Chapter 25: Metabolism, Nutrition, and Energetics

Define metabolism

the sum of all chemical and physical changes that occur in body tissues

What is the difference between catabolic and anabolic reactions?

catabolic reactions break down large molecules into smaller ones

anabolic reactions build up small molecules into larger ones

When electrons pass from one molecule to another, the electron donor is __________ and the electron acceptor is _________.

oxidized, reduced

During glucose metabolism, __________ is an anaerobic process because it does not require oxygen to proceed.

glycolysis

What initial organic compound is catabolized during glycolysis? (starting molecule)

glucose

Where does glycolysis take place in the cell?

cystosol

How many net ATP molecules are formed during the glycolysis of one molecule of glucose?

2

During glycolysis, four ATP are created, but the end product is two net ATP. Why is this so?

Because the process of glycolysis costs the cell two ATP molecules

How many pyruvate molecules are produced during glycolysis from one molecule of glucose?

2

How many NADH molecules are produced during glycolysis from one molecule of glucose?

2

Where does the NADH produced during glycolysis get transported to?

to the mitochondria

NAD+ gains an electron to become NADH, so NADH is the _______ form of NAD+. FADH2 loses an electron to become FADH, so FADH is the _______ form of FADH2.

reduced, oxidized

What happens to pyruvate if there are inadequate amounts of oxygen in the cell? (the molecule produced is also known as lactic acid)

pyruvate is reduced to form lactate

In the presence of oxygen, where is pyruvate transported to in the cell?

mitochondria absorb the pyruvate into the mitochondrial matrix using a carrier protein

In the process of glycolysis, what are the end products from the catabolism of one glucose molecule?

two pyruvate molecules, 2 NADH molecules, and two net ATP molecules

Two pyruvate molecules undergo a series of reactions to form two molecules of what molecule during the intermediate step?

acetyl-CoA (acetyl-coenzyme A)

How many ATP are produced from the synthesis of acetyl-CoA from pyruvate?

zero

What is the difference between substrate-level phosphorylation and oxidative phosphorylation?

substrate level produces a small amount of energy through transferring phosphate group to a suitable accepter molecule

oxidative produces more than 90% if the ATP used by body cells through the transfer of electron from coenzymes(NADH and FADH2) to oxygen

Which step of cellular respiration produces 90-95% of the ATP used by body cells?

oxidative phosphorylation

Which step of cellular respiration utilizes molecules called cytochromes?

electron transport chain

The reactions of the electron transport chain produce ATP by which type of phosphorylation.

chemiosmotic phosphorylation

The kinetic energy produced by passing hydrogen ions through ATP synthase to generate ATP is called _________________.

chemiosmosis

During the process of cellular respiration, how many ATP are formed from one molecule of glucose?

30-32 net gain

Define gluconeogenesis

the synthesis of glucose (mainly by liver cells) from noncarbohydrate molecules

What is glycogen?

stored formed of glucose, energy reserve

In what two places is glycogen mainly stored in the body?

liver and skeletal muscles

What is the difference between glycogenesis and glycogenolysis?

glycogenesis - formation of glycogen from excess glucose molecules

glycogenolysis - breakdown of glycogen into glucose monomers

Which molecule is the most abundant storage form of lipid in the body?

triglycerides

What are the component parts of one triglyceride molecule?

1 molecules of glycerol and 3 fatty acid molecules

After triglyceride are catabolized into their component parts, enzymes in the cytosol convert glycerol into what molecule?

pyruvate

What process is used to catabolize fatty acids in the mitochondria?

beta-oxidation

What molecule is produced from the catabolism of fatty acids in the mitochondria?

acetyl-CoA

How many ATP molecules are produced from the catabolism of one 18-carbon fatty acid molecule?

120 molecules

Define lipogenesis

synthesis of lipids

Why are linolenic acid and linoleic acid considered essential fatty acids?

because the body is unable to produce them, so they must be included in a person’s diet

Which group of lipoproteins carry absorbed lipids from the food we eat to the bloodstream?

chylomicrons

Which group of lipoproteins is considered “bad cholesterol”?

low-density lipoproteins

Which group of lipoproteins is considered “good cholesterol”?

high-density lipoproteins

What two types of chemical reactions remove amine groups from amino acids during amino acid catabolism?

transamination and deamination

List three factors that make protein catabolism an impractical source of quick energy.

proteins are more difficult to break apart than complex carbs or lipids

one of the by-products, ammonium ions, are toxic to cells

extensive catabolism threatens homeostasis at both the cellular and system levels

What occurs during the absorptive state?

follows a meals, cells absorb nutrients to be used for growth, maintenance, and energy reserves

What occurs during the postabsorptive state?

hours after a meal, metabolic reactions are focus on maintaining blood glucose levels to meet the needs of nervous tissue

What is a ketone body?

organic compound produced by fatty acid metabolism that dissociates in a solution, releasing a hydrogen ion

If ketone bodies release hydrogen ions, how does this affect the pH of the blood?

lowers the blood pH

High levels of ketone bodies occur during prolonged starvation. Why is this dangerous?

can cause pH to drop to dangerous levels disrupting tissue activities and can lead to death

List the 5 main food groups

fruits, vegetables, grains, protein, and dairy

What is the difference between a complete and incomplete protein?

complete proteins provide all the essential proteins

incomplete proteins which do not provide at least one of the essential proteins

List three reasons why minerals are important

ions such as sodium and chloride determine the osmotic concentrations of body fluids

ions in various combinations play major roles in important physiological processes

ions are essential cofactors in a variety of enzymatic reactions

What is the difference between a fat-soluble and water-soluble vitamin?

fat soluble vitamins dissolve in lipids and are absorbed in the digestive tracts

water soluble vitamins are components of coenzymes and are rapidly exchanges between fluid compartments of the digestive tract and circulating blood

Define basal metabolic rate

measurement of the rate at which the body expends energy while at rest to maintain vital functions such as breathing and keeping warm

Define obesity

body weight for than 20% above the ideal weight for a given individual

What occurs during the processes of heat exchange called radiation?

objects warmer than the environment lose heat

What occurs during the processes of heat exchange called convection?

heat loss to the cooler air that moves across the surface of the body

What occurs during the processes of heat exchange called evaporation?

when water from the body absorbs heat and turned to a gas, cooling the surface where it occurs

What occurs during the processes of heat exchange called conduction?

transfer of heat(energy) through physical contact with something cooler

What is the final goal for both shivering- and non-shivering thermogenesis?

produce heat to warm the body up

What is brown fat?

thermogenic tissue with far cells

What gives brown fat its color?

multiple small liquid droplets and numerous heme-collecting mitochondria

Reactions within _______ provide most of the energy needed by a typical cell

the mitrochondria

The first steps of catabolism generally take place in the

cytosol

Glycolysis produces how many pyruvate molecules and how many ATP molecules?

2 pyruvate molecules with a net gain of 2 ATP molecules

The function of the citric acid cycle is to

remove hydrogen atoms from organic molecules and transfer them to coenzymes

All of the following occur during glycolysis, except

a molecule of carbon dioxide is produced

Although other nutrients can feed into the citric acid cycle, _______ yields energy the quickest

glucose

The end products of aerobic respiration are

carbon dioxide, water, and ATP

Most of the ATP from metabolism is produced in the

electron transport system

The process of synthesizing glucose from noncarbohydrates is called

gluconeogenesis

The two most important coenzymes for glycolysis and the citric acid cycle are

NAD and FAD

The formation of GTP from GDP in the citric acid cycle is an example of

substrate-level phosphorylation

Synthesis of fatty acids start with _______.

acetyl-CoA

The smallest lipoproteins, called _______, transport cholesterol from peripheral tissues to the liver

high-density lipoproteins

By keeping the other two variables constant and changing only one at a time, based on the formula: LDL = cholesterol - HDL - (Triglycerides/5), which of the following would have the greatest effect in reducing LDL levels?

reducing cholesterol levels

Where does beta-oxidation take place?

in the mitochondria

The lipoproteins that carry absorbed triglycerides from the intestinal tract to the bloodstream are

chylomicrons

In order to determine the LDL level in a patient’s blood, it is necessary to measure

total cholesterol level, HDL level, and triglyceride level

_______ carry excess cholesterol from peripheral tissues to the liver

High-density lipoproteins

Fatty acids that are necessary for proper health but cannot be synthesized by the body are called _______ fatty acids

essential

During amino acid catabolism, the enzyme that removes the amino group from amino acids requires a co-enzyme derived from the vitamin _______

B-6

Which organ produces most of the urea in the body?

liver

The conversion of ammonia into a less toxic substance produces

urea

A high uric acid level (above 7.4 mg/dI) can lead to the painful condition known as

gout

Catabolism of protein is not a practical source of quick energy because of all the following except that

most individuals have little proteins to spare before harming vital organs

The removal of an amino group from a protein to prepare it to enter the citric acid cycle is termed

deamination

Protein malnourishment may occur if the diet is deficient in

essential amino acids

When the body is relying on internal energy reserves to continue meeting its energy demands, it is the _______ state

postabsorptive

On a tour of Africans countries, Mark contracts a bad case of traveler’s diarrhea. Because he can’t eat much, his body starts to use energy sources other than carbohydrates, This would result in all of the following, except

glycogenesis

Frank has diabetes mellitus and his blood pH has dropped. What is the most likely cause of his acidosis?

excess ketone formation

An element that is a component of hemoglobin, myoglobin, and cytochromes is

iron

The element that is necessary for the proper function of the enzyme carbonic anhydrase is

zinc

The vitamin that plays a role in maintaining epithelia and is required for the synthesis of visual pigments is vitamin

A

The vitamin that is essential for the production of several clotting factors is vitamin

K

Inadequate exposure to sunlight could result in decreased amounts of vitamin _______ in the body

D

Eating disorders are common. They can cause inadequate or excessive food consumption. Two major eating disorders are anorexia nervosa and

bulimia