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Biochemistry > Metabolism of enzymes > Flashcards

Metabolism of enzymes Flashcards

1
Q

Define Metabolism

A

sum total of all chemical reactions involved in maintaining the living state of the cells, and thus the organism
Metabolism manages the material and energy resources in the cell

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2
Q

Catabolic pathways [energy conserving]

A

degradative processes that release energy by breaking down complex molecules to simpler compounds (energy release and conservation as ATP)

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3
Q

Anabolic pathways

A

processes of building (synthesis) complicated molecules from simpler ones that require energy (requires ATP and electron source stored in a form of reducing power)

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4
Q

what are metabolites- fun fact

A

reactants, inter-mediates, and products of metabolic reactions
over 2000 known metabolic reactions

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5
Q

Phototrophs use what as their energy source

A

light

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6
Q

chemotrophs receive their energy from what

A

organic [chemoorganotrophs] or inorganic [chemolithotrophs] compounds

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7
Q

what is carbon source of autotrophs

A

CO2

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8
Q

what is the carbon source of heterotrophs

A

organic molecules from other organisms

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9
Q

electron source of lithotrophs

A

reduced inorganic compounds

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10
Q

organotrophs electron source

A

reduced organic compounds as electron source

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11
Q

oxidizing agent of aerobes

A

O2

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12
Q

oxidizing agent of anaerobes

A

sulfate or nitrate

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13
Q

facultative anaerobes can grow?

A

in presence or absence of O2 i.e. E.coli

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14
Q

obligate anaerobes

A

poisoned by O2

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15
Q

DEFINITION of energy- units

A

capacity to do work- calories of joules [J]

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16
Q

ATP id the energy x of the cell

A

currency

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17
Q

what are the 3 major types of work carried out by living cells

A

-Chemical work - synthesis of all cell components i.e. anabolism
-Transport work - take up nutrients/ions, eliminate waste
-Mechanical work - motility

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18
Q

what are metabolic pathways

A

series of chemical oxidation-reduction reactions

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19
Q

role of enzymes in metabolic pathways

A

mediated by enzymes

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20
Q

what is metabolic channelling

A

localising metabolites and enzymes into different parts of the cell

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21
Q

amount an enzyme that is synthesised is regulated by?

A

transcription and translation

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22
Q

direct stimulation or inhibition of critical enzymes is controlled by?

A

posttranslational regulation

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23
Q

role of oxidoreductases

A

catalyse the transfer of electrons from one molecule (the reductant, also called the hydrogen or electron donor) to another (the oxidant, also called the hydrogen or electron acceptor)

24
Q

transferases

A

catalyse the transfer of a functional group (e.g. a methyl or phosphate group) from one molecule (called the donor) to another (called the acceptor)

25
Q

Hydrolases

A

catalyse the hydrolysis of a chemical bond

26
Q

lysases

A

catalyse the breaking of various chemical bonds by means other than hydrolysis and oxidation

27
Q

isomerases

A

catalyse the structural rearrangement of isomers

28
Q

Ligases

A

: catalyse the joining of two large molecules by forming a new chemical bond, usually with accompanying hydrolysis of a small chemical group pendant to one of the larger molecules

29
Q

what are the 2 forms of cofactors

A

Prosthetic group – cofactor firmly attached to the apoenzyme
Coenzyme – cofactor loosely attached to the apoenzyme and can dissociate after product is formed

30
Q

what are 4 examples of iron cofactors and give 1 e.g. of enzymes they work with [inorganic]

A

Iron – catalase
Magnesium – DNA polymerase
Manganese - arginase
Copper – cytochrome oxidase

31
Q

give 4 examples of organic cofactors

A

NAD+, NADP+ [Niacin B3], biotin [Biotin], ascorbic acid [on vit C] and cobalamine [B12]

32
Q

full name of ATP - function - it is a ..
type of energy molecule it is?

A

adenosine 5’-triphosphate ATP - stores energy produced form exergonic reactions to drive endergonic reactions [links the reactions] - is a nucleotide - high energy molecule

33
Q

ATP can be hydrolysed -> what 2 forms

A

ADP and P or AMP and energy = released [ delta G = -7.3mmol/l

34
Q

definition of -delta G

A

high phosphate group transfer potential

35
Q

what is substrate-level phosphorylation

A

Process of transferring a phosphate group from a high-energy molecule to ADP to form ATP
Observed during catabolic processes

36
Q

ATP chemiosmosis

A

ATP synthase = used -> synthesise ATP and the energy used for this is made from proton motive force produced by electron transport chain

37
Q

release of energy from an energy source normally involves?

A

oxidation-reduction reactions

38
Q

what is a redox couple

A

electron donor and acceptor

39
Q

standard reduction potential Eo is what?

A

tendency of a donor to loose electrons

40
Q

standard reduction potential Eo is what?

A

tendency of a donor to loose electrons

41
Q

electron carriers are organised into ?

A

electron transport chain

42
Q

what is the precursor for NAD and NADP- what does it accept from donor

A

niacin - 2e- and 1H+…… a second proton is released – 320mB - begining of electron transfer chain

43
Q

carbohydrate catabolism /glycolysis reaction[stage 1 and 2 of catabolism

A

glucose/fructose -> pyruvate + ATP + NADH + smaller 3-C molecules

44
Q

LIPID CATABOLISM REACTION- GIVE 2 e.g.s of essential fatty acids that must be obtained from diet [stage 1 and 2 of catabolism]

A

Lipids - fatty acids + glycerol
linoleic, arachidonic, linolenic acids

45
Q

protein catabolism reaction
how many Essential A.A. are there and where are they obtained from [stage 1+2 of catabolism]

A

protein -> A.A
10 ess. A.A. obtained from diet

46
Q

Tricarboxylic acid cycle [other names - TCA, krebs or citric acid] is what type of pathway and what is it used for? - stage 3 of catabolism processes

A

amphibolic pathway [catabolism + anabolism for oxidation of F.acids-> CO2 [NADH, FADH2 and ATP = also produced]

47
Q

Oxidative phosphorylation = in stage 3 of catabolic process give e.g.s of molecules reduced

A

is a catabolic pathway that provides ATP for anabolic processes
high energy molecules like NADH and FADH2 = reduced -> drive phosphorylation of ADP -> ATP

48
Q

for food to be oxidised during catabolism something else must be?

A

reduced

49
Q

reduced NADH and NADPH function as?

A

sources of electrons during anabolic reactions

50
Q

cellular respiration is a ? process that transfers energy from x -> form y

A

exergonic process
x= glucose bonds
y= ATP

51
Q

Stage 1:
* x molecules (proteins, CHO, etc.) are broken down
into y
* - - energy is generated in this phase
Stage 2:
* Small molecules (sugars, fatty acids, glycerol, some amino
acids) are -
* Mostly converted into the ?
* A x ATP is generated at this stage
Stage 3:
* The x and y , final common
pathways in the cell’s oxidation of fuel molecules
* Acetyl CoA brings acetyl units into the x and they are
completely oxidized to y
* x pairs of electrons are transferred to the electron acceptors, NAD+
and FAD, for each acetyl group oxidized:
* ATP is generated as the electrons x of these
coenzymes to y
in the process called oxidative phosphorylation
* Over ?% of the ATP generated by the oxidation of foodstuffs = generated in this stage

A

large, smaller units
no-useful energy = generated in this stage
stage 2
- degraded into to simple units that play key role in metabolism
- acetyl unit of acetyl coenzyme A
- little
stage 3
- citric acid cycle and oxidative phosphorylation
- citric acid cycle —completely oxidized to CO2
- flow from reduced forms of these coenzymes -> O2
- 4
- 90%

52
Q

regulation of metabolic processes = controlled by controlling ? x3

A
  1. The amounts of the different enzymes present
    * Regulation of transcription and translation
  2. The catalytic activities of the various enzymes
    * Direct stimulation or inhibition (allosteric regulation)
    * Posttranslational regulation (+/- phosphoryl, methyl or
    adenyl groups)
  3. The accessibility of substrates
    * Metabolic channelling – localising metabolites & enzymes
    into different parts of the cell
53
Q

the amount of enzyme present depends on

A

rate of synthesis versus the rate of degradation of the enzyme

54
Q

control of enzyme catalytic activity involves reversible covalent modifications how is this done?
also controlled by feed-back inhibition/reversible allosteric inhibition- how is this one done

A

Enzyme activation/ inactivation by the addition or removal of a
functional group
* Fast method of enzymatic control (secs)
- first reaction of the pathway is inhibited by the final product of the pathway - milliseconds

55
Q

accessibility of substrate helps regulate metabolic processes

A

regulates the availability of the substrate

56
Q

synthesis of ATP is x favourable and energy released can be coupled with - to link x with y

A

thermodynamically favourable [does not require energy]
- thermodynamically unfavourable reaction-> link exergonic and endergonic reactions

Biochemistry (9 decks)

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