Chapter 8 Metabolism

What is metabolism?

The sum of all chemical reactions occurring in the body.

What is energy metabolism?

The conversion of chemical energy in food to ATP.

What are the kcal/g values for macronutrients?

Carbs: 4 kcal/g, Protein: 4 kcal/g, Fat: 9 kcal/g, Alcohol: 7 kcal/g

What is anabolism?

Building larger molecules, requires energy.

What is catabolism?

Breaking down molecules, releases energy.

Which cells are most metabolically active?

Liver cells.

What are coenzymes?

Organic compounds that help enzymes function.

Which vitamins are important coenzymes in energy metabolism?

B vitamins like thiamin, niacin, riboflavin, pantothenic acid.

What are NAD+ and FAD?

Coenzymes that carry electrons; NAD+ from niacin, FAD from riboflavin.

What is ATP?

High-energy compound used by cells for energy.

How is ATP reformed?

By phosphorylation of ADP using energy.

What is glycolysis?

Conversion of glucose to pyruvate, produces 2 ATP and 2 NADH.

What is the anaerobic fate of pyruvate?

Converted to lactate (Cori cycle) in absence of oxygen.

What is the aerobic fate of pyruvate?

Converted to acetyl CoA in mitochondria.

Where does the citric acid cycle occur?

In the mitochondria.

What is the first step of the citric acid cycle?

Acetyl CoA joins oxaloacetate to form a 6-carbon compound.

What is the yield of the citric acid cycle per glucose?

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

What is the electron transport chain?

A series of proteins that use electrons to generate ATP.

What are the ATP yields from NADH and FADH2?

NADH: 3 ATP, FADH2: 2 ATP.

What is gluconeogenesis?

Synthesis of glucose from non-carbohydrate sources.

What is beta-oxidation?

Breakdown of fatty acids into acetyl CoA.

What is ketogenesis?

Production of ketone bodies from acetyl CoA.

What is ketoacidosis?

Dangerous drop in blood pH due to excess ketones.

What is deamination?

Removal of amino group from amino acids.

What are glucogenic amino acids?

Amino acids that can be converted to pyruvate or citric acid intermediates.

What are ketogenic amino acids?

Amino acids converted to acetyl CoA.

What hormone promotes anabolic metabolism?

Insulin.

What hormones promote catabolic metabolism?

Glucagon, cortisol, and epinephrine.

What is the main action of insulin?

Promotes glucose uptake and storage, protein and fat synthesis.

What is the role of cortisol?

Promotes protein breakdown and gluconeogenesis.

What is the role of epinephrine?

Stimulates glycogenolysis and lipolysis during stress.

What is the main function of thyroid hormone?

Regulates metabolic rate, can be anabolic or catabolic.

What is the kcal yield from a 16-carbon fatty acid?

129 ATP.

What happens to excess energy during feasting?

Stored as fat.

What happens during fasting?

Uses glycogen, then breaks down protein and fat.

What is the alcohol metabolism pathway?

Alcohol → acetaldehyde → acetate → acetyl CoA.

What enzyme metabolizes alcohol in the stomach?

Gastric alcohol dehydrogenase.

What is Wernicke-Korsakoff syndrome?

Neurological disorder caused by alcohol-related thiamin deficiency.

The sum of all the chemical pathways that enable the human body to obtain and use energy from macronutrients and alcohol is called energy….

metabolism

To produce the energy-rich molecule called ATP, one phosphate is added to….with an input of energy.

ADP

Mitochondria are responsible for:

transferring energy released from macronutrients to ATP and facilitating anabolism in storage cells

Metabolism is the sum of chemical reactions that occur in living cells including….

using energy to build new molecules and breaking down molecules to release energy

Which of the following vitamins serve as coenzymes or are components of coenzymes?

Niacin, vitamin b6, thiamine, and riboflavin.

Which of the following can be a product of anaerobic metabolism of pyruvate?

Lactic acid and lactate

When an ATP molecule loses its third phosphate group, it becomes….

ADP

The purpose of the Cori cycle is to….

recycle lactate into glucose

Glycogenolysis occurs in the….

Liver

Metabolic reactions may be:

Catabolic or anabolic

During anaerobic conditions, pyruvate is converted to….

Lactic acid

stages of glucose breakdown in order

Glycolysis, Pyruvate, Ctric Acid, and Electron Transport

The most energy-dense group of macronutrients is …..

Triglycerides

The availability of carbon atoms in fatty acids increases the potential to form more:

Acetyl CoA, NADH, FADH2

Liver cells convert extra acetyl CoA molecules to ______ which are known as ketone bodies.

Acetone, beta-hrdoxybutyrate, and acetoacetate

Gluconeogenesis is the making of glucose from:

Lactate, glycerol, pyruvate, and amino acids

During beta-oxidation, fatty acid molecules are separated into ______-carbon segments that are converted into ______

two; acetyl CoA

The conversion of amino acids into other molecules such as glucose and fatty acids is dependent on the overall needs of the body and the….

specific amino acid

Which of the following ketone bodies formed during ketogenesis produces a "fruity" odor similar to nail polish remover?

Acetone

Which vitamin deficiency would have a potentially limiting effect on protein metabolism?

B-6

Once the basic functions of amino acids have been met (e.g., synthesizing enzymes), the remaining amino acids can be used for energy or converted to:

Glucose and fatty acids