Fundamentals of Biochemical Reactions Flashcards Preview

Medical Biochemistry > Fundamentals of Biochemical Reactions > Flashcards

Flashcards in Fundamentals of Biochemical Reactions Deck (28):
1

What is metabolism?

A series of biochemical reactions that can be either metabolic or anabolic in nature to harness energy from biomolecules.

2

The concept of Delta G and how to apply it.

G is the free energy change

g=0 Rxn is at equillibrium
g>0 rxn is NON-spontaneous (energonic)
g<0 rxn is spontaneous (exergonic)

3

What is Keq?

Keq is the ratio of the products/reactants within an equation

4

What is the relationship between Keq and Go'

Go'=-RTLnK

Keq is directly proportional to Go'

When:
Keq=1 Go'= 0 Reaction is at Eq (no change)

Keq>1 Go'<0 Reaction is Spontaneous (rxn will proceed to the right)

Keq<1 Go'>0 Reaction is NOT SPONTANEOUS
(Will proceed to the left)

5

What are the Reaction Drivers? How can you make a reaction go in the direction you want?

a.) Mass Action--> Based on Le Chatelier's Principle, you can make the reaction go in the direction that you want by altering reaction kinetics
- If reaction is NOT SPONTANEOUS and pushes
to left, you can push it to the right by removing
product or adding reactants.

b.) Input of Energy/ Energy Coupling
- endergonic rxns coupled with exergonic
reactions to make the former happen
****THE FINAL DELTA G of sum of rxns will
determine the fate of the reaction coupling
mechanism

6

List the type of reactions and give examples of each.

1.) Addition/ Elimination Rxn
Addition Rxn--> adding a product to a double bond
Elimination Rxn--> removing a product to form a double
bond

2.) Substitution Rxn--> a SN1 or SN2 rxn that uses a nucleophile to attack an electrophile to create a substitution.

3.) Rearrangements--> shift of a functional group on a molecule via isomerase/ mutase

4.) Oxidation/Reduction--> a reaction that causes electrons to be transferred from one molecule to another

5.) Acid-Base Rxn--> involves molecules that donate protons and accept protons

7

What is the body's buffering system? What type of rxn is this an example of?

The buffering system is an example of an acid-Base rxn.

HC03- +H+ --> H2CO3--> H20 + C02

8

What is the normal physiological PH of the body's buffering system?

pH= 7.37- 7.43

9

What are enzymes? What do they do?

Enzymes are biological catalysts that increase the reaction rate.

Bind to substrates and convert them into products by lowering the activation energy (Ea)

10

What are some examples of oxidoreductases?

Dehydrogenases
Oxidases
Peroxidases
Reductases
Monooxygenases
Dioxygenases

11

Lock and Key Hypothesis vs. Induced Fit Hypothesis

Lock and Key Hypothesis- substrate fits enzyme like a perfect fit like a key to a lock

Induced Fit Hypothesis- substrate binds to enzyme and causes conformational changes

12

What is the difference between a cofactor and a coenzyme?

Cofactors are not organic molecules

Coenzymes are organic molecules

**Both play a functional role in aiding an enzyme perform its duties in making reactions occur.

13

Example of Coenzymes

FAD, FMN, Heme (not just Fe BRO!!!!!), NAD+, Lipoic Acid, Panthoneic Acid, Pyroddoxil Phosphate, THF, Thiamine Pyrophosphate

14

Examples of Cofactors

Cu, Fe, Mg, Se, Zn

15

How does the H+/K+ ATPase pump work in the STOMACH?

H+/K+ ATPase uses ATP to push H+ into the stomach to combine with Cl- --> HCL

HCl acid is good because the acidity will activate pepsinogen--> pepsin for protein digestion!

16

What are some of the common proton pump inhibitors that work on the H+/K+ ATPase Pump?

Omeprazole, Lansoprazole, Esmoprazole

-all the "prazoles"

17

What is the rate of an enzymatic reaction based on?

[substrate]
affinity of the enzyme (Km)
Velocity (v, Vmax)

18

What are the different types of Enzyme Inhibition?

Competitive Inhibition--> Vmax the same, Km increased
-How to Overcome: Increase [SUBSTRATE]

NON-Competitive Inhibition--> binds to the E and ES complex at site other than substrate binding which results in DECREASED [Vmax], SAME [Km]

***Uncompetitive Inhibition--> only binds to ES complex; results in DECREASE of BOTH Vmax & Km

19

What are examples of Competitive Inhibitors?

Malonate
Sulfanilamide
Methotrexate

20

What are Chelating agents and how are they used?

Chelating agents are agents that bind more strongly to a poison than its affinity for another substrate.

-Example--> Pb and Ca-EDTA

21

What does it mean when an enzyme is inactive or irreversibly inactive?****

COVALENT MODIFICATION

It means the enzyme has lost its function irreversibly from destruction or covalent modification of key functional groups that were important for the enzyme to function.

-Km unchanged, Vmax DECREASED (SIMILAR TO NON-COMPETITIVE INHIBITION)

22

What is an irreversible enzyme inactivation similar to in terms of competitive, noncompetitive, and uncompetitive rxns?

COVALENT MODIFICATION

Very similar to noncompetitive inhibition because just like an irreversible reaction:

-the Km is unchanged, Vmax is DECREASED

23

Examples of Irreversible Inhibitors

Pb
Organophosphates
Aspirin
Cyanide
Sulfide

24

Allosteric Enzymes are modified through covalent or non-covalent interactions? And what are activators vs. inhibitors?

Allosteric inhibitors bind via NON-COVALENT interactions.
Activators--> INCREASE activity
Inhibitors--> DECREASE activity

25

Allosteric Enzymes are modified through covalent or non-covalent interactions? And what are activators vs. inhibitors?

Allosteric inhibitors bind via NON-COVALENT interactions.
Activators--> INCREASE activity
Inhibitors--> DECREASE activity

26

What type of graph do you use for allosteric enzymes?

You use a sigmoidal graph where:

(+) activator --> shift to left
(-) inhibitor --> shift to the right

27

What are isozymes?

Enzymes that have same function, but different AA sequences
ex: CK-MB, AST, LDH

28

What are proenzymes/zymogens?

Proenzymes/Zymogens are inactive forms of the enzyme that have to be activated via cleavage

Ex: pepsinogen, chymotripsinogen