Biochemistry Metabolic Pathways Unit

What is the terminal electron acceptor in the ETC?

O2

This kind of pathway breaks down molecules, releasing energy that can be used by the other kind of pathway

Catabolic Pathway

This kind of pathway synthesizes molecules, using up energy provided by the other kind of pathway

Anabolic Pathway

Endergonic Reaction

A non-spontaneous reaction that requires an input of energy to occur

What are the signs of endergonic and exergonic reactions, respectfully?

Positive; Negative

Which reactions in glycolysis are irreversible?

1st, 3rd, 10th

What are the activators and inhibitors of Hexokinase?

A: none; I: Glucose-6-phosphate, ATP

Explain the effect of an increase of entropy (disorder) on delta G (change in free energy)

As entropy increases, delta G decreases

Is cellular respiration exergonic or endergonic? Is photosynthesis exergonic or endergonic?

Exergonic; Endergonic (requires energy from the sun)

What are the activators and inhibitors of PFK-1?

A: Fructose-2,6-bisphosphate, AMP; I: citrate, ATP

What is substrate-level phosphorylation?

An anaerobic reaction where ATP is produced by directly transferring a phosphate group to ADP

What are the enzymes that catalyze the irreversible reactions in glycolysis?

Hexokinase (1), PFK-1 (3), Pyruvate kinase (10)

What are the activators and inhibitors of Pyruvate-kinase?

A: Fructose-1,6-bisphosphate, AMP; I: Acetyl-CoA, ATP

What is the difference between substrate-level and oxidization-level phosphorylation?

Substrate-level utilizes kinase to transfer phosphates.

How much ATP is made in the entire process of cellular respiration from 1 glucose molecule and where does it come from?

38 ATP; 2 from Krebs, 2 from glycolysis, 34 from oxidative phosphorylation

What high-energy molecules come from the Krebs Cycle?

2 ATP, 6 NADH, 2 FADH2

What high-energy molecules come from glycolysis?

2 Net ATP, 2 NADH

What high-energy molecules come from the link step?

2 NADH

Maltase

The hydrolase enzyme that converts maltose to glucose

How many molecules of CO2 are produced in the link step? How many in the Krebs Cycle?

2; 4

Pyruvate + NADH --> lactate + NAD+

The reaction for fermentation

What enzyme catalyzes fermentation?

Lactate dehydrogenase

How many ATP can be produced in the absence of oxygen (fermentation/anaerobic respiration)?

2

NADH + H+ --> NAD+ + 2e- + 2H+

Oxidation

Which (matrix or intermembrane space) has a lower pH, and why?

Intermembrane space: has a greater concentration of hydrogen ions

How many ATP molecules are made by substrate-level phosphorylation?

4

What molecules besides pyruvate can feed into the Krebs Cycle?

Fatty acids

What and where is chemiosmosis?

The moving of H+ ions across a membrane producing a proton gradient used to generate ATP. The ions move from the matrix across the inner membrane and into the intermembrane space

How does ATP synthase catalyze the formation of ATP?

ATP synthase transports H+ ions back to the matrix which results in the synthase turning like a motor, generating mechanical energy which forms bonds between ADP and Pi

What is the equation that relates enthalpy and entropy?

delta G = delta H - T * delta S

If the delta G's of a coupled reaction add up to be negative...

It is spontaneous

In cellular respiration, what reactant gets oxidized and which is reduced?

Oxidized - Glucose, reduced - O2

True or False: All dehydrogenases are oxidoreductases

True

Oxidoreductases...

Catalyze oxidation-reduction reactions by transferring electrons or hydrogen atoms between molecules

Transferases...

Transfer a group from one molecule to another (ex. kinases)

Hydrolases....

Catalyze hydrolysis reactions by using water to break a chemical bond

Lyases...

Break bonds in the absence of water, often forming new bonds or rearranging atoms (ex. synthases)

Isomerases...

Catalyze the conversion of one isomer to another within the same molecule

Ligases...

Catalyze the joining of two molecules, typically with the expenditure of energy (usually from ATP)

What regulates glycolysis reactions?

Equilibrium shift

What is the purpose of fermentation?

Generate energy in the absence of oxygen by regenerating NAD+ from NADH, allowing glycolysis to continue and create a small amount of ATP

What enzymes are involved in the breakdown of starch and maltose?

Amylases and maltases (both are hydrolases)