Chapter 3 protein function Flashcards Preview

MCBL > Chapter 3 protein function > Flashcards

Flashcards in Chapter 3 protein function Deck (34):
1

How many molecules can proteins bind to?

proteins are usually very specific in their binding and bind to one molecule

2

What is the molecule that proteins bind to?

a ligand

3

What is binding of a protein to a ligand made possible by?

the weak noncovalent interactions of protein and ligand

4

What are the weak noncovalent interactions?

Hydrogen
van der waals
electrostatic

5

What type of fit does the proteins have for their ligands?

like a hand to glove

6

What is the region that associates with the ligand?

ligands binding site

7

What does the binding site of protein consist of?

a cavity with different arrangements of amino acids

8

what does the neighboring parts of a polypeptide chain keeps away from the binding site?

Water,
water can form hydrogen bonds within the ligand binding site

9

What can alter the reactivity of of proteins?

clustering of neighboring polar amino acids

10

how does the clustering of neighboring polar amino acids alter proteins activity?

If folding forces together negatively charged side chains, this increases the affinity for a positive molecule.
When side chains react with each other through hydrogen bonding unreactive side groups become reactive

11

Why does two different conformations differ in chemistry?

chemical reactivity depends on which amino acids are exposed and orientation relative to one another

12

What is similar in protein domain families?

3D structure (tertiary and quaternary structures)

13

What are enzymes?

enzymes are proteins that speed up reactions by breaking and making bonds

14

name the parts in the steps of protein reaction?

Substrate and enzyme
Substrate/Enzyme
Enzyme /product
Enzyme and product

15

What are characteristics of and Enzyme?

not consumed or destroyed by chemical reaction
may be localized to specific region or compartment
do not change delta G
only present in low concentrations
increase probabilty of a reaction occurring/increase reaction rate
enzye activity can be regulated

16

What is the activity of a hydrolase?

catalyze hydrolytic cleavage reactions

17

What is the activity of nucleases?

break down nucleic acids

18

What is the activity of proteases?

breakdown proteins by cleaving peptide bond

19

What is the activity of sythases?

Used in anabolic reaction to polymerize two molecules

20

What is the activity of kinases?

catalyze addition of phosphate group to a molecule
protein kinases add PO4 to a protein

21

What is the activity of phosphotases?

Catalyze the removal of a phosphate group

22

What is the activity of ATPases

hydrolyze ATP

23

What is the Michaelis-Menten kinetics equation

V= Vmax *[S]/Km + [S]

24

What is Km?

Is the substrate concentration when the Velocity is equal to 0.5Vmax

25

What is velocity equal to when Substrate concentration is less than Km?

zero

26

What is the rate of the reaction dependent on when the substrate concentration is less than Km?

it is substrate dependent

27

What is the velocity equal to when substrate concentration s greater than Km?

Velocity = Vmax

28

What is the rate of reaction dependent on if substrate concentration is greater than Km?

it is enzyme dependent

29

What is velocity equal to when substrate concentration is equal to Km?

velocity = 0.5Vmax

30

How are the enzyme activity regulated in the cell?

-effect enzyme concentration
-regulatory molecules
-regulation by covalent modifications

31

how is enzyme activity regulated with regulatory molecules?

competition for active site
allosteric regulation
feedback control (positive or negative)

32

how is enzyme activity regulated by covalent modifications?

phosphorylation/dephosphorylation
cleavage (zymogens)

33

How does competitive inhibition changes Vmax and Km?

no change in Vmax
increased Km

34

how does allosteric inhibition change Vmax and Km?

decrease in Vmax
no change in Km

Decks in MCBL Class (70):