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
