Sponge: Set up Cornell Notes on pg. 71
Topic: 8.1 Intro to Cellular Respiration
Essential Question: How is cellular
respiration directly related to
photosynthesis?
BIOZONE: p. 116-124
due WED 2/4
8.1 Intro to Cellular Respiration
How is cellular respiration directly related to
photosynthesis?
Key Vocabulary:
Catabolic pathway
Anabolic pathway
Oxidation
Reduction
Mitochondria
Cellular Respiration
Chemical reactions carried out by an organism
• Anabolic pathways: result in the
synthesis of more complex
molecules from simpler ones
• Photosynthesis
• Building a sugar molecule
• Catabolic pathways: result in the
breakdown of complex molecules
to smaller molecules
• Cellular respiration
• Breaking down sugar molecules
Two general types of chemical reactions:
Oxidation and reduction
• Oxidation: is the loss of electrons or • Reduction: is the gain of electrons or
an increase in oxidation state by a
a decrease in oxidation
molecule, atom, or ion.
(reduce) state by a molecule, atom,
or ion.
Tree map
on P. 70
Oxidation vs Reduction – Add to tree map
Oxidation
Reduction
Loss of Electrons
Gain of Oxygen
Loss of Hydrogen
Results in many C-O (Carbonoxygen) bonds
Results in a compound with
LOWER potential energy
Gain of Electrons
Loss of Oxygen
Gain in Hydrogen
Results in many C-H (carbon-hydrogen)
bonds
Results in a compound with
HIGHER potential energy
Oxidation and reduction P.70
Oxidation
Reduction
Loss of electrons
Gain of electrons
Gain of Oxygen
Loss of Oxygen
Loss of hydrogen
Gain of hydrogen
Results in many C-O (carbon-oxygen) bonds
Results in many C-H (carbon-hydrogen) bonds
Results in a compound with lower potential energy
Results in a compound with higher energy
These two reactions occur together during chemical
reactions
• One compound’s or element’s loss is another compound or
element’s gain
• Because they always occur together, they are considered
redox reactions
• Plays a key role in the flow of energy through living systems
Energy
• Energy is a topic of discussion every day in our modern world
• IB students know what it is like to be tired and need a nap after a long day of
school
• We talk about being hungry all the time
• Cellular respiration allows us to release the chemical energy stored in
our food (glucose and other carbohydrates) to fuel all of our life
processes.
Cellular Respiration
• Organic molecules contain energy in their molecular structures
• Each covalent bond in glucose, amino acids or fatty acids represents
stored chemical energy
• When we burn wood in a fire, we are releasing that stored
chemical energy in the form of heat and light
• Burning is the release of chemical energy called rapid oxidation
• This is not controlled by enzymes and results in the breaking of
many, many covalent bonds in a very short period of time and thus a
nearly uncontrolled energy release
Mitochondria
• It is inside the mitochondria and in the presence of oxygen that the
majority of cellular respiration occurs
Mitochondria
• Supply energy to the cell “POWER HOUSE” of the cell
• Convert the molecules you eat into usable energy
• Rod shaped organelles that appear throughout the
cytoplasm
• Their size is close to that of a bacterial cell
• Have their own DNA
• Contains ribosomes
• Double-membrane
• Outer membrane is smooth
• Inner membrane is folded into cristae
• Inside the inner membrane is a semi-fluid called
matrix
Mitochondria
• Draw and label a diagram showing the structure of a mitochondrion
as seen in electron micrographs
Bottom
of P. 70
Mitochondria
• Draw and label a diagram showing the structure of a mitochondrion
as seen in electron micrographs
Cristae
Outer Membrane
(crista- singular)
Matrix
Inner Membrane
Cellular Respiration
• Cellular Respiration: Cells break down (metabolize) their organic nutrients
by way of slow oxidation (vs. rapid oxidation in the case of burning wood). The ultimate
goal of releasing energy in a controlled way is to trap the released energy
in the form of ATP molecules
Cellular Respiration
• A molecule, such as glucose is acted on by a series of enzymes which
catalyze a sequential series of reactions in which the covalent bonds
are broken (oxidized) one at a time
• As each covalent bond is broken a small amount of energy is released
• If a cell does not have glucose available, other organics molecule may be
substituted, such as fatty acids or amino acids
Cellular Respiration Equation
All organisms need to produce ATP for energy, so all organisms carry out
respiration
Crash Course: Cellular Respiration (0-4m13s)
https://www.youtube.com/watch?v=00jbG_cfGuQ
Sponge: Set up Cornell Notes on pg. 73
8.1 Cellular Respiration:
Glycolysis & Krebs Cycle
Topic: 8.1 Cellular Respiration: Glycolysis & Krebs
Cycle
Essential Question: None
BIOZONE: p. 116-124
due WED 2/4
Key Vocabulary:
Glycolysis
Krebs Cycle
Glycolysis in a nutshell
All cells begin the process of cell respiration of glucose the same way.
Glycolysis:
• Glucose enters a cell and floats in the cytoplasm
• Enzymes modify the glucose
• A series of reactions will split the 6-carbon glucose molecule into two 3carbon molecules called pyruvate
• Energy from the breaking of these bonds was used to form a small amount
of ATP
of pyruvate
c c c c c c
6-carbon glucose
2 ATP
Glycolysis
2 ADP
P
P
Fructose-1, 6-biphosphate
P
P
Glyceraldehyde-3-phosphate (G3P aka triose phosphate)
1 NAD+
1 NAD+
1 NADH
1 NADH
P
P
P
P
2 ADP
2ADP
2 ATP
2 ATP
Pyruvate
Pyruvate
Glycolysis
• Glycolysis means "sugar splitting"
• It uses no oxygen
• Occurs in the cytosol (cytoplasm) of
the cell
• No required organelles
• Occurs both in aerobic (oxygen) and
anaerobic (no oxygen) environments
• Occurs both in prokaryotic and
eukaryotic cells
Glycolysis: 1
• Two molecules of ATP are used
to begin glycolysis.
• Phosphorylation: The
phosphates from the ATPs
attach to the glucose to form
fructose-1, 6-biphosphate
*Remember when ATP (adenosine
triphosphate) loses a phosphate it
becomes ADP (adenosine diphosphate)
Glycolysis: 2
• Lysis “to unbind”: The 6-carbon
phosphorylated fructose is split
into two 3-carbon sugars called
glyceraldehyde-3-phosphate
(G3P aka triose phosphate)
Glycolysis: 3
• Each G3P molecule undergoes
oxidation to form a reduced
molecule of NAD+ into NADH.
• As NADH is being formed, released
energy is used to add an inorganic
phosphate to the remaining 3carbon compound
Glycolysis: 3
• Enzymes then remove the
phosphate groups so they can be
added to ADP to produce ATP
The end result is the formation of:
• 4 ATP molecules
• 2 NADH molecules
• 2 Pyruvate molecules
Krebs Cycle
• Once glycolysis has occurred and there is oxygen present, pyruvate
enters the matrix of the mitochondria via active transport
Pyruvate
c c c
o CO²
c o
c c
Acetyl CoA
The Krebs Cycle
CoA
(Occurs in Mitochondria)
NAD+
NADH
c c c c
Oxaloacetate
The Link Reaction
(occurs in mitochondria)
NADH
c c c c c c
Citrate 6c aka Citric acid
o CO²
c o
NAD+
NADH
NAD+
c c c c c
o CO²
c
o
FADH₂
FAD
NAD+
ATP
NADH
ADP + P i
c c c c
The Krebs cycle will run twice
for each glucose molecule
entering cellular respiration
• Once for each pyruvate
The Link Reaction
• Each pyruvate is decarboxylated
when it loses a carbon dioxide
molecule (released as a waste gas)
• The acetyl group is then oxidized
with the formation of reduced NAD+
• The acetyl group combines with
coenzyme A and becomes known as
acetyl-Coenzyme A (uh-C-tyl)
1.
• Acetyl CoA combines with a 4carbon compound called
oxaloacetate (oxa-lo-ass-itate)
• The result is a 6-carbon compound
known as citric acid
2.
• Citrate (6-carbon compound) is
oxidized (H+ lost) to form a 5-carbon
compound
• Decarboxylation: Carbon is released
from the cell as CO²
• While the 6-carbon compound is
oxidized, NAD+ is reduced to form
NADH (H+ added)
3.
• The 5-carbon compound is oxidized
(H+ lost) to form a 4-carbon
compound
• Decarboxylation: another carbon is
released from the cell as CO²
• Another NAD+ is reduced to form
NADH (H+ added)
4.
• The 4-carbon compound undergoes
various changes resulting in several
products:
• NAD reduced (H+) to NADH
• Coenzyme FAD reduced (H+) to
form FADH₂
• Phosphorylation: reduction of
an ADP to form ATP
5.
• The 4-carbon compound is changed
during step 4 to re-form the starting
compound of the cycle,
oxaloacetate
• The oxaloacetate may then begin
the cycle again!
PRODUCTS OF THE KREBS
CYCLE
• 2 ATP molecules
• 6 molecules of NADH (allow
energy storage and transfer)
• 2 molecules of FADH₂
• 4 molecules of carbon dioxide
(released)
****REMEMBER: The cycle
rotates twice!!!!!!
• So far, only 4 ATPs have been
gained (6 generated, but it
“costs” two to start glycolysis)
Crash Course: Cellular Respiration (4m13s-11m3s)
• https://www.youtube.com/watch?v=00jbG_cfGuQ
Sponge: Set up Cornell Notes on pg. 75
Topic: 8.1 Cellular Respiration: ETC
Essential Question: Compare the ETC to the
photosystems (II/I) in photosynthesis.
BIOZONE: p. 116-124
due TOMORROW
8.1 Cellular Respiration: ETC
Compare the ETC to the photosystems (II/I) in
photosynthesis.
Key Vocabulary:
Oxidative Phosphorylation
Oxidative Phosphorylation: ETC/ ATP synthase
Oxidative Phosphorylation: ETC/ ATP synthase
• The ETC is where most of the ATPs from glucose break down are
produced
• It is the first stage of CR where O² is actually needed
• Occurs on the inner mitochondrial membrane and on the membrane
of the cristae
• In this chain, electrons pass from one carrier to another because the
receiving molecule has a higher electronegativity (therefore a
stronger attraction) for electrons
• The source of the electrons are the coenzymes NADH and FADH₂
from the Krebs Cycle
Oxidative Phosphorylation: ETC/ ATP synthase
Cyt∙c
FMN
Q
Fe∙S
Electron Transport Chain
Oxidative Phosphorylation
1.
• Proteins inside the inner membrane of the
mitochondria take high energy electrons
from NADH and FADH₂
• NADH is oxidized to become
• NAD+
H+
e• Electrons enter the ETC into the
FMN protein
• FADH₂ is oxidized to become:
• FAD
H+
e• Electrons enter the ETC into the Fe∙S
protein
• Electrons will continue on to the Q electron
carrier (not a protein) which will take them
to the next protein in the chain
Electron Transport Chain
Inside of membrane
2.
• High energy electrons travel
through the proteins in the ETC
losing energy at each protein
• The proteins use energy from
the electrons as they are deenergized to pump the
hydrogen ions across the inner
membrane to produce a
chemiosmotic gradient
• The hydrogen ions build up on
the inside of the inner
membrane
Electron Transport Chain
3.
• Oxygen enters the cellular
respiration process as the final
electron acceptor in the ETC
• Water of metabolism: The O² picks
up electrons and 2 H+ (from the
aqueous surroundings of the matrix)
to form water
• The H²O molecules are given off as a
waste product
ATP Synthase
4.
• Energy is now available as a result of
the ETC
• Chemiosmosis: H+ diffuse through the
protein channel of the ATP synthase
back into the matrix
• As H+ move through ATP synthase, the
enzymes harness the available energy
allowing the phosphorylation of ADP
to ATP (adding of phosphates)
Products of Oxidative Phosphorylation
• H²O
• 32 ATP (approx.)
Cellular Respiration Overview
2
2
6
32
6
6
The Reactants of Cellular
Respiration
• Glucose (from Photosynthesis)
• O²
The Products of Cellular
Respiration
• CO²
• H²O
• 36 ATP (approx.)
Cellular Respiration Overview
Process
2
6
2
ATP
Net ATP
produced
gain
4
2
2
2
0
32
32
2
38
36
chemiosmosis
32
6
Glycolysis
Krebs
Cycle
ETC/
ATP
used
2
0
TOTAL
6
Cellular Respiration Overview
• Theoretically 36 ATPs are produced by
CR, but in reality the # is closer to 30
Process
Glycolysis
Krebs
Cycle
ETC/
ATP
used
2
0
ATP
Net ATP
produced
gain
4
2
2
2
0
32
32
2
38
36
chemiosmosis
TOTAL
• This is thought to be due to some H+
moving back to the matrix WITHOUT
going through the ATP synthase
• The 30 ATPs generated by CR
account for approx 30% of the
energy present in the chemical
bonds of glucose
• The remainder of the energy is
lost from the cell as heat
• The products of cellular respiration are
the reactants of photosynthesis
• The reactants of cellular respiration
are the products of photosynthesis
Crash Course: Cellular Respiration (11m-13m25s)
• https://www.youtube.com/watch?v=00jbG_cfGuQ
Sponge: Set up Cornell Notes on pg. 77
8.1 Other Aspects of Cellular
Respiration
Topic: 8.1 Other Aspects of Cellular Respiration
Essential Question:
Key Vocabulary:
Electromagnetic spectrum
Action spectrum
Alcoholic Fermentation
• P. 76
Lactic Acid Fermentation
The mitochondria and cellular respiration
• In biology, the relationship between structure and function is a universal theme
Chloroplast Structure
Function Allowed
Outer mitochondrial
membrane
• Separates the contents of the mitochondrion
from the rest of the cell
Matrix
• Internal semi-fluid that contains the enzymes
for the link reaction in the Krebs cycle
Cristae
• Increase surface area for oxidative
phosphorylation (ETC/ATP synthase)
Inner mitochondrial membrane • Contains the protein carriers for the ETC and
ATP synthase for chemiosmosis
Space between inner and outer • Reservoir for hydrogen ions (protons), the high
concentration of hydrogen ions is necessary for
membranes
chemiosmosis
Anaerobic Respiration
• All pathways of cellular respiration start with glycolysis
• If an organism derives their ATP completely without the use of oxygen
they are referred to as anaerobic
• This is known as fermentation
Draw a
small
picture on
p. 77
Anaerobic Respiration
Fermentation
There are two main anaerobic pathways:
• Alcoholic fermentation
• Lactic acid fermentation
Alcoholic Fermentation
• Glycolysis occurs first (net gain 2 ATP- 2 pyruvate)
• Yeast will convert both the 3-carbon pyruvates into molecules of ethanol
• Ethanol is a 2-carbon molecule, so a carbon atom is “lost” in this
conversion
• The “lost” carbon atom is given off as a CO² molecule
• Both ethanol and CO² that are produces are waste products to the yeast
and are simply given off to the environment
glycolysis
Alcoholic Fermentation
Ethanol
Ethanol
Draw on
top of
p. 76
Ex:
• Yeast is added to baker’s bread as the generation of CO² molecules helps
the dough rise
• It is also common to use yeast in the production of ethanol as drinking
alcohol
Alcoholic Fermentation
Lactic Acid Fermentation
Organisms that use an aerobic cell respiration pathway sometimes find
themselves in a metabolic situation where they cannot supply enough
oxygen to their cells
Lactic Acid Fermentation
Ex: A person pushing beyond their normal exercise pattern or routine
• In this situation, the person’s pulmonary and cardiovascular systems
(lungs and heart) supply as much oxygen to their cells as is physically
possible
• If a person’s exercise exceeds their capacity of supplying oxygen, then at
least some of the glucose entering into cellular respiration will follow the
anaerobic pathways called lactic acid fermentation
Lactic Acid Fermentation
• Glycolysis first (net gain 2 ATP- 2 pyruvate)
• In a low-oxygen situation excess pyruvate molecules are converted into
lactic acid molecules
• Lactic acid molecules are 3-carbon molecules (so there is no
production of CO²)
Lactic Acid Fermentation
What benefit then?
• It allows glycolysis to continue with the small gain of ATP generated in
addition to the ATP which is already being generated through the
aerobic pathway
glycolysis
Lactic Acid Fermentation
Lactate
Reaction reversible with O² present
Lactate
Draw on
bottom of
p. 76
• Lactic acid fermentation is used in food production using bacteria:
– yogurt
– cheese
– Turns soy beans into soy
sauce
– Turns cabbage into
sauerkraut
Aerobic Cell Respiration is the most Efficient!!!