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MEDSCI second half > Cellular Metabolism > Flashcards

Cellular Metabolism Flashcards

1
Q

2 Laws of thermodynamics

A

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)

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2
Q

Thermodynamics =

A

Study of energy transformations

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3
Q

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

A

-ve

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4
Q

Entropy =

A

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

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5
Q

• Energy is stored in

A

molecules which are ‘ordered’ such as

glucose (many carbon bonds)

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6
Q

• Energy transfer from glucose breaks down the molecule into

smaller parts and creates

A

a more disordered state (↑ entropy)

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7
Q

Closed system =

– Open system =

A

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

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

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8
Q

Highly ordered living organisms are ____systems

A

open

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9
Q

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

A

decrease

increase

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10
Q

Processes that Supply Energy (ATP)

A
  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
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11
Q

Anaerobic Processes that Supply Energy (ATP)

A
  1. Anaerobic
    (a) Alactic (i.e. doesn’t produce lactate)
    (i) Creatine phosphokinase reaction
    (ii) Adenylate kinase reaction
    (b) Lactic
    Glycolysis (and glycogenolysis)
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12
Q

The Creatine Phosphokinase Reaction eqn

A

CrP + ADP Cr + ATP

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13
Q

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.

A

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

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14
Q

The Creatine Phosphokinase Reaction
rate?
What size/extent?

A
  1. extremely rapid (a function of enzyme kinetics)

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

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15
Q

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

A

90%

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16
Q 
Creatine phosphate “\_\_\_\_\_\_\_” chemical
energy
from \_\_\_\_\_\_\_\_\_ to the various cellular
locations of the ATPases (e.g. Na+K+ATPase,
SRCa2+ATPase, actomyosinATPase)
A

shuttles

mitochondria

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17
Q
  • 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.
A

ATP
sinks
mitochondria
shuttles

18
Q

The Adenylate Kinase Reaction eqn

A

2ADP AMP + ATP

19
Q
  • catalysed by the enzyme adenylate kinase
  • independent of _____ -________
  • “____ _____” process used only when ATP is v. low
A

Adenylate Kinase Reaction
Creatine Phosphate
Last ditch

20
Q

Adenylate Kinase Reaction
rate?
size/ extent?

A

• characterised by small extent & rapid kinetics

21
Q 
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 ______ -________

A

AMP deaminase

22
Q

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

A

muscle contraction

actomyosin ATPase activity

23
Q

Alactic anaerobic metabolism does not require

A

O2 or substrate

24
Q

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

A

maximal aerobic rate

of energy expenditure

25
Q 
glucose yields net \_\_\_\_
through glycolysis
• glycogen yields net \_\_\_\_
through glycolysis
(glycogenolysis)
A

2ATP

3ATP

26
Q

Anaerobic Lactic Processes:
Glycolysis/Glycogenolysis
rate?
extent?

A

moderate kinetics

• moderate extent

27
Q

Anaerobic glycolysis eqn

A

1glucose + 2ADP +↔ 1Lactate + 2ATP

28
Q

Goldfish and Crucian Carp can live in ______ water

for months! By getting drunk with blood alcohol > 50 mg per ml

A

anoxic

29
Q 
\_\_\_\_\_ 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.
A

Glycogen

glucose

30
Q

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

A

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).

31
Q

– In muscle, glycogen provides fuel for ?

– In contrast, liver glycogen is largely converted to ?

A

muscle contraction.

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

32
Q

The Cori cycle

A

Gluconeogenesis

The liver uses ATP to convert lactate back to glucose

33
Q

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

A

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

34
Q

Anaerobic

Energy Production with decr. pH on cellular level

A

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).

35
Q

• 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

A

aerobic
lactate
Lactate

36
Q

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

A

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

37
Q

Oxidative phosphorylation eqn

A

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

38
Q

Oxidative phosphorylation
rate?
extent?

A

slow kinetics

– enormous extent (provided at sub-maximal rates)

39
Q

high energy electron carriers

A

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

40
Q

Link between glycolytic and oxidative metabolism

A

Lactate Shuttle Hypothesis:

Lactate as Mitochondrial Fuel

41
Q

Hence, rate of energy expenditure can exceed?

A

VO2

max – but only briefly.

42
Q

The Adenylate Kinase Reaction:

degradation products

A

IMP & NH4+

MEDSCI second half (10 decks)

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