Transcript cellular respiration - OCC

Review
define the following terms in your notesheet
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Autotroph
Heterotroph
ATP
Biochemical Pathway
Photosynthesis (w/ equation)
Cellular Respiration
Mitochondria & Cristae
Oxidation Rxn
Reduction Rxn
Chemiosmosis
Ch.7 How Cells
Harvest Energy
OCC BIO-161
Dave Werner
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Can you write the chemical equations for
Photosynthesis & Cellular Respiration
Can you describe their relationship?
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Video Clip – Overview of Cellular Resp
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Overview of Cellular Respiration
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Remember: PHOTOSYNTHESIS
EQUATION: 6CO2 + 6H2O + LIGHT
ENERGY = C6H12O6 + 6O2
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CELLULAR RESPIRATION EQUATION:
C6H12O6 + 6O2 = 6CO2 + 6H2O
+ ENERGY RELEASED (ATP)
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Cellular Respiration takes place in
TWO STAGES.
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STAGE 1 - Cellular Respiration BEGINS with a Biochemical
Pathway called GLYCOLYSIS, that takes place in the Cells
Cytosol
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YIELDS a relatively Small amount of ATP and does not require
oxygen.
STAGE 2 - OXIDATIVE RESPIRATION, follows Glycolysis.
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Oxidative Respiration takes place within the Mitochondria.
This is far more effective than Glycolysis at recovering energy from
food molecules.
OXIDATIVE RESPIRATION IS THE METHOD BY WHICH PLANT
AND ANIMAL CELLS GET THE MAJORITY OF THEIR ENERGY.
TWO TYPES OF CELLULAR
RESPIRATION
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B/C they operated in the Absence of Oxygen,
the FERMENTATION PATHWAYS are said to
be ANAEROBIC PATHWAYS.
If OXYGEN is PRESENT, the products of
Glycolysis ENTER the PATHWAYS of
AEROBIC RESPIRATION.
Aerobic Respiration produces a much Larger
Amount of ATP, UP TO 20 TIMES MORE ATP
PRODUCED.
GLYCOLYSIS – Video Clip
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1. Both types of PATHWAYS BEGIN with
Glycolysis.
2. Glycolysis is a pathway in which One SixCarbon Molecule of GLUCOSE is Oxidized to
Produce 2 Three-Carbon Molecules of PYRUVIC
ACID OR PYRUVATE.
3. The word "GLYCOLYSIS" means "The
Splitting of Glucose".
4. SOME OF ITS ENERGY IS RELEASED.
5. Occurs in CYTOSOL OF THE CELL.
GLYCOLYSIS
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6. Whether or not O2 is present, Glycolysis SPLITS (BY
OXIDATION) GLUCOSE INTO 3-CARBON
MOLECULES OF PGAL. PGAL IS THEN CONVERTED
TO 3-CARBON PYRUVIC ACID.
7. Glucose is a Stable molecule that DOES NOT Break
down Easily.
8. For a Molecule of Glucose to undergo Glycolysis, a
Cell must First "SPEND" ATP to energize the Glucose
Molecule. The ATP provides the Activation Energy
needed to begin Glycolysis.
GLYCOLYSIS Cont’d
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9. Although ATP (ENERGY) is used to begin
Glycolysis, the reactions that make up the
process eventually produce A NET GAIN OF
TWO ATP MOLECULES.
10. Glycolysis is followed BY THE BREAK
DOWN OF PYRUVIC ACID.
Glycolysis: FOUR MAIN STEPS
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STEP 1 - TWO Phosphates are attached to Glucose, forming
a NEW Six-Carbon Compound. The Phosphate Groups
come From 2 ATP, which are Converted to ADP.
STEP 2 - The Six-Carbon Compound formed in Step 1 is
SPLIT into TWO Three-Carbon Molecules of PGAL.
STEP 3 - The TWO PGAL Molecules are Oxidized, and
each Receives a Phosphate Group Forming Two NEW
Three-Carbon Compounds. The Phosphate Groups are
provided by Two molecules of NAD+ forming NADH.
Steps cont.
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STEP 4 - The Phosphate Groups added in Step 1 and Step 3
are Removed from the Three-Carbon Compounds. This
reaction produces Two molecules of Pyruvic Acid. Each
Phosphate Group is combines with a molecule of ADP to
make a molecule of ATP. Because a total of Four Phosphate
Groups were Added, FOUR MOLECULES OF ATP ARE
PRODUCED.
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TWO ATP Molecules were used in Step 1, but FOUR are
Produced in Step 4. Therefore, Glycolysis has a NET
YIELD of TWO ATP Molecules for every Molecule of
Glucose that is converted into Pyruvic Acid. What
happens to the Pyruvic Acid depends on the Type of Cell
and on whether Oxygen is present.
AEROBIC RESPIRATION
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In most cells, the Pyruvic Acid (P.A.) that is
produced in glycolysis does not undergo
fermentation. Instead, if O2 is available,
P.A. enters the pathway of Aerobic
Respiration, or Cellular Respiration that
requires O2.
Remember - Aerobic Resp. produces
nearly 20 times as much ATP than
glycolysis alone.
Aerobic Respiration has TWO
Major STAGES
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THE KREBS CYCLE – Video Clip
ELECTRON TRANSPORT CHAIN (ETC)
OVERVIEW OF AEROBIC
RESPIRATION
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BREAK DOWN OF P.A. IN PRESENCE OF O2 =
AEROBIC RESP.
AEROBIC RESP. TAKES PLACE INSIDE CELL'S
MITOCHONDRIA ("POWER HOUSE").
DURING AEROBIC RESP., ATP IS PRODUCED IN
TWO PATHWAYS KNOWN AS THE KREBS CYCLE &
ETC.
THE SERIES OF OXIDATION Rxns THAT MAKE UP
THE 2nd PHASE OF AEROBIC RESP. = KREBS
CYCLE.
THE KREBS CYCLE IS A BIOCHEMICAL PATHWAY
THAT BREAKS DOWN acetyl CoA, producing ATP, H,
AND CO2
OVERVIEW OF AEROBIC
RESPIRATION
In Prokaryotes the rxns of Krebs cycle
take place in Cytosol of the Cell.
 In EUKARYOTIC CELLS, these rxns take
place in the MITOCHONDRIA
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OVERVIEW OF AEROBIC
RESPIRATION
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The P.A. that is produced in glycolysis Diffuses
across the Double Membrane of a Mitochondrion
& enters the MITOCHONDRIAL MATRIX (Space
Inside the Inner Membrane of a Mitochondrion).
When P.A. enters the Mitochondrial Matrix, it
Reacts with a molecule called COENZYME A to
form ACETYL COENZYME A, abbreviated acetyl
CoA.
CO2, NADH, and H+ are produced in this rxn.
OVERVIEW OF AEROBIC
RESPIRATION
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DURING PROCESS FROM GLYCOLYSIS
THROUGH KREBS CYCLE, 1 GLUCOSE
MOLECULE YIELDS 4 ATP, 10 NADH AND 2
FADH2
THE ENERGETIC e- IN THE MOLECULES OF
NADH & FADH2 THAT ARE FORMED DURING
THE KREBS CYCLE ARE USED TO MAKE ATP
IN A SERIES OF RXNS = ETC.
MOST of the ATP Produced during Aerobic
Respiration is MADE BY the ETC
THE KREBS CYCLE
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The Krebs cycle is a biochemical pathway
that breaks down Acetyl CoA, producing
CO2, H+, NADH, FADH2, and ATP.
The rxns that make up the cycle were
identified by Hans Krebs (1900-1980), a
German-British biochemist.
The Krebs cycle has 5 Main Steps
(All occur in the mitochondria)
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STEP 1 - A 2-Carbon Molecule of Acetyl CoA
Combines with a 4-Carbon Compound,
OXALOACETIC ACID (AHKS-uh-loh-SEET-ik), to
Produce a 6-Carbon Compound CITRIC ACID.
STEP 2 - Citric Acid Releases a CO2 Molecule
and a H+ to Form a 5-Carbon Compound. By
LOSING a H+ with its Electron, Citric Acid is
OXIDIZED. The H+ is transferred to NAD+,
REDUCING it to NADH.
Kreb Cycle cont.
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STEP 3 - The 5-Carbon Compound Releases a CO2
Molecule and a H+, forming a 4-Carbon Compound. NAD+ is
reduced to NADH. A Molecule of ATP is also Synthesized
from ADP.
STEP 4 - The 4-Carbon Compound Releases a H+ to form
another 4-Carbon Compound. The H+ is used to Reduce
FAD (Flavin Adenine Dinucleotide) to FADH2, a Molecule
similar to NAD+ that Accepts Electron during Redox
Reactions.
STEP 5 - The 4-Carbon Compound Releases a H+ to
REGENERATE OXALOACETIC ACID, which keeps the
Krebs cycle operating. The H+ Reduces NAD+ to NADH.
More info
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In Glycolysis one Glucose Molecule produces 2 Pyruvic Acid
Molecules, which can then form 2 Molecules of Acetyl CoA.
1 Glucose Molecule causes 2 Turns of the Krebs cycle.
The 2 Turns produce 6 NADH, 2 FADH2, 2 ATP, and 4 CO2
Molecules.
The CO2 is a WASTE PRODUCT that Diffuses out of the
cells & is given off by the organism.
The BULK of the Energy released by the Oxidation of
Glucose still has NOT been transferred to ATP. Only 4
Molecules of ATP - 2 from Glycolysis and 2 From the Krebs
cycle
ELECTRON TRANSPORT CHAIN
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Video Clip
NADH and the 2 FADH2 Molecules from
the Krebs cycle DRIVE the Next Stage of
Aerobic Respiration - The ETC.
That is Where MOST of the Energy
Transfer from Glucose to ATP Actually
Occurs.
ELECTRON TRANSPORT CHAIN
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In EUKARYOTIC CELLS
the Electron Transport
chain LINES the INNER
MEMBRANE of the
Mitochondrion, the inner
membrane has many
long folds called
CRISTAE.
In Prokaryotes, the
Electron Transport
Chain LINES the CELL
MEMBRANE
ELECTRON TRANSPORT CHAIN
fig.7.13
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ATP is produced by the ETC when NADH &
FADH2 RELEASES H+, REGENERATING NAD+
and FAD, which return to the Krebs Cycle to be
reused.
The e- in the H+ from NADH and FADH2 are at a
High Energy Level.
These High Energy e- are PASSED Along a
Series of Molecules. As the move from Molecule
to Molecule, the e- LOSE some of their Energy
ELECTRON TRANSPORT CHAIN
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The Energy they LOSE is used to PUMP Protons of the H+
from the Mitochondrial Matrix to the other side of the Inner
Mitochondrial Membrane.
The Pumping builds up a High Concentration (A
Concentration Gradient) of Protons in the space Between the
INNER and OUTER Mitochondrial Membranes.
The Concentration Gradient of Protons Drives the Synthesis
of ATP by Chemiosmosis.
ATP Synthase (enzyme) molecules are located in the Inner
Mitochondrial Membrane. The ATP Synthase MAKES ATP
from ADP as Protons move down their Concentration
Gradient into the Mitochondrial Matrix.
ENERGY YIELD
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Through Aerobic Respiration a Maximum Yield
of 38 ATP Molecules can be
PRODUCED. (Figure 7-9)
A. 2 - Glycolysis
B. 2 - Krebs cycle
C. 34 - Electron Transport Chain
The actual number of ATP Molecules generated
through Aerobic Respiration varies from Cell to
Cell.
Most Eukaryotic Cells Produce only about 36
ATP Molecules per Glucose Molecule.
Anaerobic Pathways
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1. In the Absence of Oxygen, Some Cells can
Convert Pyruvic Acid into other compounds
through Additional Biochemical Pathways that
also Occur in the Cytosol.
2. The Combination of Glycolysis PLUS these
Additional Pathways are known as
FERMENTATION.
3. THE CHEMICAL REACTIONS THAT
RELEASE ENERGY FROM FOOD MOLECULES
IN THE ABSENCE OF OXYGEN ARE ALSO
CALLED ANAEROBIC RESPIRATION.
LACTIC ACID FERMENTATION AND
ALCOHOLIC FERMENTATION
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During the processes of Fermentation NO ADDITIONAL
ATP IS SYNTHESIZED.
LACTIC ACID FERMENTATION IS THE PROCESS THAT
PYRUVIC ACID IS CONVERTED TO LACTIC ACID.
Lactic Acid involves the Transfer of TWO Hydrogen atoms
from NADH and H+ to Pyruvic Acid. In the process, NADH is
Oxidized to form NAD+ which is needed to Keep Glycolysis
Operating.
Lactic Acid Fermentation by Microorganisms plays an
Essential role in the manufacture of Food Products such as
YOGURT and CHEESE.
LACTIC ACID FERMENTATION AND
ALCOHOLIC FERMENTATION
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CERTAIN ANIMAL CELLS, INCLUDING OUR MUSCLE
CELLS CONVERT PYRUVIC ACID TO LACTIC ACID.
DURING EXERCISE, BREATHING CANNOT PROVIDE
YOUR BODY WITH ALL THE OXYGEN IT NEEDS FOR
AEROBIC RESPIRATION. WHEN MUSCLES RUN OUT OF
OXYGEN, THE CELLS SWITCH TO LACTIC ACID
FERMENTATION.
This process provides your muscles with the energy then
need during exercise.
The side effects of Lactic Acid Fermentation is Muscle
Fatigue, Pain, Cramps, and you feel Soreness.
ALCOHOLIC FERMENTATION CONVERTS
PYRUVIC ACID TO CARBON DIOXIDE AND
ETHANOL (ETHYL ALCOHOL
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Bakers use Alcoholic Fermentation of YEAST to make Bread.
As Yeast Ferments the Carbohydrates in dough, CO2 is produced
and trapped in the dough, causing it to rise.
When the dough is baked the Yeast Cells Die, & the Alcohol
Evaporates, You cannot get drunk from eating bread!
Alcoholic Fermentation is used to make wine, beer, and the ethanol
added to gasoline to make gasohol.
The fact that alcohol is used to power a car indicated the amount of
Energy that remains in the Alcohol Molecules.
Alternative Energy Sources in the
Body
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In humans & other mammals, the entrance of
glucose/organic compounds into an energyreleasing pathway depends on the kinds &
portions of carbs, fats, & proteins in the diet.
Ex: Glucose at mealtime is transported to the
blood, which tells the pancreas to create insulin in
order to help cells take up glucose faster.
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Less activity = Glycogen as storage
Hormones control whether to use free glucose as energy
source or store it.
More Examples
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Energy from Fats
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Body stores most fats as triglycerides, accumulate in fat
cells of adipose tissue.
Used as alternate energy when blood glucose levels fall.
Too much glucose ends up as fat.
Energy from Proteins
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Body splits proteins into amino acids, which are used by
cells to make more proteins or nitrogen-containing
compounds.
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