Lecture 8 - cellular respiration

Question 1

What cells do photosynthesis?

Answer 1

Plants

Question 2

What cells do cellular respiration?

Answer 2

Plants and animals

Question 3

In context to energy, what do all eukaryotes have?

Answer 3

All eukaryotes have organelles that are responsible for converting an external energy into a usable form.

Question 4

What is ATP?

Answer 4

ATP is an energy carrier.

Question 5

What is the structure of ATP?

Answer 5

A triphosphate group, ribose and adenine

Question 6

How does ATP create energy?

Answer 6

Due to a reaction where the triphosphate group releases a phosphate to become diphosphate. When this bond breaks, energy is released.

Question 7

What does the cell need energy for?

Answer 7

For mechanical work
To make new materials
For transport
To maintain order

Question 8

What is the mitochondria?

Answer 8

The mitochondria is the site of cellular respiration.

Question 9

What determines number of mitochondria in a cell

Answer 9

The amount of energy that is required for the cell.

Eg. Muscle cells need more mitochondria

Question 10

What does mitochondria contain and what does it mean for the mitochondria?

Answer 10

Mitochondrial DNA and ribosomes.

This means they can produce some but not all mitochondrial proteins

Question 11

Describe the structure of the mitochondrion.

Answer 11

The mitochondria and has two membranes (the inner and outer mitochondrial membranes) and the mitochondrial matrix which is inside the inner membrane.

Question 12

Describe the inner membrane

Answer 12

The inner membrane is made of highly folded cristae which provides a bigger surface area for activity.

Question 13

Describe the intermembrane space

Answer 13

This is the space between the two membranes

Question 14

Describe the mitochondrial matrix

Answer 14

The space between the inner membrane. Equivalent to the cytosol of the cell.

Question 15

What are the three stages of cellular respiration?

Answer 15

1) Glycolysis
2) Pyruvate oxidation and citric acid cycle
3) oxidative phosphorylation

Question 16

Describe what happens in stage one of cellular respiration

Answer 16

In the cytosol sugar-glucose is converted into a smaller molecule pyruvate. This reaction generates 2ATP and releases two electrons which are transferred to the high energy electron carrier -NAD+ making it NADH.

Question 17

Describe stage two of cellular respiration

Answer 17

Stage two happens in the mitochondrial matrix and pyruvate is converted into Acetyl CoA (+CO2). As we do that we extract more high energy electrons( 2NADH)
The Acetyl CoA then enters the citric acid cycle. As a result we produce 2ATP, more high energy electrons (NADH) and another high energy electron accepting molecule FADH2 (+2CO2)

Question 18

Summarise stages one and two of cellular respiration

Answer 18

We start with glucose and we end up with ATP and some NADH and FADH2

Question 19

Compare NADH to FADH2

Answer 19

FADH2 is similar to NADH but it has a little bit less energy in it

Question 20

Describe stage three of cellular respiration

Answer 20

Stage three happens in the inner membrane of the mitochondrion and occurs in two parts:
Part 1 - electron transport (electrons from NADH and FADH2)
Part 2 - Chemiosmosis (ATP production)

Question 21

Describe part one of stage three of cellular respiration.

Answer 21

In part 1 the movement of electrons allow for a proton gradient to be established.

Question 22

Describe the electron transport chain.

Answer 22

The electron carriers (NADH and FADH2) shuttle high energy electrons to the end of mitochondrial membrane. These electrons then move through protein complexes embedded in the inner membrane. As these electrons move, protons (H+) are pumped across the membrane into the into membrane space.

Question 23

Describe how the proton gradient and cellular respiration is generated.

Answer 23

Due to the electron transport chain, protons accumulate in the innermembrane space. This makes the protein concentration on either side of the inner mitochondrial membrane different, creating a proton gradient. This gradient then leads into part 2 of stage 3 in cellular respiration.

Question 24

Describe part two of stage three of cellular respiration

Answer 24

In part 2 the proton gradient established in part 1 allows for chemiosmosis to occur.

Question 25

Describe chemiosmosis

Answer 25

The inner mitochondrial membrane contains the protein complex ATP synthase. This complex spans the membrane from the inner membrane space in the mitochondrial matrix. ATP synthase converts ADP + Pi into ATP and the established proton gradient powers this process to occur.

Question 26

Summarise cellular respiration

Answer 26

Chemical energy is converted from one form to another. From glucose to ATP.
The structure of the mitochondrion enables the protein gradient to be established across the inner membrane and this drives the production of ATP

Question 27

What is consumed in cellular respiration?

Answer 27

Glucose and oxygen

Question 28

What is produced in cellular respiration?

Answer 28

Carbon dioxide, water and ATP

Question 29

What does ATP power?

Answer 29

Cellular activity

Question 30

What does ATP enable

Answer 30

The controlled release of energy.