UNIT 1: (1.4) Proteins

Question 1

what subunits are proteins made up of?

Answer 1

subunits called amino acids

Question 2

How many different amino acids are there?

Answer 2

20

Question 3

How are amino acids held together?

Answer 3

amino acids are held together by peptide bonds to form long polypeptide chains

Question 4

what do polypeptide chains go onto form?

Answer 4

chains form the protein molecule

Question 5

what does the structure of a protein depend on?

Answer 5

specific sequence of amino acids

Question 6

what does the sequence of amino acids determine?

Answer 6

The sequence of amino acids determines the shape and function of the protein

Question 7

what would happen if the order of bases is incorrect?

Answer 7

The protein shape will be altered and it may not be able to do its job

Question 8

what is the function, shape and example of a structural protein?

Answer 8

• collagen makes up the body cartilage
  keratin makes up hairs and nails
• composed of fibres

Question 9

what is an example, function and shape of an enzyme?

Answer 9

• examples: amylase, pepsin, lipase, phosphorylase
• involved in metabolism, break down or build-up
• globular proteins with a shape that fits snugly with the chemicals they work on

Question 10

Describe an example, function, shape of a hormone.

Answer 10

• e.g insulin
• act as chemical messengers in the body
• insulin controls blood glucose levels
• small globular proteins

Question 11

Describe the function and shape of a antibodies

Answer 11

• combine with foreign proteins ( antigens) and mark them to be destroyed by the body’s immune system
• globular proteins, shaped to recognise and bind with the foreign protein

Question 12

Describe the function and shape of receptors

Answer 12

• found on the surface of particular cells which allow hormones to target these cells
• the shape of a receptor protein on a cell allows the cell to respond to a specific hormone

Question 13

what are enzymes known as?

Answer 13

biological catalysts which are present in all living cells. They speed up chemical reactions but remain unchanged by these reactions

Question 14

what effect do enzymes have on activation energy?

Answer 14

lower the activation energy needed for metabolic reactions to proceed in cells

Question 15

name which are the catalyst, reactant and products

manganese dioxide
water + oxygen
hydrogen peroxide

Answer 15

manganese dioxide= catalyst
water + oxygen= products
hydrogen peroxide= reactant

Question 16

what is the function of the enzyme catalase?

Answer 16

breakdown hydrogen peroxide which is produced in living cells into harmless oxygen and water

Question 17

why does dead tissue show no reaction when boiled?

Answer 17

as boiling denatured the enzyme

Question 18

what does denatured mean?

Answer 18

The change in the shape of a protein such as an enzyme that results in them no longer fitting their substrate

Question 19

what are different variables?

Answer 19

• volume
• mass/substrate
• concentration
• temprature

Question 20

what is a degradation reaction?

Answer 20

A breakdown reaction - when a chemical compound splits into smaller parts.

Question 21

what is a synthesis reaction?

Answer 21

A build-up reaction - when two or more substances join together to form one product.

Question 22

how are enzymes different from other catalysts?

Answer 22

• enzymes are made inside living cells

- all enzymes are proteins but all catalysts are not

Question 23

why are enzymes vital to living organisms?

Answer 23

speed up chemical reactions inside cells to sustain life

Question 24

what temperature do enzymes work best in the human body?

Answer 24

37°C

Question 25

why do you use different syringes for different liquids?

Answer 25

to prevent cross-contamination of the solutions

Question 26

what is the function of phosphorylase?

Answer 26

builds up glucose-1-phosphate into starch

Question 27

what is meant by a control?

Answer 27

control acts as a comparison to show that it is the factor being investigated that is having an effect

Question 28

what is meant by optimum?

Answer 28

the conditions under which an enzyme is most active (eg temperature and pH)

Question 29

what happens during digestion?

Answer 29

large insoluble molecules are degraded with the help of enzyme action into smaller soluble ones

Question 30

what are the 3 main groups of digestive enzymes?

Answer 30

- carbohydrases - proteases - lipases

Question 31

what is the function of carbohydrates?

Answer 31

break down carbohydrates into sugars such as maltose and glucose

Question 32

what is the function of proteases?

Answer 32

break down proteins into polypeptides then into amino acids

Question 33

what is the function of lipases?

Answer 33

break down fats into fatty acids and glycerol

Question 34

what happens during an enzyme controlled reaction?

Answer 34

where the substrate joins temporarily at the active site on the surface of the enzyme

Question 35

why is the shape of the active site of an enzyme important?

Answer 35

the shape of the active site of an enzyme molecule is complementary to its specific substrate

Question 36

what is the function of a substrate molecule?

Answer 36

substrate molecules fit into the active site creating the enzyme-substrate complex

Question 37

what can the structure and shape of all proteins be affected by?

Answer 37

- temperature | - pH

Question 38

what are enzymes made of?

Answer 38

proteins

Question 39

in general what pH are most enzymes most active?

Answer 39

neutral pH ( pH 7 )

Question 40

draw a conclusion about the working range of different enzymes

Answer 40

Each enzyme has a different working range

Question 41

what will happen when pepsin on egg albumen cylinders is investigated?

Answer 41

- pepsin will digest the insoluble egg protein - decrease in length of cylinders ( indicates the amount of digestion) - the greater the decrease in length of the cylinders, the more active the enzyme pepsin

Question 42

how do you work out percentage change?

Answer 42

difference ÷ original number x 100

Question 43

how does the change of pH in solutions relate to the activity of the enzyme used?

Answer 43

- As the pH of the solution decreases enzyme activity increases. - can be observed as a greater percentage change in length

Question 44

what are the names of the substrate, enzyme and product(s) in the egg albumen investigation

Answer 44

substrate - egg albumen enzyme - pepsin product(s) - solid white albumen

Question 45

what happens to enzymes at higher pHs ( 6.7)?

Answer 45

the enzymes active site changes shape and is no longer complementary to its substrate so is not active

Question 46

what happens to enzymes at high temperatures?

Answer 46

enzymes can be denatured resulting in a change to their shape

Question 47

in the investigation of the effect of temperature on the activity of invertase, why was the sucrose and invertase adjusted to the correct temperature before being mixed?

Answer 47

so they would not start to react with each other before reaching the required temperature

Question 48

what can be done to make results more reliable?

Answer 48

class results can be compared and averages calculated to make it more reliable

Question 49

if the temperature denatured the enzyme but was brought back to a normal temperature. what would happen to enzyme activity?

Answer 49

the rate would stay at 0% as the enzyme has denatured and the shape change is permanent

Question 50

what are the 2 types of enzyme reactions?

Answer 50

- degradation reaction | - synthesis reaction

Question 51

what are examples of a degradation reaction?

Answer 51

hydrogen peroxide + catalyase = oxygen + water surcrose + invertase = glucose + frucose starch + amylase = maltose

Question 52

what is an example of a synthesis reaction?

Answer 52

glucose-1-phosphate + phosphorylase = starch

Question 53

what is a test for starch?

Answer 53

``` benedicts reagent orange= sugar present brick red ( once heated) = maltose ```

Question 54

where does sugar come from?

Answer 54

broken down starch

Question 55

what are examples of proteins?

Answer 55

- hormones - enzymes - antibodies - receptors - structural proteins ( HEARS )

Question 56

what is the active site?

Answer 56

location on the surface of the enzyme which matches the shape of the substance that it works on ( its substrate)

Question 57

around what temperature will it denature the enzyme?

Answer 57

45 or above