Chapter 12- Energy and Respiration

Question 1

State 3 uses of energy in cells

Answer 1

• moving substances across membranes via A.T
• Movement such as contracting muscles or moving organelles in cells
• Anabolic reactions
• Maintanence of a constant body temperature

Question 2

what is an ATP molecule made up of

Answer 2

• adenine base
• ribose sugar
• 3 phosphate groups

Question 3

What makes ATP the perfect energy currency

Answer 3

• The hydrolysis of a molecule of ATP can be done quickly and easily
• Releases a good amount of energy which is enough but not wasted
• ATP is a stable molecule

Question 4

What are 2 ways to synthesise ATP

Answer 4

• Substrate-linked reactions
• chemiosmosis

Question 5

Define substrate- linked reactions

Answer 5

• The transfer of phosphate group from a substrate molecule to ADP to produce ATP by energy directly from a chemical reaction

Question 6

What is Aerobic respiration

Answer 6

This is the breakdown of organic molecules in a series of stages to release chemical potential energy with the use of oxygen

Question 7

what are the 4 stages that glucose can be broken down into

Answer 7

• Glycolysis
• Linked reactions
• Krebs cycle
• Oxidative phosphorylation

Question 8

Define Glycolysis and where does it take place

Answer 8

• This is the breakdown of glucose and takes place in the cytoplasm

Question 9

summarise the series of steps for glycolysis

Answer 9

• 1 Glucose is phosphorylated by ATP
• 2 Raises the energy level and forms fructose biphosphate by the splitting of glucose (uses ATP)
• 3 Breaks down to 2 triose phosphate (releases 2 ATP)
• This is then dehydrogenated and the H+ is transferred to NAD
• 4 two reduced NAD formed from each triose phosphate
• 5 two pyruvate molecules are produced (3C) (Releases 2ATP)

Question 10

Descibe how ATP is used to break down glucose in the first step of glycolysis

Answer 10

• Two ATP molecules are used in this stage
• One ATP molecule is used to create glucose phosphate which later forms fructose phosphate
• The second ATP molecule is used further to form Fructose 1,6 biphosphate

Question 11

Why is glucose phosphorylated in glycolysis

Answer 11

• Avoid it from leaving the cell
• Activate the glucose
• for it to become unstable
• for its energy level to increase
• for the concentration gradient to be maintained.

Question 12

Describe the substrate linked phosphorylation in glycolysis

Answer 12

• a phosphate group is directly transferred from a substrate which is a phosphorylated molecule from the intermediates

Question 13

Describe the linked reaction in steps

Answer 13

• Pyruvate enters the mitochondrial matrix with Active trannsport
• Enzymes then remove both CO2 (decarboxylation) and H (dehydrogenation)
• the remaining molecule combines Co enzyme A (CoA)
• finally forms Acetyl CoA

Question 14

Describe the components of CoA

Answer 14

• a ribose sugar
• adenine base
• a vitamin

Question 15

Summarise the Krebs cycle in steps

Answer 15

• 1 Acetyl CoA (2C) combines with oxaloacetate (4C) to form citrate (6C)
• 2 Citrate is further decarboxylated twice and dehydrogenated 4x making carbon combine with O2 to form CO2 as a waste and H is carried with NAD and FAD to form reduced NAD & FAD
• 3 Oxaloacetate is again formed to begin the cycle

Question 16

How many molecules of:
CO2
NAD
FAD
ATP
are produced during the Krebs cycle for 1 pyruvate molecule

Answer 16

• 2 CO2
• 3 reduced NAD
• 1 reduced FAD
• 1 ATP

Question 17

Where does oxidative phosphorylation occur?

Answer 17

The inner mitochondrial
membrane

Question 18

Describe the steps of oxidative phosphorylation

Answer 18

• Reduced NAD and FAD are passed to the electron transport chain(ETC)
• Hydrogen is then released from the reduced NAD/FAD and splits into electron and proton (H+)
• The energy released from the movement of the electrons across the ETC pushes the H+ to the inter membrane space
• Because of an accumulation of H+ at the space, they diffuse back through ATP synthase down their gradient
• Oxygen accepts the electron and proton to form water while ATP is being produced

Question 19

what are the functions of NAD in the cytoplasm of a cell

Answer 19

• Acts as a hydrogen carrier
• acts as a coenzyme
• used in glycolysis

Question 20

Make 2 similarities between the structure of ATP and NAD

Answer 20

1- Both have ribose sugars
2 - both have adenine base

Question 21

differences between NAD and ATP

Answer 21

• ATP has 1 ribose while NAD has 2
• NAD has nicotinamide base
• ATP has 3 phosphates while NAD has 2

Question 22

what is anaerobic respiration

Answer 22

Is a type of cellular respiration that occurs in the absence of oxygen

Question 23

Describe anaerobic respiration in alcoholic fermentation

Answer 23

• Pyruvate is decarboxylated into ethanal (acetylaldehyde)
• ethanal takes hydrogen from the reduced NAD to form ethanol and NAD is formed

Question 24

What was the name of the enzyme that reduced ethanal to ethanol

Answer 24

Ethanol dehydrogenase

Question 25

Describe anaerobic respiration in Lactic fermentation

Answer 25

- Pyruvate is reduced to lactate by the enzyme lactate dehydrogenase - In this pathway, reduced NAD transfers its hydrogens to pyruvate to form lactate - Pyruvate is the hydrogen acceptor - The final product lactate can be further metabolised

Question 26

What are the differences between Lactic and alcoholic fermentation

Answer 26

yeast- Irreversible reaction Lactic - Reversible reaction Yeast- 2 steps Lactic- 1 step Yeast- Releases CO2 Lactic- No CO2

Question 27

Describe mitochondrion' structure with relation to its function

Answer 27

1 - inner membrane is folded to provide a large surface area where ATP synthase, carrier proteins are. 2 - Mitochondrial matrix contains enzymes and acts as the site of link reaction and Krebs cycle 3 - The outer membrane has protein carriers for pyruvate and reduced NAD 4 - Inter membrane space has low pH due to high conc of protons from the ETC which creates a proton gradient resulting to synthesis of ATP 5 - The inner membrane is impermeable however the outer membrane is permeable so as to allow products of glycolysis to enter.

Question 28

Why do Lipids have a higher energy value than carbs

Answer 28

This is due to the higher number of C-H bonds which yield more reduced NAD so more ATP per gram

Question 29

What is the Respiratory quotient

Answer 29

This shows the substrate used in respiration whether anaerobic respirations is occurring

Question 30

The RQ formula:

Answer 30

Volume of CO2 given out in unit time / Volume of O2 takin in in unit time