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Cell metabolism Flashcards

1
Q

What are the types of metabolic pathways and explain each?

A

Anabolic: Pathways require energy and are involved in the biosynthesis of complex molecules from simpler molecules

Catabolic: Pathways release energy and involve breakdown of molecules

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2
Q

What forms can metabolic pathways be?

A
  1. linear
  2. Branched
  3. Circular
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3
Q

The me for the number of carbons 3-9 their category name and relevant examples for each?

A
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4
Q

How are monosaccharides classified in humans?

A

According to the number of carbons they contain in their backbone

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5
Q

How many carbon atoms dows the main monosaccharide contain?

A

4-6 carbon atoms

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6
Q

What 2 functions does the oxidative catabolism of glucose serve?

A
  1. The production of ‘free energy’ in the form of ATP
  2. The production of intermediated from glycolysis and the TCA cycle to provide material for other metabolic pathways
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7
Q

Whats the definition of Oxidative metabolism?

A

a chemical process in which oxygen is used to make energy from carbohydrates, also called aerobic metabolism, aerobic respiration, and cells respiration

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8
Q

Tell me the importance of glucose

A
  1. Energy requirement of the cell
  2. material requirements of the cell

However these cannot be done at the same time

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9
Q

Whats the equation for the reaction between glucose and oxygen ?

Whats the standard free energy change for this reaction?

A

C6H12O6 + 6O2 <–> 6CO2 + 6H2O

∆Gø’ = -2834 kj/mol

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10
Q

Energy released from fuel oxidation that is not used for work is transformed into what?

A

its transformed into and released as heat

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11
Q

Whats the definition of ∆Gø ?

A

This is the change in Gibbs free energy at pH 0 (1 M [H+]) under standard conditions

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12
Q

Whats the definition of ∆Gø’ ?

A

The change in Gibbs free energy at pH 7.0 under standard conditions

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13
Q

What information does the ∆Gø’ provide?

A

What happens to the free energy (energy available to do work) during chemical/ biological reactions

The amount of free energy available to do work is related to the difference in energy levels between products and reactions

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14
Q

If ∆Gø’ is negative and free energy, the reaction is said to be…?

A

Exergonic

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15
Q

If ∆Gø’ is positive and free energy is absorbed, the reaction is said to be…?

A

Endergonic

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16
Q

What processes can release energy?

Give an example for each?

A
  1. mechanical work e.g. muscle contraction
  2. Transport work e.g. establishment of ionic gradients
  3. Heat generation
  4. Biochemical work e.g. energy-requiring chemical reactions
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17
Q

The heart is a specialist in the transport of what?

If the heart wasn’t able to do this, what would happen?

A

The heart is a specialist in the transformation of ATP chemical bond energy into mechanical work

If the heart were not able to regenerate ATP, all of its ATP would be hydrolysed in less than 1 min- absolute requirement for oxidative phosphorylation

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18
Q

Whats the equilibrium constant ?

A
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19
Q

Tell me about the magnitude of the equilibrium constant?

A
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20
Q

whats the value of ∆Gø at equilibrium?

A

0

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21
Q

Whats the Van’t Hoff isotherm equation and what does each part of the equation represent?

A
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22
Q

What does the equation ∆Gø= -RT ln K allow us to predict/ estimate?

A
  1. To predict if a reaction happens spontaneously or notm if K is known
  2. To estimate if the reaction lied to the left or right, if ∆Gø is known
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23
Q

The table shows the value of Kc and ∆G

A
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24
Q

Why is ∆Gø’ used?

A

In order to compare free energy changes for different reactions, it is necessary to express ∆G values relative to some standard state hence the use of ∆Gø’

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25
The relationship between the free energy of reaction at any moment in time (∆G) and the standard-state free energy of a reaction (∆Gø’) is described by what equation?
∆G = ∆Gø' + RT lnQ where Q= [Products]/ [Reactants]
26
At equilibrium, ∆G=0 so what does ∆Gø' equal?
∆Gø' = -RT lnQ
27
∆G is dependent on what two parts?
1. A constant term whose value depends only on the reaction taking place 2. A variable term that depends on the concentration of reactants and products
28
if ∆G is negative, the equilibrium lies in favour of what?
the products
29
If ∆G is positive, the equilibrium lies in favour of what?
The reactants
30
If ∆G is large and negative what does this mean? If ∆G is large and positive what does this mean?
If ∆G is large and negative, the reaction equilibrium is essentially irreversible. If ∆G is large and positive, the reaction will not proceed.
31
Whats **La Chatelier's** principle?
Any deviation from equilibrium stimulates a process that tends to restore the system to equilibrium
32
Some metabolic reactiond are close to their equilibrium concentrationm hence if [substrate] increases, what direction does the reaction proceed?
To the right and more products are made
33
In energy producing and energy utilising metabolic pathways, ∆G values are additive
A --\> B --\> C --\> D ∆G(A-D) = ∆G(A-B) + ∆G(B-C) + ∆G(C-D)
34
Any one reaction can have a positive ∆G, but if the overall ∆G is negative then what happends to the pathway?
It will proceed
35
Couples reactions drive endergonic processes example below...
36
What are the characteristics of metabolic pathways? Give an explanation of each?
1. **Metabolic pathways are irreversible.** A highly exergonic reaction is irreversible; that is, it goes to completion. If such a reaction is part of a multistep pathway, it confers directionality on the pathway. 2. **Every metabolic pathway has a first committed step**. Although most reactions in a metabolic pathway function close to equilibrium, there is generally an irreversible (exergonic) reaction early in the pathway that “commits” its product to continue down the pathway. 3. **Catabolic and anabolic pathways differ**. The existence of independent interconversion routes allows independent control of the two processes. 4. **Feedback inhibition**. The product of a late or last step frequently acts as an inhibitor of the first committed step. Hence, end product controls its own synthesis. All metabolic pathways are regulated. 5. In eukaryotes, metabolic pathways occur in **specific cellular locations.** 6. **Metabolic pathways are controlled by switching on/off the gene for the first enzyme**. If the gene to produce the first enzyme is switched off, the enzyme is not produced, and the rest of the pathway stops. Control of flux is based on the number of key enzymes and the presence of tissue specific isoenzymes and their regulation once made. 7. Enzymes often **act in groups or as multi-enzyme complexes**.
37
These diagram shows feedback inhibition
38
Tell me some facts about feedback inhibition and steps...
39
Whats the definition of **1 calorie**
1 calorie= the heat energy required to raise 1g of H2O by 1˚c
40
You can have a high or low metabolic rate but NOT a fast or slow metabolism
41
Draw the open and cyclic forms of glucose and the % of them found in nature
Be aware of location of OH on the linear glucose and what side its on
42
In glycolysis there are 3 irreversible steps, whats the first irreversable reaction?
43
Name the enzyme that removes phosphate and one that adds phosphate?
**Phosphorylase:** adds a phosphate **Phosphatase:** removes a phosphate
44
Whats the second irreversible step of glycolysis ?
* Step 2 is a coupled reaction as provides energy from ATP * Sequential addition of phosphate groups: AMP --\> ADP --\> ATP * Bisphosphate means 2 phosphates added to different places
45
Whats the 3rd irreversible step of glycolysis ?
This ones ADP --\> ATP rather than in the other two steps
46
why are those steps in glycolysis irreversible?
because of their large, negative ∆G
47
Whats a **cofactor?**
A non-protein component of enzymes
48
Name the divisions of cofactors?
49
If the cofactor is organic, then what is it called?
A coenzyme
50
What are many coenzymes derived from?
Vitamins
51
Name 5 vitamins, their coenzyme and their function?
52
When coenzymes are involved in catabolism of glucose what are they considered to be?
A co-substrate
53
Whats a coenzymes role?
Their role is to deliver chemical groups or atoms e.g. H+, phosphate, to/from the active site
54
Name the coenzyme which is involved in the transfer of protons
Nicotinamide adenine dinucleotide (NAD+)
55
Whats the coenzyme thats involved in the transfer of phosphate groups?
Adenosine triphosphate (ATP)
56
Draw the structure of NADH/NAD+
57
Tell me about oxidation and reduction
58
Write the NADH/NAD+ redox reaction
NAD+ + 2H+ + 2e- NADH + H+
59
Give an example of redox from metabolism
As the NADH is oxidised, the pyruvate is reduced. This reaction occurs in your muscles under low oxygen conditions
60
Give me an redox example from glycolysis
Phosphate is added from solution not ATP Goes from a low energy --\> high energy
61
As well as being involved in the transfer of phosphate groups what does ATP/ADP + Pi play a key role in?
metabolism coupling together energy producing (**exergonic**) reactions with energy requiring (**endergonic**) reactions
62
the equilibrium of endergonic reactions lies in favour of what?
the substrate- but coupling it to an exergonic reaction can shift the equilibrim in favour of product An example of this is below...
63
draw the reaction of ATP and write the direction of the endergonic/ exergonic reactions
64
Draw the structure of ATP
65
Draw the structure of GTP
66
Is GTP a high energy nucleotide ?
yes
67
Is ATP an energy transducer ?
yes
68
does ATP store energy?
no
69
Is ATP produced on demand or is it always made?
it is produced on demand by the phosphorylation of ADP and Pi
70
What are the phosphate groups of ATP stabilised by?
resonance
71
When would phosphate groups repel each other?
if you were to put the like-poled ends together they repel each other
72
When a phosphodiester bond is cleaved, whats the energy from those bonds used for? give an example
Those bonds can be used to perform biochemical work, such as transferring a functional group from one molecule to another
73
are phosphorylation reaction endergonic or exergonic
endergonic
74
Why does phosphorylation need to be a coupled reaction?
to provide energy to make the reaction occur
75
Is Dephosphorylation endergonic or exergonic
exergonic
76
What is the value of ∆G in the oxidation of an aldehyde to a carboxylate? What is this reaction coupled to ?
large and negative This is coupled to the endergonic phosphorylation reaction and the NAD+ reduction
77
What is used to form ATP?
The energy of oxidation is initially trapped as a high-energy phosphate (1,3- biphosphoglycerate) compound and then used to form ATP
78
Is carboxylation of the methyl group an endergonic or exergonic process ?
endergonic
79
is the De-carboxylation endergonic or exergonic ? When a phosphate is then added is the reaction endergonic or exergonic?
De-carboxylation is exergonic addition of a phosphate is endergonic
80
What can GTP also act as?
A co-substrate
81
Are oxidation reactions exergonic or endergonic ?
exergonic
82
Energy from oxidation of NADH is used to drive what?
The formation of ATP
83
For every 1 NADH oxidised, how many ATPs are made ?
3
84
is there a lot of energy trapped in NADH?
yes

BIOL1008 (8 decks)

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