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biochemistry > metabolism > Flashcards

metabolism Flashcards

1
Q

what is metabolism?

A
  • the sum of chemical reactions occurring in a living organism
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2
Q

describe what all reactions are and what they are governed by

A
  • reversible reactions
  • governed by principle of mass conservation
  • some can be complex but often form linked pathways
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3
Q

what do metabolic pathways involved and what do they do?

A
  • involve a number of different metabolites that undergo reactions in order to derive each other
    e.g., glycolysis
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4
Q

what is thermodynamics?

A
  • study of the flow of energy changes in chemical systems
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5
Q

what is bioenergetics?

A
  • study of energy changes in living organisms
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6
Q

how do chemical reactions take place in cells?

A
  • take place between products and reactants with different energy content
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7
Q

free energy change equation

A

change in FE = enthalpy - (temp x entropy)
G= H- (T x S)

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8
Q

what are the units of change in free energy?

A
  • kcal
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9
Q

what is enthalpy?

A
  • amount of bond energies in either product or reactants
  • directly related to energy required to break bonds
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10
Q

what bonds are harder to break and what is the energy influenced by?

A
  • double and triple bonds are harder to break
  • influenced by amount of free energy available/ consuming
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11
Q

what is entropy?

A
  • appreciation of disorder or randomness
  • increases when disorder increases
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12
Q

what does the second law of thermodynamics state?

A
  • state of entropy of an isolated system will always increase over time
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13
Q

are reactions isolated? what does this do to the entropy?

A
  • many aren’t isolated so increase in order and hence decreases entropy
    e.g. reaction that links amino acids to form proteins
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14
Q

what solution has a lower entropy; proteins or unlinked amino acids?

A
  • solution of proteins have a lower entropy (more order) than a solution of unlinked amino acids
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15
Q

what must happen for the linking reaction to proceed?

A
  • compensatory decrease in free energy must occur elsewhere in the system
  • in a linked reaction
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16
Q

what factors influence change in free energy?

A
  • temperature, pressure, initial amounts of products+ reactants, pH
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17
Q

what is the standard free energy change of reaction delta G nought prime?

A
  • value of the change of free energy in standard conditions
  • 25 degrees, 1atm pressure, pH 7
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18
Q

describe the free energy change in biochemical reactions where there is a different temperature and initial concentration

A
  • G= G ‘ + RT InQ = G’ + RT In products/ reactants
  • R= gas constant
  • Q = initial ratio of products to reactants
19
Q

what is an exergonic reaction?

A
  • free energy of products is lower than the reactants <0
  • favoured thermodynamically> energy released for work
20
Q

what is an endergonic reaction?

A
  • free energy of products is higher than the reactants <0
  • unfavoured as energy consumed
21
Q

describe equilibrium

A
  • free energy = 0
  • dynamic state whereby energy of products and reactants is equal
22
Q

can expression of free energy be useful?

A
  • yes because comparison of free energy changes between different reactions provides context
    e.g., free energy derived from different biomolecules
23
Q

what is 1kcal?

A
  • amount of energy required to raise the temperature of one kilogram of water by 1 degree
24
Q

in the case of exergonic reactions what does G nought tell us?

A
  • how much energy is available for work
25
Q

what is the main source of energy? describe its structure

A
  • adenosine trisphosphate
  • ribose linked to an adenine and three phosphoryl groups (alpha, beta+ gamma)
26
Q

what does hydrolyse of ATP create and what is important?

A
  • phosphoryl group is removed to form adenosine diphosphate
  • hydrolysed twice to form adenosine monophosphate
  • bond energy of phosphate bonds is important in providing energy
27
Q

what is the equation of ATP hydrolysis ?

A

ATP + H20 –> ADP + Pi + H+

28
Q

what is the standard free energy change of ATP hydrolysis and what does this show?

A
  • ATP + 2h20 - AMP+ 2Pi+ H+ = -12kcal. mol -1 (very negative)
  • favoured thermodynamically so ATP referred to as a high energy compound
29
Q

what is catabolism

A
  • series of reactions that break down biomolecules into smaller molecules
30
Q

why is the synthesis of ATP linked to catabolic reactions?

A
  • because synthesis of ATP is endergonic so unfavoured
  • linkage allows it to proceed as its manipulated to a favourable reaction
31
Q

what is anabolism? what is it needed for?

A
  • formation of structures needed for growth, cell division, energy storage
32
Q

what does synthesis require and what type of reaction is it?

A
  • synthesis requires energy so it is endergonic and hence unfavoured
  • more ATP hydrolysis needed
33
Q

describe redox reactions

A
  • oxidation= compound gains H and loses 02
  • reduction= compound loses H and gains 02
  • constant equilibrium
34
Q

what is oxidation usually involved in?

A
  • breakdown of large molecules
35
Q

what is reduction usually involved in?

A
  • generation of large molecules
36
Q

how do oxidation and reduction work?

A
  • work in constant equilibrium as no atoms are lost or gained
  • when one substance is reduced another is oxidised
37
Q

describe NAD

A
  • exists in oxidised and reduced forms
  • oxidised form NAD+ accepts H from an oxidising metabolite forming NADH (reduced form)
38
Q

what does NAD do and how is it formed?

A
  • works to lend and receive hydrogen atoms
  • AMP plus nicotinamide mononucleotide derived from vitamin Niacin
39
Q

what other redox compounds assist hydrogen transactions?

A
  • nicotinamide adenine dinucleotide phosphate (NADP +/ NADPH)
  • flavin adenine dinucleotide (FA
40
Q

what does the transfer of electrons from NADH and FADH2 to 02 mean?

A
  • marks the end of oxidation of metabolites within cells
  • creating water
41
Q

how many atoms do NAD and FAD receive?

A
  • FAD receives 2; NAD receives 3
42
Q

what compounds serve as oxidants?

A
  • NAD+, NADP+ and FAD
  • accept H from metabolites
43
Q

what compounds serve as reductants?

A
  • NADH, NADPH and FADH2
  • donate H (or more precisely, electrons)

biochemistry (15 decks)

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