9/11/24 - Digestion and Metabolism (Reading 3) Lecture Questions

What is Metabolism?

What is Anabolism? Catabolism?

Sum of all metabolic reactions / processes in the body

Anabolism — turning small things into big things (Ex. Monomers —> Polymers)

Catabolism — turning big things into small things (Ex. Polymers —> Monomers)

What is the structure of ATP?

Adenine (nucleotide), Ribose sugar, and 3 Phosphate Groups

What is Glucose?

Hexose sugar used by humans as an immediate, primary source of energy

What is Gluconeogenesis?

Process of turning non-carbohydrates into Glucose

What is Glycogen?

Storage form of Glucose in animals, stored in the Liver or Skeletal Muscles for the long-term

What is Glycogenesis?

Process of turning Glucose into Glycogen

What is Glycogenolysis?

Process of turning Glycogen into Glucose

What is Glycolysis?

Process of turning Glucose into Pyruvate

What is Glucagon?

Catabolic hormone that raises blood sugar by triggering the Liver to release / convert stored Glucose

What is the purpose of Catabolic Hormones?

What are some examples of Catabolic Hormones?

Hormones used to breakdown large molecules

Examples include:

• Cortisol

• Glucagon

• Epinephrine (A.K.A Adrenaline)

What is the purpose of Anabolic Hormones?

What are some examples of Anabolic Hormones?

Hormones used to build large molecules from small molecules

Examples include:

• Growth Hormone

• Insulin-Like Growth Factor

• Insulin

• Testosterone

• Estrogen

Where is Glucagon released from?

What is its main function?

How does it achieve this?

Released from Alpha cells of the Pancreas

Raises blood sugar levels

Promotes the breakdown of Glycogen into Glucose through Glycogenolysis

Where is Insulin released from?

What is its main function?

How does it achieve this?

Released from Beta cells of the Pancreas

Lowers blood sugar levels

Promotes the synthesis of Glycogen from Glucose through Glycogenesis

What happens if a cell does not have ATP?

Cell cannot do the necessary cellular functions it needs to do and dies

Which biomolecules does the body prefer to break down for energy first?

Body breaks down Glucose first, then Glycerol & Fatty Acids, and then Amino Acids / Proteins

Body will always prioritize Glucose first!!!

How is ATP used for energy?

Hydrolyzed to form ADP and Energy

What type of reaction occurs to form NADH from NAD+?

NAD+ from NADH?

NAD+ to NADH = Reduction (gains electrons)

NADH to NAD+ = Oxidation (loses electrons)

What type of reactions occurs to form FADH2 from FAD?

FAD from FADH2?

FAD to FADH2 = Reduction (gains electrons)

FADH2 to FAD = Oxidation (loses electrons)

Where is FADH2 produced from?

Riboflavin (Vitamin B2)

What processes can be used for Carbohydrate Metabolism when there is Oxygen present?

When there is NO Oxygen present?

O2 Present —> Complete Oxidation OR Aerobic Respiration

O2 NOT Present —> Incomplete Oxidation or Anaerobic Respiration

What are the steps of Carbohydrate Metabolism in the presence of Oxygen?

1. Glycolysis

2. Pyruvate Oxidation (“Linking Step”)

3. Krebs Cycle / Citric Acid Cycle

4. Oxidative Phosphorylation

   • Electron Transport Chain

   • Chemiosmosis / Chemiosmotic Coupling

What are the steps of Carbohydrate Metabolism in the absence of Oxygen?

1. Glycolysis

2. Fermentation

What are the inputs of Glycolysis?

Outputs?

Net Outputs?

Inputs:

• 1 Glucose

• 2 ATP

• 2 NAD+

• 4 ADP

Outputs:

• 2 Pyruvate

• 2 ADP

• 2 NADH

• 4 ATP

Net Outputs:

• 2 Pyruvate

• 2 ATP

• 2 NADH

Where does Glycolysis occur?

In the Cytoplasm of the cell

What are the inputs of Pyruvate Oxidation?

Outputs?

Inputs:

• 2 Pyruvate

• 2 NAD+

• 2 CoA

Outputs:

• 2 CO2

• 2 NADH

  • 2 Acetyl-CoA

Where does Pyruvate Oxidation occur?

In the Matrix of the Mitochondria

What are the inputs of the Krebs / Citric Acid Cycle?

Outputs?

Inputs:

• 2 Acetyl-CoA

• 6 NAD+

• 2 FAD

• 2 ADP

Outputs:

• 2 CoA

• 6 NADH

• 2 FADH2

• 2 ATP

• CO2 Byproduct

Where does the Krebs / Citric Acid Cycle occur?

In the Matrix of the Mitochondria

What are the two steps of Oxidative phosphorylation?

Where do each of them occur?

What is the final electron acceptor?

The Electron Transport Chain and Chemiosmotic Coupling

ETC is embedded into Inner Mitochondrial Membrane, pumps protons into the Intermembrane Space

Chemiosmotic Coupling uses ATP Synthase to pump protons into the Mitochondrial Matrix from the Intermembrane Space

Final electron acceptor is Oxygen (O2)

What is used to turn ADP into ATP?

Does this process consume energy or release energy?

ATP Synthase

Releases energy (creates a bond)

What are the inputs of Oxidative Phosphorylation?

Outputs?

Inputs:

• NADH

• FADH2

• O2

• ADP

Outputs:

• NAD+

• FAD

• H2O

• ATP

About how many ATP are produced for every oxidized NADH? FADH2?

What is the total number of ATP produced via the complete oxidation of ONE glucose molecule?

For every 1 oxidized NADH, ~3 ATP are produced

For every 1 oxidized FADH2, ~2 ATP are produced

36 ATP TOTAL from ONE glucose molecule

What happens when we have excess Glucose?

Can either be turned into Glycogen through Glycogenesis (stored in Liver or Skeletal Muscles) or turned into Adipose Tissue through Lipogenesis

What happens when we have no Glucose?

We have to turn to alternative sources of energy like Gluconeogenesis (non-carb sources turned into Glucose) or Glycogenolysis (breakdown of Glycogen into Glucose from storage)

What are some examples of Non-Carb sources that can be turned into Glucose through Gluconeogenesis?

Pyruvate, Lactate, Glycerol, and some Amino Acids