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BCM210 > FSE Study > Flashcards

FSE Study Flashcards

1
Q

T10: What is metabolism and what are the two types of reactions that occur with in cells?

A

Metabolism: Sum of ALL biochemical reactions w/in cell

Catabolic (exergonic) reactions: energy-liberating (∆G is -ve). Spontaneous.

Anabolic (endergonic) reactions: energy-requiring (∆G is +ve). Not sponaneous.

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2
Q

T10: What is causes thermodynamically unfavourable (endergonic/anabolic) reactions to occur?

A

They are coupled w/ exergonic/catabolic reactions so overall process has a -ve free energy change and so will occur spontaneously.

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3
Q

T10:What is reciprocal regulation and why does it occur?

A

Activation of one pathway, suppression of another.

Used to prevent simultaneous synthesis and degradation which is wasteful

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4
Q

T10: When ∆G is -ve, what happens to a reaction?

A

Reaction:

releases energy
is exergonic/catabolic
thermodynamically favourable
Can proceed in absence of energy -spontaneous

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5
Q

T10: When ∆G is +ve, what happens to a reaction?

A

Reaction:

Requires energy
is endergonic/anabolic
thermodynamically unfavourable
Energy must be supplied

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6
Q

T10: Please remind yourself of the ∆G’˚/Keq equation, ∆G equation and did you know this is related the free energy change?!
How are they related? *hint use an equation

A

Keq = [C] [D]/ [A] [B]

products/reactants

  • Related because ∆G’˚ = -RT In Keq
  • ∆G = G’˚ + RT Ln Keq

R=gas constant 8.315 J/mol. K

T=absolute temp (K) 298

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7
Q

T10: When Keq is
>1.0
1.0

A 
>1.0 = -ve
1.0 = zero
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8
Q

T10: What is reduction potential? What is the equation used to measure energy made available from these reactions?

+ve E (reduc. potent.) =?

-ve E (reduc. potent.) =?

A 
Reduction potential (E) is a measure of a reducing agents affinity for electrons
∆G = -nF ∆E
Where n= number of electrons transferred
F= Faraday constant (96 480 J/V.mol)

+ve E= Gives rise to -ve ∆G
strong tendency to accept electrons and become reduced

-ve E= strong tendency to lose electrons and become oxidised

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9
Q

T11: Write out the net equation of Glycolysis

A

Glucose + 2NAD+ + 2ADP + 2Pi
=>
2 Pyruvate + 2NADH + 2ATP + 2H+ + 2H2O

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10
Q

T11: Draw a flow chart giving the brief details of glycolysis

A

PIPCIRSIDS

  1. IR, Phosphorylation (6C) COST 1 ATP
  2. R, Isomerisation 6C
  3. IR, Phosphorylation (6C) COST 1 ATP
    - rate limiting, 1st committed step
  4. R, Cleavage (6C=> 2 x 3C)
  5. R, Isomerisation 3C=>3C
  6. R, REDOX (3C) GAIN 2 NADH
  7. R, Substrate-level phosphorylation (3C) GAIN 2 ATP
  8. R, Isomerisation (3C)
  9. R, Dehydration 3C
  10. IR, Substrate-level phosphorylation (3C) GAIN 2 ATP
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11
Q

T11: What is the cost and yield of:
Glycolysis?
GNG?

A

Glycolysis:
Cost = 2 ATP
makes = 4 ATP
Net yield = 2 ATP, 2 NADH

GNG:

Cost = 6 ATP
Yield =glucose

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12
Q

T11: How much ATP is generated from..
Aerobic respiration?
Anaerobic respiration?

A

Aerobic = 30/32 ATP

Anaerobic = 2 ATP

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13
Q

T11: Write out the equation (stoichiometry) for the glycolytic pathway in relation to ATP production & electron balance

A 
Glucose + 2ATP + 2 NAD + 4ADP + 2Pi
=>
2Pyru + 4 ATP + 2NADH + 2H + 2ADP + 2H2O
reduces to
Glucose + 2NAD + 2ADP + 2Pi
=>
2Pyru + 2ATP + 2NADH + 2H + 2H2O
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14
Q

T11: Gluconeogenesis

Describe 1st bypass step

A

Last step of glycolysis (10)

Pyruvate converted to PEP

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15
Q

T11: Gluconeogenesis

Describe 2nd bypass step

A

Step 3 of glycolysis

Conversion of fructose 1,6bisphos. (ase) to fructose 6P
=> does not require ATP unlike glycolysis step
∆G˚ = -16.3 kJ/mol

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16
Q

T11: Gluconeogenesis

Describe 3rd bypass step

A

Step 1 of glycolysis

Conversion of glucose 6P (ase) to glucose

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17
Q

T11: Write the overall GNG equation

A

2Pyru + 4ATP + 2NADH + 2H + 4H2O
=>
Glucose + 4ADP + 2GDP + 6Pi + 2NAD

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18
Q

T12: Draw flow chart of glycogen catabolism and synthesis.

  • Endeavour to include sugar nucleotide pathway and names of enzymes
  • Try to explain if you can
A

see book

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19
Q

T12: Reciprocal regulation of reaction 3

Draw the flow chart (sl 35) of RRR3 identifying:

GNG is on or off
Glycolysis on or off
enzymes and energy molecules
Which signal molecules inhibit/activate either side

A

this is the one with the triangles and X’s

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20
Q

T12: Describe the role of hormones in carbohydrate metabolism

Draw the flow chart showing the influence of insulin (High BGL)

A

…

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21
Q

T12: Describe the role of hormones in carbohydrate metabolism

Draw the flow chart showing the influence of glucagon (low BGL)

A

…

22
Q

T12: Reciprocal regulation of reaction 3

Enzymes

Describe the actions of Glycogen Phosphorylase (look at diagram in book to help with understanding or sl 17)

A

Catalyses breakdown of glycogen
Activated when BGL. Insulin activity
-inactive form (b) is unphosphorylated

23
Q

T12: Reciprocal regulation of reaction 3

Enzymes

Describe the actions of Glycogen Synthase (look at diagram in book to help with understanding or sl 17)

A

Catalyses synthesis of glycogen
Activated when BGL>. Insulin activity
-active form (a) is unphosphorylated
Inactivated when BGL

24
Q

T13: ​*Define cellular respiration & ID 3 stages of aerobic respiration

Define aerobic respiration and ID the 3 stages

A 
Complete oxidation of glucose (pyruvate) to Co2 & H2O
-30-32 ATP produced
Requires O2 =>terminal electron acceptor
Occurs in mitchondria
3 stages:
1. Formation of acetyl-CoA (link rxn)
2. Citric Acid cycle
3. Oxidative phosphorylation (e transport chain)
25
Q

T13: *Describe the “link” reaction incl. components of the pyruvate DH complex & cofactors

A 
Catalysed by pyru DH complex
Composed of 3 distinct enzymes to form a multiple enzyme complex:
-E1 (thiamine pyrophosphate attached)
-E2 (lipolic acid att.)
-E3 (FAD att.)

5 cofactors:

  • Coenzyme A
  • NAD+
  • FAD
  • Thiamine pyrophosphate (TPP)
  • Lipolic acid

3 distinct rxns:

  1. Decarboxylation rxn
  2. Acylation rxn
  3. REDOX rxn
26
Q

T13: Describe the 8 reactions of the citric acid cycle

A

RXN 1:
High E, IR condensation. E released by hydrolysis of acetyl-CoA thioester bond

RXN 2:
R, dehydration a) => hydration b)

RXN 3:
High E, IR oxidative decarboxylation. NAD reduced to NADH

RXN 4:
High E, IR oxidative decarboxylation. Similar to link rxn (E1, E2, E3). NAD reduced to NADH

RXN 5:
Substrate-level phosphorylation. Produces ATP/GTP

RXN 6:
Dehydrogenation. C=C produced, FAD reduced to FADH

RXN 7:
Hydration

RXN:
Dehydrogenation. ∆G’ strongly favours malate production -but proceeds to R due to removal of oxaloacetate by highly exergonic rxn 1 to produce citrate.

27
Q

T13: Look at CA cycle diagram.
Which are the intermediates?
How many carbons do they have?

A

acetyl-coa = 2C

Citrate = 6C

Isocitrate = 6C

a-ketoglutarate = 5C

Succinyl-CoA = 4C

Succinate = 4C

Fumarate = 4C

Malate = 4C

Oxaloacetate = 4C

28
Q

T13: *Describe the major controls operating on pyruvate DH & the CC cycle
draw diagram

A 
Pyruvate DH complex
Inhibited by high e levels
-ATP
-Acetyl-CoA
-NADH
-FA
Stimulated by low e levels
-AMP
-Coenzyme A
-NAD+
Citrate Synthase
Inhibited by high e levels
-ATP
-Succinyl-CoA
-NADH
-Citrate
Stimulated by low e levels
-ADP
Isocitrate DH
Inhibited by high e levels
-ATP
Stimulated by low e levels
-ADP

a-ketoglutarate
Inhibited by high e levels
-Succinyl-CoA
-NADH

29
Q

T13: Energy released by oxidation of acetyl-CoA in the CA cycle is conserved in the production of….?

A 
3 NADH & 1FADH2
1 GTP (ATP)
30
Q

T14: Give a brief overview of the ETC

A

Occurs in IMM
e from NADH/FADH2 transferred along chain to O2
Exergonic transfer of e is coupled w/ endergonic pumping of p to intermembrane space (IMS)
P move down their gradient back to matrix. This exergonic process is coupled w/ endergonic synthesis of ATP from ADP and Pi

31
Q

T14: *Outline the sequence of e carriers

Draw the diagram of e carriers as shown in lecture with labels!!
Dont forget: IMS, p and n, matrix, succinate, fumarate, Cyt C, NADH, NAD+ etc

A

…

32
Q

T14: *Account for the production of ATP during e transport according to chemiosmotic theory

A

e transport results in H transport -pumping of H ions out of matrix
Creates proton gradient -protons pass back through IMM through H+ pore in ATP synthase
Flow of H+ down [ ] leads to ATP synthesis -passage of h+ down proton-motive gradient causes a conformational change in 3D structure of ATP synthase, causing synthesus & release of ATP

33
Q

T14: Calculate ATP yields for various substrates, given the stoichiometry of the reactions of these substrates in terms of yields of NADH & FADH2

A

10 protons are pumped per pair electrons from NADH
- 4 at CI
-4 at CIII
-2 at CIV
6 protons are pumped per pair electrons from FADH2
-4 at CIII
​-2 at CIV
~ 4 protons are required to drive synthesis of one ATP molecule ::
-2.5 ATP are formed from one pair of electrons from NADH
-1.5 ATP are formed from one pair of electrons from FADH2

34
Q

T14: The chemiosmotic theory

Flow of 2 electrons from NADH through ETC to O2 can be written as?
This net reaction is highly ……
?? kJ/mol?
How many H+ ions are pumped?

A

NADH + H+ + 1/2O2 => NAD+ + H2O
Highly exergonic
-220kJ/mol
For each 2 electrons transferred from NADH to O2 through ETC, 10 H+ ions are pumped from matrix to IMS

35
Q

T14: *Describe the role of the malate-aspartate & glycerol 3P shuttles in transport of NADH from the cytoplasm

Describe the process of the malate-aspartate shuttle

A

NADH transferred as NADH

Generates 2.5 ATP

36
Q

T14: *Describe the role of the malate-aspartate & glycerol 3P shuttles in transport of NADH from the cytoplasm

Describe the process of the glycerol-3P shuttle

A

NADH entered as FADH2

Bypasses CI; generates 1.5 ATP

37
Q

T14: Regulation points

Energy (ATP) producing pathways are reciprocally regulated.
When ATP high/ADP low=?
When ATP low/ADP high=?

A 
High ATP/Low ADP
-glycolysis inhibited
-CAC inhibited
-Oxidative phosphorylation inhibited
Low ATP/High ADP
-Glycolysis activated
-CAC activated
-Oxidative phosphorylation activated
38
Q

T15: *Describe action of lipases in hydrolysis of triacylglycerols

Describe a basic overview of the fate of dietary triacylglycerols

A

TAG’s are digested by pancreatic lipase
Produce FA, glycerol
Products are absorbed by intestinal cells
IC convert them back into TAGs and chylomicrons
Chylomicrons are released into blood stream/lymph sys to adipose/skeletal muscle
TAGs are hydrolysed to FAs & glycerol by lipoprotein lipase
Skeletal muscle = FA degraded (b-oxidation), producing ATP
Adipose = FA are re-esterified to TAGs for storage

39
Q

T15: *Describe action of lipases in hydrolysis of triacylglycerols

Describe the function of hormone-sensitive lipase

A

Found in adipose
Catalyses breakdown of stored TAGs to FFA & glycerol
Regulation:
-activated by glucagon & adrenaline
-Glycerol is transported via blood to liver, enters glycolysis or gluconeogenesis
-FAs transported in blood to liver/skeletal muscle, used as fuel for b-oxidation

40
Q

T15: *Outline processes of b-oxidation in FA catabolism

Define steps of FA catabolism

A
  1. FAs are activated by attachment of CoA
    Converted to fatty acyl-CoA by acyl-CoA synthetase in cytoplasm
    Requires ATP
  2. The activated FA (fatty acyl-CoA) is transported to mitochondrial matrix via the carrier carnitine
    see diagram in book = draw it
3. B-OXIDATION
In final cycle, 2 acetyl-CoA released
1 NADH & 1 FADH2 produced
1. Oxidation
 acyl-CoA-DH
  1. Hydration
    enoyl-CoA-hydratase
  2. Oxidation
    hydroxyacyl-CoA DH
  3. Thiolytic cleavage
    thiolase
41
Q

T15: Please check lecture for slides 37 & 39 this is VERY IMPORTANT YOU CAN DO THIS CALCULATION

A

(n-2) / 2
C10 - 2 = 8
8 / 2 = 4 (4 rounds b-oxidation)

Always 1 round less than number of acetyl groups (or no# rounds + 1 = no# acetyl-CoA)

So = 5 acetyl-CoA

………………………………………………………

C14 = 7 rounds b-oxi
1 FADH2 & 1 NADH produced for every round
per FADH2 = 1.5 ATP
per NADH = 2.5 ATP
No# ATP ultimately formed
for NADH = 7x2.5 = 17.5
for FADH2 = 7x1.5 = 10.5
42
Q

T15: *Outline synthesis of triacylglycerols from surplus CHD

Describe the actions of acetyl-CoA carboxylase & FA synthase complex

see book

A

A-CoA carboxylase=>uses cofactor biotin
Acetyl-CoA (2C) + HCO3 + ATP => Malonyl-CoA (3C) + ADP + Pi

FA synthase complex (reverse of b-oxi)
2c + 3c => 4c + 3c => 6C
condensation
reduction (NADPH consumed)
dehydration
reduction (NADPH consumed)
43
Q

T15: *Describe regulation of FA metabolism

What do high glucose levels lead to?

A

> FA synthesis

inhibits carnitine acyl-transferase :: inhibits FA degradation

44
Q

T15: *Describe regulation of FA metabolism

What do low glucose levels lead to?

A 
FA degradation
Glucagon release
∆PKA => GNG
∆hormone sensitive lipase =>mobilises stored FA
X acetyl-CoA carboxylase;
45
Q

T16: Describe amination

A

Glutamine synthetase catalyses addition of NH4+ onto glutamate => glutamine
Allows transport of NH4+ in blood
Liver; NH4+ re-released by glutaminase => urea

46
Q

T16: Describe deamination

A

reverse of amination
Glutaminase (liver, kidney cortex)
-removes NH4+ from glutamine => glutamate

Glutamate DH (liver)
-removal of amino group from glutamate => a-ketoglutarate
47
Q

T16: Describe Transamination

A

aa transfers its amino group to a-ketog & is converted to keto acid
glutamate formed
no net deamin.
need PLP as cofactor

48
Q

T16: Describe aa catabolism. When is it a energy source?

A 
Is NOT a major energy source under NORMAL conditions
Significant under 3 conditions:
-dietary protein ingested in excess
-severe starvation
-stress situations

Catabolism in 4 easy steps!

  1. catabolism of protein w/in muscle results in formation of aa’s glutamine & alanine
  2. Transport of Glu & Ala into blood
    - Ala => liver
    - Glu => liver & kidney
  3. Kidney - Glu deaminated twice => a-keto g. Ammonium excreted in urine. C skeleton used in glucose formation
  4. Liver - Ala & Glu from muscle, & all 20 aa from diet are deaminated => glutamate. C skeleton => glucose or ketone body. Glutamate deamin. in mitochondria & NH4+ converted to urea. Urea => liver => blood => kidney => excretion
49
Q

T16: DRAW THE DIAGRAM THAT SUMMARISES AA CATABOLISM

Remember to include:
Where there us organic or inorganic N
transamination rxns
deamination rxns
PLP
Where NH4+ is produced/released
muscle/kidney/liver cell section
mitochondria cell section
A

…

50
Q

T11/12: Name, in order, the 11 enzymes of GNG

could use flow chart?

A
  1. Pyruvate carboxylase
  2. PEP carboxykinase
  3. Enolase
  4. Phosphoglycerate mutase
  5. Phosphoglycerate kinase
  6. Glyceraldehyde phosphate dehydrogenase
  7. Triose phosphate isomerase
  8. Aldolase
  9. Fructose 1, 6 Bisphosphatase
  10. Phosphohexose isomerase
  11. Glucose-6-phosphatase

BCM210 (18 decks)

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