Cell and Molecular Biology Chapters 9 and 10: Glycolysis, Fermentation, and Aerobic Respiration

What is a phototroph

This is an organism that obtains energy form light for cellular processes and the synthesis of the compounds that they need to live

What is a chemotroph?

The need to obtain energy from small organic building blocks of outside sources (consumed).

What does anabolic mean

Building up

What does catabolic

Breaking down

What is the cells metabolism

All of the anabolic and catabolic processes used in the metabolic pathways

What is the primary energy currency model of the cells

ATP

What are some energy molecules other than ATP

GTP, Acetyl CoA, and Creatine Phosphate

What is a molecule that stores electrons that can be used to reduce

NADH

What is the chemotropic energy metabolism

This is the process that catabolizes nutrients to release energy

What does the chemotropic energy metabolism involve

It involves the series of enzyme driven reactions

What are the types of molecules received from the input sources

It uses fats, proteins, and carbohydrates.

What are the five basic steps to aerobic cellular respiration of glucose

1. Glycolysis

2. Pyruvate Oxidation

3. TCA Cycle

4. Electron Transjport

5. ATP synthesis

What part of aerobic cellular respiration is cytosolic

Glycolysis

Where do the rest of the steps occur

The mitochondria

How many steps are in glycolysis

10

What is each step of glycolysis catalyzed by

Each step is catalyzed by a specific enzyme.

Summarize Glycolysis

What does the fate of pyruvate depend upon?

It depends on whether O2 is available or not.

What happens to pyrubate if oxygen is not available?

Pyruvate is reduced.

What does the reduction of pyruvate of mammals result in?

It results in lactate

What is the product of reduced lactate in other organisms

Other organisms produce alcohol.

What is the fate of pyruvate if oxygen is available?

If it is available, it enters the tricarboxylic acid cycle to be completely oxidized which releases a lot more ATP.

What is the main source of energy used by animal cells

Glucose!

What is the level of glucose that is maintained in the blood by hormone systems

80-100mg/100mL

Where does the body have reserves of glucose? What is it called?

It is in the muscles and liver as glycogen.

What sugars do we take in as a part of our diet?

Monosaccharides like galactose, fructose, as well as three and five carbon sugars.

Where can sugars also be found?

They can be liberated from polysaccharides that have α bonds and not β bonds.

What is the main reason that gluconeogenesis cannot simply reverse all of glycolysis.

This is because some glycolysis reactions are irreversible and myst be bypassed with different enzymes.

Which of the glycolysis steps are irreversible

Gly-1 and Gly-3

Why can Gly1 not be reversed?

It is an irreversible ATP driven step. What

What is is the enzyme that bypasses the GLy1 step during the gluconeogenesis

Glucose-6-phosphatase

What is the reaction that the glycose-6-phosphatase catalyzes

It removes a phosphate from glucose-6-phosphate to form glucose

What happens in Gly-3 during glycolysis?

Fructose-6-phosphate is phosphorylated to fructose-1,6-bisphosphate.

Why can the Gly-3 reaction not simply run backward during gluconeogenesis?

Because it is also an irreversible, ATP-driven reaction.

What enzyme bypasses the Gly-3 step during gluconeogenesis?

Fructose-1,6-bisphosphatase.

What reaction does fructose-1,6-bisphosphatase catalyze?

It removes a phosphate from fructose-1,6-bisphosphate to form fructose-6-phosphate.

Why does the slide say these bypass reactions cannot be coupled to ATP synthesis?

Because the phosphate is released directly as inorganic phosphate instead of being used to make ATP.

What does it mean that the reactions are “uncoupled”?

It means phosphate removal happens separately and is not linked to ATP production.

How is the phosphate removed in these gluconeogenesis bypass steps?

By hydrolysis using water.

What is released when the phosphate group is removed during these steps?

Inorganic phosphate (Pi).

Does gluconeogenesis when it has to reverse the irreversible glycolysis steps?

NO! ATP IS NOT MADE!

What is the purpose of the bypass reactions in gluconeogenesis

This is to get aroudn the irreversible glycolysis steps so that glucose can be synthesized.

Why is gluconeogenesis not able to convert pyruvate directly back to PEP?

This is because glycolysis from PEP to pyruvate is irreversable.

What is the intermediate between pyruvate and PEP in gluconeogenesis?

Oxaloacteate

What is the molecule that is required to convert the pyruvate to oxaloacetate?

ATP

What is the cofactor that is used by pyruvate carboxylaase

Biotin

What molecule is required to convert oxaloacetate to PEP

GTP

What happens to the CO2 in the bypass pathway

The CO2 is added to the pyruvate to form the oxaloacetate and then removed when it is converted to the PEP.

For gluconeogenesis, how much ATP is used to make 1 glucose

It uses 6 ATP

How much ATP does glycolysis generate per glucose

2 ATPT

If gluconeogenesis is used, what is the Net ATP gained

(-2 ATP)

What is a method that the body uses to avoid the waste of resources?

The body takes advantage of a separation of the reaction sites

What is an example of separation of the reaction sites

The Cori Cycle

Where does most gluconeogenesis take place?

This takes place in the liver where the glycolysis rates do not need to be high.

What is the biological reason that the liver would perform gluconeogenesis.

The liver has glucose-6-phosphatase, which converts glucose-6-phosphate into free glucose that can leave the cell. The tissues like the brain and red blood cells depend on glucose for energy, so if there are no nutrients, the G6P can catalyze conversion of gluconeogenesis causing you to stay alive. Yay for not dying!

What is the primary regulator of glycolysis and gluconeogenesis?

F-2,6-BP

What does the F-2,6-BP do?

It stimulates the Gly 3 step, inhibiting the corresponding step in glucose synthesis.

What does F-2,6-BP respond to

It responds tohormones via the cAMP messenger

To extract the remaining energy out of pyruvate, what cycle, involving citric acid as a key component, occurs?

It is the citric acid Cycle

When and who was the citric acid cycle first elucidated?

1930s by Hans Krebs

What are some of the names for the TCA cycle

Citric Acid Cycle, Krebs Cycle, or Tricarboxylic acid cycle.

Where is pyruvate moved to begin TCA

It is moved into the mitochondrial matrix

What is the pyruvate that is moved to the mitochondreial matrix converted to?

Acetyl CoA, CO2, and NADH

Where does the enzyme conserve the energy?

It conserves it in a thioester bond

Is this conversion endergonic or exergonic

It is exergonic with it being -7.5Kcal/mole

How many times does TCA cycle run?

2 times

What are all of the Carbon-Oxygen bonds released as

They are released as CO2. W

What are all of the hydrogen electrons used for?

They are channeled into reducing the electron carriers.

Similarly to gluconeogenesis, is the TCA cycle regulated?

Yes!

How does fatty acid catabolism proceed

It happens through β-oxidation

How many carbons are liberated through the oxidation of the 2nd Carbon

2 Carbon units are liberated

What do the liberated units of carbon produce

Acetyl CoA

What happens to the acetyl CoA that is produced via fatty acid catabolism

It goes through TCA to be oxidized

If there is a 16 carbon fatty acid that is broken down, how many acetyl-CoA molecules are produced

8

What process releases amino acids

Proteolysis of proteins

What are the amino acids received by proteolysis used for

To be converted to TCA intermediates for breakdown

What is the first step of proteolysis?

Deamination

What happens to amino acids after deamination?

Some enter the citric acid cycle directly while others require more paths to make TCA intermediates.

What is deamination

This is the removal of an amino group from an amino acid

Why is it necessary that the amino acids are deaminated

This is crucial because TCA uses Carbon not nitrogen

Are the reactions to convert amino acids to TCA molecules reversible?

YES!

if the reactions to convert the amino acids to the TCA cycle is reversible, what does this mean

It means that the TCA cycle can be used to make aino acids.

What are the ATP/Glucose after glycolysis? After TCA? lWhat is the energy payoff?

2 ATP. After TCA, 4 ATP. The energy payoff is in the 10 NADH and the 2 FADH2.

What does the electron transport chain do

1. It removes the electrons from the carriers

2. It passes the electrons to reduce O2 ,releasing energy as a part of the process

How are the electrons removed from the high energy electron carriers

They are transported out with H+ acorss the inner mitochondrial membrane stored as a proton gradient.

Where can the electron transport chain do with electron carriers?

It can put them in order based on reduction potential

In the mitochondrial membrane, what are most carriers a part of?

They are a part of large protein complexes

Does this increase or decrease the efficinecy of the transfer of electrons?

This increases electron transfer efficiency

What is the process that transfers the electrons through the chain?

This is a spontaneous exergonic process

What is the enrgy that pumps the protons out of the matrix and into the cristae?

It is the E- energy

What is the characteristic number of H+ ions for every 2 electrons that are transported

Complex I is four H+, Complex III is four H+, and Complex IV is 2 H. This means that there is a total of 10 H+ pumped out. The Q cycle can add more under certain conditions

What is the complex responsible for synthesizing ATP

FoF1

How does f0f1 synthesize the ATP

It uses the movement of the H+ into the mitochondrial matrix from the cristae>

What is the process in the mitochondria that uses the electron transport chain and a proton gradient to drive ATP synthesis via ATP synthase called?

Oxidative phosphorylation

What is the F0F1 complex made of

Protein subunits that all have different functions

What are the subunits designed to do

They are designed to create a molecular motor that rotates as H+ is transferred.

What is the process of energy conversion

Chemical to electron to chemiosmotic to mechanical energy to chemical energy.

Is the Max value of ATP synthesis achieved?

No!

How much ATP per NADH? FADH2?

2.5 and 1.5

So, summarize the reaction

1 Sugar, and 6 O2 yields 6 H2O and 6 CO2.

Additionally, there is 4 ATP from the reaction, 25 ATP from the 10 NADH, and 3 ATP from the FADH2.