Chapter 25: Metabolism and Nutrition

What processes directly elevate blood glucose during the postabsorptive state, and where does each occur?

Processes that directly elevate blood glucose during the postabsorptive state include lipolysis (in adipocytes and hepatocytes), gluconeogenesis (in hepatocytes), and glycogenolysis (in hepatocytes).

In the case of a person who consumes a normal, balanced diet, proteins are essential to the body for which processes?

Production of enzymes, clotting factors, and antibodies, formation of functional molecules like hemoglobin and cytochrome, and production of some hormones.

Define negative nitrogen balance.

Protein breakdown exceeds protein synthesis.

True or False: The increased use of noncarbohydrate molecules for energy to conserve glucose is called glucose sparing.

True

True or False: The most abundant dietary lipids in the diets of most Americans are triglycerides.

True

True or False: Thyroid hormones promote glycolysis.

True

True or False: Vitamin E is a fat-soluble vitamin.

True

Which substance is the gateway into the Krebs cycle for molecules that are being oxidized to generate ATP?

Acetyl coenzyme A is the gateway into the Krebs cycle for molecules being oxidized to generate ATP.

When the terminal phosphate is cut off ATP what is formed?

Adenosine Diphosphate

What group is removed from an amino acid before it can enter the Krebs cycle, and what is this process called?

Before an amino acid can enter the Krebs cycle, an amino group must be removed via deamination.

Provitamins are

Building Blocks of Vitamins

When in cellular respiration is carbon dioxide given off?

Carbon dioxide is given off during the production of acetyl coenzyme A and during the Krebs cycle.

Glycogenolysis is ________ and stimulated by ___________

Catabolic, Epinephrine

Chemical reactions that break down complex organic molecules into simpler ones are called:

Catabolism

How many molecules of oxygen are used, and how many molecules of carbon dioxide are produced during the complete oxidation of one glucose molecule?

During the complete oxidation of one glucose molecule, six molecules of oxygen are used and six molecules of carbon dioxide are produced.

Thyrotropin-releasing hormone is secreted by the

Hypothalamus

True or False: Blood volume affects heat production.

False

True or False: Except for lactose and some glycogen, the carbohydrates we ingest are mainly from animals.

False

True or False: Glycogen is a major nutrient the body needs.

False

True or False: Glycogenesis is one way to make glucose.

False

True or False: Lipogenesis is a postabsorptive state reaction.

False

True or False: Processes that break down complex molecules into simpler ones are anabolic.

False

True or False: The net result of the complete oxidation of glucose includes oxygen.

False

How many ATPs can come from substrate level phosphorylation during glycolysis?

2

How many reactions take place during the Krebs cycle?

8

Liver cells convert:

Ammonia Into Urea

Chemical reactions that combine simple molecules and monomers to form complex structures are known as

Anabolism

Accumulation of a large amount of H+ between the inner and outer mitochondrial membranes, is described as

Chemiosmosis

These transport dietary lipids.

Chylomicrons

This is a mechanism of heat transfer that involves direct contact.

Conduction

Prostaglandins play a role in ________.

Control of Blood Pressure

Excess amino acids in the body are

Converted Into Glucose

What hormone stimulates gluconeogenesis?

Cortisol

Where does glycolysis take place?

Cytosol

Oxidation-reduction reactions are catalyzed by which enzymes?

Dehyrodgenases and Oxidases

What factors can increase metabolic rate and thus increase the rate of heat production?

Exercise, the sympathetic nervous system, hormones (epinephrine, norepinephrine, thyroxine, testosterone, human growth hormone), elevated body temperature, and ingestion of food increase metabolic rate, which results in an increase in body temperature.

This is a derivative of riboflavin.

FAD

True or False: All athletes require diets high in protein and calories in order to perform and to maintain their muscle mass.

False

True or False: Beta oxidation is the initial phase of fatty acid oxidation, and it occurs in the cytoplasm.

False

Neuropeptide Y stimulates

Food Intake

What are used in "metabolic crossroads"?

Glucose 6-phosphate, pyruvic acid, and acetyl coenzyme A.

Glycolysis, formation of acetyl CoA, Krebs cycle and the electron transport chain are all involved in:

Glucose Catabolism

In the absorptive state, most glucose that enters the liver is converted to

Glycogen

Which process is also called anaerobic cellular respiration?

Glycolysis is also called anaerobic cellular respiration.

In which part of the cell does glycolysis occur?

Glycolysis occurs in the cytosol.

What types of cells can carry out lipogenesis, beta oxidation, and lipolysis?

Hepatocytes and adipose cells carry out lipogenesis, beta oxidation, and lipolysis.

What cells can carry out gluconeogenesis and glycogenesis?

Hepatocytes can carry out gluconeogenesis and glycogenesis.

What type of cell can carry out ketogenesis?

Hepatocytes carry out ketogenesis.

In a pancreatic cell that produces digestive enzymes, does anabolism or catabolism predominate?

In pancreatic acinar cells, anabolism predominates because the primary activity is synthesis of complex molecules (digestive enzymes).

The most dramatic metabolic change that occurs with fasting is

Increase in Lipolysis

What hormone stimulates glycogenesis?

Insulin

What happens to carbon dioxide given off during cellular respiration?

It diffuses into the blood, is transported by the blood to the lungs, and is exhaled.

Why is the enzyme that catalyzes step three of glycolysis called a kinase?

Kinases are enzymes that phosphorylate (add phosphate to) their substrate.

This reaction oxidizes acetyl CoA to produce carbon dioxide, ATP, NADH+H+ and FADH2.

Krebs Cycle

Which type of lipoprotein delivers cholesterol to body cells.

LDLs deliver cholesterol to body cells.

Cardiac muscles can produce ATP from

Lactic Acid

This process is the synthesis of triglycerides.

Lipogenesis

The process of breaking triglycerides down into glycerol and fatty acids is known as ________.

Lipolysis

What is the outcome of ketosis?

Metabolic Acidosis

Where can pyruvate dehydrogenase be found?

Mitochondria

Where does the Krebs cycle take place?

Mitochondria

Lipogenesis occurs when

More calories are consumed than required for ATP need

The primary reason elderly people should decrease their caloric intake is that ________.

Muscle mass and metabolism decline with age

Describe complete protein.

Must meet all the body's amino acid requirements for maintenance and growth

According to the standard height-weight chart, 4'8" Maria should weigh 100 pounds. She currently weighs 125 pounds. Clinically, Maria is described as ___.

Obese

This is the key regulator of the rate of glycolysis.

Phosphofructokinase

Are the reactions that occur during the absorptive state mainly anabolic or catabolic?

Reactions of the absorptive state are mainly anabolic.

The most abundant product of the reactions of the Krebs cycle is

Reduced Coenzymes

When a person's hypothalamic thermostat is set to a higher level and the actual body temperature is below that level, the person may ________.

Shiver

Besides hepatocytes, which body cells can synthesize glycogen? Why can't they release glucose into the blood?

Skeletal muscle fibers can synthesize glycogen, but they cannot release glucose into the blood because they lack the enzyme phosphatase required to remove the phosphate group from glucose.

The heat promoting center stimulates parts of the brain that

Stimulates skeletal muscle activity

What are the forms of phosphorylation?

Substrate level phosphorylation, oxidative phosphorylation, and photophosphorylation.

Reduction is the

The Addition of Electrons

Oxidation is

The Removal of Electrons

True or False: The amount of protein needed by each person is determined by the age, size, and metabolic rate of the person.

True

Where is the concentration of hydrogen ions highest?

The concentration of hydrogen ions is highest in the space between the inner and outer mitochondrial membranes.

What is the energy source that powers the proton pumps?

The energy source that powers the proton pumps is electrons provided by NADH and hydrogen ions.

Why is the production of reduced coenzymes important in the Krebs cycle?

The production of reduced coenzymes is important in the Krebs cycle because they will subsequently yield ATP in the electron transport chain.

For each glucose molecule that undergoes glycolysis, how many ATP molecules are generated?

The reactions of glycolysis consume two molecules of ATP but generate four molecules of ATP, for a net gain of two.

What does the wider base of each band in MyPyramid mean?

The wider base of each band represents foods with little or no solid fats or added sugars.

True or False: The higher the relative humidity the lower the rate of evaporation.

True

True or False: Antioxidant vitamins can inactivate oxygen free radicals.

True

True or False: Carbohydrate and fat pools are oxidized directly to produce cellular energy, but amino acid pools must first be converted to a carbohydrate intermediate before being sent through cellular respiration pathways.

True

True or False: Ghrelin, produced by the stomach, is a powerful appetite stimulant.

True

True or False: Glucose-6-phosphate can be converted to pyruvic acid

True

True or False: Glucose-6-phosphate can be dephosphorylated to glucose

True

True or False: Glucose-6-phosphate can be used to make ribose-5-phosphate

True

True or False: Glucose-6-phosphate can be used to synthesize glycogen

True

True or False: In the absorptive state storage of energy is important.

True

True or False: Proteins will be used by most cells for ATP synthesis if insufficient carbohydrates are ingested.

True

True or False: Release of epinephrine is a normal consequence of the activation of the heat-promoting center.

True