Cellular Respiration

Question 1

What are a few differences between cellular respiration and photosynthesis?

Answer 1

• Resp breaks down molecules to capture energy
• Resp uses energy stored in chemicals e.g. proteins, fats and proteins
• Gets rid of electrons by giving them to oxygen

Question 2

What is the definition of cellular respiration?

Answer 2

A metabolic pathway that releases energy from food, using oxidation and reduction reactions catalysed by enzymes.

Question 3

What is NAD/NADH?

Answer 3

It’s a coenzyme that is continually reduced and oxidised to move electrons around.

Question 4

What is FAD?

Answer 4

Carries electrons as two hydrogen atoms and is reduced to FADH2

Question 5

How do we obtain energy from ATP?

Answer 5

By breaking the last two phosphate bonds in ATP using ATPase

Question 6

How many ATP molecules are produced in the breakdown of one molecule of glucose?

Answer 6

36

Question 7

What are the three steps of cellular respiration?

Answer 7

1. Glycolysis
2. Krebs cycle/TCA cycle
3. Electron Transport Chain/ Oxidative Phosphorylation

Question 8

How many ATP molecules are produced in glycolysis?

Answer 8

2

Question 9

How many ATP molecules are produced in Krebs?

Answer 9

2

Question 10

How many ATP molecules are produced in the Electron Transport Chain?

Answer 10

34

Question 11

Where does glycolysis happen?

Answer 11

Cytoplasm

Question 12

Where does Krebs and ETC happen?

Answer 12

Mitochondria
Krebs- matrix
ETC- cristae

Question 13

What happens in Glycolysis?

Answer 13

Glucose (six carbon molecule) is split into two 3 carbon sugar phosphate molecules by hydrolysis of 2ATP into 2ADP+2P.
They are then converted into two pyruvate molecules (3 carbon) by the reduction of 2NAD+ into 2NADH and the substrate level phosphorylation of 2ADP+2P into 2ATP.

Question 14

What are the outputs of Glycolysis?

Answer 14

2 Pyruvate + 2 ATP and 2NADH

Question 15

What are the outputs of Glycolysis?

Answer 15

2 Pyruvate + 2 ATP and 2NADH.

Question 16

What do we achieve from one turn in the Krebs cycle?

Answer 16

3 molecules of NAD+ reduced to NADH

1 molecule of FAD reduced to FADH2

Question 17

What has to occur before the Krebs cycle?

Answer 17

The oxidation of pyruvate into Acetyl CoA. Pyruvates carboxyl group is fully oxidised is given off as a carbon dioxide molecule. NAD+ is reduced to NADH due to extracted electrons are transferred and stored energy in the form of NADH.

Question 18

What happens during the Krebs cycle?

Answer 18

Two carbons enter the Krebs cycle from Acetyl CoA and adds the two carbon acetyl group to oxaloacetate to form a 6 carbon molecule - Citrate. Look at diagram drawn in notebook

Question 19

What happens if the reduced electron carriers in the Krebs cycle are reoxidised without oxygen present?

Answer 19

Fermentation but oxidative phosphorylation if oxygen is present.

Question 20

What happens during the electron transport chain?

Answer 20

NADH and FADH2 contain energised electrons from Krebs cycle, NADH carry their electrons to the inner mitochondrial membrane where they transfer them to membrane bound proteins. As the electrons are passed down the chain, NADH and FADH2 are oxidised.

Question 21

What is the final acceptor in the ETC?

Answer 21

Oxygen, an NADH molecule donates two hydrogen atoms to oxygen and it forms water.

Question 22

How is an electrochemical gradient made?

Answer 22

Protons (hydrogen ions) are pumped into the intermembrane space, forming a high chemical gradient outside the matrix. Protons are driven back into the matrix and have to bypass ATP synthase molecules that drives the oxidative phosphorylation of ATP.

Question 23

Why does anaerobic respiration not produce as much ATP?

Answer 23

Sugars are not completely oxidised

Question 24

What oxidation of other molecules gives the highest yield of ATP?

Answer 24

Fatty acids. Net yield is 106 ATP.

Question 25

What is the pentose pathway?

Answer 25

A metabolic process parallel to glycolysis. It generates NAPH, pentoses and a ribose 5 phosphate for the synthesis of nucleotides.

Question 26

What is metabolism?

Answer 26

Chemical transformations within the cells of living organisms

Question 27

What are the three main purposes of metabolism?

Answer 27

1. Conversion of fuel to energy to run cellular processes
2. Conversion of food for building blocks of proteins, nucleic acids, lipids and some carbohydrates
3. Elimination of nitrogenous waste

Question 28

What are catabolic reactions?

Answer 28

Breaking down organic matter

Question 29

What are anabolic reactions?

Answer 29

Building up components of cells - proteins

Question 30

What is essential in metabolism?

Answer 30

Regulation of metabolic pathways in response to changes in the cell’s environment or to signals from other cells

Question 31

Why are enzymes so important in metabolism?

Answer 31

Act as catalysts and drive reactions that require energy that wouldn’t happen without it and also allow regulation of metabolic pathways in response to changes in the cell’s environment.