Cellular Metabolism

Question 1

2 Laws of thermodynamics

Answer 1

Energy can be transferred and transformed, but it cannot be
created or destroyed (energy of the universe is constant)

• Every energy transfer or transformation makes the universe
more disordered (every process increases the entropy of the
universe)

Question 2

Thermodynamics =

Answer 2

Study of energy transformations

Question 3

Gibbs free energy or spontaneous potential of reaction. What is favorable?

Answer 3

-ve

Question 4

Entropy =

Answer 4

Quantitative measure of disorder that is proportional to randomness (designated by the letter S)

Question 5

• Energy is stored in

Answer 5

molecules which are ‘ordered’ such as

glucose (many carbon bonds)

Question 6

• Energy transfer from glucose breaks down the molecule into

smaller parts and creates

Answer 6

a more disordered state (↑ entropy)

Question 7

Closed system =

– Open system =

Answer 7

collection of matter under study
that is isolated from its surroundings.

one in which energy can be transferred between the system and its surroundings.

Question 8

Highly ordered living organisms are ____systems

Answer 8

open

Question 9

in an Open System the entropy of a system may ________, but the entropy of the system plus its surroundings must always _________.

Answer 9

decrease

increase

Question 10

Processes that Supply Energy (ATP)

Answer 10

1. Anaerobic
   (a) Alactic (i.e. doesn’t produce lactate)
   (i) Creatine phosphokinase reaction
   (ii) Adenylate kinase reaction
   (b) Lactic
   Glycolysis (and glycogenolysis)
2. Aerobic
   Oxidative phosphorylation

Question 11

Anaerobic Processes that Supply Energy (ATP)

Answer 11

1. Anaerobic
   (a) Alactic (i.e. doesn’t produce lactate)
   (i) Creatine phosphokinase reaction
   (ii) Adenylate kinase reaction
   (b) Lactic
   Glycolysis (and glycogenolysis)

Question 12

The Creatine Phosphokinase Reaction eqn

Answer 12

CrP + ADP Cr + ATP

Question 13

Catalysed by creatine phosphokinase.
• In a resting cell 99% of total adenine pool exists as ___.
• ________acts as a buffer to maintain [ATP] high during high energy demand.

Answer 13

The Creatine Phosphokinase Reaction
ATP.
ATP
• CrP acts as a buffer to maintain [ATP] high.

Question 14

The Creatine Phosphokinase Reaction
rate?
What size/extent?

Answer 14

1. extremely rapid (a function of enzyme kinetics)

2. of small extent (a function of reactant concentrations)

Question 15

ATP conc. remains stable until ____ of PCr is converted to Cr

Answer 15

90%

Question 16

Creatine phosphate “\_\_\_\_\_\_\_” chemical
energy
from \_\_\_\_\_\_\_\_\_ to the various cellular
locations of the ATPases (e.g. Na+K+ATPase,
SRCa2+ATPase, actomyosinATPase)

Answer 16

shuttles

mitochondria

Question 17

• Cr is phosphorylated by newly generated ____in mitochondria.
• CrP then diffuses to the various cellular “_____” where it re-phosphorylates ADP.
• Cr & Pi diffuse down their conc gradients to the _________.
• Benefit is that it is the small (mobile) Cr molecule that “_____” back & forth with Pi.

Answer 17

ATP
sinks
mitochondria
shuttles

Question 18

The Adenylate Kinase Reaction eqn

Answer 18

2ADP AMP + ATP

Question 19

• catalysed by the enzyme adenylate kinase
• independent of _____ -________
• “____ _____” process used only when ATP is v. low

Answer 19

Adenylate Kinase Reaction
Creatine Phosphate
Last ditch

Question 20

Adenylate Kinase Reaction
rate?
size/ extent?

Answer 20

• characterised by small extent & rapid kinetics

Question 21

The Adenylate Kinase Reaction:
degradation products
• In the absence of ATP (to regenerate ADP), AMP is
deaminated to inosine monophosphate:
AMP -> IMP + NH4+

catalysed by the enzyme ______ -________

Answer 21

AMP deaminase

Question 22

The Adenylate Kinase Reaction:
degradation products
IMP & NH4+ both inhibit what?

Answer 22

muscle contraction

actomyosin ATPase activity

Question 23

Alactic anaerobic metabolism does not require

Answer 23

O2 or substrate

Question 24

the weight-lifter’s maximal
anaerobic, alactic rate of
energy expenditure is several
times his?

Answer 24

maximal aerobic rate

of energy expenditure

Question 25

``` glucose yields net ____ through glycolysis • glycogen yields net ____ through glycolysis (glycogenolysis) ```

Answer 25

2ATP | 3ATP

Question 26

Anaerobic Lactic Processes: Glycolysis/Glycogenolysis rate? extent?

Answer 26

moderate kinetics | • moderate extent

Question 27

Anaerobic glycolysis eqn

Answer 27

1glucose + 2ADP +↔ 1Lactate + 2ATP

Question 28

Goldfish and Crucian Carp can live in ______ water | for months! By getting drunk with blood alcohol > 50 mg per ml

Answer 28

anoxic

Question 29

``` _____ consists of long chains of ________molecules joined end-to-end with many branches. Completed chains can have up to 6000 ____residues making glycogen one of the largest molecules in living cells. ```

Answer 29

Glycogen | glucose

Question 30

Advantage of converting G6P to glycogen is that it compacts all the molecules into single large polymers for ?

Answer 30

storage by the cell as large granules of sugar. Mammalian glycogen stores glucose in times of plenty (after a meal) and supplies glucose in times of need (during fasting or in “fight-or-flight” situations).

Question 31

– In muscle, glycogen provides fuel for ? | – In contrast, liver glycogen is largely converted to ?

Answer 31

muscle contraction. glucose that exits liver cells and enters the bloodstream for transport to other tissues that require it [The Cori Cycle].

Question 32

The Cori cycle

Answer 32

Gluconeogenesis | The liver uses ATP to convert lactate back to glucose

Question 33

Consequences of Anaerobic Energy Production Extensive glycolytic activity leads to decreased?

Answer 33

cellular pH (i.e. increases [H+]

Question 34

Anaerobic | Energy Production with decr. pH on cellular level

Answer 34

Protons: I. inhibit Ca2+ release from the sarcoplasmic reticulum & II. compete with Ca2+ for binding-sites on Troponin-C, III. thereby potentially diminishing contractile force (thus potentially contributing to skeletal muscle fatigue).

Question 35

• With more intense exercise, _______metabolism alone is not ‘fast’ enough to meet the ATP demand • Anaerobic metabolism contributes ATP and produces ______ • ______begins to accumulate and rise exponentially at ~55% VO2max for an untrained subject

Answer 35

aerobic lactate Lactate

Question 36

Oxidative phosphorylation • Glycogen, fats & proteins can be broken down & enter the ? • Series of reactions take place in mitochondria in combination with electron transfer chain.

Answer 36

tricarboxylic acid (citric acid or Kreb’s) cycle.

Question 37

Oxidative phosphorylation eqn

Answer 37

1 glucose + 6O2 + 32ADP + 32Pi 6CO2 + 6H2O + 32ATP

Question 38

Oxidative phosphorylation rate? extent?

Answer 38

slow kinetics | – enormous extent (provided at sub-maximal rates)

Question 39

high energy electron carriers

Answer 39

NADH and FADH2 produced by the citric acid cycle is used in the electron transport chain at complex I & II A transmembrane charge is set up (via transport of H+ ions at complex I to IV) which is then utilised to generate ATP at complex V

Question 40

Link between glycolytic and oxidative metabolism

Answer 40

Lactate Shuttle Hypothesis: | Lactate as Mitochondrial Fuel

Question 41

Hence, rate of energy expenditure can exceed?

Answer 41

VO2 | max – but only briefly.

Question 42

The Adenylate Kinase Reaction: | degradation products

Answer 42

IMP & NH4+