ch 12 - Bioenergetics and Regulation of Metabolism

Question 1

open systems

Answer 1

biological systems that exchange both energy and matter with the environment

Question 2

Internal engery

Answer 2

italicized U - sum of all of the different interactions between and within atoms in a system; vibration, rotation, linear motion, and stored chemical energies are all contributors

Question 3

First Law of Thermodynamics

Answer 3

deltaU=Q-W. Work refers to changes in pressure and volume. Q = heat or heat exchange

Question 4

enthalpy

Answer 4

delta-italicized H. measures overall change in heat of a system during a rxn. at constant pressure and volume, enthalpy and thermodynamics heat exchange (Q) are equal

Question 5

entropy

Answer 5

delta italicized S. measures the degree of disorder or energy dispersion in a system. Units J/K

Question 6

Gibbs Free energy equation

Answer 6

deltaG=deltaH-TdeltaS. H is enthalpy. T is temp. S is entropy. Spontaneous reactions move forward and have a negative G value. Moves toward zero as reaction approaches equilibrium

Question 7

standard free energy

Answer 7

deltaG-degree sign - energy change that occurs at standard concentrations of 1 M, pressure of 1 atm and temp of 25 C.

Question 8

standard free energy relationship to Gibb’s free energy

Answer 8

deltaG=delta G-degree sign + RT ln (Q). delta G is Gibb’s free energy. delta G-degree sign is standard free energy. R is universal gas constant. T is temp. Q is reaction quotient.

Question 9

modified standard state

Answer 9

modified because a 1 M concentration of protons would have pH 0 and be far too acidic. modified standard state is [H+]=10^-7 M with pH of 7. with this delta G-degree sign is changed to delta G-degree sign’.

Question 10

amount of energy produced by ATP under physiological conditions

Answer 10

30 kJ/mol

Question 11

role of cAMP and amount and deltaG-degree sign’

Answer 11

second messenger, delta G degree sign’ = -50.4 kJ/mol

Question 12

function of creatine phosphate and modified standard state of free energy

Answer 12

direct phosphorylation in muscle, delta G degree sign’ = -43.3 kJ/mol

Question 13

function of ATP and modified Gibb’s free energy

Answer 13

energy turnover in all cell types (mid-level energy carrier); delta G degree sign’ = -30.5 kJ/mol

Question 14

function and modified Gibb’s free energy of Glucose 6-phosphate

Answer 14

intermediate of glycolysis and gluconeogenesis; delta G degree sign’ = -13.9

Question 15

function and modified Gibb’s free energy state of AMP

Answer 15

ATP synthesis; delta G degree sign’ = -9.2

Question 16

ADP

Answer 16

adenosine diphosphate - produced if one phosphate group is removed from ATP.

Question 17

AMP

Answer 17

adenosine monophosphate - produced if two phosphate groups are removed from ATP

Question 18

what do many coupling reactions use

Answer 18

energy harnessed from hydrolysis of ATP

Question 19

ATP cleavage

Answer 19

transfer of a high-energy phosphate group from ATP to another molecule, which generally activates or inactivates the target molecule

Question 20

Phosphoryl group transfers

Answer 20

ATP provides phosphate group as a reactant.

Question 21

Hess’s law to calculate the difference in free energy between reactants and products

Answer 21

creatine phosphate + H2O -> creatine + P sub i – (free energy = -43.3 kJ/mol) + ADP + P sub i -> ATP + H2 – (free energy = 30.5 kJ/mol for a total of creatine phosphate + ADP -> creatine + ATP (free energy total = -12.8 kJ/mol)

Question 22

half-reactions

Answer 22

division of oxidation-reduction reactions into components to determine how many e-s are being transferred. Number of e-s must be equal on both sides of reaction. Spontaneous have -delta G and positive elecromotive force (E)

Question 23

high-energy electron carriers in the cytoplasm

Answer 23

soluble - NADH, NADPH, FADH2, ubiquonone, cytochromes and glutathione

Question 24

flavin mononucleotide (FMN)

Answer 24

membrane-bound e- carrier embedded in the inner mitochondrial membrane; bonded to complex I of ETC.

Question 25

Flavoproteins

Answer 25

contain modified vit B2 (riboflavin). nucleic acid derivatives, generally either flavid adenine dinucleotide (FAD) or flavin mononucleotide (FMN); present in mitochondria and chloroplasts as e- carriers; function in modification of other B vits to active forms and as coenzymes for enzymes in the oxidation of fatty acids, decarboxylation of pyruvates and the reduction of glutathione

Question 26

postprandial state

Answer 26

absorptive or well-fed state marked by great anabolism (synthesis of biomolecules) and fuel storage than catabolism (breakdown of biomolecules for energy). lasts generally 3-5 hours after eating; glucose levels rise and stimulate release of insulin

Question 27

major target tissues for insulin

Answer 27

liver, muscle, adipose tissue

Question 28

tissues insensitive to insulin

Answer 28

nervous tissue and RBCs

Question 29

hormones that oppose actions of insulin (counterregulatory hormones)

Answer 29

Glucagon, cortisol, epi, norepi, growth hormone

Question 30

Postabsorptive (fasting) state

Answer 30

characterized by counterregulatory hormones; stimulate glycogen degredation and release of glucose in the blood; hepatic gluconeogenesis is stimulated by glucagon but glycogenolysis begins almost immediately at the beginning of the postabsorptive state and takes about 12 hours to hit max velocity.

Question 31

Prolonged Fasting (starvation)

Answer 31

glucagon and epi are markedly elevated; increased levels of glucagon result in rapid degradation of glycogen stores in the liver when depleted gluconeogenic activity maintains glucose levels; at 24 hours gluconeogenesis takes over for glucose production. After weeks, muscle tissue will utilize fatty acids as major fuel source and brain will adapt to using ketones for energy, reserving amino acids and proteins. Glucose is used for those cells with little or no mitochondria

Question 32

peptide hormones

Answer 32

water-soluble, able to rapidly adjust the metabolic processes of cells via second messenger cascades (ex insulin)

Question 33

amino acid-derivative hormones

Answer 33

fat-soluble; enact longer-range effects by exerting regulatory actions at the transcriptional level (ex. thyroid hormones and steroid hormones like cortisol)

Question 34

Insulin

Answer 34

peptide hormone secreted by the beta-cells of the pancreatic islets of Langerhans; key player in uptake and storage of glucose

Question 35

tissues that require insulin for effective uptake of glucose

Answer 35

adipose and resting skeletal

Question 36

tissues in which glucose uptake is not affected by insulin

Answer 36

nervous tissue, kidney tubules, intestinal mucosa, RBCs (erythrocytes), beta-cells of the pancreas

Question 37

glucokinase and glycogen synthase

Answer 37

insulin increases glycogen synthesis in the liver by increasing activity of these enzymes

Question 38

glycogen phosphorylase and glucose-6-phosphatase

Answer 38

insulin decreases these enzymes in the liver - they promote glycogen breakdown

Question 39

Increasing effects of insulin on metabolism of fats

Answer 39

-glucose and triacylglycerol uptake by fat cells; -lipoprotein lipase activity increases, which clears VLDL and chylomicrons from the blood; -triacylglycerol synthesis (lipogenesis) increases in adipose tissue and the liver from acetyl-CoA

Question 40

decreasing effects of insulin on metabolism of fats

Answer 40

Insulin decreases: -tracylglycerol breakdown (lipolysis) in adipose tissue; -formation of ketone bodies by the liver

Question 41

controller of insulin secretion

Answer 41

plasma glucose; above threshold of 100 mg/dL or abot 5.6 mM of glucose, insulin secretion is directly proportional to plasma glucose

Question 42

Glucagon

Answer 42

peptide hormone secreted by the alpha-cells of the pancreatic islets of Langerhans; primary target is the hepatocyte

Question 43

effects of glucagon

Answer 43

-increased liver glycogenolysis (activates glycogen phosphorylase and inactivates glycogen synthase); -increased liver gluconeogenesis (promotes conversion of pyruvate to phosphoenolpyruvate by pyruvate carboxylase and phosphoenolpyruvate carboxykinase (PEPCK); increases conversion of fructose 1,6-bisphosphate to fructose 6-phosphate by fructose-1,6-bisphosphatase); -increased liver ketogenesis and decreased lipogenesis; -increased lipolysis in liver (activates hormone-sensitive lipase in liver); not a major fat-mobilizing hormone

Question 44

important promoter of glucagon

Answer 44

low plasma glucose (hypoglycemia); some amino acids, especially the basic one (arginine, lysine, and histidine); secreted in response to a meal rich in protein

Question 45

important inhibitor of glucagon

Answer 45

high plasma glucose (hyperglycemia)

Question 46

glucocorticoids

Answer 46

class of corticosteroids that come from the adrenal cortex; responsible in part for stress response; cortisol is an example

Question 47

Cortisol

Answer 47

glucocorticoid and steroid hormone secreted with most forms of stress; promotes mobilization of energy stroes through the degradation and increased delivery of amino acids and increased lipolysis; elevates bgl, increasing glucose availability for nervous tissue

Question 48

mechanisms through which cortisol increases availability of glucose for nervous tissue

Answer 48

1. inhibits glucose uptake in most tissues (muscle, lymphoid and fat) and increases hepatic output of glucose via gluconeogenesis. 2. has permissive function that enhances the activity of glucagon, epi, and other catecholamines

Question 49

Catecholamines

Answer 49

secreted by adrenal medulla. epi and norepi (adrenaline and noradrenaline). increase activity of liver and muscle glycogen phosphorylase (promoting glycogenolysis in muscle and liver). act on adipose tissue to increase lipolysis by increasing activity of hormone-sensitive lipase

Question 50

Thyroid hormones

Answer 50

kept largely constant; increase the basic metabolic rate evidenced by increased O2 consumption and heat production; primary effects in lipid and carb metabolism. accelerate cholesterol clearance from plasma and increase rate of glucose absorption from the small intestine. Epi requires it to have a significant metabolic effect

Question 51

thyroxine (T sub 4)

Answer 51

occurs after latency of several hours but may last for days; increases metabolic rate. subscript is number of iodine atoms in hormone

Question 52

triiodothyronine (T sub 3)

Answer 52

produces more rapid increase in metabolic rate than T sub 4 and has a shorter duration of activity. subscript is number of iodine atoms in the hormone

Question 53

deiodonases

Answer 53

enzymes that remove iodine from a molecule and are located in target tissues to convert T4 to T3

Question 54

respirometry and respiratory quotient

Answer 54

respiratory quotient differs depending on the fuels being used by an organism. RQ = CO2produced/O2consumed for the complete combustion of a fuel source

Question 55

Calorimeters

Answer 55

measure basal metabolic rate (BMR) based on heat exchange with environment.

Question 56

Ghrelin

Answer 56

hormone secreted by the stomach in response to signals of an impending meal. sight, sound, taste and smell; stimulates release of orexin

Question 57

orexin

Answer 57

hormone that further increases appetite; also involved in sleep-wake cycle; also triggered by hypoglycemia

Question 58

Leptin

Answer 58

hormone secreted by fat cells that decrease appetite by suppressing orexin production

Question 59

Body Mass Index (BMI)

Answer 59

mass/(height squared)