proteins and enzyme

Question 1

what other elements does protein contain?

Answer 1

phosphorus, sulfur, and nitrogen

Question 2

what are amino acids

Answer 2

monomer units used to make proteins

Question 3

basic structure of amino acids

Answer 3

a central carbon atom bonded to a carboxyl group, an amino group, a hydrogen atom, and an R group

Question 4

R group can vary by:

Answer 4

• size
• polarity
• charge

Question 5

how many levels of structure does protein have

Answer 5

primary
secondary
tertiary
quaternary

Question 6

what is the primary structure of a protein?

Answer 6

the primary structure of a protein is the sequence of amino acids

Question 7

what is the secondary structure of a protein?

Answer 7

the secondary structure of a protein is the the curling or folding of the polypeptide chain into a-helices and b-pleated sheets due to the formation of hydrogen bonds

Question 8

why is the secondary structure of a protein determined by hydrogen bonding

Answer 8

the hydrogen in -NH is slightly positive and the oxygen in -c=o is slightly negative. This results in a hydrogen bond between amino acids

Question 9

structure of a-helix

Answer 9

In an a-helix, the polypeptide chain coils with the hydrogen bonds keeping the coil stable

Question 10

structure of b-pleated sheets

Answer 10

In b-pleated sheets, the chains form a zig-zag and fold over themselves

Question 11

when does an a-helix form

Answer 11

occur when the hydrogen bonds form between every fourth peptide bond (between the oxygen of the carboxyl group + hydrogen of the amine group)

Question 12

when does a b-pleated sheet form

Answer 12

forms when the protein folds so that two parts of the polypeptide chain are parallel to each other enabling hydrogen bonds to form between parallel peptide bonds

Question 13

what is the tertiary structure of proteins?

Answer 13

the tertiary structure of a protein is the overall specific 3d shape of a protein. This is determined by interactions between R groups and the properties of those R groups

Question 14

what is the bond that forms between sulfur atoms in R groups?

Answer 14

Disulphide links

Question 15

what is the quaternary structure of proteins?

Answer 15

the quaternary structure of proteins is the specific 3D shape of a protein that is determined by the multiple polypeptide chains and/or prosthetic groups bonded together

Question 16

what bonds are present in the primary structure

Question 17

what bonds are present in the secondary structure

Answer 17

hydrogen

Question 18

what bonds are present in tertiary structure

Answer 18

hydrogen (between R groups)
disulfide (between cysteine amino acids)
ionic (between charged R groups)

Question 19

what bonds are present in quaternary structure

Question 20

what is the importance of protein structure

Answer 20

the primary structure determines the secondary, tertiary, and quaternary structure which gives proteins their unique shapes

Question 21

what factors can affect the structure of a protein

Answer 21

temperature
pH

Question 22

How does the change in bond affects the protein?

Answer 22

change in bond = change in shape, preventing the protein from being able to carry out its function - resulting in them being denatured

Question 23

what are globular proteins

Answer 23

A globular protein is a protein with a spherical shape that is soluble in water. Globular proteins typically have metabolic roles

Question 24

what are fibrous proteins

Answer 24

A fibrous protein is a very long, strong, and insoluble protein that often has a structural role in organisms

Question 25

properties of globular proteins

Answer 25

- roughly spherical in shape, with hydrophobic R groups on the inside and hydrophilic R groups on the outside - soluble in water

Question 26

what is a conjugated protein

Answer 26

a prosthetic group attached to each polypeptide chain

Question 27

what is a prosthetic group

Answer 27

a prosthetic group is a non-protein component that is necessary for the protein to carry out its function

Question 28

what are the prosthetic groups in hemoglobin called?

Answer 28

haem groups

Question 29

examples of globular proteins

Answer 29

hemoglobin insulin pepsin

Question 30

structure of insulin

Answer 30

composed of two polypeptide chains- one of which has an a-helix and the other of a b-pleated sheet joined together by disulphide links

Question 31

where is pepsin found?

Answer 31

pepsin is found in the stomach with a very low pH

Question 32

how does the charged R groups affect the protein

Answer 32

the positively charged R groups can affect the ionic bonds and hydrogen bonds around the proteins-this denatures the enzyme and therefore alters its functions

Question 33

properties of fibrous proteins

Answer 33

- contains long polypeptide chains with repeating sequences of amino acids - insoluble in water (non-polar R groups) - able to form fibers

Question 34

examples of fibrous protein

Answer 34

keratin elastin collagen

Question 35

roles of collagen

Answer 35

- found in artery walls to prevent vessels from bursting from high-pressure - making tendons, which connect muscles to bone, allowing the skeleton to move - used to make bones

Question 36

where is keratin found

Answer 36

hard body parts such as fingernails, horns, and hooves

Question 37

structure of keratin

Answer 37

the primary structure of keratin contains high amounts of cysteine (amino acids containing sulphur) this results in disulphide links forming between the two polypeptide chains which make the molecule very hard and strong

Question 38

where is elastin found

Answer 38

- found in the lungs to help them inflate and deflate during ventilation - found in our bladder to help it expand to hold urine - found in the blood vessel walls where it helps maintain blood pressure by stretching and recoiling

Question 39

what is a catalyst

Answer 39

a catalyst is a chemical that speeds up the rate of reaction and remains unchanged and reusable at the end of the reaction

Question 40

what are enzymes

Answer 40

a biological catalyst

Question 41

what is an enzyme turnover number

Answer 41

the number of substrates an enzyme can catalyze in one minute

Question 42

what is complementary binding

Answer 42

complementary binding refers to when two molecules fit together to complete each other

Question 43

what factors can affect the shape of the active site (list at least 3)

Answer 43

temperature pH presence of inhibitors or cofactors

Question 44

what is the activation energy

Answer 44

activation energy is the energy required to start a reaction

Question 45

what are enzyme inhibitors

Answer 45

inhibitors are any molecules that reduce or stop a reaction

Question 46

what is a competitive inhibitor?

Answer 46

an inhibitor molecule that competes with the substrate for binding to the active site of the enzyme, preventing the substrate from binding

Question 47

what is a non-competitive inhibitor

Answer 47

an inhibitor that doesn't bind to the active site but binds to a different part of the enzyme (allosteric site) and changes the shape of the enzyme

Question 48

what is an end-product inhibition?

Answer 48

when the inhibitor is non-competitive and the last product in the pathway

Question 49

structure of hemoglobin

Answer 49

is a globular conjugated protein that has a quaternary structure consisting of 2 alpha chains and 2 beta chains each containing a haem prosthetic group which have iron ions that can bind to oxygen