Digestion and Metabolism 3

Flashcards covering key concepts, processes, and hormones involved in metabolism, including carbohydrate metabolism pathways (glycolysis, pyruvate oxidation, Krebs cycle, oxidative phosphorylation), and glucose regulation.

What is metabolism?

The sum of all metabolic processes.

What is the difference between anabolic and catabolic reactions?

Anabolic reactions build large molecules, while catabolic reactions break down large molecules.

What is ATP and what is its structure?

ATP (adenosine triphosphate) is a nucleotide consisting of adenine, a ribose sugar, and three phosphate groups.

In an oxidation-reduction reaction, what happens during oxidation?

Oxidation is the process of losing electrons.

What happens during a reduction reaction?

Reduction is the process of gaining electrons.

What is glucose?

A hexose sugar that humans use as an immediate source of energy.

What is gluconeogenesis?

The process of glucose synthesis from pyruvate or other non-carbohydrate molecules.

What is glycogen?

The storage form of glucose in animals, found primarily in the liver and skeletal muscle.

What is glycogenesis?

The process of converting glucose to glycogen.

What is glycogenolysis?

The process of breaking down glycogen into glucose.

What is glycolysis?

A series of metabolic reactions that breaks down glucose into pyruvate and produces ATP.

What is glucagon's role in metabolism?

Glucagon stimulates the breakdown of glycogen in the liver to raise blood glucose levels via glycogenolysis.

Name two catabolic hormones.

Cortisol and Glucagon.

Name two anabolic hormones.

Insulin and Growth Hormone.

What is the primary action of insulin?

Insulin lowers blood sugar levels by converting glucose to glycogen via glycogenesis.

Why do cells need ATP?

ATP powers nearly every activity that requires energy input, such as chemical reactions, DNA synthesis, and movement.

What organelle is known as the powerhouse of the cell because it produces ATP?

The mitochondria.

What happens to cells if they lack ATP?

They die.

What type of reaction breaks down ATP to release energy?

Hydrolysis.

How is NAD+ converted to NADH?

NAD+ gains electrons and a hydrogen ion, undergoing a reduction reaction.

What are the four main pathways of carbohydrate metabolism that occur in the presence of oxygen?

Glycolysis, Pyruvate Oxidation, Krebs Cycle, and Oxidative Phosphorylation (ETC and Chemiosmotic coupling).

What are the pathways of carbohydrate metabolism that occur in the absence of oxygen?

Glycolysis and Fermentation.

Where does glycolysis occur?

In the cytoplasm.

What are the net outputs of glycolysis per glucose molecule?

2 ATP, 2 NADH, and 2 pyruvate.

Where does pyruvate oxidation (the linking step) occur?

In the mitochondrial matrix.

What are the outputs of pyruvate oxidation per glucose molecule?

2 acetyl CoA, 2 NADH, and 2 CO2.

Where does the Krebs Cycle (Citric Acid Cycle) occur?

In the mitochondrial matrix.

What are the outputs of the Krebs Cycle per glucose molecule (after 2 acetyl CoA enter)?

6 NADH, 2 FADH2, 2 ATP, and 4 CO2.

What is the primary goal of the Electron Transport Chain (ETC) in oxidative phosphorylation?

To create a high concentration of H+ (protons) in the intermembrane space.

What is the final electron acceptor in the Electron Transport Chain?

Oxygen.

What is the goal of chemiosmotic coupling in oxidative phosphorylation?

To make ATP using the proton gradient established by the ETC.

How much ATP is produced from the complete oxidation of one glucose molecule, considering the cost of moving NADH into the mitochondrial matrix?

Approximately 36 ATP.

What happens to excess glucose in the body?

It is converted into glycogen in the liver and skeletal muscle, or converted into triglycerides and stored in adipose tissue.

When there is no glucose available, how does the body produce it?

Through glycogenolysis (breaking down stored glycogen) and gluconeogenesis (converting non-carbohydrates like amino acids, lactate, or pyruvate into glucose).