Download Cellular Respiration Chapter 9

CELLULAR RESPIRATION
CHAPTER 9
9-1 Chemical Pathways
Chemical Energy and Food
PHOTOSYNTHESIS
6 CO
6H O
2 + _________
2
___________
+ ___________
C6H12O6 + __________
6O2
→_______________
CELLULAR RESPIRATION
C6H12O6 + _________
6O2
_____________
6 CO2 + __________
6 H2O + __________
→________
The two equations are exact opposites!
Comparing Photosynthesis &
Cellular Respiration:
• Which type(s) of organisms carry out
photosynthesis?
Autotroph
Heterotroph
• Which type(s) of organisms carry out cellular
respiration?
Autotroph
Heterotroph
Overview of Cellular Respiration
• Cellular respiration is the process that releases
energy from food in the presence of oxygen.
• If oxygen is available, organisms can obtain
energy from food by a process called cellular
respiration.
• The summary of cellular respiration is presented
below.
6 O2 + C6H12O6  6 CO2 + 6 H2O + Energy (ATP)
Structure of the Mitochondria:
Chemical Energy and Food
• Cellular respiration happens slowly and in
many steps.
• If all the energy was release in one step…
Most would be lost as light and heat!
• Cellular respiration breaks down glucose molecules and
banks their energy in ATP
Chemical Energy and Food
• Amount of heat it takes
to raise 1 gram of water
1o Celsius = calorie
• Unit for measuring
energy in food = Calorie
• 1 Calorie = 1 kilocalorie
= 1,000 calories
Comparing Photosynthesis & Cellular Respiration
Photosynthesis
Cellular Respiration
Function
Produces food (chemical
energy) for the plant
(glucose C6H12O6)
Produces chemical energy
(ATP) for the cell
Location
Chloroplast
Mitochondria
Reactants
Water (H2O),
Carbon dioxide (CO2)
and sunlight
Oxygen (O2) and
Glucose (C6H12O6)
Products
Oxygen (O2) and
Glucose (C6H12O6)
Water (H2O),
Carbon dioxide (CO2)
and energy (ATP)
Energy Consumption - Virtual Cell Animation (4:41)
H2O
Compare
Photosynthesis
to Cellular
Respiration
CO2
Chloroplast
Light Energy
NADP+
ADP + P
LIGHT
REACTIONS
(in thylakoids)
CALVIN
CYCLE
(in stroma)
ATP
NADPH
How Cells Obtain Energy (14 min)
O2
NADH
High-energy
electrons
carried by
NADH
NADH FADH2
and
CITRIC
ACID
CYCLE
GLYCOLYSIS
Glucose
Pyruvate
OXIDATIVE
PHOSPHORYLATION
(Electron Transport
and Chemiosmosis)
Mitochondrion
Cytoplasm
ATP
Substrate-level
phosphorylation
CO2
ATP
CO2
Substrate-level
phosphorylation
ATP
Oxidative
phosphorylation
Sugar (C6H12O6)
An Overview
of Cellular
Respiration:
Stages of Cellular Respiration
The three main
stages of cellular
respiration are
1. Glycolysis
2. Krebs cycle
3. Electron transport
chain.
Oxygen and Energy
• Glycolysis is an ANAEROBIC
processes. It does not directly
require oxygen, nor does it
rely on an oxygen-requiring
process to run.
• Glycolysis is still considered
part of cellular respiration.
• Glycolysis takes place in the
cytoplasm of a cell.
Glycolysis Overview - Virtual Cell Animation (3:00)
Oxygen and Energy
• Pathways of cellular respiration
that require oxygen are called
AEROBIC.
• The Krebs cycle and electron
transport chain are both aerobic
processes.
• Both processes take place inside
the mitochondria.
Citric Acid Cycle An Overview (3:17)
Electron Transport Chain (3:48)
Overview of Cellular Respiration
Occurs in three main stages:
Stage 1
Stage 1: Glycolysis
•
•
Occurs in the cytoplasm
Breaks down glucose into
pyruvate, producing a small
amount of ATP
Stage 2
Stage 2: The Citric Acid Cycle
(Krebs cycle)
•
•
•
Takes place in the mitochondria
Stage 3
Completes breakdown of
glucose, produces a small
amount of ATP
Provides third stage of cell
respiration with electrons
Overview of Cellular Respiration
Stage 3: Oxidative
phosphorylation (ETC)
• Occurs in the
mitochondria
• Uses the energy
released by “falling”
electrons to pump H+
across a membrane
• Harnesses the energy of
the H+ gradient through
chemiosmosis,
producing ATP
Stage 3
Understanding Oxidation and Reduction
•Oxidation is the loss of electrons; electrons are removed
from hydrogen atoms contained in glucose.
•Reduction is the gain of electrons; oxygen atoms accept
hydrogen and electrons forming water H2O.
• Remember:
• OIL RIG (Oxidation Is Loss, Reduction Is Gain)
• LEO the lion goes GER (Lose Electrons – Oxidation)
(Gain Electrons – Reduce)
Electron Carriers (enzymes) Involved
•NAD+ (Nicotinamide adenine dinucleotide)
Accepts H+ to become NADH
•FAD (Flavin adenine dinucleotide)
Accepts 2H+ to become FADH2
Overview of Cellular Respiration
NADH
High-energy electrons
carried by NADH
NADH
FADH2
and
Stage 1
Stage 3
Stage 2
OXIDATIVE
PHOSPHORYLATION
(Electron Transport
and Chemiosmosis)
GLYCOLYSIS
Glucose
CITRIC ACID
CYCLE
Pyruvate
Krebs
Mitochondrion
Cytoplasm
ATP
Substrate-level
phosphorylation
CO2
CO2
ATP
ATP
Substrate-level
phosphorylation
Oxidative
phosphorylation
9.2 Glycolysis
•
•
•
•
(Glykos = sweet, Lysis = split apart)
The first step in cellular respiration = Glycolysis
Happens in the CYTOPLASM outside the mitochondria
Does not require oxygen, BUT it needs some energy to get
it started.
What molecule is going to supply the energy?
ATP
Glycolysis
________
↓
GLUCOSE
___________
ATP
→
PYRUVIC ACID
→ 2 _____________
↓
ATP
ATP
ATP
NADH
NADH
____________________ + _______________
PUT IN 2 ATP and GET BACK 4 ATP
Net gain of 2 ATP and 2 NADH
Glycolysis
• Produces pyruvic
acid (pyruvate – a 3
carbon compound)
• Cell needs to invest
some energy to get a
higher return (2 ATP
gained)
• Occurs quickly, in
miliseconds to
respond to increased
energy demand
Glycolysis Reactions - Virtual Cell Animation (5:00)
9-2 The Krebs Cycle and
Electron Transport
Mitochondria Structure
•Has a double membrane, with an intermembrane space
between the two layers.
•Cristae are folds of the inner membrane
•The matrix is the innermost compartment, which is filled
with a gel-like fluid.
•Krebs Cycle occurs in the matrix of the mitochondria.
The Krebs Cycle
Carbon dioxide is lost to the
atmosphere as waste
ATP can be used directly to
supply energy for the cell
High energy electron carriers
move into the ELECTRON
TRANSPORT CHAIN
The Krebs Cycle
• During the Krebs cycle, the 2nd
stage of cellular
respirationpyruvic acid
produced in glycolysis is
broken down into carbon
dioxide in a series of energyextracting reactions.
• The Krebs cycle is also known
as the citric acid cycle because
citric acid is the first compound
formed in this series of
reactions.
The Krebs Cycle
• Pyruvic acid enters the
mitochondria matrix
• Pyruvic acid is converted
into an intermediate 2
carbon molecule called
Acetyl-CoA before entering
the Krebs Cycle.
• The Krebs cycle breaks
down carbon compounds
into carbon dioxide (waste),
ATP, NADH, and FADH2
The Citric Acid Cycle The Reactions (4:13)
The Krebs Cycle
• Pyruvic acid
from glycolysis
enters the
matrix, the
innermost
compartment of
the
mitochondrion.
Kreb’s Cycle
• Pyruvic acid from
glycolysis enters the
matrix
• NAD+ accepts 2 highenergy electrons to form
NADH.
• One molecule of CO2 is
also produced.
• The remaining 2 carbon
atoms react to form acetylCoA.
Diagram by Riedell
The Krebs Cycle
• Acetyl-CoA
combines with a
4-carbon molecule
(oxaloacetic acid)
to produce citric
acid.
The Citric Acid Cycle The Reactions (4:13)
The Krebs Cycle
• Citric acid is broken down
into a 5-carbon compound
and then a 4-carbon
compound.
• Two molecules of CO2 are
released.
• The 4-carbon compound can
then start the cycle again by
combining with acetyl-CoA.
The Citric Acid Cycle The Reactions (4:13)
KREBS
CYCLE
Krebs Cycle Animation-(select #3)
KREBS CYCLE
PRODUCES
____
____
3
____
____
1
1
4
Electron Transport Chain
• Enzymes (protein complexes) for the electron
transport chain are located on the inner
mitochondrial membrane.
• Several complexes are called cytochromes.
Electron Transport Chain (3:48)
Electron Transport Chain
•Electrons from NADH and
FADH2 travel down the
electron transport chain,
between protein complexes to
oxygen (final electron
acceptor), which picks up H+
to form water
NADH
NAD
+
H
+
ATP

2e
+
Controlled
release of
energy for
synthesis of
ATP

2e
2
•Energy released by the redox
reactions is used to pump H+
into the space between the
mitochondrial membranes
H
1
+
2
H2O
Electron Transport Chain (2:00)
O2
Chemiosmosis
• In chemiosmosis, the H+ diffuses back through the
inner membrane through ATP synthase complexes.
• Drives the synthesis of ATP
H+
H+
H+
H+
+
Intermembrane
space
Inner
mitochondrial
membrane
.
H
H+
Protein
complex
H+
Electron
carrier
FADH2
Electron
flow
NADH
H+
H+
FAD
NAD+
H+
1O
+ 2 H+
2 2
+
Mitochondrial
matrix
ATP
synthase
H
H+
H2O
ADP
Electron Transport Chain
OXIDATIVE PHOSPHORYLATION
+
P
ATP
H+
Chemiosmosis
Fermentation
• Pyruvic acid moves to the next step
• If there is no oxygen = anaerobic
• If there is oxygen = aerobic
Fermentation
• Fermentation – process by which cells
release energy in the absence of oxygen
• Two types of fermentation:
• Alcoholic Fermentation
• Lactic Acid Fermentation
Alcoholic Fermentation
PYRUVIC
ACID +_____
_______
+
ALCOHOL
CO
NAD
2
→__________ + ______ + _____
• Happens when yeast makes bread dough rise, CO2
bubbles make air spaces in bread.
(Alcohol evaporates during cooking)
• Happens when:
• Yeast make beer
• Bacteria make wine
Lactic Acid Fermentation
PYRUVIC
ACID +_____
_______
+
LACTIC
ACID
NAD
→______________ + ________
• Happens in muscles during exercise when body can’t get
oxygen to tissues fast enough.
• Lactic acid builds up in muscles causing soreness.
• Bacteria use lactic acid fermentation to make:
yogurt, cheese, sour cream, pickles, sauerkraut, kimchi
The Totals
• Cellular Respiration (aerobic: with oxygen)
1 glucose
→
36 ATP
• Fermentation (anaerobic: without oxygen)
1 glucose
→
2 ATP
Respiration Questions
1.
2.
3.
4.
List the reactants and products of respiration
List the three steps (stages) involved in respiration
Name two electron carriers involved
What step produces the most ATP
Respiration Questions
•
1.
2.
3.
4.
In your group:
See if you can write the chemical equation for
respiration (inputs and outputs)
What is the organelle in cells that is “releasing”
energy during respiration?
What primary molecule is energy being
“released” from?
How is the sun indirectly involved in respiration?
Fermentation Questions
1.
2.
3.
4.
5.
6.
List two types of fermentation
List the reactants for both types of fermentation
List the products for fermentation used to brew beer
List the products for fermentation used to make
yogurt
What important molecule cycles back from
fermentation to keep glycolysis going?
What process starts fermentation?
Krebs Cycle
1.___________
2.___________
7.________
3.________
4.________
6.________
5.________
Electron Transport Chain (ETC)
H+
H+
H+
H+
+
Intermembrane
space
H
H+
Protein
complex
H+
Electron
carrier
.
H+
H+
ATP
synthase
Inner
mitochondrial
membrane
Electron
flow
FADH2
NAD+
NADH
Mitochondrial
matrix
FAD
H+
1
O2 + 2 H+
2
H+
H+
H2O
Electron Transport Chain
OXIDATIVE PHOSPHORYLATION
ADP
+
ATP
P
H+
Chemiosmosis
Cellular Respiration - Glycolysis, Krebs
Cycle, ETC (6:00)