CH 24. Nutrition, Metabolism, & Energy Balance

How is the chemiosmotic process shown in the figure similar to secondary active transport (cotransport) of solutes (discussed in Chapter 3)?

Both processes use an electrochemical gradient to store energy.

How is an excess of glucose handles?

-Excretion in the urine -Storage as glycogen -Conversion to fat and storage in adipose tissue: lipogenesis

when lipolysis occurs

-Glycerol portion can be converted into glucose (gluconeogenesis) to generate ATP -Fatty acids are split into numerous 2-carbon fragments (acetyl CoA): Beta oxidation

what kind of saccharide is glycogen

Polysaccharide

The major metabolic function for most vitamins is that they assist enzymes by serving as __________.

coenzymes

LDL

contain the most cholesterol and are transported to peripheral tissues for membrane or hormone synthesis (excess is is deposited in arterial membranes)

What is glycogenesis?

conversion of glucose to glycogen that occurs when glucose in in excess

Which of the choices below is not a fate of carbohydrate taken into the body?

conversion to a nucleic acid

Select the correct sequence of steps as energy is extracted from glucose during cellular respiration.

glycolysis → acetyl CoA → citric acid cycle → electron transport

What are the three main metabolic pathways involved in cellular respiration?

glycolysis, Krebs cycle, and electron transport chain

Winston was running a marathon on a hot day in July. He was close to the finish line when he collapsed. His body temperature increased, his blood pressure dropped, and he was perspiring. Winston was suffering from __________.

heat exhaustion

when oxidized, lipids yield

high amount of energy

what happens when a protein is denatured?

hydrogen bonds are broken (ie pH drops or temperature rises)

After completing a marathon on a particularly warm day, Dave consumes four liters of water. Soon after, he begins to feel nauseous and starts vomiting. What is likely happening to Dave?

hyponatremia; very low extracellular sodium ion concentration

What part of the brain maintains body temperature?

hypothalamus

Which of these conditions is associated with a decrease in body temperature and vital signs, leading to drowsiness and potentially coma and death?

hypothermia

Which of the following is NOT involved in triggering the thirst mechanism?

increase in blood pressure

the rold of ADH is what?

increase water reabsorption

What results from increased levels of aldosterone?

increased Na+ reabsorption

Which of the following is represented by the membrane indicated in the figure?

inner mitochondrial membrane

denaturation can be reversed except if

irreversible denaturation has occurred when pH or temp is so extreme

NAD+

is reduced to NADH + H+

Which organs are the long-term acid-base regulatory organs?

kidneys

The energy value of foods is measured in units called ________.

kilocalories (kcal) or Calories

Polysaccharides are

large and insoluble- ideal for storage (lack sweetness of simple and double sugars)

Anabolism includes reactions in which ________.

larger molecules or structures are built from smaller ones

what determines how solid the molecule is at given temperature?

length of chain and degree of saturation with H atoms

excess glucose is easily converted to

lipids (why people get fat from eating too many fats)

Steroids are

lipids composed of 4 interlocking carbon rings fat soluble and contain little oxygen like triglycerides

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

lipolysis

Which of the following blood workups would most likely demonstrate metabolic acidosis?

pH: 7.33; PCO2: 30 mmHg; HCO3-: 20 mEq/L

in the ETC, electrons and H atoms that were generated during catabolic processes are

passed from carrier to carrier in the mitochondrial membranes

why are pools interconvertible?

pathways are linked by common intermediates -Amount and direction of conversion are directed by liver, adipose tissue, and skeletal muscle

when globular proteins denature, they can no longer

perform their physiological roles; active sites (binding) can be destroyed (ie transport proteins hgb becomes inactive because structure is destroyed)

Glycogenesis

polymerizes glucose to form glycogen

Amelie has hypothyroidism. What hormone supplement will improve Amelie's condition?

thyroxine

What hormone is most responsible for determining the basal metabolic rate?

thyroxine

The total amount of kilocalories the body must consume to fuel all ongoing activities, which increases dramatically during physical exertion, is called the ________.

total metabolic rate (TMR)

HDL

transport fats and cholesterol to the bile for excretion

VLDL (very low density lipoprotein)

transported to adipose tissue for storage

The most abundant dietary lipids are ________.

triglycerides

what is the body's most efficient and compact form of stored energy?

triglycerides

Blood acidity results in depression of the CNS, whereas blood alkalosis results in overexcitement of the CNS.

true

Dehydration can be caused by endocrine disturbances such as diabetes mellitus or diabetes insipidus.

true

Excessive loss of water from the extracellular fluid (ECF) leads to a rise in osmotic pressure in the ECF which causes cells to shrink as water leaves by osmosis.

true

The eight essential amino acids are ones the body cannot make and must be consumed through our diet.

true

When proteins undergo deamination, the waste substance found in the urine is mostly________.

urea

If the kidneys are failing, what happens to the urea?

urea builds to toxic levels- uremia

Falling arterial blood pressure promotes ________.

vasoconstriction

all vitamins must be supplied in the diet except for which one?

vitamin D

When is gluconeogenesis active?

when the diet is low in carbs, starvation or stress reaction(Stimulated by the stress hormones: epinephrine, cortisol, thyroxine)

When is protein used for energy?

when there are not enough lipids or carbohydrates or when huge excesses of proteins are ingested

How are disaccharides formed?

when two monosaccharides are joined in a dehydration synthesis

three stages in processing nutrients are:

•Stage 1: Digestion, absorption, and transport to tissues •Stage 2: Cellular processing (in cytoplasm) :synthesis or catabolism •Stage 3: Oxidative breakdown of intermediates into CO2, water, and ATP (Occurs in mitochondria)

all energy produced in the body is a result of

biological oxidation

What are isomers?

compounds with the same molecular formula but different structures and properties

Glycolysis

converts glucose to pyruvic acid

The ETC produces about how many ATP per each glucose molecule?

28-30

how many carbon atoms does a monosaccharide have?

3-7

Water soluble vitamins are

C, B complex, niacin, folic acid; excess excreted in urine

Which one of the following is NOT true of cholesterol?

Cholesterol provides energy fuel for muscle contraction.

Which of these carries excess cholesterol from body cells to the liver?

HDL

Which of the following refers to the death of chilled skin or possible loss of extremities?

frostbite

electron transport chain is

a series of oxidation in the mitochondria

In order to buffer a strong acid into a weak acid, which has a less dramatic effect on pH, what chemical should be used as the buffer?

a weak base

Which one of the following is NOT a main role of the liver?

add ammonia to the blood

Which is the most common?

alpha helix

what are the two functional groups fo amino acids?

amine (basic group) and organic acid group

what is the importance of these two groups?

amino acids can be either a base (proton acceptor) or acid (proton donor)

what is formed during deamination?

ammonia is formed

The basal metabolic rate can most effectively be defined as the __________.

amount of energy needed to maintain life

What is a coenzyme?

an organic cofactor

what contains all 20 amino acids?

animal products. (no single plant does)

Some enzymes are purely protein. In other cases, the functional enzyme consists of two parts

apoenzyme (protein portion) and cofactor together these form a holoenzyme

Pyruvic acid enters the mitochondria but it can not enter the Krebs cycle until

it is converted to acetyl CoA

Where does the citric acid cycle (Krebs cycle) occur?

mitochondria

In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?

mitochondrion

what are the monomers of carbohydrates?

monosaccharides

amino acid pools:

supply of free amino acids •Proteins are lost in urine, hair, and skin cells•Replaced typically by die Pool is the source for: •Resynthesizing amino acids and proteins •Gluconeogenesis

hydrophilic and hydrophobic r groups are present in what structure?

tertiary (globular)

Unlike glycogen storage which is very limited

the body has a virtually unlimited ability to store fat

Lipids generate more ATP per molecule than glucose but...

the body prefers glucose

Lipolysis is?

the breakdown of stored lipids (lipids to fatty acids and glycerol)

oxidation is

the gain of oxygen or the loss of hydrogen (LOSES energy)

what stimulate glycogenolysis?

glucagon and epinephrine (fight or flight)

what is used to create ATP?

glucose

what is storage stimulated by?

insulin

FAD

is reduced to FADH2

Where are the two primary sources of glucose during the postabsorptive state?

Liver and skeletal muscle

________ refers to all chemical reactions necessary to maintain life.

Metabolism

What serves as the energy source for the proton pumps in oxidative phosphorylation?

electrons passing from transfer molecules to oxygen

In the case of a person who consumes a normal, balanced diet, proteins are essential to the body for all of the following EXCEPT ________.

production of energy

what eicosanoid is plays a role in blood clotting, regulation of blood pressure, inflammation, and labor contractions?

prostaglandins

Glucose (6 carbons) is converted to

pyruvate x 2 (3 carbons each)

where is glycogen primarily stored?

skeletal muscle and liver cells

What is glycogen?

storage carbohydrate in animal tissues

What is starch?

storage form of glucose in plants

Hypersecretion of aldosterone results in hypokalemia, which causes hyperpolarization of neurons; this in turn results in ______.

the need for a stronger than normal stimulus in order to trigger an action potential

What is the absorptive state?

the period following a meal when nutrient absorption is under way

What is a substrate?

the substance on which an enzyme acts

What do pyruvate molecules depend on?

oxygen

lipids have a lower content of what than carbs?

oxygen

high levels of_________ are linked with artherosclerosis, heart attack, and strokes

cholesterol

what is the raw material for synthesis of vitamin D, steroid hormones (ie sex hormones), and bile salts?

cholesterol

The absorptive state

-Occurs during and up to 4 hours after eating a meal when nutrients are plentiful -Glucose in food is burned immediately for energy -Amino acid, glycerol and fatty acids in food are used to build larger molecules or stored as fat for later use

Too much lipids means too much acetyl CoA; how does the body respond?

-The liver convert excess acetyl CoA to ketones (ketogenesis) -The most common ketone is acetone, which has the smell of nail polish -Ketones make the blood acidic (ketoacidosis) and spills into the urine (Ketonuria)

Energy produced by EACH pyruvic acid

1 ATP molecules (actually GTP)•4 NADH + H+ and 1 FADH2 are sent to the ETC

Three stages of metabolism of nutrients are:

1) GI tract 2) tissue cells (glycolosis/pyruvate and acetyl CoA) 3) mitochondria (Krebs cycle)

steps in protein metabolism

1) transamination-amine is turned to Keto 2)oxidative deamination- ammonia and CO2 are combined to make urea 3)Keto acid modification- ketones are altered so they can enter Krebs cycle

A fatty acid containing an 18 carbon chain yields nine acetyl CoA molecules and can enter the Krebs and ETC to generate

147 ATP

C6 H12 O6 + 6 O2

6 H2O + 6 CO2 + 32 ATP + heat

How many of the 20 amino acids are essential?

8

what is the single most important molecule in steroid chemistry?

cholesterol

lipid soluble vitamins are

A, D, E, K

what is the structure of ATP?

Adenine (nitrogenous base); ribose (5- carbon sugar) and 3 phosphate groups

The process whereby excess glucose is stored in cells is called __________.

glycogenesis

Major minerals (macromineral)that are needed in amounts of 200 mg or more daily are

Calcium, potassium, sodium, chlorine, sulfur, magnesium, phosphorous

carbohydrate and fat pools:

Carbohydrates and fats are easily interconverted through key intermediates

What are lipoproteins?

Cholesterol and other lipids are insoluble in water thus must be packaged with protein by the liver for transport through the blood

what is the catabolic-anabolic steady state?

Dynamic state in which organic molecules (except DNA) are continuously broken down and rebuilt

The preferred energy fuel for the brain is fat.

False

what are the major two difference between amino acid and fat/carb pools?

Fats and carbohydrates are oxidized directly to produce energy (Amino acids must first be converted to a citric acid cycle keto acid) Excess carbohydrate and fat can be stored as such (Amino acids are not stored as proteins)

__________ is the key hormone regulator of the postabsorptive state.

Glucagon

during oxidation

H atoms are stripped off the oxidized substance• (The "lost" H atoms can be "recycled" to get even more energy!)

products of lipids and proteins can also feed the Krebs cycle:

Intermediates of the Krebs cycle can leave the cycle to synthesize fats and amino acids

Minerals are

Inorganic molecules needed in very small amounts

What is the primary process by which insulin is released after a meal is ingested?

Insulin is secreted in direct response to blood glucose.

Trace minerals needed in amounts of 20 mg or less daily are

Iron, cobalt, nickel, chromium, copper, fluorine, selenium, zinc, manganese

what is stored glucose called?

glycogen

__________ is the conversion of acetyl CoA into ketone bodies.

Ketogenesis

reduction is

Loss of oxygen or gain of hydrogen •Reduced substances gain energy

What is BUN?

Measurement of blood urea nitrogen (BUN) is a measure of protein metabolism (the body is burning protein) or poor kidney function

what blocks synthesis and inflammatory actions of prostaglandins?

NSAID's

Two coenzymes accept the H atoms and can "recycle" them to get their energy

Nicotinamide adenine dinucleotide (NAD) Flavin adenine dinucleotide (FAD)

post absorbative state

Occurs between meals when blood glucose levels are falling YOU MUST KEEP BLOOD GLUCOSE LEVELS NEAR NORMAL OR YOU WILL GO INTO A COMA! Stored glucose (glycogen) is broken down (glycogenolysis) to raise blood glucose •Excess proteins and triglycerides (lipolysis) are converted to glucose (gluconeogenesis) to raise blood glucose

what is the final product of the ETC?

Oxygen

What makes amino acids different?

R group

After NAD and FAD are reduced, what happens?

The H will later be cleaved from these coenzymes to produce lots of ATP

Why are high-density lipoproteins (HDLs) considered "good"?

The cholesterol transported by HDLs is destined for destruction.

What are trans fats?

The type of fat produced when manufacturers add hydrogen to the fat molecules in vegetable oils. contributes to heart disease for that solid animal fats

What is the primary objective during the postabsorptive state?

To maintain blood glucose at around 70-110 mg/100 ml of blood

what is the major function of carbohydrates?

To provide a major source source of energy or ATP

what happens in transamination and Keto acid modification?

Transfer of an amino group from one amino acid to another to form essential amino acids The process creates a ketoacid that can enter the Krebs cycle to generate ATP

What is gluconeogenesis?

When not enough glucose is available in the diet, the body creates "new" glucose by converting fats and proteins to glucose

Glycogen is formed in the liver during the ________.

absorptive state

how are amino acids linked to form proteins?

acid end of one linked to amine end of next

what are the two types of secondary structure?

alpha helix and beta pleated sheet

cholesterol is not used as an energy source but it serves as

an essential component of plasma membranes

if the body has excess protein (such as protein shakes), amino acids

are converted to pyruvic acid and other Krebs cycle intermediates and are burned for energy (gluconeogenesis)

how is fat synthesis formed?

attaching three fatty acid chains to a single glycerol molecule by dehydration synthesis

Stored lipids and dietary fats are not normally oxidized for energy until

blood glucose and glycogen stores are used up (this is why it is hard to lose fat once it forms!)

Glycolysis is a source of fast energy

but only yields two ATP per glucose molecule

excess amount of lipid soluble vitamins are stored and

can lead to hypervitaminosis

How are sugars and starches classified?

carbohydrates

What are carbohydrates made of?

carbon, hydrogen, oxygen (included sugars and starches; is 1-2 % of cell mass)

In general metabolic terms, food digestion is a form of __________, while building new protein molecules is a form of __________.

catabolism; anabolism

the complete catabolism of glucose is called

cellular respiration

what starch is the body unable to digest?

cellulose; helps with moving feces through colon

LDL has the highest ________ content?

cholesterol

Which nutrient molecule CANNOT be used in the oxidative pathways?

cholesterol

Lipogenesis is

creation of new fat molecules (forms lipids from acetyl CoA and glyceraldehyde 3-phosphate)

where does the first stage of catabolism of glucose take places?

cytoplasm

in alpha helixes hydrogen bonds always link

different parts of the same chain together

in beta pleated sheets the hydrogen bonds link

different polypeptide chains as well as different pars of the same chain that has folded back on itself

What are eicosanoids?

diverse lipids derived from 20-carbon fatty acid found in all cell membranes

An allele that can mask another allele is said to be __________.

dominant

what causes unsaturated fat to turn into liquid at room temperature?

double bonds that that cause chained to kink so they are not close enough to solidify

When is protein used as an energy source?

during starvation or when carbs or lipids aren't available

Glycogen is a highly-branched polysaccharide. Why is this beneficial?

each branch can be attacked by an enzyme, many glucose molecules can be broken and used at the same time

when oxygen is present, what can pyruvate then do?

enter the Krebs cycle and continue to generate energy

A(n) __________ nutrient is one that the body cannot synthesize rapidly enough to be useful.

essential

nitrogen is not present in

fats or carbohydrates

building blocks of lipids

fatty acids and glycerol

what are the two ways proteins are classified?

fibrous (structural ) and globular (functional)

Enzymes cannot

force reactions between molecules it wouldn't normally react too; can only speed reaction

Gluconeogenesis

formation of glucose from noncarbohydrate sources

what are two hexoses that are isomers of glucose?

galactose and fructose

Several hours after your last meal, declining blood glucose levels stimulate release of the hormone ________, which stimulates glycogenolysis, lipolysis and fat mobilization, and gluconeogenesis.

glucagon

When blood glucose level is low, the liver can make glucose from amino acids and fats. What is this process called?

gluconeogenesis

The major fuel for making ATP in most cells of the body is a type of carbohydrate known as ________.

glucose

What fuel is preferred by most body cells to produce ATP?

glucose

In gluconeogenesis, during the postabsorptive state, amino acids and ________ are converted to glucose.

glycerol

most cells use energy from glucose right away, only ______ and ________ store it

liver, skeletal muscle

what does the liver use their stored glycogen for?

maintain blood sugar which allows cell to get fuel they need skeletal uses it for themselves

Phospholipids are

modified triglycerides with two fatty acid groups and a phosphorus group

anabolism requires

new chemical bonds and energy

what does urea and ammonia contain?

nitrogen

What is the postabsorptive state?

nutrients are no longer plentiful

vitamins are

organic molecules that are required in the diet in very small amounts; many are coenzymes in metabolism

why does the body conserve protein?

they form critical substances which are present in small amounts: •Some hormones •All enzymes are proteins •Muscle proteins (actin & myosin) •Fibers in connective tissues

because ammonia is toxic, how does the body get rid of it?

through urine in the from of urea

what is the backbone of the protein molecule?

primary structure- "beads" of amino acids

what has the most varied functions of any molecule?

protein (10-30% of cell mass)

HDL has the highest _____ content?

protein content

what happens to pyruvate under anaerobic conditions?

pyruvic acid is reduced to lactic acid

what are two or more polypeptide chain in a regular manner to form a complex protein?

quaternary structure

when catabolism occurs, and energy is released from chemical bonds

released energy may be used right away or stored for later use in ATP

What is deamination?

removal of an amino (NH2) group

what are fatty acid chains with only one single covalent bond?

saturated

what two polysaccharides are important?

starch and glycogen (polymers of glucose)

What is glycogenolysis?

stored glycogen converted back to glucose between meals when the body needs glucose

what are nutrient pools?

stores of amino acids, carbohydrates, and fats

Phases of Glycolysis

sugar activation sugar cleavage sugar oxidation and ATP formation

where is most of the energy in the catabolism of glucose is produced?

the electron transport chain

Glycogenolysis

the hydrolysis of glycogen to release glucose monomers

what happens to other absorbed monosaccharides?

the liver converts them to glucose

What is beta oxidation?

the process of Converting fatty acids to Acetyl-CoA

why are minerals needed on a daily basis?

they are not stored

what happens when lipids are in excess?

they can be converted to acetyl CoA and enter the Krebs cycle to produce ATP

what is the general formula for a monosaccharide?

(CH2O)n --n is the numbers of carbons in the sugar---

Vitamins and minerals

A balanced diet is needed to get all of these nutrients, used mostly as coenzymes. / This group includes inorganic nutrients found mostly in vegetables, legumes, milk, and some meats.

Carbohydrates

Animal sources include lactose in milk and glycogen in meat./Monosaccharides are sugars, and polysaccharides include starch. / This group includes the preferred fuel source in all cells of the body.

What is the correct general equation for cellular respiration?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energy

the pentose deoxyribose is part of

DNA

Proteins

Eggs, milk, meat, and fish provide a complete source of this nutrient group. / Molecules in this group are composed of amino acids.

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

False

This chemical equation shows the reaction of a strong acid and weak base in the bicarbonate buffer system. Provide the products of the following reaction. HCl + NaHCO3 →

H2CO3 + NaCl

Lipids

Most of what we eat from this group is classified as neutral fats (triglycerides). / Cholesterol, in this group, is used to make steroid hormones and cell membranes.

Which of the following molecules is most directly involved in the transfer of energy from food to the proton pumps depicted in this figure?

NADH

Which of the following statements is FALSE?

The amino acid pool is the body's total supply of amino acids in the body's proteins.

What must occur before a fatty acid can be metabolized by cellular respiration?

The fatty acid must be broken down into acetic acid, a two-carbon molecule.

Which statement describes the citric acid cycle?

This process produces some ATP and carbon dioxide in the mitochondrion.

Which statement describes glycolysis?

This process splits glucose in half and produces 2 ATPs for each glucose.

Which statement describes the electron transport chain?

This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.

It would not be healthy to eliminate all fats from your diet because they serve a useful purpose in maintaining the body.

True

The increased use of noncarbohydrate molecules for energy to conserve glucose is called glucose sparing.

True

Which of the following would NOT be associated with a rise in K+ concentration in the extracellular fluid (ECF)?

a drop in Na+ reabsorption

Fat oxidation products can acidify the blood, a condition known as ________.

acidosis or ketoacidosis

Molecules that can act reversibly as acids or bases depending upon the pH of their environment are called ________.

amphoteric

The process by which larger molecules or structures are built up from smaller ones is called ________.

anabolism

What hormone helps to maintain correct extracellular fluid (ECF) osmolality when concentrations become too high?

antidiuretic hormone (ADH)

Disaccharides are too large to transport through cell membranes so they must

be hydrolyzed to monosaccharides before they can be absorbed

What is the primary buffer in the plasma?

bicarbonate buffer system

Which chemical buffer system resists pH changes in the extracellular fluid (ECF)?

bicarbonate buffer system

the hexose glucose is

blood sugar

Glycogen accounts for 80-85% of stored energy in the body.

false

Most ATP in cellular respiration is regenerated in substrate level phosphorylation.

false

Which of the following processes takes place in the cytosol of a eukaryotic cell?

glycolysis

Which of the choices below describes the pathway of cellular respiration (the complete oxidation of glucose)?

glycolysis, citric acid (Krebs) cycle, electron transport chain, oxidative phosphorylation

What organ manufactures and stores most of the body's glycogen as a ready source of glucose?

liver

Which lipoprotein transports cholesterol and other lipids to body cells?

low-density lipoprotein or LDL

Carbohydrates, proteins, and lipids are considered ________.

macronutrients

Carbohydrates, proteins, and lipids are considered ________.

major nutrients

It is important to ensure that your diet is adequately rich in vitamins because ________.

most vitamins are coenzymes needed to help the body utilize essential nutrients

Which of the following is NOT correctly matched?

oxidative phosphorylation: no energy is produced

Atrial natriuretic peptide (ANP) is a hormone that is made in the atria of the heart. The influence of this hormone is to ________.

reduce blood pressure and blood volume by inhibiting sodium and water retention

What is the most important trigger for aldosterone release?

renin-angiotensin-aldosterone mechanism

Which acid-base imbalance would be caused by overaccumulation of CO2 in the blood?

respiratory acidosis

Important Disaccharides

sucrose (glucose + fructose) maltose (glucose + glucose) lactose (glucose + galactose)

Adenosine triphosphate (ATP) is produced in greatest quantity during ________.

the electron transport chain

pentose (5 carbon) and hexose (six carbons) are

the most important in the body