Week 3 Introduction To Metabolism Flashcards

1
Q

Metabolism

A

The chemical processes that occur in living organisms, resulting in growth, production of energy and elimination of waste

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2
Q

Catabolism

A

The breakdown of complex molecules, releasing energy or lost as heat
Into a simple molecule
Breaking bonds

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3
Q

Synthesis (anabolism)

A

Formation of complex molecules from simple starting materials

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4
Q

Metabolic pathways

A

A sequence of reactions
Reversible reactions
High concentration of A leads to high production of E and vice versa

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5
Q

Pathways

A

Many pathways can be reversed
Some steps are slower than others, or only occur in one direction (rate limiting steps)

Direction and speed of pathways controlled by enzymes

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6
Q

Gibbs free energy

A

A measure of available chemical energy

All chemical systems tend naturally towards states of minimum Gibbs free energy

G= H-TS
WHERE
G= Gibbs free energy
H= Enthalpy (heat content)
T= temperature in kelvins
S= entropy (mainly heat loss)

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7
Q

Exergonic and endogonic reactions

A

Exergonic reactions= spontaneous, energy is released

Endergonic reaction= not spontaneous
Energy is added

Action of enzymes
Exergonic reaction
Endergonic reaction

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8
Q

Action of enzymes

A

Normal (no enzyme reaction)
Proceeds at a slow rate (if at all) due to prohibitive activation energy threshold

Enzyme catalysed reaction
Reaction proceeds at a significantly faster rate as the activation energy threshold is reduced

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9
Q

Enzymes

A

Proteins
Catalyse (speed up) reactions in metabolism
Very specific
Act as control points in metabolism

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10
Q

Enzyme action

A

Action affected by
—substrate concentration
— enzyme activity and concentration
—inhibition
—co-enzymes/ co factors

Have binding sites for
—substrates
—coenzymes
—cofactors
—inhibitors

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11
Q

Enzyme inhibition

A

Competitive =
Prevents the substrate from binding
Competes for active site

Non-competitive=
does not prevent substrate binding
Alters shape of enzyme

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12
Q

Allosteric enzymes

A

Usually contain 2 or more subunits
Binding of the substrate alters shape of enzyme
Substrate binding, increases affinity for substrate, hence activity
The binding of the first improves the binding of the next ones

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13
Q

Naming of enzymes

A

Two parts
First part = substrate
Second part = reaction

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14
Q

Kinase

A

Add/remove phosphate group

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15
Q

Dehydrogenase

A

Remove H

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16
Q

Decarboxylase

A

Add/remove carboxyl group

17
Q

Isomerase/ mutase

A

Rearranges (forms isomers)

18
Q

Transferase

A

Transfers functional groups

19
Q

Hydrolase/ lipase

A

Adds H2O (hydrolysis)

20
Q

Enzymes in metabolism gatekeepers

A

Entry point into pathway

21
Q

Enzymes in metabolism feedback regulation

A

Enzymes can inhibit other enzymes

22
Q

Control points

A

Many pathways have irreversible steps
These are potential control points

Activity of enzyme B and enzyme C1, Help determine direction of the pathway

23
Q

Enzyme control in metabolism

A

Substrate concentration
Eg glucose concentration

Feedback inhibition
-concentration of end product

Co-enzymes= eg vitamins
CoFactors= eg trace elements (eg iron)
Hormones= inhibit or increase enzyme activity

24
Q

Energy

A

Is needed for
Synthesis of complex molecules

Active transport
—movemt of molecules and ions
Eg across a cell membrane

Mechanical work
- muscle contraction
- cellular movement

25
Q

Energy why ?

A

ATP->ADP
2 high energy bonds in ATP one between the phosphates
95g of ATP in muscles
ATP maintained 1-2 mmol/kg
Each ATP molecules is recycled some 1000-1500 times per day

26
Q

Recycling

A

Anabolism (synthesis)
Uses ATP

Catabolism
Production of ATP eg from fat, CHO and alcohol

27
Q

Nutrition and metabolism

A

Carbohydrates, lipids, alcohol
-broken down or stored for energy
-synthesis of body molecules

Protein (amino acids)
-synthesised of a body molecule
-can be used for energy

Minerals
-act as co-factors
-nervous/muscle action

Vitamins
Act as co enzymes
Act as antioxidants