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CHEM71030 > Unit 9: Metabolism > Flashcards

Unit 9: Metabolism Flashcards

1
Q

Disaccharides are formed from oligosaccharides in this type of reaction?

A

Catabolic

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2
Q

When NAD+ becomes NADH, the coenzyme has been__________.

A

Reduced

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3
Q

Anabolic reactions use energy by___________.

A

Removing a phosphate group from ATP

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4
Q

Glycolysis results in the production of two _______ molecules from a single molecule of glucose. In the absence of _______, the end product of glycolysis is ________.

A

Pyruvate, Oxygen, Lactate

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5
Q

The Krebs cycle converts __________ through a cycle of reactions. In the process, ATP, _________, and __________ are produced.

A

acetyl CoA, FADH2, NADH

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6
Q

Which pathway produces the most ATP molecules?

A

The electron transport chain

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7
Q

Aerobic cellular respiration results in the production of these two products:

A

ATP and water

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8
Q

Lipids in the diet can function in all of the following ways EXCEPT:
1) converted into acetyl CoA
2) combined with CO2 to make urea and water
3) catabolized for energy
4) stored as triglycerides for later use

A

2) combined with CO2 to make urea and water

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8
Q

The gallbladder provides _______ that help(s) in the transport of lipids across the intestinal membrane.

A

Bile salts

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9
Q

Triglycerides are transported by chylomicrons because ____________.

A

They cannot move easily in the bloodstream because they are hydrophobic

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10
Q

Acetyl CoA can be converted to all of the following except:
1) Fatty acids
2) Ketone bodies
3) Triglycerides
4) Polysaccharides

A

4) Polysaccharides

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11
Q

Digestion of proteins begins in the _________ where ________ and HCL mix with food to break protein down into _________.

A

Stomach, Pepsin, Amino acids

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12
Q

Stimulates the growth of muscle and bone while also inhibiting cell death (apoptosis)

A

Insulin-like growth factor (IGF)

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13
Q

Increase in muscle mass and strength as well as the growth and strengthening of bone

A

Testosterone

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14
Q

Synthesized and released from the pituitary gland; stimulates the growth of cells, tissues, and bones

A

Growth hormone (GH)

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15
Q

Produced by the beta cells of the pancreas; plays an essential role in carbohydrate and fat metabolism, controls blood glucose levels, and promotes the uptake of glucose into body cells; causes cells in muscle, adipose tissue, and liver to take up glucose from the blood and store it in the liver and muscle as glycogen; its effect is the opposite of glucagon; glucagon and insulin are a part of a negative-feedback system that stabilizes blood glucose levels

A

Insulin

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16
Q

Produced primarily by the ovaries, it is also produced by the liver and adrenal glands; its anabolic functions include increasing metabolism and fat deposition

A

Estrogen

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17
Q

Nice try - that’s a catabolic hormone

A

Cortisol

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18
Q

Compared to the post-absorptive state, during the absorptive state, glucose levels are _______, insulin levels are _________, and glucagon levels are ___________.

A

high, high, low

19
Q

The postabsorptive state relies on stores of glycogen in the liver.

A

True

20
Q

The body’s temperature is controlled by the _______.

A

Hypothalamus

21
Q

A crowded room warms up through the mechanisms of ________.

A

Radiation

22
Q

What is not considered a part of cellular respiration?

A

Urea cycle

23
Q

From glycogen to energy, list the following intermediary products in the order they are created.
Pyruvate, Acetyl CoA, Glucose

A

1) Glucose
2) Pyruvate
3) Acetyl CoA

24
Q

Electrons move from the Krebs cycle to the electron transport chain through this process:

A

Reduction of NAD+ and FAD

25
Q

The oxidation of glucose yields these products that are later used in oxidative phosphorylation:

A

NADH and FADH2

26
Q

Dietary fats are digested in the following order:
Emulsified with bile.
Incorporated into chylomicrons.
Broken down with lipases.
Moved into the intestine, the lymph, and then the blood.

A

1) Emulsified with bile.
2) Broken down with lipases.
3) Moved into the intestine, the lymph, and then the blood.
4) Incorporated into chylomicrons.

27
Q

A long-chain saturated fatty acid will yield more energy than a shorter-chain unsaturated fatty acid.

A

True

28
Q

Products from the breakdown of dietary carbohydrates, lipids, and protein can all enter the Krebs cycle?

A

True

29
Q

Carbs: Glycolysis

A
  1. Glucose, ATP, NADH+, and phosphate break down 2 pyruvate to generate 4 ATP and 2 NADH.
  2. NADH will then be used to produce ATP in the mitochondria.
  • Generates energy for the cell and creates pyruvate molecules that can be used in Krebs cycle, can be converted in lactic acid by fermentation, or used for synthesis of glucose through gluconeogenesis.
30
Q

Carbs: Krebs Cycle

A
  1. Pyruvate molecules generated in glycolysis are transported across the
    mitochondrial membrane into the inner mitochondrial matrix, where they are
    metabolized by enzymes in a pathway called the Krebs cycle.
  2. The Krebs cycle is also commonly called the citric acid cycle or the tricarboxylic
    acid cycle.
  3. The acetyl CoA is systematically processed through the cycle and produces high-energy NADH, FADH2, and ATP molecules.
31
Q

Carbs: Electron Transport Chain

A
  1. The electron transport chain uses the NADH and FADH2 produced by the Krebs cycle to generate ATP.
  2. Electrons from NADH and FADH2 are transferred through protein complexes embedded in the inner mitochondrial membrane by a series of enzymatic reactions.
  3. The electron transport chain consists of a series of four enzyme complexes and two coenzymes, which act as electron carriers and proton pumps used to transfer H+ ions into the space between the inner and outer mitochondrial membranes.
32
Q

Lipids: Lipid Digestion

A
  1. Lipid chemical metabolism from foods starts in the intestines where pancreatic lipases break down triglycerides into monoglycerides, after they’ve been emulsified from bile salts.
  2. When food reaches the small intestine in the form of chyme, cholecystokinin (CCK) is release by intestinal cells into the mucosa, stimulating the release of pancreatic lipase and the contraction of the gall bladder.
33
Q

Lipids: Gluconeogenesis

A
  1. Gluconeogenesis is the synthesis of new glucose molecules from pyruvate, lactate, glycerol, or the amino acids alanine or glutamine.
  2. This process takes place primarily in the liver during periods of low glucose, that is, under conditions of fasting, starvation, and low carbohydrate diets.
  3. Gluconeogenesis is not simply the reverse of glycolysis.
  4. Pyruvate is a common starting material for gluconeogenesis.
  • The process uses the following energy: 4 ATPs, 2 GTPs, and 2NADHs.
34
Q

Lipids: Ketone Oxidation

A
  1. When glucose is limited, ketone bodies can be oxidized to produce acetyl CoA to be used in the Krebs cycle to generate energy.
35
Q

Lipids: Ketone Body Oxidation

A
  1. Organs that have classically been thought to be dependent solely on glucose, such as the brain, can actually use ketones as an alternative energy source.
  2. This effect provides one way of telling if a person with diabetes is properly controlling the disease.
  3. The carbon dioxide produced can acidify the blood, leading to diabetic ketoacidosis, a dangerous condition in people with diabetes.
  4. Ketones oxidize to produce energy for the brain.
36
Q

Lipids: Lipogenesis

A
  1. When glucose levels are plentiful, the excess acetyl CoA generated by glycolysis can be converted into fatty acids, triglycerides, cholesterol, steroids, and bile salts.
  2. This process, called lipogenesis, creates lipids from the acetyl CoA and takes place in the cytoplasm of adipocytes and hepatocytes.
  3. Lipogenesis begins with acetyl CoA and advances by the subsequent addition of two carbon atoms from another acetyl CoA; this process is repeated until fatty acids are the appropriate length.
  4. Although lipogenesis occurs in the cytoplasm, the necessary acetyl CoA is created in the mitochondria and cannot be transported across the mitochondrial membrane.
  5. Thus, acetyl CoA is converted into citric acid to cross the mitochondrial membrane.
37
Q

Proteins: Energy from Amino Acids

A

Amino acids can be broken down into precursors for
glycolysis or the Krebs cycle.
Amino acids (in bold) can enter the cycle through more than one pathway.

38
Q

Proteins: Urea Cycle

A
  1. The urea cycle is a set of biochemical reactions that produces urea from ammonium ions in order to prevent a toxic level of ammonium in the body.
  2. In these reactions, an amine group, or ammonium ion, from the amino acid is exchanged with a keto group on another molecule.
  3. This transamination event creates a molecule that is necessary for the Krebs cycle and an ammonium ion that enters into the urea cycle to be eliminated.
  4. Because the processing of amino acids results in the creation of metabolic intermediates, including pyruvate, acetyl CoA, acetoacyl CoA, oxaloacetate, and α-ketoglutarate, amino acids can serve as a source of energy production through the Krebs cycle.
39
Q

How do carbohydrates serve was sources of energy for the body?

A
  • Most common source of energy.
  • Complex carbs (polysaccharides like starch and glycogen).
  • Simple sugars (monosaccharides like glucose and fructose).
  • Sugar catabolism breaks down polysaccharides into monosaccharides.
  • GLUCOSE is the most common fuel for ATP production in the cells.
  • Excess glucose is stored as energy reserve in the liver and skeletal muscles as glycogen or converted to fat (triglycerides) in adipose cells (adipocytes).
40
Q

How do lipids serve was sources of energy for the body?

A
  • Triglycerides are the most often used for energy through beta-oxidation.
  • 50% of excess fat is stored in adipocytes in the subcutaneous tissue.
  • Remainder is stored in adipocytes in other tissues and organs.
41
Q

How do proteins serve was sources of energy for the body?

A

-Can be broken down into their monomers, individual amino acids.
- Can be used as building blocks for new proteins or broken down further for production of ATP.
- When someone is starving, this use of amino acids for energy production can lead to body deterioration as more and more proteins get broken down.

42
Q

Describe the relationship between amino acid degradation and the urea cycle.

A

the amino acids are degraded to yield NH4+ (ammonia), and then enters the urea cycle, then excreted by the body.

43
Q

Metabolic States of the Body: Absorptive State

A
  • Occurs after a meal when your body is digesting the food and absorbing the nutrients.
  • Food is broken down into its constituents (carbs, fats, proteins) to be absorbed by the intestine.
  • The constituents are transported across the intestinal wall and enter the bloodstream of the lymphatic system.
  • The rise of glucose concentrations in the bloodstream stimulates pancreatic beta cells to release insulin into the bloodstream, where the absorption of blood glucose by liver hepatocytes, adipose, and muscle cells is initiated.
44
Q

Metabolic States of the Body: Post-absorptive State

A
  • The fasting state
  • Occurs when the food has been digested, absorbed, and stored.
  • In response to a drop in blood glucose concentration, the hormone glucagon is released from alpha cells of the pancreas.
  • Glucagon acts upon the liver cells to inhibit the synthesis of glycogen and stimulates the breakdown of stored glycogen back into glucose.
  • Gluconeogenesis will also begin in the liver to replace the glucose that has been used by peripheral tissues.
  • The gluconeogenesis that has been ongoing in the liver will continue after fasting to replace the glycogen stores that were depleted in the liver.
45
Q

Metabolic States of the Body: Starvation State

A
  • When the body is deprived of nourishment for an extended period of time it goes into survival mode.
  • First priority: provide enough glucose or fuel for the brain.
  • Second priority: conservation of amino acids for proteins.
  • Body uses ketones to satisfy the energy needs of the brain and other glucose-dependent organs and to maintain proteins in the cells.

CHEM71030 (12 decks)

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