Chapter 4.4, 4.5 Notes - Lake Central High School

Chapter 5 

Section 3 Cellular Respiration 

Objectives 

• Summarize how glucose is broken down in the first 

stage of cellular respiration. 

• Describe how ATP is made in the second stage of 

cellular respiration. 

• Identify the role of fermentation in the second stage 

of cellular respiration (next class) 

• Evaluate the importance of oxygen in aerobic 

respiration. 

Chapter menu 

Resources 

Copyright © by Holt, Rinehart and Winston. All rights reserved.

New Vocabulary 

• Aerobic 

• Anaerobic 

• Glycolysis 

• Krebs Cycle 

• NADH 

• FADH 2 

• Fermentation 


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• What type of organic compounds are made during 

photosynthesis 

• Before organisms use the energy in organic 

compounds, they must convert this energy to 

_________ ATP during the process of _______________ 

cellular 

respiration 

__________________ 

all 

Sugars (carbohydrates) 

• Remember, ________ organisms respire…even 

plants 

expire 

• If they don’t respire, they ____________ 


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Oxygen 

• __________________ in the air you breathe makes 

the production of ATP more efficient, although some 

ATP is made ______________ without oxygen. 

• Metabolic processes that require oxygen are called 

___________________. 

aerobic 

• Metabolic processes that do not require oxygen are 

called _______________, anaerobic which means “without air. 


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• In the process of 

cellular respiration, 

__________________ 

glucose 

is broken down to 

produce 

____________ energy within 

__________________ 

a mitochondrion 


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Structure of the mitochondrion 

2 

• _____ membranes 

• Inner membrane is 

_________ folded 

• Space between the two 

membranes is called 

the ______________ 

intermembrane 

space 

• Space inside the inner 

membrane is called the 

mitochondrial 

____________ matrix 

matrix 

Intermembrane space 


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• The equation for cellular respiration is… 

C 6 H 12 O 6 + 6O 2 

6CO 2 + 6H 2 O + ATP 

Which reactant is needed for cellular respiration to be 

efficient 

oxygen 

In addition to energy, what other products are made 

Carbon dioxide, water 


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The Stages of Cellular Respiration 

• Cellular respiration occurs in three main stages: 

Stage 1 Glycolysis: occurs in the ______________ 

Stage 2 Krebs Cycle: occurs in the _____________ 

_________ matrix 

Stage 3 Electron Transport Chain: occurs along the 

folded __________ membrane 

inner 

cytoplasm 

mitochondrial 


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Glycolysis 

• Process in which ___________ is 

broken down into ____________ pyruvates 

or _____________ pyruvic acid 

• Occurs in the ______________ 

• Does _____ need oxygen! 

• 4 steps 

not 

glucose 

cytoplasm 


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Glycolysis: Step 1 

2 

• _____ ATP jumpstart 

glycolysis 

2 

• ____ phosphates from ATP 

join __________ glucose to form an 

unstable 6-carbon 

compound 


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• This unstable 6-carbon 

compound immediately 

breaks into ____ 2 

3-carbon compounds 

called ___________ PGAL 


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• As glucose is broken 

down some of its 

___________ hydrogen atoms join 

_________ NAD + to form 

__________, NADH which is an 

energy storing molecule 

• The hydrogen atoms are 

replaced by two more 

__________ phosphate groups 


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• The ____ 4 phosphates bond 

with 4 molecules of ADP to 

make 4 _______ ATP molecules 

• The remaining products are 

two 3-carbon pyruvates, 

which are ions of 

___________ pyruvic ________ acid 

• Remember that 2 ATP are needed to start the process, 

so glycolysis produces a net gain of ______ 2 ATP 


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Entering the Mitochondria 

• The 3-carbon pyruvates are small enough to 

___________ diffuse through the mitochondrial membranes, 

where they are each broken down into…. 

– One ________ CO 2 

– One 2-carbon compound called an ___________ acetyl 

____________ group 


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• This process releases another hydrogen atom which 

joins NAD + to make one more molecule of 

__________ NADH 

• The acetyl group is attached to a molecule called 

______________, Coenzyme A (______) CoA forming the compound 

_________________ 

Acetyl-CoA 


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• Each acetyl CoA enters the _________ Krebs cycle to start 

stage 2 of cellular respiration 

– It turns __________, twice once for each acetyl CoA 

– This cycle is name after ___________________, 

Hans Krebs 

the scientist who discovered it 

– Occurs in ____ 4 main steps 


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Stage Two: Krebs Cycle (Step 1) 

• Acetyl-CoA 

enters the Krebs 

cycle by joining 

a 4-carbon 

compound 

called 

_____________ 

oxaloacetic 

_____________ 

acid 


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• The new 6-carbon 

compound is called 

_____________ citric 

___________ acid 

• Since this is the 

first product of the 

Krebs cycle, it also 

often called the 

_____________ citric 

_________ acid cycle 


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CO 2 

5 

• _____ is released 

from citric acid, 

resulting in a ___ 

carbon compound 


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CO 2 

4 

• _____ is released 

from the 5-carbon 

compound, forming 

a ____ carbon 

compound 

• So how many 

molecules of CO 2 

are made during 

the Krebs cycle 

2, but it turns 

twice so 4 


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• The 4-carbon 

compound is 

_____________, 

rearranged 

making 

oxaloacetic acid 

available for the 

cycle again 


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• This cycle also 

makes energy 

storing 

compounds… 

– ____ 3 NADH 

– ____ 1 ATP 

– ____ 1 FADH 2 

• Remember that the 

cycle turns twice, 

so it is really… 

– ____ 6 NADH 

– ____ ATP 

– ____ 2 FADH 2 

2 


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Stage Three: Electron Transport Chain 

• _________ NADH and ________ FADH 2 carry high energy 

_________ electrons to the inner membrane of the 

mitochondria, where they pass through an 

______________ electron _____________ transport chain 


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• The energy released from the moving electrons is 

used to pump _____________ hydrogen ions from 

mitochondrial matrix to the _______________ intermembrane space 


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• This creates a build-up of hydrogen ions which will 

_____________ diffuse through the ATP _____________ 

synthetase 

pump, producing __________ large amounts of ATP 


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• As the diffusion of water is called osmosis, the 

diffusion of chemicals, like H + , is called 

___________________ 

chemiosmosis 


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• The last molecule in the electron transport chain to 

receive an electron is oxygen gas _______. O 2 It binds 

with hydrogen ions to make _________ H 2 O 


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• Without ___________, oxygen the electron transport chain 

cannot pass along electrons and it easily gets 

_________ blocked or clogged up 


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• This is why oxygen is so essential for most 

organisms…without it the electron transport chain will 

_____ stop working and _____ ATP will no longer be produced 


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• The process of making large amounts of ATP in the 

electron transport chain is called ______________ 

oxidative 

______________________ 

phosphorylation 

– Oxidation results when ___________ electrons are lost or 

donated to other molecules 

• Electrons are _________ passed from molecule to 

molecule in the electron transport chain 

– Phosphorylation occurs when a ____________ phosphate 

group is added to a molecule 

• Phosphates are added to _____ ADP 


Resources 


• Summary of ATP made during cellular respiration 

– Glycolysis = ____ 2 ATP 

– Krebs Cycle = ____ 2 ATP 

– Electron Transport Chain = ____ 32 ATP to ___ 34 ATP 

– Total… = ____ 36 ATP to ___ 38 ATP 


Resources 


Question 1 

• What substance is broken down during cellular 

respiration 

A. CO 2 (carbon dioxide) 

B. H 2 O (water) 

C. O 2 (oxygen) 

D. C 6 H 12 O 6 (glucose) 


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Question 2 

• Why must glucose be converted to 2 pyruvates in 

the cytoplasm, before these molecules cross 

through the mitochondrial membranes 

Glucose is too big to diffuse across 

the membranes 


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Question 3 

• What is the first compound made during the Krebs 

cycle 

A. Oxaloacetic acid 

B. Citric acid 

C. Acetyl CoA 

D. pyruvate 


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Question 4 

• Which energy storing compound is not made during 

the Krebs cycle 

A. ATP 

B. NADH 

C. NADPH 

D. FADH 2 


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Question 5 

• Which molecule is necessary to prevent the electron 

transport chain from becoming clogged or backed 

up 

A. CO 2 (carbon dioxide) 

B. H 2 O (water) 

C. O 2 (oxygen) 

D. C 6 H 12 O 6 (glucose) 


Resources

Chapter 4.4, 4.5 Notes - Lake Central High School

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