Mitochondria - non synchronous

Question 1

What is the scientific definition of energy?

Answer 1

The ability to do work

Question 2

State the different types of energy.

Answer 2

Heat
Light
Motion
Electrical
Chemical
Gravitational

Question 3

State the two scientific categories the various form of energy can be categorised into.

Answer 3

• Potential or stored energy
• Kinetic or working energy

Question 4

What types of energy are involved in the human body?

Answer 4

• Movement = mechanical energy
• Metabolism = chemical energy
• Heat generation = chemical energy
• Nerve transmission = chemical energy

Question 5

What molecule is involved in all energy production reactions in the human body?

Answer 5

ATP

Question 6

Describe the structure of ATP

Answer 6

Composed of:
- Nitrogenous base adenine
- Ribose sugar
- Three phosphate molecules joined together by phospho anhydride bonds

Question 7

Name the bond that hold the ribose and phosphate together in ATP.

Answer 7

Phosphate ester bond

Question 8

What are anhydride bonds susceptible to?

Answer 8

Hydrolysis and thus cleavage - this process releases much energy

Question 9

Describe the Gibbs free energy of hydrolysis reactions.

Answer 9

ΔG = negative so reacts almost spontaneously

Question 10

How do you calculate ΔS?

Answer 10

ΔS = ΔS (system) + ΔS (surroundings) >0

Question 11

At constant temp and pressure how do we calculate ΔG?

Answer 11

ΔG= ΔH - TΔS

Question 12

When ΔG is negative what is the process referred to?

Answer 12

Exergonic

Question 13

What does acetic anhydride react with?

Answer 13

• Spontaneously reads with OH to form esters
• E.G. the conversion of morphine into heroine
• It is itself a controlled substance/chemical; this illustrates the reactivity of anhydrides

Question 14

Describe the stability of anhydride bonds.

Answer 14

• Able to break down rapidly and release a good supply of energy
• Rapid energy release is essential in the human tissue

Question 15

What dos the hydrolysis of ATP generate?

Answer 15

ADP and energy

Question 16

How is the energy released by ATP hydrolysis used to power other reactions in a cell?

Answer 16

• Reaction coupling in which an energetically favourable reaction is directly linked with an energetically unfavourable reaction.

Question 17

Give an example of reaction coupling.

Answer 17

• It is energetically unfavourable to move sodium ions out of, or potassium ions into a cell because this movement is against the conc. gradients of the ions.
• ATP provides energy for the transport of sodium and potassium by a sodium-potassium pump

Question 18

Describe the role of ATP in the sodium-potassium pump.

Answer 18

• ATP transfers one of its phosphate groups to the pump protein, forming ADP and a phosphorylated ‘intermediate’ form of the pump
• The phosphorylated pump is unstable so it becomes more stable by changing shape, opening towards the outside of the cell and releasing sodium ions inside
• When extracellular potassium ions bind to the phosphorylated pump they trigger the removal of the phosphate group making the protein unstable in its outward-facing form
• The protein will become more stable by returning to its original shape, releasing the potassium ions inside the cell

Question 19

State the role of the mitochondria.

Answer 19

It is the site of ATP synthesis for the cell

Question 20

What does the number of mitochondria indicate?

Answer 20

• A good indicator of the cell’s rate of metabolic activity
• Cells which are metabolically active such as hepatocytes will have many mitochondria

Question 21

Describe the electron transport chain.

Answer 21

• NADH and FADH2 donate their electrons to complex 1 and complex 2 - these electrons are then passed to the next complex in the chain
• This process generates energy which is used to pump hydrogen ions into the inter membrane space
• This creates an electrical and chemical gradient of hydrogen ions between the inter membrane space and the matrix
• The main route back into the matrix is through ATP synthase
• This creates ATP from ADP

Question 22

Describe the pathway of glycolysis.

Answer 22

• Glucose is phosphorylated via series of enzymes to glucose-6-phosphate; this needs ONE molecule of ATP
• An enzyme phosphate-glucose-isomers rearranges into fructose-6-phospahte
• Third step adds another phosphate to the molecule and obtains this from ATP
• Fructose-1,6-biphospahte splits to form two three-carbon sugars

Question 23

Describe the second phase of glycolysis (producing energy)

Answer 23

• One of the 3C carbon sugars is oxidised whilst NAD+ is reduced to NADH and H+; overall reaction releases energy which is used to phosphorylate the molecule forming 1,3-biphosphoglycerate
• 1,3-biphosphoglycerate idonates one of its phosphate group to ADP making a molecule of ATP and turning into 3-phosphoglycerate
• It is then covered into its isomer, 2-phosphoglycerate
• This loses a molecule of water becoming PEP which is an unstable molecule
• PEP donates its phosphate group to ADP making a second molecule of ATP
• PEP is covered to pyruvate

Question 24

What are the products of glycolysis?

Answer 24

• Net 2 ATP
• 2 NADH
• 2 pyruvate molecules