proteins

Question 1

how is there a variety of protein shapes and functions

Answer 1

due to different sequences of amino acids
and due to hydrogen bonds

Question 2

what are the different functions of proteins

Answer 2

structural
hormones
antibodies
receptors
enzymes

mnemonic : S.H.A.R.E

Question 3

what is the order of amino acids determined by

Answer 3

by the sequence of bases in DNA

Question 4

role of STRUCTURAL protein
example
specific function

Answer 4

proteins are a major component of many tissues

example: muscles

function: contraction

Question 5

role of ENZYME protein
example
specific function

Answer 5

speed up chemical reactions without changing themselves

example: lipase

function: breaks down fats to glycerol and fatty acids

Question 6

role of HORMONES protein
example
specific function

Answer 6

chemical messengers which carry information in the blood

example: insulin

function: control of blood glucose concentration

Question 7

role of ANTIBODIES protein
example
specific function

Answer 7

produced by lymphocytes to destroy pathogens

example: immunoglobulin

function: provides immunity, present in breast milk

Question 8

role of RECEPTOR protein
example
specific function

Answer 8

recognition of chemicals arriving at a cell membrane

example: insulin receptor

function: recognition of insulin, present in plasma membrane

Question 9

what are enzymes

Answer 9

enzymes function as biological catalysts and are made by all living cells. they speed up cellular reactions and are unchanged in the process.

Question 10

how do enzymes speed up chemical reactions

Answer 10

by lowering the energy input (activation energy) needed for it to proceed

Question 11

why are enzymes specific

Answer 11

enzymes are specific as each chemical reaction is catalysed by a particular enzyme.
the shape of the ACTIVE SITE of an enzyme molecule is COMPLEMENTARY to its specific SUBSTRATE.

Question 12

how can an enzyme combine with another substrate molecule after speeding up one reaction?

Answer 12

because the shape of enzyme is unaltered during a chemical reaction

Question 13

2 types of enzyme catalysed reactions

Answer 13

degradation and synthesis

Question 14

definition of degradation reactions
example

Answer 14

degradation (breaking down) reactions catalyse the breakdown of large complex molecules into smaller simpler ones

Question 15

definition of synthesis reactions

examples

Answer 15

synthesis (building up) reactions catalyse joining together of many simple molecules to form a larger more complex molecule

Question 16

example of degradation reaction

Answer 16

digestive enzyme amylase breaks down starch into maltose (in pancreas)

lipase breaks down fat into glycerol (in liver)

Question 17

example of synthesis reaction

Answer 17

phosphorylase builds up glucose-1-phosphate into starch (in muscle)

Question 18

each enzyme is most active in its optimum condition.

what can enzymes and other proteins be affected by?

Answer 18

temp and pH

Question 19

what happens if enzymes are denatured

Answer 19

a change in their shape of the active site, the rate of reaction decreases rapidly and activity stops

Question 20

when can enzymes be denatures

Answer 20

at high temperatures such as 60 degrees Celsius

Question 21

what factors affect enzyme activity

Answer 21

suitable temperature, pH and an adequate supply of substrate

Question 22

what is the effect of temperature on the rate of reaction

Answer 22

at low temps, enzyme and substrate molecules move around slowly, collide RARELY, and rate of reaction is LOW

at high temps, enzyme and substrate molecules move around faster, MORE collisions occur, and rate of reaction INCREASES

Question 23

what is the optimum temperature

what temp in human cell is this?

Answer 23

the temp at which the rate of reaction is the fastest

37 degrees Celsius

Question 24

the temp at which rate of reaction is fastest is called

Answer 24

the enzyme’s optimum temperature

Question 25

why does one specific enzyme only catalyse on reaction

Answer 25

enzymes are SPECIFIC because the shape of their ACTIVE SITE is COMPLIMENTARY to the SUBSTRATE. only then will a PRODUCT be produced.

Question 26

catalase breaks down hydrogen peroxide into____

Answer 26

oxygen and water

Question 27

why does enzyme activity decrease at temperatures above the optimum

Answer 27

the enzyme begins to denature, its active site’s shape starts to change

Question 28

enzymes _____ the energy input required
enzymes ____ the rate of reaction
the shape of the _____ is complementary to its substrate

Answer 28

1) lower
2) increase
3) active site

Question 29

why does a denatured enzyme no longer work

Answer 29

the shape of its active site changes such that it is no longer complementary to the shape of its substrate