Biochem: Ch 12, 4 Flashcards
open system
matter and energy can be exchanged with the environment
closed system
only energy can be exchanged with the envrionment
no work is performed in a ___ system because
closed
pressure and volume remain constant
entropy
measure of energy dispersion in a system
ΔU =
Q - W
ATP
mid level energy molecule
ATP contains ____ that are stabilized upon …
high energy phosphate bonds that are stabilized upon hydrolysis by resonance, ionization, and loss of charge repulsion
ATP provides energy through
hydrolysis and coupling to energetically unfavorable reactions
ATP can participate in ____ as a _____
phosphoryl group transfers
phosphate donor
ATP is formed from
substrate-level phosphorylation and oxidative phosphorylation
ATP consists of
adenosine molecule attached to 3 phosphate groups
ATP is consumed through
hydrolysis or the transfer of a phosphate group to another molecule
what is the result of one phosphate group being removed from ATP?
adenosine diphosphate (ADP)
what is the result of two phosphate groups being removed from ATP?
adenosine monophosphate (AMP)
ATP hydrolysis is most likely to be encountered in the context of
coupled reactions
ATP cleavage
transfer of high energy phosphate group from ATP to another molecule
this activates or inactivates the target molecule
how does coupling with ATP hydrolysis alter the energetics of a reaction?
ATP hydrolysis yields about 30 kJ/mol of energy, which can be harnessed to drive other rxns forward
this may either allow a nonspontaneous reaction to occur or increase the rate of a spontaneous reaction
explain why ATP is an inefficient molecule for long term storage
intermediate energy storage molecule and not energetically dense
the high energy bonds and presence of significant change make it an inefficient molecule
long term storage molecules are characterized by
energy density
stable, nonrepulsive bonds
(primarily seen in lipids)
many redox reactions involve
electron carrier to transport high energy electrons
electron carrier can be either
soluble or membrane bound
flavoproteins
type of electron carrier
derived from riboflavin (vitamin B2)
high energy electron carrier exs
NADH, NADPH, FADH2, ubiquinone, cytochromes
equilibrium is an undesirable state for most biochemical reactions bc
organisms need to harness free energy to survive
postprandial (absorptive) state
aka well fed
insulin secretion is high and anabolic metabolism prevails
observed in short term fasting (overnight)
prolonged fasting
aka starvation
increase glucagon and catecholamine (epinephrine) secretion
at max, 2/3 of brain’s energy can be derived from ketone bodies
anabolism
synthesis of biomolecules
catabolism
breakdown of biomolecules for energy
types of cells that are insensitive to insulin
nervous tissue and red blood cells
counterregulatory hormones
oppose the actions of insulin
act on skeletal muscles, adipose tissue, liver
counterregulatory hormones ex
glucagon, cortisol, epinephrine, norepinephrine, growth hormone
what tissue is least able to change its fuel source in periods of prolonged starvation?
cells that rely solely on anaerobic respiration are least adaptable to different energy sources
ex: red blood cells - stay reliant on glucose
during what stage is there the greatest decrease in the circulating concentration of insulin?
postabsorptive state
effects of insulin on metabolism
inc vs dec
- dec in blood glucose levels by increasing cellular uptake
- dec: triaglycerol breakdown in adipose tissue, formation of ketone bodies by liver
- inc rate of anabolic metabolism
- inc: glucose and triacylglycerol uptake by fat cells, lipoprotein lipase activity, triacycglycerol synthesis
insulin secretion by _____ is regulated by _____
pancreatic beta cells
blood glucose levesl
effects of glucagon on metabolism
inc blood glucose levels by promoting gluconeogenesis and glycogenolysis in liver
glucagon secretion by _____ is stimulated by _____
pancreatic alpha cells
low glucose and high amino acid levels
effect of glucocorticoids on metabolism
inc blood glucose in response to stress by mobilizing fat stores and inhibiting glucose uptake
inc the impact of glucagon and catecholamines
effect of catecholamines on metabolism
inc glycogenolysis in liver and lipolysis in adipose tissue
inc basal metabolic rate through their sympathetic nervous system activity
effect of thyroid hormones on metabolism
module the impact of other metabolic hormones
inc basic metabolic rate
T3 and T4
T3 is more potent than T4, but has a shorter half life and is available in lower conc in the blood
T__ is converted to T__ in the ___
T4
T3
tissues
insulin is a ___ hormone
peptide
thyroid hormones are ___ hormones
amino acid derivative
cortisol is a ___ hormone
steroid
glucose is absorbed by ___ via ___
peripheral tissues
facilitated transport mechanisms that utilize glucose transporters located in cell membrane
effect of cortisol on metabolism
inc lipolysis and amino acid mobilization
dec glucose uptake in certain tissues
hepatocytes
maintenance of blood glucose levels by glycogenolysis and gluconeogenesis in response to pancreatic hormone stimulation
liver function
processing of lipids and cholesterol, bile, urea, and toxins
adipose tissue stores __ under the influence of ___ and releases them under the influence of ___
lipids
insulin
epinephrine
skeletal muscle metobolism
differes based on current activity level and fiber type
resting muscle metabolism
conserves carbs in glycogen stores
uses free fatty acids from bloodstream
active muscle metabolism
may use anaerobic metabolism, oxidative phosphorylation of glucose, direct phosphorylation from creatine phosphate, or fatty acid oxidation
depending on fiber type and exercise duration
cardiac muscle metabolism
uses fatty acid oxidation in both wwell fed and fastin gstates
brain and nervous tissue metabolism
consume glucose in all metabolic states except for prolonged fasts, where it comes from ketone bodies
chylomicrons
carry triacyglycerols absorbed from gut
creatine phosphate
transfers a phosphate group to ADP to form ATP
what is the preferred fuel for most cells in the well fed state? what is the exception and its preferred fuel?
preferred: glucose
exception: cardiac muscle - prefers fatty acid
metabolic rates can be measured using
calorimetry, respirometry, consumption tracking, or measurement of blood conc of substrates and hormones
respiratory quotient (RQ)
estimated composition of fuel that is actively consumed by the body
hormones that play a role in body mass
leptin, ghrelin, orexin
long term changes in body mass result from changes in
lipid storage
what must happen for weight change?
changes in consumption or activity must surpass a threshold
the threshold is ___ for weight gain than for weight loss
lower
calorimeters
measure basal metabolic rate (BMR)
orexin
increase appetite
involved in alterness and sleep wake cycle
ghrelin
increases appetite
stimulates secretion of orexin
leptin
decreases appetite by suppressing orexin production
how is the respiratory quotient expected to change when a person transitions from resting to brief exercise?
as a person begins to exercise, the proportion of energy erived from glucose increases
this transition to almost exclusively carb metabolism will cause the respiratory quotient to approach 1
True or False? Coupled reactions tend to occur simultaneously.
True. Coupled reactions tend to occur simultaneously.
ATP has three phosphate groups directly next to one another. What about this structure makes ATP a high-energy molecule?
Phosphate groups are very negatively charged, and negatively charged groups do not want to be next to each other. This is a high-energy situation.
Think about it like two similar charges being next to each other. The closer the charges, the higher the electric potential energy. As these charges separate, the high amount of electric potential energy is converted into kinetic energy.
If ATP hydrolysis has a very negative ∆G value, why doesn’t ATP hydrolyze spontaneously all the time? How is our body able to control when ATP hydrolysis occurs?
Although ATP hydrolysis has a very negative ∆G value, the reaction has a very high activation energy (Ea). When an enzyme is used in conjunction with ATP, the Ea is lowered, allowing the reaction to occur. This way, reactions with ATP will primarily occur only in the presence of the needed enzyme.
Which of the following are also names for the Absorptive State?
I. Postprandial State
II. Well-Fed State
III. Counterregulatory State
(A) I only
(B) I and II only
(C) II and III
(D) I, II and III
(B) I and II only
The Absorptive State can also be called the Well-Fed State and the Postprandial State.
Adipose Tissue can receive which of the following for subsequent energy storage?
I. Triglycerides
II. Fatty Acids
III. Glucose
(A) I Only
(B) I and II Only
(C) II and III Only
(D) I, II, and III
(D) I, II, and III
Adipose Tissue can receive Triglycerides from VLDLs. It can also receive glucose, which it will then convert into Fatty Acids and subsequently Triglycerides.
Mike just ate a big Thanksgiving feast. Which state is Mike likely in?
(A) Absorptive
(B) Post-absorptive
(C) Excretion
(D) Filtration
(A) Absorptive
The absorptive state is also known as the “well-fed state” and is characterized by energy storage.
The Post-absorptive State is also known as the “fasting state” and is characterized by energy utilization.