Energy Reactions In Cells

Question 1

Define cell metabolism

Answer 1

Metabolism is a set of processes which derive energy and raw materials from food stuffs and use them to support repair, growth and activity of the tissues of the body to sustain life

Question 2

Describe the process of a catabolic pathway

Answer 2

Breaks down large molecules into smaller manageable ones
Releases large amounts of free energy
Is oxidative- releases H atoms

Question 3

Describe the process of an anabolic pathway

Answer 3

Synthesises larger cell components from intermediatry metabolites
Usesenergy from catabolism (ATP)
Is reductive (uses H Atom)

Question 4

List the products of a catabolic metabolic reaction

Answer 4

Building block materials
Organic precursors (acetyl coA)
Biosynthetic reducing power (NADH NADPH)
Energy for cell functions (ATP)

Question 5

How do we workout the bodies energy requirements?

Answer 5

Basal metabolic rate+activity done+specific dynamic action of food

Question 6

Describe the main points an exergonic reaction

Answer 6

The only reactions that can occur spontaneously
They release energy
Negative change in free energy

Question 7

Describe main points for an endergonic reaction

Answer 7

Requires energy input
Not spontaneous
Positive Gibbs free energy change

Question 8

Why are the standard conditions used to work out free energy change not useful in our body?

Answer 8

As our body does not work under the set standard conditions of ph and temp.

Question 9

What are H carrier molecules?

Answer 9

Complex molecules (contain components from vitamin B)
Convert to reduced form by adding 2 H atoms
H+ dissociate into solution

Question 10

How can energy released in oxidative (catabolic) metabolism be used?

Answer 10

Directly- use of NADPH in biosynth
Indirectly- mytichondiral system uses it to couple NADH to the production of ATP to be used as an intermediate energy source

Question 11

Why do cells need a constant energy supply?

Answer 11

ATP is in limited concentration in a cell.
There is only a few seconds of energy in each, it acts as a carrier not a store.
The cycle must keep going so energy must be readily available

Question 12

How do we control the flow of energy in a cell?

Answer 12

ATP is stable in the absence of a specific catalyst so this allows its release to be controlled

Question 13

How des our body know when to retrieve more energy from reactions?

Answer 13

When ATP is high, anabolic pathways are activated to prevent extra energy release and start using the energy store.

When ATP is low, and ADP and AMP are high, catabolic pathways are active to start rebuilding the energy stores.

Question 14

What other ways can energy be stored in cells?

Answer 14

If supply exceeds demand energy is stored as polymer macromolecules such as glycogen or triglyceride
Cells that need to increase metabolic activity fast, like muscles, have a reserve of high energy stores that can be used immediately in the form of Creatine PHosphate

Question 15

How does creatine phosphate work?

Answer 15

It contains high energy phosphate bonds .

When ATP is high, creatine phosphate is formed

If ATP falls suddenly the reaction reverses providing a short term boost to ATP levels.

Question 16

How can Creatine KInase be used as a diagnostic tool and what values are needed to make a diagnosis?

Answer 16

It can be used to diagnose a MI as it is released by cardiac myocytes when damaged.

In skeletal muscle isotopes are MM 98% and MB 1%
In cardiac muscle isotopes are MM 70% and MB 30%

So the ratio of isotopes in a blood sample tell us if the damage is skeletal or cardiac

Question 17

How can CReatine be used as a clinical marker?

Answer 17

It is broken down spontaneously at a set rate every day so we can use the concentration in the urine to determine how dilute the urine is.

Gives us a good comparison for dilution to see how much of measured markers are actually in urine. Ie hormones in pregnancy (how dilute the urine is shows the true value of hormone present)