Unit 8: Metabolism & Entergetics
The vitamin that plays a role in maintaining epithelia and is required for the synthesis of visual pigments is vitamin
A
Homeostatic control of body temperature is termed
thermoregulation
In transamination, the amino group of an amino acid is ________, yielding a different amino acid.
transferred to another molecule
Low-density lipoproteins function to:
transport cholesterol to cells for use in plasma membranes or hormone synthesis
For each molecule of glucose converted to pyruvic acid:
two molecules of ATP are broken down and four are synthesized
Lack of exercise and a caloric intake > basal metabolic rate plus external work for a prolonged period may result in:
type II diabetes
The conversion of ammonia into a less toxic substance produces
urea
Pellagra, an epithelial and mucosal deterioration, results from a deficiency in
vitamin B3 (niacin)
Which of the following is an end product of the electron transport chain?
water
An increased caloric intake without an increase in external expenditure would most likely lead to:
weight gain
The food pyramid recommends many servings a day of dark-green and orange vegetables. Which vitamin is particularly abundant in this food group?
A, C, E, folic acid
All cells use which of the following directly for energy to fuel their work?
ATP
The molecule that supplies our cells with an immediate source of energy is:
ATP
________ is deficient in one or more of the essential amino acids.
An incomplete protein
glycolysis:
There is a net gain of two ATP molecules for each glucose molecule.
True or False: One of the major results of cellular respiration is heat.
True
True or False: When ATP breaks down, the products can then be used to synthesize more ATP.
True
All of the following take place during the absorptive state except a) ketone bodies begin to form b) blood glucose levels rise. c) blood lipid levels rise d) insulin stimulates glycogenesis.
a) ketone bodies begin to form.
Which of the following hormones is most directly involved during the post-absorptive state?
glucagon
Which of the following hormones increase the blood glucose level?
glucagon and epinephrine
The process of synthesizing glucose from noncarbohydrates is called
gluconeogenesis
Although other nutrients can feed into the citric acid cycle, ________ yields energy the quickest.
glucose
During the absorptive phase of metabolism:
glucose is the primary energy source for most cells
Which of the following is most likely to occur if blood glucose levels are elevated?
glycogenesis
Blood glucose levels are increased by:
glycogenolysis
When the blood glucose level becomes low, which of the following would most likely increase?
glycogenolysis
End product is pyruvic acid
glycolysis
A high uric acid level (above 7.4 mg/dl) can lead to the painful condition known as
gout
The hormone ________, which suppresses appetite and stimulates satiety, is released by adipose tissue.
leptin
The nutrients that yield the most energy per gram when metabolized are
lipids
When a cell needs energy, glycogen may be hydrolyzed to:
many glucose molecules.
The sum of all of the biochemical processes going on within the human body at any given time is called
metabolism
ATP can be used for
muscle contraction. ion transport. protein synthesis. glycogen synthesis.
NAD, which acts as a hydrogen carrier in the cell, is derived from:
niacin (nicotinic acid)
Resting energy expenditure is most directly determined by monitoring
respiration
During cellular respiration, how much of the original energy in the glucose molecule is transferred into ATP and how much is instead converted into (lost as) heat?
40% to ATP and 60% to heat.
Glycolytic breakdown of glucose first results in ________ molecules.
-2 pyruvate (pyruvic acid) -2 NADH -2 ATP (net)
A person decides to go on a hunger strike to further one of his favorite causes. After many days with nothing but water you would expect to observe
-elevated levels of glucocorticoids. -ketone bodies in his urine. -lowered blood pH.
A balanced diet should
-include adequate substrates for the production of energy. -provide essential amino acids and fatty acids. -contain adequate amounts of vitamins and minerals.
In the metabolism of proteins, amino acids may be converted to:
-nitrogen containing derivatives such as hormones -structural proteins -new enzymes -carbohydrates and fats
The electron transport system
-receives electrons from coenzymes. -produces more the ATP than Glycolysis -is located on the inner mitochondrial membrane (the cristae).
egulation of body temperature is controlled by:
-shivering -vasodilation of cutaneous vessels -is regulated by a center in the hypothalamus
Cells synthesize new organic components for which of the following reasons?
-structural maintenance -growth and repair -production of secretions
There are ________ essential amino acids that the body either cannot synthesize or that cannot be produced in amounts sufficient for growing children.
10
Obesity is defined as a body weight more than ________ percent above the ideal body weight for an individual.
20
________ contains all of the essential amino acids.
A complete protein
The "good" type of lipoprotein that carries cholesterol from tissues to liver is:
HDL (high-density lipoproteins)
Deficiency in what vitamin can result in a condition called scurvy?
C
Which of the following carry excess cholesterol from peripheral tissues to the liver?
High-density lipoproteins (HDLs)
Inadequate exposure to sunlight can result in decreased amounts of vitamin ________ in the body.
D
The vitamin that is required for proper bone growth and for calcium absorption and retention is vitamin
D
Compare glycogenesis and glycogenolysis
Glycogenesis is the formation of glycogen from glucose. Glycogenolysis is the breakdown of glycogen to glucose
The vitamin that prevents breakdown of vitamin A and fatty acids is vitamin
E
An adult weighing 130 lb. requires the same amount of energy to walk up a flight of stairs as does an adult weighing 280 lb.
False. It requires more energy for the larger adult because he/she has a higher BMI.
Which of the following is true about the citric acid, or Krebs, cycle?
It occurs in the matrix of mitochondria
Describe the roles of LDLs and HDLs
LDLs deliver cholesterol to tissues and HDLs absorb unused cholesterol and return it to the liver
What two coenzymes transfer hydrogen atoms to the electron transport chain?
NAD and FAD
Carbohydrates and proteins may be converted to triglycerides and stored as fat.
True. Any calorie containing nutrient can be stored as fat in the body.
Ketone bodies can result from excess production of:
acetyl CoA
Amino acids and fatty acids may enter the citric acid cycle by way of:
acetyl-CoA
Lipogenesis generally begins with
acetyl-CoA
Growth and repair involve primarily what type of reactions?
anabolic
All of the following are reasons why glucose is the primary energy source for cells except a) glucose is a small, soluble molecule. b) glycogen breakdown occurs very slowly. c) glucose can be stored efficiently. d) glycogen breakdown involves only a single enzymatic step. e) glycolysis does not require oxygen to generate ATP.
b) glycogen breakdown occurs very slowly.
All of the following occur during the postabsorptive state except that a) glycogen is broken down into glucose in the liver. b) levels of blood glucose are elevated. c) ketone bodies may be formed. d) lipid mobilization may occur.
b) levels of blood glucose are elevated.
The minimum resting energy expenditure of an awake, alert person is called
basal metabolic rate
The citric acid cycle
begins with the formation of a molecule of citric acid
Pathway for fatty acid breakdown
beta-oxidation
The process that catabolizes fatty acids to acetyl-CoA is called
beta-oxidation
The process that catalyzes fatty acids using enzymes that generate acetyl-CoA is called
beta-oxidation
Which of the following is the first step in ATP production from fat?
beta-oxidation
In a healthy individual who has just finished eating a large nutrient-balanced meal:
blood plasma will have an increased concentration of fats, glucose, and amino acids
About 60% of the heat loss from a nude person standing in a room at 70 degrees (F) is by radiation. Heat loss in this manner is based on the principal that:
body temperature is greater than the surrounding temperature, so the nude person releases more heat than he receives
Cellular respiration is best described as the:
breakdown of glucose into CO2 and H2O and production of ATP.
All of the following are true of beta-oxidation except that a) it occurs in the mitochondria. b) fatty acids break down into acetyl-CoA that enter the citric acid cycle. c) lipids are converted into glycogen molecules. d) it requires coenzyme A, NAD, and FAD. e) it ultimately yields large amounts of ATP.
c) lipids are converted into glycogen molecules.
Which of the following terms describes the process by which glucose is metabolized to produce CO2, H2O, and energy?
catabolism
The largest lipoproteins, ________, are produced by intestinal epithelial cells from the fats in food.
chylomicrons
The lipoproteins that carry absorbed lipids from the intestinal tract to the bloodstream are the
chylomicrons
Starting material is acetyl-CoA
citric acid cycle
Where in the cell does electron transport occur?
cristae of mitochondria
Site of oxidation/reduction reactions in electron transport
cytochromes
Where does the breakdown of glucose to pyruvic acid occur?
cytoplasm
Where in a cell does glycolysis occur?
cytoplasm
Which of the following occurs when water is released (lost) during a reaction?
dehydration synthesis
28 ATP produced
electron transport
Most of the ATP in our cells is produced during:
electron transport
Which part of glucose metabolism yields the greater amount of ATP?
electron transport system
Which step of glucose metabolism yields the greater amount of ATP?
electron transport system
Which of these is a hormone that causes an increase in blood glucose concentration?
epinephrine
Which of the following increases the breakdown of triglycerides in adipose tissue?
epinephrine, thyroid hormone, exercise
Fatty acids that are necessary for proper health but cannot be synthesized by the body are called
essential fatty acids
Linoleic acid and linolenic acid are examples of
essential fatty acids.
Acetyl CoA for the citric acid cycle may be formed through metabolism of:
fatty acids, glucose, amino acids
Amino acids can be converted into:
fatty acids, other amino acids, glucose
The vitamin that is a coenzyme in amino acid and nucleic acid metabolism is
folic acid (folate)
Decreasing blood glucose is a stimulus for the secretion of:
glucagon
A disorder caused by the ingestion of excessive quantities of a fat-soluble vitamin is known as
hypervitaminosis.
The area of the brain that regulates body temperature is the
hypothalamus
A decrease in body weight occurs when caloric intake:
is less than basal metabolism plus external work
Body temperature:
is regulated primarily by regulating heat loss
Epinephrine:
is released from the adrenal medulla and acts to stimulate glycogenolysis
The energy content of foods is commonly given in units of
kilocalories (also, kcal or Cal).
In the absence of oxygen, what is produced at the end of glycolysis?
lactic acid
In skeletal muscle, one major disadvantage of relying solely on glycolysis under anaerobic conditions is that:
lactic acid accumulates in the muscle.
When the body is relying on internal energy reserves to continue meeting its energy demands, it is in the ________ state.
postabsorptive
A person with untreated diabetes mellitus would be in a prolonged:
postabsorptive state
The carbohydrates in an uneaten candy bar can best be described as:
potential energy
The mitochondria are often called the "powerhouses" of the cell because they:
produce most of the ATP (cell energy) generated from glucose
Glycolysis breaks down glucose into
pyruvic acid
The function of the citric acid cycle is to
remove hydrogen atoms from organic molecules and transfer them to coenzymes
Acetyl CoA is important in cellular metabolism because it:
serves as an intermediate in multiple energy pathways, for the metabolism of glucose, fatty acids, and amino acids.
Most nutrient absorption takes place in the
small intestine
The carbon dioxide of respiration is formed during
the citric acid cycle.
Reactions within ________ provide most of the energy needed by a typical cell.
the mitochondria
