Chapter 9 Teacher Lecture Flashcards
In the absence of oxygen, cells can undergo_______ to produce energy.
fermentation or anaerobic respiration
There are two main types of fermentation/anaerobic respiration:
Lactic Acid Fermentation
Alcohol Fermentation
______ Fermentation (in animals and some bacteria):
Pyruvate is converted into ______.
NADH is oxidized back to NAD+, allowing glycolysis to continue.
This process occurs in muscle cells during intense exercise when oxygen is scarce.
lactic acid
_____ Fermentation (in yeast and some microbes):
Pyruvate is converted into ____ and _____.
NADH is oxidized to regenerate NAD+.
Alcohol, ethanol and carbon dioxide
Why do we need to breathe in oxygen?
Oxygen acts as the final electron acceptor in the electron transport chain (ETC), which is the last step of cellular respiration.
The ETC would stop working.
ATP production would drop drastically.
Cells would switch to fermentation, which only produces a small amount of ATP.
In tissues that can’t rely on fermentation for long, like the brain and heart, oxygen deprivation can quickly lead to damage.
_____ is the ability to do work or cause change
Energy
-All cells and organisms require a consistent supply of usable energy.
-Energy is not always available for cells to use.
An energy source that is used by photosynthetic organisms (e.g., plants, algae, some bacteria)
Light Energy. It then produces chemical energy.
An energy source that is used by non-photosynthetic organisms (e.g., animals, fungi) via food intake.
Chemical energy turns into chemical energy to use
True or False: Not all organisms can use both light and chemicals.
True
Cells take environmental energy (light or chemicals), process it through metabolic pathways, and convert it into _____, the primary energy currency.
ATP
Reactions where electrons are moved from one substance to another.
Redox Reactions (Oxidation-Reduction Reaction)
Reaction that transfers electrons between molecules
Oxidation-Reduction Reaction
Molecule that gives electrons to another substance.
Lose Electron ______
Electron Donor, Reducing Agent, Oxidation
Molecule that receives electrons.
Gain Electron _____
Electron Acceptor, Reduction
“OIL RIG”
Oxidation Is Loss (electrons), Reduction Is Gain (electrons).
molecule that loses its electrons and is oxidized.
Reducing Agent
Molecule that gains electrons and is reduced.
Oxidizing agent
Electron loss; the molecule is the reducing agent and is oxidized.
Oxidation
Electron gain; the molecule is the oxidizing agent and is reduced
Reduction
Oxidation & Reduction always occur
together
When glucose donates electrons to NAD+ creating NADH, the glucose molecule becomes
Oxidized
Organelles that are used for most ATP production in animals and protozoa
Mitochondria
Aerobic Cellular Respiration occurs in ____ stages, most of which occur inside the _____.
It is ____ -dependent.
three (four according to textbook), mitochondria, oxygen
What is a by-product of cellular respiration?
Water
-Double-membrane system organelles in eukaryotic cells.
-Inner Membrane: Site of ATP production.
Mitochondria
2 ATP Production Pathways
-Aerobic Respiration: Oxygen-dependent, main focus.
-Fermentation: Oxygen-independent, secondary process. (Humans can do it for a short period of time).
Breakdown of an organic, energy-rich molecule (usually glucose) to produce ATP, using oxygen as the final electron acceptor.
Aerobic Respiration
-Extract electrons/hydrogens from organic molecules, produce ATP, and release CO₂ and H₂O as waste.
-Generate ATP
Aerobic Respiration
Requirements for Aerobic respiration::::
Electron Donor(s):.
Electron Acceptor:.
Various Enzymes: Catalyze reactions. Used to breakdown _____, move_____, and create _____.
Electron Donor(s): Usually organic molecules, most common glucose (a sugar).
Electron Acceptor: Oxygen.
Various Enzymes: Catalyze reactions. Used to breakdown glucose, move electrons, and create ATP.
The overall chemical equation for Aerobic Cellular Respiration is a ____ reaction.
By the end of the process, glucose is ____ while oxygen is _____
redox, oxidized, reduced
Four stages of Aerobic Cellular Respiration in order
(Giant Pandas Killed Einstein)
Glycolysis, Pyruvate Oxidation, Kreb’s Cycle, Electron Transport Chain & Chemiosis
Glucose has___carbon atoms, all of which end up being converted to CO₂ in the 2nd & 3rd steps of respiration.
□ ONLY step that occurs outside mitochondria (in the cell’s ____) & does ___ require Oxygen.
Glucose has 6 carbon atoms, all of which end up being converted to CO₂ in the 2nd & 3rd steps of respiration.
□ ONLY step that occurs outside mitochondria (in the cell’s cytoplasm) & does not require Oxygen.
Glycolysis occurs ____ the mitochondria in the ____ of the cell.
It breaks down glucose into two molecules of _____. After glycolysis, the ____ molecules enter the mitochondria if oxygen is present, where the next steps of cellular respiration (Krebs cycle and Electron Transport Chain) occur.
Glycolysis occurs outside the mitochondria in the cytoplasm of the cell.
It breaks down glucose into two molecules of pyruvate. After glycolysis, the pyruvate molecules enter the mitochondria if oxygen is present, where the next steps of cellular respiration (Krebs cycle and Electron Transport Chain) occur.
Where does the first stage of aerobic cellular respiration take place within a cell?
the cytoplasm of the cell
Glycolysis consists of a series of 10 reactions, which can be grouped into 2 phases:
**Energy Investment Phase: requires an input of energy by using __ATP molecules.
**Energy Harvest Phase: produces energy by forming __ NADH & __ ATP molecules.
Glycolysis consists of a series of 10 reactions, which can be grouped into 2 phases:
Energy Investment Phase: requires an input of energy by using 2 ATP molecules. Energy Harvest Phase: produces energy by forming 2 NADH & 4 ATP molecules.
Net products from 1 single glucose molecule = __ pyruvate, __NADH, & __ ATP molecules.
□ __ pyruvates are transported to the mitochondrial matrix for the next step of cellular respiration (Krebs cycle).
Net products from 1 single glucose molecule = 2 pyruvate, 2 NADH, & 2 ATP molecules.
□ 2 pyruvates are transported to the mitochondrial matrix for the next step of cellular respiration (Krebs cycle).
Ending molecule(s): Glycolysis Net Gain:
2 ATP (4 produced, 2 invested).
2 NADH (energy carriers).
2 Pyruvate (3-carbon sugar molecules).
+Extra water and hydrogens
Ending molecule(s): Glycolysis Net Gain:
__ATP (4 produced, 2 invested).
__ NADH (energy carriers).
__ Pyruvate (3-carbon sugar molecules).
+Extra water and hydrogens
Ending molecule(s): Glycolysis Net Gain:
2 ATP (4 produced, 2 invested).
2 NADH (energy carriers).
2 Pyruvate (3-carbon sugar molecules).
+Extra water and hydrogens
Process of Glycolysis (Lecture):
Process:
1. Glucose is brought into the cell
2. Glucose is phosphorylated (__ ATP invested).
Once phosphorylated, the enzyme comes along and splits into two 3-carbon molecules: glyceraldehyde-3-phosphate (G3P).
G3P undergoes reactions to produce the ending molecules…
Process:
Glucose is brought into the cell
Glucose is phosphorylated (2 ATP invested).
Once phosphorylated, the enzyme comes along and splits into two 3-carbon molecules: glyceraldehyde-3-phosphate (G3P).
G3P undergoes reactions to produce:
In Glycolysis, __ATP are used during Energy Investment, __ATP are used during Energy Harvest, and the Net Produced is __ATP.
Additionally it produces __NADH and __ pyruvate molecules.
2, 4, 2, 2, 2
Which of the following is a result of glycolysis?
a) A net gain of four ATP per one glucose molecule. b) Conversion of FAD to FADH₂. c) Conversion of one glucose molecule to two pyruvate molecules. d) Conversion of NADH to NAD+.
c) Conversion of one glucose molecule to two pyruvate molecules.
Starting with one molecule of glucose, glycolysis results in the net production of what sets of energy-containing products?
2 NADH, 2 pyruvate, and 2 ATP.
Glycolysis results in _____ pyruvate molecules, which are then transported to the ______________.
2, mitochondrial matrix
Pyruvate Oxidation: 2nd step of cellular respiration that converts each pyruvate into a molecule of _________.
□ Occurs in mitochondrial matrix & produces ___ acetyl-CoA, ____ NADH, & ____ CO2 molecules (per 1 glucose).
Acetyl-CoA.
Occurs in the mitochondrial matrix & produces 2 acetyl-CoA, 2 NADH, & 2 CO₂ molecules (per 1 glucose).
Each pyruvate is converted into __ Acetyl-CoA, releasing __ CO₂ and producing __ NADH.
Each pyruvate is converted into 1 Acetyl-CoA, releasing 1 CO₂ and producing 1 NADH.
Pyruvate oxidation occurs in the _______ _______. Glycolysis occurs in the _____, but once pyruvate is formed, it moves into the ______ for oxidation.
Pyruvate oxidation occurs in the mitochondrial matrix, not in the cytoplasm. Glycolysis occurs in the cytoplasm, but once pyruvate is formed, it moves into the mitochondria for oxidation.
During pyruvate oxidation:
Each pyruvate is converted into \_\_\_\_\_\_\_. NAD+ is reduced to \_\_\_\_\_\_.
___is released as a by-product.
During pyruvate oxidation:
Each pyruvate is converted into Acetyl CoA. NAD+ is reduced to NADH. CO₂ is released as a by-product.
Kreb’s Cycle/Citric Acid Cycle Process:
*Pyruvate oxidation with coenzyme-A forms acetyl-CoA, releasing CO₂.
Acetyl-CoA enters a reaction cycle, producing: high amounts of __ and ___.
Minor ATP (not primary goal).
Ending molecule(s):
___ &____
___
Process:
Pyruvate oxidation with coenzyme A forms acetyl-CoA, releasing CO₂.
Acetyl-CoA enters a reaction cycle, producing:
Produces high amounts of NADH and FADH₂.
Minor ATP (not primary goal).
Ending molecule(s):
NADH &FADH₂
CO2
Kreb’s Cycle (Citric Acid Cycle/Tricarboxylic Acid Cycle):
Location:_____.
Starting Molecule: _____.
Purpose:
**Use energy from ____ to make ____
**Extract electrons to produce _____ for the next stage.
Kreb’s Cycle (Citric Acid Cycle/Tricarboxylic Acid Cycle):
Location: Mitochondrial matrix.
Starting Molecule: Pyruvate.
Purpose: Use energy from pyruvate to make NADH
Extract electrons to produce NADH/FADH₂ for the next stage.
●______________ Cycle: 3rd stage of aerobic cellular respiration; also known as the Citric Acid Cycle & the TCA Cycle.
□ Oxidizes acetyl-CoA producing energy in the form of ATP, NADH, & FADH2.
Kreb’s
●Krebs Cycle consists of a series of multiple reactions, which can be grouped into _____ phases:
a) Acetyl-CoA Entry: 2 carbons of Acetyl-CoA enter & react with oxaloacetate, producing _____________.
□ NOTE: “CoA” does __________ enter the Krebs Cycle (just the _____ carbons enter).
b) Citrate Oxidation: Rearrangement & _________________ of citrate.
□ Produces of 1 ATP & 2 NADH, & 2 CO2 molecules.
c) Oxaloacetate Regeneration: _____________________ of oxaloacetate by oxidation.
□ Produces 1 NADH & 1 FADH2 molecule.
●______ rounds of the Krebs Cycle occur for every 1 glucose molecule (1 round of Krebs Cycle per acetyl-CoA).
Krebs Cycle consists of a series of multiple reactions, which can be grouped into 3 phases:
a) Acetyl-CoA Entry: 2 carbons of Acetyl-CoA enter & react with oxaloacetate, producing citrate.
□ NOTE: “CoA” does _
Not enter the Krebs Cycle (just the 2 carbons enter).
b) Citrate Oxidation: Rearrangement & oxidation of citrate.
□ Produces of 1 ATP & 2 NADH, & 2 CO2 molecules.
c) Oxaloacetate Regeneration: regeneration of oxaloacetate by oxidation.
□ Produces 1 NADH & 1 FADH2 molecule.
●2 rounds of the Krebs Cycle occur for every 1 glucose molecule (1 round of Krebs Cycle per acetyl-CoA).
Stage 3 or 4: ____:
*Produces most __.
*Location: Inner mitochondrial membrane.
Starting Molecules: NADH and FADH₂.
*Purpose: Use electrons and hydrogens (protons) from NADH to make __
Stage 3: Electron Transport Chain (ETC):
Produces most ATP.
Location: Inner mitochondrial membrane.
Starting Molecules: NADH and FADH₂.
Purpose: Use electrons and hydrogens (protons?) from NADH to make ATP
●_______: 4th step of aerobic respiration; consists of mitochondrial inner-membrane proteins.
□ Harnesses energy of _________________ from NADH & FADH2 in a series of ______________ reactions.
□ ETC uses energy from electrons to generate a ______ gradient by pumping H+ into the intermembrane space. □ Final Electron Acceptor: the final molecule that accepts the ETC’s electrons is _________________ gas (O2).
□ When Oxygen gas (O2) serves as the final electron acceptor, it interacts with H+ to form water (H2O).
*electrons
*redox (Redox = reduction and oxidation reactions)
*proton
*oxygen
In the electron transport chain, the final electron acceptor is
oxygen
Oxygen (O₂) is the final electron acceptor in the electron transport chain (ETC).
It combines with electrons and protons (H⁺) to form water (H₂O).
The ETC’s primary function is to use electrons from NADH and FADH₂ (produced in glycolysis, pyruvate oxidation, and the Krebs cycle) to generate a ____ _____ for __ production.
The ETC’s primary function is to use electrons from NADH and FADH₂ (produced in glycolysis, pyruvate oxidation, and the Krebs cycle) to generate a proton gradient for ATP production.
ETC Process:
*NADH is produced in the Krebs cycle
*NADH moves to the inner mitochondrial membrane
*NADH donates electrons to ________ (redox reactions).
*Electrons move through carriers; ______ accumulate in the intermembrane space.
*Oxygen accepts electrons and _____, forming H₂O.
*_____ pass through ATP synthase (channel enzyme), driving ADP + Pi → ATP (chemiosmosis).
*Ending Molecule(s):
ATP & Water
*Total Yield: 1 glucose → 38 ATP (gross), 36 ATP (net, after 2 invested).
Process:
NADH is produced in the Krebs cycle
NADH moves to the inner mitochondrial membrane
NADH donates electrons to carrier proteins/metals (redox reactions).
Electrons move through carriers; hydrogens accumulate in the intermembrane space.
Oxygen accepts electrons and hydrogens, forming H₂O.
Hydrogens pass through ATP synthase (channel enzyme), driving ADP + Pi → ATP (chemiosmosis).
Ending Molecule(s):
ATP
Water
Total Yield: 1 glucose → 38 ATP (gross), 36 ATP (net, after 2 invested).
Chemiosmotic creation of ATP is driven by:
a) Phosphate transfer through the plasma membrane.
b) Potential energy of the H+ concentration gradient created by the electron transport chain.
c) Substrate-level phosphorylation in the mitochondrial matrix.
d) Large quantities of ADP in the mitochondrial matrix.
b) Potential energy of the H+ concentration gradient created by the electron transport chain.
______ refers to the movement of H⁺ ions across the mitochondrial inner membrane.
The electron transport chain (ETC) creates a ____ _____by pumping H⁺ ions into the intermembrane space.
The stored potential energy in this gradient drives ATP synthesis as H⁺ flows back into the matrix through ATP synthase.
Chemiosmosis refers to the movement of H⁺ ions across the mitochondrial inner membrane.
The electron transport chain (ETC) creates a proton gradient by pumping H⁺ ions into the intermembrane space.
The stored potential energy in this gradient drives ATP synthesis as H⁺ flows back into the matrix through ATP synthase.
The electron transport chain pumps H+ ions into which location of the mitochondria?
a) Mitochondrial intermembrane space. c) Mitochondrial inner membrane.
b) Mitochondrial matrix.
d) The H+ ions are pumped out of the mitochondria.
(a) Mitochondrial intermembrane space.
The ETC pumps H⁺ ions from the mitochondrial matrix into the ______ space, creating a high concentration of protons.
This forms the electrochemical gradient used to drive ATP production through ______.
The ETC pumps H⁺ ions from the mitochondrial matrix into the intermembrane space, creating a high concentration of protons.
This forms the electrochemical gradient used to drive ATP production through chemiosmosis.
The H+ gradient built by the ETC has tremendous potential energy that can be captured via _______.
The H+ gradient built by the ETC has tremendous potential energy that can be captured via chemiosmosis.
_______: The diffusion of ions across a membrane down their concentration gradient (high to low).
Chemiosmosis: The diffusion of ions across a membrane down their concentration gradient (high to low).
___ Synthase: An enzyme that facilitates chemiosmosis & synthesizes __.
ATP Synthase: An enzyme that facilitates chemiosmosis & synthesizes ATP.
_____ ______: ETC redox reactions & chemiosmosis power phosphorylation to make ATP.
Oxidative Phosphorylation: ETC redox reactions & chemiosmosis power phosphorylation to make ATP.
Without oxygen, aerobic cellular respiration ____ occur.
□ The ETC gets “backed up” (like a traffic jam) without O₂ as the final electron acceptor.
□ The amount of NADH ___ while the amount of NAD+ ____.
Without oxygen, aerobic cellular respiration cannot occur.
□ The ETC gets “backed up” (like a traffic jam) without O₂ as the final electron acceptor.
□ The amount of NADH increases while the amount of NAD+ decreases.
Process that uses the electrons from NADH to reduce pyruvate & regenerate NAD+.
Fermentation
Fermentation: process that uses the electrons from NADH to reduce ___________________ & regenerate NAD+.
□ Depending on the organism, pyruvate can be reduced to ________________ acid or __________________.
□ Makes very _________________ ATP, so only some unicellular organisms can survive on just fermentation.
□ Regeneration of NAD+ allows glycolysis to continue in the absence of Oxygen.
pyruvate
lactic acid
ethenol
Fermentation allows a cell to:
a) Recycle NADH to NAD+ for glycolysis.
c) Reduce NAD+ to NADH for glycolysis.
b) Use NADH as a terminal electron acceptor.
d) Synthesize ATP via ATP synthase.
(a) Recycle NADH to NAD+ for glycolysis.
●_____________ Acid Fermentation: pyruvate is reduced by NADH to form lactic acid/________________ & NAD+.
□ Occurs in human _________________ cells & in bacteria that gives yogurt its sour taste.
Lactic Acid Fermentation: Pyruvate is reduced by NADH to form lactic acid (or lactate) & NAD+.
□ Occurs in human muscle cells & in bacteria that give yogurt its sour taste.
●____________________ Fermentation: pyruvate is reduced by NADH to form ___________________ & NAD+.
□ Produces beer from barley & wine from grapes.
Alcoholic Fermentation: Pyruvate is reduced by NADH to form ethanol & NAD+.
□ Produces beer from barley & wine from grapes.
In both lactic acid fermentation and alcoholic fermentation, ___ is oxidized to __.
This allows glycolysis to continue by regenerating __, which is essential for the continued production of ATP in the absence of oxygen.
In both lactic acid fermentation and alcoholic fermentation, NADH is oxidized to NAD+.
This allows glycolysis to continue by regenerating NAD+, which is essential for the continued production of ATP in the absence of oxygen.
Which of the following describes a primary function of both lactic acid fermentation and alcohol fermentation?
a) Reduction of NAD+ to NADH.
c) Reduction of FAD to FADH2.
b) Oxidation of NADH to NAD+.
d) Hydrolysis of ATP to ADP.
(b) Oxidation of NADH to NAD+.
Fermentation
*Definition: ATP production without ___, using an _____ electron acceptor (typically pyruvate).
*Context: Used by humans during high activity (e.g., exercise) when ____ is scarce; not sustainable long-term.
Location: _____.
Fermentation
Definition: ATP production without oxygen, using an organic electron acceptor (typically pyruvate).
Context: Used by humans during high activity (e.g., exercise) when oxygen is scarce; not sustainable long-term.
Location: Cytoplasm.
___ is reduced to ___ during glycolysis, pyruvate oxidation, and the Krebs cycle.
NAD+, NADH
Fermentation Requirements:
*Electron Donor(s): ____ molecules, Usually glucose.
*Electron Acceptor: ____ molecule (____ in humans).
*Various Enzymes: Catalyze reactions.
Used to break down glucose, move electrons, and create ATP
Requirements:
Electron Donor(s): Organic molecules, Usually glucose.
Electron Acceptor: Organic molecule (pyruvate in humans).
Various Enzymes: Catalyze reactions.
Used to break down glucose, move electrons, and create ATP
Fermentation Process:
Glycolysis: Glucose → 2 pyruvate + 2 ATP + 2 NADH.
Stops after glycolysis; pyruvate is converted to:
____: In humans.
____: In some organisms (e.g., yeast).
*Purpose: Produce small ATP amounts (net __ATP) in low-oxygen conditions.
Process:
Glycolysis: Glucose → 2 pyruvate + 2 ATP + 2 NADH.
Stops after glycolysis; pyruvate is converted to:
Lactic Acid: In humans.
Alcohol: In some organisms (e.g., yeast).
Purpose: Produce small ATP amounts (net 2 ATP) in low-oxygen conditions.
The oxygen atom in the water molecules produced in aerobic respiration comes from __, which is the final electron acceptor in the electron transport chain (ETC). It combines with electrons and protons (H⁺) to form water (H₂O).
The oxygen atom in the water molecules produced in aerobic respiration comes from O₂(oxygen gas), which is the final electron acceptor in the electron transport chain (ETC). It combines with electrons and protons (H⁺) to form water (H₂O).
The complete oxidation of one molecule of glucose through aerobic cellular respiration generally produces __-__molecules of ATP.
*This includes ATP produced in glycolysis, pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation (ETC and chemiosmosis).
The complete oxidation of one molecule of glucose through aerobic cellular respiration generally produces 30-38 molecules of ATP.
Through the first three stages of cellular respiration only 4 ATP molecules have been produced from the initial glucose molecule. In which of the products of these stages is the potential energy to produce more ATP molecules stored?
a) The 6 molecules of CO2.
b) The H+ ions produced.
c) The 10 NADH and 2 FADH2 molecules.
d) The 4 molecules of ATP.
The 10 NADH and 2 FADH₂ molecules produced in the earlier stages of cellular respiration (glycolysis, pyruvate oxidation, and the Krebs cycle) contain high-energy electrons.
These electrons are used in the electron transport chain (ETC) to produce a significant amount of ATP through oxidative phosphorylation.
The energy stored in NADH and FADH₂ is what drives the production of ATP in the later stages of cellular respiration.
