Transcript 8.1 Cell Respiration - IB BiologyMr. Van Roekel Salem High School

3.7/8.1 Cell Respiration
IB BIO II
11/8/13
Van Roekel
BILL
• What process in the body converts energy
from macromolecules into usable energy in
the cells? What is the formula for this
process? (may use phones to find answers)
• Cell Respiration
• C6H12O6 + 6O2  6CO2 + 6H2O + Energy
Data-Based Questions (DBQ)
Read all the information given to you and use
this information, plus information you can
interpret from the graph to answer the
questions.
Will need to use previous knowledge and critical
thinking to answer questions.
Answer 2 practice DBQs on cellular respiration in
groups of 2.
BILL
• What do you think of when you hear the word
respiration? How do you think this relates to
cellular respiration?
Cellular Respiration
•
•
•
•
Cellular respiration is the controlled release of
energy from organic compounds in cells to
form ATP.
Controlled by enzymes, metabolic pathways, and
end-product inhibition
Usually breaks down glucose/carbs, but sometimes
uses lipids/fatty acids or proteins
Energy derived from the potential energy stored in
the covalent bonds of organic compounds such as
glucose, amino acids, fatty acids etc.
Cellular Respiration
• Cellular respiration is the controlled release of
energy from organic compounds in cells to
form ATP.
Cellular Respiration
• Cellular respiration is the controlled release of
energy from organic compounds in cells to
form ATP.
Cell Respiration - ATP
• ATP – molecule used for energetic processes in
the body, including:
– Muscle Contraction
– Protein Synthesis
– Active Transport
– DNA Replication
– Cell Signaling
– Etc.
Cell Respiration
• Cell respiration occurs via oxidation-reduction
reaction-loss of electrons from one substance and
the gain of electrons by another, or a transfer of
electrons)
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 bonds
Results in many C-H bonds
Results in compounds with lower
potential energy
Results in compounds with high
potential energy
Overall Reaction
Oxidation (loss of
hydrogen atoms)
Reduction (gain of
hydrogen atoms)
• In Redox reactions, reduced form of a molecule has more
potential energy than oxidized form.
• Electrons carry energy with them as they move from one
molecule to the next
Cell Respiration
• Oxidation-reduction reactions both occur in
chemical reactions together (transfer
electrons from one molecule to another
• In cell respiration:
– Glucose is oxidized (transfers electrons to oxygen)
– Oxygen atoms are reduced (gain electrons)
• Chemical reactions referred to as redox
reactions
Cell Respiration
• Three aspects to consider:
– Glycolysis (cytoplasm and no oxygen)
– Anaerobic Respiration (cytoplasm and no oxygen)
gives a small yield of ATP
– Aerobic Respiration (mitochondria and need
oxygen) gives a large yield of ATP
BILL
• What is an oxidation reduction reaction? How is cellular
respiration an oxidation-reduction reaction? Why is this
important?
• Redox reactions occur when one reactant transfers
electrons to another (one loses electrons, one gains
electrons)
• In cell respiration, glucose is oxidized and loses electrons,
which are transferred to oxygen, when it is reduced and
gains electrons
• It is important because the electrons carry energy as they
are transferred and the cells can harness this energy in
order to produce ATP
Aerobic Cell Respiration
• Occurs in 3 stages:
– Glycolysis: occurs in cytoplasm, breaks glucose
down into pyruvic acid
– Krebs Cycle or Citric Acid Cycle: takes place in
mitochondria, breaks pyruvate down into CO2 and
electrons (carried in NADH & FADH2)
– Oxidative Phosphorylation: involves electron
transport chain and produces the most ATP
Cell Respiration Glycolysis Overview
• Occurs in cytoplasm.
• A molecule of glucose(
a 6-carbon sugar) is
split up into two
molecules of 3-carbon
sugar, which are then
converted into
pyruvate.
Cell Respiration – Glycolysis Overview
• This pathway consists of ten steps, each
catalyzed by a specific enzyme.
• In the first five steps the energy(ATP) is
expended, while the last five steps result in
some ATP production.
• NAD+ is reduced to NADH by oxidation of
food.
Cell Respiration – Glycolysis Process
• Cen be effectively summarized in three steps
• 1) Two molecules of ATP are used to start
glycolysis. These molecules phosphorylate
glucose to form fructose-1, 6-biphosphate,
this process involves phosphorylation
(addition of a phosphate)
2 ATP
Glucose
2 ADP
fructose-1, 6biphosphate
Cell Respiration – Glycolysis Process
• 2) fructose-1, 6-biphosphate is split into two
3-carbon sugars called glyceraldehyde-3phosphate (G3P), this process involves lysis,
or breaking a molecule down, by use of
enzyme Aldolase
fructose-1, 6biphosphate
Aldolase
glyceraldehyde-3phosphate (G3P)
Cell Respiration – Glycolysis Process
• 3) G3P molecules are oxidized, forming ATP
and producing NADH from NAD+
– When NAD+ is reduced to NADH, a phosphate is
added to the three carbon molecule.
– Enzymes remove the phosphates from substrates
and add them to ADP molecules to form ATP, this
is called substrate level phosphorylation
– End result is 4 molecules of ATP, two molecules of
NADH, and two molecules of pyruvate
2 molecules of G3P are oxidized
2 NAD+
2 NADH
2 molecules of
1, 3-Biphosphoglycerate
undergoes substrate level
phosphorylation
4 ADP
4 ATP
2 pyruvate
Glycolysis Animation
2 minute quiz
• Where does Glycolysis occur?
– Cytoplasm
•
is broken down into
.
– Glucose; pyruvate
• What is phosphorylation?
– Addition of a phosphate group, typically making a
molecule less stable
• What are the final products of glycolysis?
– 2 pyruvate molecule, net gain of 2 ATP, 2 molecules of
NADH
Cell Respiration – Glycolysis
• Summary:
– Occurs in cytoplasm
– 2 ATP begin reaction
– Produce 4 ATP, net gain of 2 ATP; 2 NADH, and 2
pyruvate molecules
– Involves substrate level phosphorylation: an
enzyme transfers a phosphate group from a
substrate molecule to ADP, forming ATP
– Controlled by enzymes and feedback inhibition
Aerobic Respiration
• After glycolysis occurs, pyruvate molecule will
enter the mitochondria in the presence of
oxygen
• Remainder of cellular respiration occurs inside
the mitochondria
• Know the parts of mitochondria and what
happens at each part.
Parts of Mitochondrion
Outer Mitochondrial
Membrane
Separates contents of
mitochondrion from rest of cell.
Controls entry/exit of materials
Matrix
Cytosol like area of
mitochondria…enzymes for Kreb’s
cycle and link reaction
Cristae
Tubular regions of IMM increases
surface area for oxidative
phosphorylation
Inner Mitochondrial
Membrane
Space between inner
and outer membranes
Contains carriers for the ETC and
ATP synthase for chemiosmosis.
Reservoir for H+ ions (necessary for
chemiosmosis)
BILL
Label the parts of the mitochondria below and
describe the function of each part.
BILL Answers
• A- matrix, which contains
enzymes for the krebs cycle and
the link reaction.
• B – Cristae, which increase
surface area of Inner
mitochondrial membrane to
increase ability to perform
oxidative phosphorylation
• C – Outer mitochondrial
membrane, which separates the
interior and exterior parts of the
mitochondrion and controls
what goes in and out of the
mitochondrion
The Link Reaction
• Pyruvate enters the mitochondria via active
transport
• Pyruvate then loses a carbon molecule via
decarboxylation to form acetyl group (link
reaction) removes CO2
• Acetyl group is oxidized (forms NADH) and
combines with coenzyme A
• Final Products: Carbon Dioxide, NADH, Acetyl
CoA
The Link Reaction
• Acetyl CoA can be produced from most carbs,
fats, and proteins.
• When ATP levels are high, Acetyl CoA will not
enter Krebs cycle, but be synthesized into a
lipid instead.
• If ATP levels are low, Acetyl CoA will enter
Krebs cycle.
Krebs Cycle (Citric Acid Cycle)
• Acetyl CoA enters the Krebs Cycle to continue
aerobic respiration
• Occurs in matrix of mitochondria
• 8 steps in cycle, each catalyzed by a specific
enzyme
• Begins and ends with Oxaloacetate, hence the
name Krebs Cycle
Krebs Cycle
• Acetyl CoA combines with Oxaloacetate to
form 6-carbon compound Citrate
• Citrate is oxidized and decarboxylated twice,
releasing CO2 and forming NADH by reducing
NAD+, forming a 4 carbon compound
Krebs Cycle
• 4-carbon compound undergoes a variety of
chemical changes such as:
– transfers phosphate group to ADP, forming ATP by
substrate level phosphorylation.
– oxidized and forms FADH2
– oxidized and forms NADH
• Eventually reforms starting compound
Oxaloacetate
Krebs Cycle Animation
• Krebs Cycle
Krebs Cycle Summary
• Acetyl CoA and Oxaloacetate combine to form Citrate
compound
• Citrate is oxidized and decarboxylated twice (forming
CO2 and NADH) to produce a 4-carbon compound
• Remaining molecule undergoes various changes
(oxidation and substrate level phosphorylation) and
forms ATP, FADH2, and NADH
• NADH & FADH2 are electron carriers and will carry the
energy of transferred electrons to electron transport
chain, where it will be harnessed to produce ATP
Krebs Cycle Summary
• Krebs Cycle will run twice for each glucose
molecule broken down in cellular respiration
because of two pyruvate molecules
• Final Products:
– 2 ATPs
– 6 NADH
– 2 FADH2
– 4 molecules of CO2
2-minute quiz
• Without using your notes, summarize the process of
aerobic cellular respiration through the Krebs Cycle.
• Work with 1 partner and take turns quizzing each other.
• Glycolysis splits glucose down into pyruvate, producing
NADH and ATP. Pyruvate is converted into Acetyl CoA,
which enters the Krebs Cycle. The Krebs cycle continues to
oxidize acetyl coA and produces NADH, FADH2, ATP, and CO2
• As oxidation occurs, energy from the electrons are captured
by electrons carriers, which will transport them to the
electron transport chain
BILL - Outline the process of cellular
respiration so far
• Glycolysis:
• Link Reaction
• Krebs Cycle
Cellular Respiration So Far
• Glycolysis:
– Breaks down glucose into pyruvate
– Produces 2 ATP, 2 NADH, 2 pyruvate molecules
• Link Reaction
– Converts pyruvate into Acetyl CoA via decarboxylation and oxidation
– Produces CO2 and NADH
• Krebs Cycle
– Combines Oxaloacetate & Acetyl CoA into Citrate
– Citrate oxidizes and decarboxylates twice into a 4-carbon sugar,
releasing CO2 and producing NADH
– 4-carbon sugar undergoes several changes, including oxidation and
substrate level phosphorylation, producing ATP, NADH, and FADH2
– 2 ATP, 6NADH, 2 FADH2, 4 CO2
•
•
Glycolysis Animation
Krebs Cycle
Cell Respiration So Far
• Total Production:
– 4 ATP
– 10 NADH
– 2 FADH2
– 6 CO2
• 32-34 molecules of ATP remain to be
synthesized by oxidative phosphorylation
Electron Transport Chain
• Collection of molecules embedded in the
inner membrane of the mitochondrion
(thousands of copies of chain in each)
• Most components are proteins, coupled with
prosthetic groups that are oxidized and
reduced as they accept and donate electrons
Electron Transport Chain
• Does not produce ATP directly
• As electrons move through ETC, proteins
pump hydrogen ions (H+) into the
intermembrane space
• Electron transport chain couples with ATP
synthase to produce ATP through process
called chemiosmosis
Chemiosmosis
Electron
Transport Chain
• Electrons transfer from
NADH/FADH2 to first
protein
• Electrons pass from one
carrier to the next
because of
electronegativity
• Higher electronegativity
= stronger attraction to
electrons
Electron
Transport Chain
• Oxygen is the final
electron acceptor (very
high electronegativity)
• Combines with
hydrogen ions from
aqueous solution and
leaves as water
• For every two NADH,
one O2 is reduced to
two waters
Electron
Transport Chain
• Eventually, energy
harnessed from each
FADH2 produces 2
ATPS, while energy
harnessed from each
NADH produces 3
ATPS
• http://highered.mcgrawhill.com/sites/0072507470/student_view0/ch
apter25/animation__electron_transport_syste
m_and_atp_synthesis__quiz_1_.html
Chemiosmosis
• Involves the movement of protons (hydrogen
ions) to provide energy for phosphorylation
(making ATP)
• Moves hydrogen ions using the electron
transport chain
• Makes ATP using enzyme called ATP Synthase,
which makes ATP by combining an ADP and
organic phosphate
Chemiosmosis
Chemiosmosis
• Certain proteins of the electron transport
chain pump protons along with electrons
• H+ ions are taken up from matrix and moved
to inter-membrane space
• The H+ ion gradient results in proton-motive
force, which powers the production of ATP
Chemiosmosis- ATP Synthase
• H+ ions diffuse through ATP Synthase because of
concentration gradient on opposite sides of Inner
mitochondrial membrane
• As ions move through ATP synthase, enzyme
harnesses energy available in protons
• Powers the ATP synthase, which combines ADP
and phosphate to form ATP
• Formation of ATP through this process is referred
to as oxidative phosphorylation (using energy
from the movement of electrons to produce ATP)
• http://highered.mcgrawhill.com/sites/0072507470/student_view0/ch
apter25/animation__electron_transport_syste
m_and_atp_synthesis__quiz_1_.html
• http://highered.mcgrawhill.com/sites/0072507470/student_view0/ch
apter25/animation__electron_transport_syste
m_and_formation_of_atp__quiz_1_.html
BILL
• Annotate the diagram showing oxidative
phosphorylation. Be sure to include the
following: electron transport chain &
movement of electrons, chemiosmosis and
the movement of H+ ions, ATP Synthase,
oxidative phosphorylation/production of ATP,
H+ ion gradient in intermembrane space,
movement of electrons from NADH/FADH2,
oxygen (O2) as final electron acceptor.
Cellular Respiration Review
• Energy flows in the general direction:
– Glucose  NADH/FADH2 Electron Transport
Chain Chemiosmosis (Proton Motive Force)
ATP
• Total ATP produced 36 ATP
• In reality about 30 molecules of ATP are
produced from 1 glucose molecule. Only
about 30% of the energy present in glucose
bonds
BILL
• What process is used to produce energy in the
absence of oxygen? What are the two types of
this process?
• Anaerobic Respiration
• Alcoholic Fermentation & Lactic Acid
Fermentation
What if there is no oxygen?
• Anaerobic Respiration – organisms derive ATP
w/out the use of oxygen through glycolysis in
cytoplasm
• Occurs through process called Fermentation
• Fermentation consists of glycolysis (2 ATP)
plus reactions that regenerate NAD+
– Alcoholic Fermentation
– Lactic Acid Fermentation
Alcohol Fermentation
• Generate 2 ATP via glycolysis when glucose
enters the cell. (Glucose → Pyruvate)
• After fermentation, pyruvate is decarboxylated
and reduced, forming ethanol, CO2, and NAD+
• Yeast can utilize anaerobic metabolism and
produce ATP via alcohol fermentation.
V
Lactic Acid Fermentation
• Pathway utilized by humans when not enough
oxygen is present to perform aerobic metabolism
(reversible when oxygen is present).
• Generate 2 ATP via glycolysis when glucose enters
the cell. (Glucose → Pyruvate)
• Pyruvate is reduced, forming lactate and producing
NAD+
• Lactate accumulates as a waste produce and can
cause muscle fatigue and pain.
http://people.cst.cmich.edu/schul1te/animations/fermentation.swf
Aerobic vs. Anaerobic Respiration
Aerobic
• Oxygen is present
• Pyruvate transferred to
mitochondria
• Involves Krebs’ Cycle &
oxidative phosphorylation
• Produces large amounts of
ATP (36-38 ATP)
Anaerobic
• No oxygen is present
• Occurs only in cytoplasm
• Involves Lactic Acid
fermentation and produces
lactic acid
• Involves alcoholic
fermentation and produces
ethanol
• Produces small amounts of
ATP (2)
Anaerobic vs. Aerobic Respiration
Similarities
• Both start w/ glucose & glycolysis
• Both Produce ATP/energy
• Both produce pyruvate and CO2
Cell Respiration Virtual Lab
• The Biology Place – Lab Bench Activity –
Cellular Respiration
• www.phschool.com  “The Biology Place” 
Lab Bench  Lab 5: Cell Respiration