for proteins?

Answer 12

add biuret A/B
positive result = purple/lilac colour
negative test = pale blue colour

Question 13

describe the primary structure of proteins and what bonds are present?
give examples

Answer 13

the sequence of amino acids in a polypeptide.
BONDS: peptide
EXAMPLES: all proteins

Question 14

describe the secondary structure of a protein and what bonds are present?
give examples

Answer 14

the coiling of a polypeptide chain to form a helix
BONDS: hydrogen - holds the helix together
peptide
EXAMPLES: protein found in
fingernails

Question 15

describe the tertiary structure of a protein and what bonds are present?
give examples

Answer 15

the folding and twisting of a polypeptide chain to form a specific 3D shape
BONDS: hydrogen
ionic
disulphide
peptide
EXAMPLES: enzymes
hormones

Question 16

describe the quaternary structure of a protein and what bonds are present?
give examples

Answer 16

two or more polypeptides linked together
BONDS: hydrogen
ionic
disulphide
peptide
EXAMPLES: haemoglobin
insulin
antibodies

Question 17

What are enzymes?

Answer 17

they are biological catalysts with a tertiary structure
they are proteins

Question 18

describe the Induced Fit Hypothesis?

Answer 18

The active site is not complementary to the substrate
The active changes shape to fit the substrate (flexible)

Question 19

describe and explain what enzymes do to activation energy?

Answer 19

Enzymes lower activation energy

when active site changes to form an E-S complex, the enzyme distorts the bonds in the substrate by placing it under tension

Question 20

what are the properties of an enzyme?

Answer 20

proteins with a tertiary structure
flexible active site
globular
not used up in a reaction
lowers activation energy

Question 21

how does temperature affect enzymes?

Answer 21

enzyme and substrate have more kinetic energy, so increased E-S complexes. faster ROR

Question 22

how does substrate concentration affect enzymes?

Answer 22

more substrates = more E-S complexes. faster ROR

Question 23

what is pH?

Answer 23

A measure of hydrogen ion concentration

Question 24

how does pH affect enzymes?

Answer 24

changes in pH affects the charges on the amino acids that make up the active site.
This affects the ionic bonding in the tertiary structure
so active site can no longer shape to fit the substrate. No E-S complexes.

Question 25

what does a competitive inhibitor do to enzymes?

Can it be overcome?

Answer 25

The competitive inhibitor binds to the enzymes active site. this reduces E-S complexes. this slows down the rate of reaction.

it can be overcome by adding more substrate

Question 26

describe the shape of a competitive inhibitor?

Answer 26

similar molecular shape to the substrate

Question 27

describe what a non-competitive inhibitor does to an enzyme?

can it be overcome?

Answer 27

the non-competitive inhibitor binds to another region of the enzyme.
this changes the enzymes tertiary structure.
the active site can no longer change shape to fit substrate, so E-S complexes do not form. Reaction stops.

cannot be overcome as the enzymes tertiary structure has permanently changed.

Question 28

describe the shape of a non-competitive inhibitor?

Answer 28

different molecular shape to the substrate

Question 29

where does protein digestion start and finish?

Answer 29

starts - in the stomach
ends - in the ileum (small intestine)

Question 30

what are the 3 enzymes involved in protein digestion?

Answer 30

endopeptidase
exopeptidase
dipeptidase

Question 31

describe the role of endopeptidase in protein digestion?

Answer 31

.hydrolyses peptide bonds in the middle of a polypeptide chain
. producing smaller polypeptide chains

Question 32

describe the role of exopeptidase in protein digestion?

Answer 32

.hydrolyse peptide bonds at the ends of smaller polypeptide chains, producing dipeptides

Question 33

describe the role of dipeptides in protein digestion?

Answer 33

hydrolyse dipeptides into amino acids

Question 34

define digestion

Answer 34

the hydrolysis of large molecules to smaller molecules that are absorbed into the bloodstream