Biochemistry Chapter 12: Bioenergetics and Regulation of Metabolism

Question 1

Biological systems are open when:

Answer 1

matter and energy can be exchanged with the environment

Question 2

Biological systems are closed when:

Answer 2

only energy can be exchanged within the environment

Question 3

In a closed system changes in enthalpy are equal to:

Answer 3

changes in internal energy, which is equal to heat exchange within the environment

Question 4

Is work performed in a closed biological system?

Answer 4

no - pressure and volume remain constant

Question 5

Entropy

Answer 5

a measure of energy dispersion in a system.

Question 6

Physiological concentrations are usually ____ than standard concentrations.

Answer 6

much less

Question 7

Free energy calculations must be adjusted for:

Answer 7

pH, temperature and concentrations

Question 8

ATP contains:

Answer 8

high-energy phosphate bonds that are stabilized upon hydrolysis by resonance, ionization and loss of charge repulsion.

Question 9

ATP provides energy through

Answer 9

hydrolysis and coupling to energetically unfavorable reactions. Can also participate in phosphoryl group transfers as a phosphate donor.

Question 10

Half-reactions

Answer 10

breakdown of biological oxidation and reduction reactions. Provide useful information about stoichiometry and thermodynamics

Question 11

Electron carriers may be:

Answer 11

soluble or membrane-bound

Question 12

Flavoproteins

Answer 12

one subclass of electron carriers that are derived from riboflavin.

Question 13

Why is equilibrium generally an undesireable state for biochemical reactions>

Answer 13

Organisms need to harness free energy to survive.

Question 14

Postprandial/well-fed (absorptive) state

Answer 14

insulin secretion is high and anabolic metabolism prevails.

Question 15

Postabsorptive (fasting) state

Answer 15

insulin secretion decreases while glucagon and catecholamine secretion increases

• short term fasting (overnight).
• transition to catabolic metabolism

Question 16

Starvation state (prolonged fasting)

Answer 16

dramatically increases glucagon and catecholamine secretion (most tissues rely on fatty acids)

Question 17

Insulin and blood glucose levels

Answer 17

decreases

Question 18

Insulin and rate of anabolic metabolism

Answer 18

increases

Question 19

Insulin secretion by pancreatic beta-cells is regulated by

Answer 19

blood glucose levels

Question 20

Glucagon and blood glucose levels

Answer 20

increases through promoting gluconeogenesis and glycogenolysis

Question 21

Glucagon secretion by pancreatic alpha-cells is stimulated by

Answer 21

low glucose and high protein levels

Question 22

Glucocorticoids

Answer 22

increase blood glucose in response to stress by mobilizing fat stores and inhibiting glucose uptake (increase the impact of glucagon and catecholamines)

Question 23

Catecholamines

Answer 23

Promote glycogenolysis and increase basal metabolic rate through their sympathetic nervous system activity

Question 24

Thyroid hormones

Answer 24

Modulate the impact of other metabolic hormones and have a direct impact on basal metabolic rate

Question 25

T3

Answer 25

More potent than T4, but has a shorter half-life and is available in lower concentration sin the blood

Question 26

T4

Answer 26

converted to T3 at the tissues

Question 27

What is the most metabolically diverse tissue

Answer 27

Liver

Question 28

Hepatocytes

Answer 28

responsible for the maintenance of the blood glucose levels by glycogenolysis and cluconeogenesis in response to pancreatic hormone activity.

Question 29

Liver participates in the processing of:

Answer 29

lipids and cholesterol, bile, urea and toxins

Question 30

Adipose tissue stores lipids:

Answer 30

under the influence of insulin and releases them under the influence of epinephrine

Question 31

Resting muscle potential

Answer 31

conserves carbohydrates in glycogen stores and uses free fatty acids from the bloodstream

Question 32

Active muscle

Answer 32

may use anaerobic metabolism, oxidative phosphorlyation of glucose, direct phosphorylation from creatine phosphate or fatty acid oxidation, depending on fiber type and exercise duration

Question 33

Cardiac muscle uses:

Answer 33

fatty acid oxidation in both the well-fed and fasting states

Question 34

Metabolic rates can be measured using:

Answer 34

calorimetry, respirometry, consumption tracking or measurement of blood concentrations of substrates and hormones

Question 35

Respiratory quotient

Answer 35

estimates the composition of fuel that is actively consumed by the body

Question 36

What three hormones play a role in body mass?

Answer 36

leptin, ghrelin and orexin

Question 37

What do long-term changes in body mass result from?

Answer 37

Changes in lipid storage

Question 38

Changes in consumption must ___ to cause weight change

Answer 38

a threshold - lower for weight gain than weight loss.