OPT 116 Energy Production : Glucose Metabolism

What can be used to produce energy?

glucose, fatty acids, and amino acids

After a carbohydrate rich meal, what is the primary source of energy?

glucose

during fasting, what is the primary source of energy?

fatty acids

After a protein rich meal, what is the primary source of energ?

amino acids

What cells rely solely on glucose for energy?

RBC: does not contain organelle to metabolize fatty acids

brain: has a barrier preventing fatty acids from entering

What types of cells rely primary on fatty acids for energy (even when glucose is present)?

liver cells, heart, and resting skeletal muscle

catabolism involves the transfer of electrons meaning

one molecule loses and electron while the other gains

catabolism

molecules are broken down into smaller ones

oxidation

when a substance loses an electron or hydrogen but gains oxygen

reduction

when a substance gains and electron or hydrogen but loses oxygen

What molecules are oxidized (loss) during energy production ?

glucose, fatty acids, amino acids

What molecules are reduced (gain) during energy production ?

NAD+ (accepts 2 e- and 1 proton to become NADH)

FAD (accepts 2 e- and 2 protons to become FADH2)

cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

The process of cellular respiration

generates ATP by oxidative phosphorylation -- most efficient method of ATP production

What is the final electron acceptor?

Oxygen

Fermentation

generates ATP by substrate level phosphorylation (less efficient) results in lactic acid production

what is the final electron acceptor in fermentation?

organic molecule rather than oxygen serves as a final electron acceptor

what are the steps of cellular respiration?

1. Glycolysis

2. Transition Reaction

3. Citric Acid Cycle (krebs)

4. Electron Transport Chain

glycolysis

oxidizes glucose to pyruvate (splitting of glucose)

Glycolysis yields

2 pyruvate, 2 ATP, 2 NADH

how many steps are there in glycolysis?

- investment phase (1-5)

-Payoff phase (6-10)

investment phase of glycolysis

uses 2 ATP to split glucose into two molecules

payoff phase of glycolysis

2 NAD+ are reduced to NADH, produces 4 ATP through substrate level phosphorylation

Transition reaction

pyruvate is shuttled into the mitochondria and converted into Acetyl CoA

What does the transition reaction produce?

CO2

1 NAD+ is reduced to 1 NADH

Krebs Cycle (Citric Acid Cycle)

metabolic process that oxidizes citrate to oxaloacetate

what does the krebs cycle produce?

1 oxaloacetate

3 NADH

1 FADH2

1 GTP

2 CO2

How is citrate formed?

by combining acetyl-CoA and oxaloacetate

Electron Transport Chain (ETC)

series of electron carrier proteins that shuttle high-energy electrons during ATP-generating reactions

Where does ETC occur?

inner membrane of mitochondria

About the electron transport chain

- 4 large complexes I-IV

- last component is oxygen

- each component of the chain is more electronegative than the last

What do NADH and FADH2 do?

they pass on their electrons down the ETC

Where does NADH start in ETC?

Complex I

where does FADH2 start in ETC?

Complex II

what is the purpose of the electron transport chain?

pump H+ from the mitochondrial matrix to the inter membrane space , creating an electrochemical gradient

chemiosmosis

H+ in the intermembrane space reenter the mitochondrial matrix by moving down the electrochemical gradient (travel through ATP synthase)

-catalyzes the joining of phosphate to ADP to form ATP

ATP synthase

Large protein that uses energy from H+ ions to bind ADP and a phosphate group together to produce ATP

How many H+ ions move through ATP synthase to synthesize 1 ATP?

4 H+

How much ATP does cellular respiration generate?

36 molecules of ATP per molecule of glucose

How much ATP does each NADH produce? (10 H+)

2.5 ATP

How much ATP does each FADH2 produce? (6 H+)

1.5 ATP

How many molecules of water are produced in cellular respiration? how many CO2?

6 H2O, 6 CO2

How much ATP is produced in oxidative phosphorylation?

28 (10 NADH= 25 ATP, 2 FADH2= 3 ATP)

What does fermentation produce?

2 pyruvate, 2 NADH, and 2 ATP net

What happens to fermentation is oxygen is not present?

pyruvate is fermented and does not enter the krebs cycle (accepts e- from NADH forming lactate and NAD+)

what happens to lactate after fermentation?

Lactate is transported to liver for conversion back to pyruvate, providing a steady supply of NAD+ that can enter glycolysis)