BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION

BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION

 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION

5.0 INTRODUCTION

a) Definition of Cellular Respiration.

⮚ Fill in the blanks by choosing the correct words in the box below.

b) Types of Cellular Respiration.

⮚ Cellular Respiration has 2
types:
i. Aerobic respiration
ii. Anaerobic
respiration
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⮚ Equation of Cellular Respiration

⮚ Structure of ATP
i. Chemically, ATP is an adenine nucleotide bound to three phosphates.
ii. There is a lot of energy stored in the bond between the second and third
phosphate groups that can be used to fuel chemical reactions.
iii. When a cell needs energy, it breaks this bond to form adenosine diphosphate
(ADP) and a free phosphate molecule.
iv. In some instances, the second phosphate group can also be broken to form
adenosine monophosphate(AMP).
v. When the cell has excess energy, it stores this energy by forming ATP from ADP
and phosphate.
vi. ATP is required for the biochemical reactions involved in any muscle contraction.
As the work of the muscle increases, more and more ATP gets consumed and must
be replaced in order for the muscle to keep moving.

How do we get energy from ATP?

⮚ By breaking the high- energy
bonds between the last two
phosphates in ATP through
 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION
hydrolysis process (adding H2O)

5.1 AEROBIC RESPIRATION

Definition of aerobic respiration

 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION

b) Need and Roles of Energy In Living Organisms

⮚ Fill in the blanks.

C) TERMINOLOGIES
1 OXIDATION AND REDUCTION
LEO say GERRRRR
LEO: Loss Electron Oxidation
GER: Gain Electron Reduction
Oxidize- to LOSE ELECTRONS and LOSE
HYDROGEN
Reduce – to GAIN ELECTRONS an GAIN
HYDROGEN
Example:

Glucose is oxidized and become CO2. So glucose become reducing agent.

O2 is reduced and become H2O. So O2 is an oxidizing agent.

2) ELECTRON CARRIER
- Molecules that is capable of accepting one or two electrons from one molecule
and donating them to another in the process of electron transport.
 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION

- As the electrons are transferred from one electron carrier to another, their
energy level decreased, and energy is released.
- Two important electron carriers, a type of coenzyme:
i) NAD+ : Nicotinamide adenine diphosphate
ii) FAD : flavin adenine dinucleotide
NAD+ + 2e- + 2 H+ NADH + H+
FAD + 2e- + 2 H+ FADH2

3) PHOSPHORYLATION & DEPHOSPHORYLATION

Phosphorylation is the addition of a phosphate (PO43−) group to a protein or other
organic molecule.
Dephosphorylation is the removal of a phosphate (PO43−) group to a protein or
other organic
molecule.

4) Two process to form ATP:

a) Substrate level phosphorylation
● formation of ATP or GTP by the direct transfer of phosphate group to ADP
or GDP
● from phosphorylated reactive intermediate (substrate).
● occur during glycolysis and Krebs Cycle
 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION
b) Oxidative phosphorylation
● A process in which ATP is formed as a result of the transfer of electrons
from NADH or FADH2 to O2 by a series of electron carriers.
● Example of electrons carrier: NADH, FADH2

Two process occur in oxidative

phosphorylation:
1. Electron transport chain
2. Chemiosmosis.

5) DECARBOXYLATION
⮚ A reaction in which a molecule of CO2
is removed from a carboxyl group of an
organic acid.
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5.1. 1 GLYCOLYSIS

(a) Ilustrate to explain glycolysis pathway: (from glucose to pyruvate).

GLYCOLYSIS PATHWAY: From Glucose To Pyruvate

Stages in Glycolysis
⮚ Consists of ten steps

⮚ Can be divided into two phases:

(i) Energy Investment Phase (step 1-5) – Cell use ATP to phosphorylate
intermediate substrate of glycolysis.
(ii) Energy Payoff Phase (Step 6-10) – Cell synthesize ATP via substrate level
phosphorylation.
BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION
STEP 1: PHOSPHORYLATION
• Enzyme hexokinase transfers a phosphate
group from ATP to the glucose
• Glucose is phosphorylated forming
glucose-6-phosphate
• Phosphorylation makes glucose:
- more chemically reactive and easily
breakdown
- easily trap in the cell because plasma
membrane is permeable to charge ions.

STEP 2: ISOMERIZATION
• Glucose-6-phosphate is rearranged to
convert it to its isomer,
fructose-6-phosphate.
• Isomerization is to stabilize the
structure

STEP 3:PHOSPHORYLATION
• Another ATP transfer a phosphate
group to fructose-6-phosphate
• fructose-6-phosphate is phosphorylated
forming fructose-1,6-bisphosphate
• catalyzed by enzyme
phosphofructokinase
• Phosphate groups are now bound at
carbon no.1 and no.6 and molecules is
ready to be split.

STEP 4: LYSIS/CLEAVAGE
● Fructose-1,6-bisphosphate is then split
into two 3-carbon sugars :
i. i) Glyceraldehyde-3-
phosphate (G3P)
ii. ii) Dihydroxyacetone
phosphate (DHAP) * Both are isomer
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STEP 5: ISOMERIZATION
• Dihydroxyacetone phosphate(DHAP) is
rearrange to its isomer,
Glyceraldehyde-3-phosphate (G3P) for
further metabolism in glycolysis.
• 2 molecules of G3P are produced.
**Next enzyme in glycolysis uses only G3P as its
substrate.
**Step 6 onward : x2 (because the production of
2 G3P in step 5)
STEP 6: OXIDATION &PHOSPHORYLATION
• Each glyceraldehyde-3- phosphate (G3P) is
oxidized by the transfer of electrons and
hydrogen atom to NAD+.
• forming NADH + H+ (NAD+ is reduced to
NADH + H+ : redox reaction)
• The product is phosphorylated, which
reacts with inorganic phosphate (Pi) (from
cytosol) to form 1,3-bisphosphoglycerate.

STEP 7: SUBSTRATE LEVEL

PHOSPHORYLATION
• Conversion of 1,3-bisphosphoglycerate
to 3-phosphoglycerate by:
One phosphate group is transferred
●
from each 1,3-bisphosphoglycerate to
ADP forming ATP.
● Production of ATP is through substrate
level phosphorylation.
STEP 8: ISOMERIZATION
• Each 3-phosphoglycerate is
rearranged forming
2-phosphoglycerate. (by relocating
their phosphate group from C3 to
C2)
 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION
STEP 9: DEHYDRATION
• Water molecule is removed from each
2-phosphoglycerate which results in
formation of double bond.
Phosphoenolpyruvate (PEP) is produced

STEP 10: SUBSTRATE LEVEL

PHOSPHORYLATION
● Each phosphoenolpyruvate (PEP) molecule
transfers its phosphate group to ADP
forming ATP.
● The production of ATP through substrate
level phosphorylation.
● Phosphoenolpyruvate (PEP) is converted to
pyruvate

Summary of glycolysis (per 1 molecule of glucose):

Number Step
No. of ATP used 2 Step 1 & 3: Phosphorylation
Production of NADH + H + 2 Step 6: Oxidation & phosphorylation
Production of ATP 4 Step 7 & 10 (2 for each): Substrate level
phosphorylation
Production of pyruvate 2 Step 10
NET ATP PRODUCED 2
Location: Cytoplasm/cytosol of a cell
Takes place with or without oxygen
AFTER GLYCOLYSIS

⮚ When oxygen is PRESENT:

⮚ Pyruvate enter mitochondria to undergo Krebs cycle.
⮚ Electrons from NADH is transported into mitochondria,where more ATP is
produced by oxidative phosphorylation.
⮚ When oxygen is ABSENT:
• NADH becomes reducing agent in the cytoplasm.
• Pyruvate will be producing lactate or ethanol.
 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION
b) Describe Link Reaction: Conversion of pyruvate to acetyl coenzyme A

● Before entering Krebs cycle, the pyruvate undergoes a Link reaction /transition
stage.
● Link reaction is a
conversion of pyruvate (3C) to
acetyl CoA (2C).
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STEPS NO
The oxidized fragment, acetate combines with coenzyme A to form
acetyl CoA which then enters into the Krebs cycle. 4
In the presence of oxygen, transport protein on membrane of
mitochondria will transport pyruvate from glycolysis into matrix of 1
mitochondria.
Pyruvate (3C) undergoes decarboxylation by removing carboxyl group
(in form of CO2) 2
CO2 will diffuse out of the cell.
The remaining 2 carbon fragment isoxidized forming acetate. NAD+
accept the hydrogen removed during oxidation and reduced into NADH 3
+ H+.

Product of Link Reaction (per 1 molecule of glucose)

NADH + 2H+ 2
Acetyl CoA 2
CO2 2

5.1.2 KREBS CYCLE /CITRIC ACID CYCLE

Definition:
● Breakdown of acetyl coenzyme A to carbon dioxide and water through a series of
chemical reaction to produce ATP, NADH + H+ and FADH2.
● Location: Mitochondrial matrix
 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION

Create a mnemonic.
Example:
Cinta———-Citrate
Ini———-Isocitrate
Akan———-alpha-ketoglutarate
Sentiasa———-Succinyl-CoA
Segar———-Succinate
Flexible———-Fumarate
Manis———-Malate
Ok!———-Oxaloacetate

Fill in the blanks with the appropriate answer. Please choose the correct ones.
STEP 1: FORMATION OF CITRATE
● Unstable bond attaching acetyl group to
coenzyme A breaks.
● 2C acetyl group becomes attached to 4C
oxaloacetate forming citrate (6C)

STEP 2: ISOMERIZATION
● Atoms of citrate (6C) are rearranged by
two preparation reactions:
- Removal of water molecule
- Addition of water molecule
BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION
● Citrate is converted to its isomer,
isocitrate (6C).
STEP 3:OXIDATION AND DECARBOXYLATION
● Isocitrate is oxidized, reducing NAD+ to
NADH+H+
● The resulting compound is decarboxylated
(CO2 is released)
● Isocitrate (6C) is converted into
α-ketoglutarate (5C)

STEP 4:DECARBOXYLATION AND OXIDATION

● α-ketoglutarate (5C) undergoes
decarboxylation (CO2 is released)
● The resulting compound is oxidized,
reducing NAD+ to NADH + H+
● The remaining molecule is attached to
coenzyme A forming succinyl CoA (4C)

STEP 5: SUBSTRATE LEVEL

PHOSPHORYLATION
● Succinyl CoA (4C) is converted to
succinate (4C).
● Bond attaching coenzyme A to succinate is
unstable
● Breakdown of succinyl coenzyme A is
coupled to phosphorylation of GDP to
form GTP
(energy released during removal of CoA is
then used by GDP to combine with Pi that
comes from matrix to form GDP).
● GTP transfers its phosphate group to ADP,
yielding ATP through Substrate Level
Phosphorylation.
STEP 6:OXIDATION
● Succinate (4C) is oxidized to fumarate (4C)
● by transferring two hydrogen atoms to
FAD.
● FAD is reduced to FADH2

STEP 7: HYDRATION
● With addition of water, fumarate (4C)
rearrange its chemical bond and is
converted to malate (4C).
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STEP 8:OXIDATION
● Malate (4C) is oxidized to oxaloacetate
(4C).
● By transferring 2 hydrogen atoms to NAD+
● NAD+ is reduced to NADH + H+
● Oxaloacetate can now combine with
another molecule of acetyl coenzyme A,
and starts new cycle .

*Mention the steps where the energy and ATP,NADH and FADH2 are produced.
Fill in the blanks with appropriate answers.

Events Steps Name of the process

Production of NADH STEP 3 Oxidation and Decarboxylation

STEP 4 Decarboxylation and Oxidation
STEP 8 Oxidation
Production of FADH2 STEP 6 Oxidation
Production of ATP STEP 5 Oxidation
Removal of CO2 STEP 3 & 4 Substrate Level Phosphorylation
.

Glycolysis produce 2 pyruvate

Link reaction produce 2 Acetyl Co A
Input Output
ONE Acetyl Co A enters 3 NADH
Krebs Cycle 1 FADH2
2 CO2
1 ATP
BUT guys..... 6 NADH
Krebs cycle needs 2 Acetyl 2 FADH2
Co A, so how many 4 CO2
molecules of NADH, FADH2, 2 ATP
CO2 and ATP are
produced?
*Total ATP produced should be justified
 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION

5.1.3: Oxidative Phosphorylation: Electron Transport Chain (ETC) and Chemiosmosis

Introduction
Definition Of Oxidative Phosphorylation
The production of ATP using energy derived from the redox reactions of an electron
transport chain
Occurrs in the mitochondria and chloroplast

a) Electron Transport Chain (ETC)

● Definition Of ETC
⮚ Series of electron carrier

⮚ embedded in inner membrane of mitochondria

⮚ carry electron from NADH and FADH2 during redox reaction

⮚ to synthesis ATP

⮚ Location: inner membrane of mitochondria

 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION
a) Component of ETC: Consists of a chain of electron carrier and an electron
acceptor
Fill in the spaces below to complete the name of each of components (electron
carrier and electron acceptor) that makes up the ETC.
Component Full Name Explanation
− Flavoprotein (conjugated protein)
i. Complex I: NADH contain iron & sulphur
dehydrogenase
− Accept 2 e- from NADH

ii. Complex II: Succinate

dehydrogenase − Accept 2 electrons from FADH2
− Hydrophobic molecules
Coenzyme Q / − Mobile within the phospholipid
iii. CoQ: Ubiquinone − Non-protein carrier
− Accept 2 e- from complex I & II
iv. Complex III: Cytochrome − Accept 2 e- from CoQ
reductase
− Protein component and mobile carrier
v. Cyt.c: Cytochrome c − Accept 2 e- from cemplex III and pass
to complex IV
vi. Complex IV: CytochromeC − Accept 2 e- from cyt C
oxidase
− Final electron acceptor
vii. Electron Oxygen
acceptor: − Accept 2H+ from matrix and 2 e- to
form H2O
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b) Chemiosmosis
Definition Of Chemiosmosis:
● Movement of hydrogen ion (H+)
● From high hydrogen ion concentration into low hydrogen ion
concentration
● From intermembrane space to the mitochondrial matrix
● through ATP Synthase
● to catalyze the synthesis of ATP from ADP and inorganic phosphate
Location: Innner membrane and matrix of mitochondria
 BIO - ACTIVE LEARNING – CELLULAR RESPIRATION & FERMENTATION
Total Production of ATP in Active Cells (per one molecule of glucose)
1. Substrate Level Phosphorylation;
Glycolysis 2 ATP
Krebs Cycle 2 ATP
2. Oxidative Phosphorylation
Glycolysis 2 NADH + 2 H+ x 3 ATP 6 ATP
Link Reaction 2 NADH + 2 H + x 3 ATP 6 ATP
Krebs Cycle 6 NADH + 6 H+ x 3 ATP 18 ATP
2 FADH2 x 2 ATP 4 ATP
TOTAL 38 ATP
5.2 : FERMENTATION AND ITS APPLICATIONS

Introduction
Definition Of Anaerobic Respiration
A type of respiration where organic molecules are partially oxidized in the absence of oxygen
Produces small amount of energy
Definition of Fermentation
The process in which pyruvic acid/ pyruvate is converted into lactate/lactic acid or
ethanol and carbon dioxide in the absence of oxygen.

a) Fermentation
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⮚ Involve glycolysis = Breaking down of glucose

⮚ Without ETC = Generate ATP by substrate level phosphorylation
⮚ Produce ethanol (in plant) or lactic acid / lactate (in animal) as end product
⮚ Involve regeneration of NAD+
⮚ Location: cytosol

i. Alcohol Fermentation

a. Complete the table below to describe about alcoholic fermentation:

Alcoholic Fermentation: Conversion of pyruvate to ethanol and CO2
Occur in Plants, yeast, bacteria
Substrate Pyruvate
Products Ethanol @ ethyl alcohol, CO2, NAD+
Total ATP 2
Location Cytosol
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ii. Lactate Fermentation

b. Complete the table below to describe about lactate fermentation:

Lactate Fermentation: Conversion of pyruvate to lactate
Occur in Active cell that derived of oxygen.
Example of cell: Muscle cell
Substrate Pyruvate
Products Lactate @ lactic acid, NAD+
Total ATP 2
Enzyme Lactate dehydrogenase
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c. List down similarities between Alcoholic and Lactate Fermentation

d. Differenciate between Alcohol and Lactate Fermentation:

ALCOHOL FERMENTATION LACTATE FERMENTATION
Produce ethanol Produce lactic acid/lactate
Carbon dioxide is removed No carbon dioxide is removed

b) Importance of Fermentation
Importance of fermentation in industry
Bakery ● Addition of yeast to dough. Release CO2, rising bread and
soften texture
Dairy industry ● Lactate fermentation by Lactobacillus sp.
● Convert lactose to lactate
● Lower pH of milk
● Causing coagulation of protein forming yogurt
Vinegar, beverage ● Wine: alcoholic fermentation of yeast in grapes
and alcohol ● Beer: alcoholic fermentation of yeast on maltose (barley
production seeds)
Local examples ● Tempe, Thosai, tapai