BSI Lecture 3 Protein Function

Question 1

6 Types of Protein Function

Answer 1

1. structural
2. regulatory
3. contractile
4. immunological
5. transport
6. catalytic

Question 2

Structural

Answer 2

form structural framework

Question 3

Regulatory

Answer 3

alters cell function (hormones, neurotransmitters, receptors)

Question 4

Contractile

Answer 4

allows shortening of muscle cells

Question 5

Immunological

Answer 5

aid responses that protect body against foreign substances and invading pathogens

Question 6

Transport

Answer 6

carry vital substances throughout body

Question 7

Catalytic

Answer 7

enzymes that regulate biochemical reactions

Question 8

Proteins interact with what molecule(s) to carry out their functions?

Answer 8

ligands

Question 9

True or False? Ligands have to fit perfectly into their binding site.

Answer 9

True

Question 10

What holds the ligand in place?

Answer 10

Many bonds between the ligand and the side chains of the proteins in binding site.

Question 11

What types of bonds and attractions hold the ligand into the binding site?

Answer 11

Non-covalent bonds (hydrogen bonds, ionic bonds, hydrophobic interactions, and Van der Waals attraction)

Question 12

What determines the function of a protein?

Answer 12

Its conformational shape

Question 13

What determines the types and locations of binding sites

Answer 13

shape

Question 14

True or False? If the conformational shape of a protein changes, the binding site may change.

Answer 14

true

Question 15

What 2 things may happen in regards to the ligand and protein if the conformational shape of the protein changes?

Answer 15

1. ligand will not bind

2. not enough bonds will be made to hold the ligand in place

Question 16

Define: Denaturation

Answer 16

The process in which a protein loses its quaternary, tertiary, and secondary structure present in their native state

Question 17

What causes protein denaturation?

Answer 17

Temperature, pH, Electrolyte concentration

Question 18

What is disrupted during denaturation?

Answer 18

Nonconvalent bonds maintaining secondary, tertiary, and quaternary structure

Question 19

Define: Protein Turnover

Answer 19

Balance between protein building and degrading.

Question 20

True or False? All proteins have a finite lifetime with in the cell.

Answer 20

True

Question 21

What reasons would cause a protein to degrade?

Answer 21

Normal turnover/renewal, mechanism of cellular control, cellular adaptation, damaged, misfolded

Question 22

What is the function of the Ubiquitin-proteasome system?

Answer 22

To identify degradation signals on protein to begin the process of degrading a protein

Question 23

What is the first step in the UPS?

Answer 23

Protein is tagged with ubiquitin

Question 24

What enzyme recognizes specific degradation signals on proteins and then adds a chain of ubiquitin?

Answer 24

Ubiquitin ligases

Question 25

What recognizes tag (chain of ubiquitin) and degrades the protein?

Answer 25

Proteasome

Question 26

What are degraded proteins turned back into?

Answer 26

peptides

Question 27

What recognizes tag (chain of ubiquitin) and degrades the protein?

Answer 27

20s cylinder and 19s caps

Question 28

20s cylinder contains ___________

Answer 28

proteases

Question 29

What is the function of the 19s caps?

Answer 29

Recognizes ubiquitin on the protein as a tag for destruction and unfolds protein and feeds it into the chamber

Question 30

Enzymes act as a __________, which lowers _________ ________

Answer 30

Catalysts; activation energy

Question 31

Define Activation Energy

Answer 31

The amount of energy required for a reaction to take place ( to convert the substrate into a transition state)

Question 32

Catalysts convert substrate into product by _______ or _______ _________ bonds.

Answer 32

Making; breaking; covalent

Question 33

What do catalyst do?

Answer 33

speed up the reaction rate that would normally be slow

Question 34

Coenzyme

Answer 34

a small molecule that functions as a transient carrier of a functional group

Question 35

Cofactor

Answer 35

inorganic ion or molecule that is required for enzyme activity

Question 36

Why, if a protein denatures, will it lose its function?

Answer 36

It causes the protein to lose its shape, the ligand will no longer bind properly to the protein and can no longer perform its function.

Question 37

What type of noncovalent bond assist the ligand to get into position?

Answer 37

Hydrophobic interactions.

Question 38

What matters in the function of the protein?

Answer 38

Size, shape, and chemical properties

Question 39

Hydrolases

Answer 39

hydrolytic cleavage reaction

Question 40

Nucleases

Answer 40

break down nucleic acids

Question 41

Proteases

Answer 41

break down proteins

Question 42

Synthases

Answer 42

synthesize molecules in an anabolic rxn

Question 43

Isomerases

Answer 43

rearrange bonds within a single molecule

Question 44

Polymerases

Answer 44

polymerization rxn

Question 45

Kinases

Answer 45

add phosphate groups to molecules

Question 46

Phosphatases

Answer 46

remove phosphate group from molecules

Question 47

Oxido-reductases

Answer 47

catalyze rxns in which one molecule is oxidized and the other reduced

Question 48

ATPases

Answer 48

hydrolyze ATP

Question 49

Ligases

Answer 49

catalyzes condensation rxns in which 2 atoms are joined using ATP or GTP

Question 50

Dehydrogenases

Answer 50

remove pairs of hydrogen atoms