0214 - Metabolic Regulation Strategies - RM Flashcards

1
Q

What are the five benefits of metabolic regulation

A

1 - Integration of Pathways (allowing things to move to other end-products)2 - Regulation of Process (reactions only occurring when and where you want them)3 - Direction of Flux (surges directed to needy processes or stored for future use)4 - Efficiency (getting the most out of every carbon)5 - Commitment of Resources (ensuring that resources are used for the desired end product)

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2
Q

Why are multi-step reactions important

A

They allow integration of reaction pathways, meaning that (until the committed step) intermediates can use branch points to meet the body’s immediate needs. Much more efficient than single-step reactions.

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3
Q

What distinguishes a linear reaction

A

One substrate goes in, and is synthesised to a different product. Reaction rates are often linked to cofactor use or production (e.g. limited by ATP supply) Early committed step, to drive the reaction quickly.

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4
Q

What distinguishes a cyclical reaction

A

They start and end with the same compoundReaction rate is set by reactant concentration, which enters early.Can re-direct metabolites to many different areas.Would be ‘futile cycles’ if they did not provide a net benefit to the body.

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5
Q

What are Partitioned Domains

A

Areas on a membrane surface containing all the enzymes needed for a particular reaction - It can release them at a desired time, allowing the end-product to be synthesised at great speed.

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6
Q

Do reactions proceed in isolation?

A

No - pathways are often clustered. The body is very complex and products, cofactors, and intermediates all influence each other and can be used by something else.

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7
Q

Why is ATP important?

A

ATP bonds easily, and ATP hydrolysis is a very favourable reaction. As a result, the addition of ATP to a molecule can allow an unfavourable reaction to proceed favourably.

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8
Q

What are the correct terms for the process of ATP production?

A

Substrate-level phosphorylation (outside of TCA cycle)Oxidative phosphorylation (in TCA cycle)

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9
Q

What are the three primary methods of metabolic regulation?

A

Reciprocal Regulation - a particular signal leads to a specific response.Control of substate availability - through compartmentalisation or otherwise controlling the flux.Control of cofactor availability

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10
Q

How does short-term metabolic regulation work?

A

By controlling the activity of an enzyme through metabolic demand. Most commonly through the relative levels of ADP/ATP, but also through hormonal influence on a signal pathway, that can alter phosphorylation and so affect the speed of reaction.

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11
Q

How does long-term metabolic regulation work?

A

Through a persistent signal, most commonly through the levels of hormones that can either alter the behaviour of enzymes, or make new ones (which is particularly slow/long-term).

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12
Q

What is feedforward (in metabolism)?

A

A process used to speed up a regulation, wherein high levels of a substrate or intermediate can stimulate a rate-limiting step (commonly the first or last enzyme in the pathway) to create supply or demand, thus stimulating the reaction.

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13
Q

What is feedback (in metabolism)?

A

A process in which high levels of an intermediate or end product can inhibit or shut down the activity of an enzyme, or supply of a substrate, earlier in the reaction, slowing or stopping the entire pathway.

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14
Q

What is a committed step?

A

A step on a reaction pathway after which there are no more branchpoints, and a substrate or intermediate is destined to continue down that pathway to the end product. A very valuable tool for metabolic regulation. To speed production of a product, stimulate the committed step enzyme. To slow or stop it, inhibit the committed step enzyme.

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15
Q

Why is compartmentalisation a valuable tool in regulation

A

It prevents the release of key substrates and enzymes in a biological ‘locked room’. Regardless of how favourable the reaction is, it cannot proceed without a transporter.Also very useful for controlling fluxes - storing things at a particular stage until they are ready to use.

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16
Q

Are all enzymes regulate?

A

No, only key enzymes are regulated, as this is all that is needed to control the pathway.