Lecture 9

Question 1

Why does a cell need energy? (5)

Answer 1

1. To do work
2. To make new materials
3. Growth and replacement
4. Movement of both the whole body and cells
5. Pumping substances across membranes, that is for accumulation so materials or generating gradients.

Question 2

Where is the cell’s energy generated?

Answer 2

1. The Cytosol (Glycolysis)
2. The Mitochondria (krebs cycle)
3. The mitochondria membrane (cristae) (oxidative phosphorylation)

Question 3

How is the energy created?

Answer 3

By releasing the chemical energy stored in food and converting this to small useable units that can be handled by cells.

Question 4

Explain the co-transport example of Sucrose - H+.

Answer 4

As the proton pump actively transports H+ out of the cell, due to another cotransporter, the H+ can naturally diffuse back into the cell as well as sucrose through the same pathway.

Question 5

Energy is also required to maintain….

Answer 5

Order

Question 6

Mitochondria Details:
How long?
How many per cell?
Enclosed by?
Name of inner membrane
What does it contain?
What movements/shapes?
May form what?

Answer 6

1-10 micrometers long
1-1000 per cell, depending on energy demand
enclosed by two lipid layers
inner membrane - cristae
Contains mitochondria DNA and ribosomes
Mobile within cell, can change shape, fuse or divide.
May form branched interconnected networks

Question 7

Cytosol:
What part occurs here? Description?
What is released?
What is the electron transfer happening here?

Answer 7

Glycolysis - turning of glucose into pyruvate
Releases 2 ATP per glucose
Transfer of electrons to the electron carrier NAD

Question 8

What are the mitochondrial compartments important for?

Answer 8

Energy generation

Question 9

Matrix:
What part occurs here? Description?
What is released?
What is the electron transfer happening here?

Answer 9

Krebs Cycle - the processing of pyruvate
Releases 2 ATP per glucose
Transfer of electrons to NAD and FAD.

Question 10

Inter membrane Space:
What occurs here?
What is released?

Answer 10

Oxidative Phosphorylation (includes ETC & Chemiosmosis)
Releases 26-28 ATP

Question 11

The overall pathway for Oxidative Phosphorylation (simple version)

Answer 11

The electrons from the electron carriers NAD, FAD are released inside the matrix. This causes multiple pumps to pump protons INTO THE INTERMEMBRANE SPACE. This happens 3 times until the remaining electrons released are accepted by o2 to form water. Then due to the H+ concentration gradient, the H+ will diffuse through ATP synthase, back into the matrix to form ATP.