Glucose Metabolism and Glycolysis

Practice questions covering glucose metabolic pathways, starch digestion, and the mechanical steps of glycolysis and the linking reaction.

Is the breakdown of glucose an anabolic or catabolic process?

It is a catabolic process because it breaks down molecules to generate energy.

How is a linear metabolic pathway defined?

A pathway where a substrate is converted into a product that serves as the starting point for the next reaction in a single line.

What are the characteristics of anabolic (biosynthetic) pathways?

They are reductive, require energy (ATP, NADPH, NADH, or FADH2), and are usually divergent.

What are the characteristics of catabolic pathways?

They are degrading, oxidative (donate electrons), use $NAD^+$ and FAD as carriers, yield energy, and are usually convergent.

What are the components of the disaccharide sucrose (table sugar)?

It consists of glucose and fructose connected by a glycosidic bond.

What is the structural difference between amylose and amylopectin in starch?

Amylose has a 1-4 connection between sugar molecules, while amylopectin has a 1-6 connection which causes branching.

Where does the enzymatic breakdown of starch begin in the human body?

It begins in the mouth through the release of salivary amylase.

Which enzyme is secreted by the pancreas into the duodenum to help break down starch?

Pancreatic amylase.

What does the term 'glycolysis' literally mean?

Sweet splitting.

In which part of the cell does glycolysis occurs?

In the cytosol.

How many carbons are in a single glucose molecule compared to a pyruvate molecule?

Glucose is a 6-carbon molecule, and it is split into two 3-carbon pyruvate molecules.

What is the net yield of energy and products from the 10 steps of glycolysis?

A net of 2 ATP, 2 NADH, and 2 pyruvate molecules.

What are the two main phases of glycolysis?

The energy investment phase and the energy generation phase.

If oxygen is available (aerobic respiration), where do the pyruvate molecules go?

They are transported from the cytosol into the mitochondria.

What is the maximum theoretical yield of ATP from one glucose molecule in aerobic respiration?

38 ATP.

What happens to pyruvate during anaerobic respiration?

It remains in the cytosol; the process is not very efficient and produces very little ATP.

What complex enzyme facilitates the linking reaction that converts pyruvate to acetyl CoA?

Pyruvate dehydrogenase.

What are the products of the linking reaction for each pyruvate molecule entering the mitochondria?

One acetyl CoA (a 2-carbon molecule), one NADH, and one $CO_2$ molecule.