Cellular Respiration

1
Cellular Respiration

• Chapter 7

2
Intro to Cellular Respiration

• Cellular respiration is the process by which
  cells break down organic compounds to release
  energy and make ATP
• It includes anaerobic pathways, which operate in
  the absence of oxygen, and aerobic respiration,
  which occurs when oxygen is present

3
(No Transcript)
4
(No Transcript)
5

• Foods store chemical energy
• This stored chemical energy can be released
  through cellular respiration

6

• Potential energy can be converted to other types
  of energy
• During cellular respiration the bonds are
  rearranged in a molecule and energy is released

7
Comparing Cells with Cars

• Within your cells, organic molecules such as
  glucose also react with oxygen in the process of
  cellular respiration. And similar to a car
  engine, working cells produce carbon dioxide and
  water as their exhaust.
• Fortunately, the process is much slower in your
  cells they convert about 40 of the energy from
  food into useful work. The remaining 60 is
  released as heat.

8
Putting Chemical Energy to Work
9
Calories

• A calorie is the amount of energy required to
  raise the temperature of 1g of water by 1Celsius
• Calories on food labels are actually kilocalories
• 1 peanut has about 5,000 calories or 5kcal
• Thats enough energy to raise the temperature of
  1 kg of water by 5C

10
ATP

• Stands for Adenosine Triphosphate
• Each phosphate group is negatively-charged,
  because of this the bond is weak and likes to
  break, which releases its potential energy

11
Uses for ATP
12
ATP Cycle
13
Relationship between Cellular Respiration
Breathing

• Cellular Respiration is an aerobic process
• Although breathing for an organism is not the
  same as cellular respiration, the 2 processes are
  interrelated
• The gases exchanged in the lungs help fuel the
  cellular respiration process

14
(No Transcript)
15
Cellular Respiration Equation
16

• When sugar is burned, oxygen atoms pull electrons
  from carbon and hydrogen, forming new chemical
  bonds.
• Burning releases energy in the form of heat and
  light.

17
(No Transcript)
18
Cellular Respiration converts energy in food to
energy in ATP
19
Mitochondrion

• The complex folding of the inner membrane allows
  for many sites where cellular respiration to occur

20
Stage 1 Glycolysis

• Cellular respiration begins with glycolysis,
  which takes place in the cytosol of cells
• During glycolysis, one glucose molecule is
  oxidized to form 2 pyruvic acid molecules
• Glycolysis results in a net production of 2 ATP
  molecules and 4 NADH molecules

21
Stage 1 Glycolysis
22
Glycolysis

• STEP 1 - TWO Phosphates are attached to Glucose,
  forming a NEW Six-Carbon Compound.  The Phosphate
  Groups come From TWO 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.
• 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.
• 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.

23

• In the presence of oxygen, pyruvic acid is
  converted into acetyl CoA
• In eukaryotic cells, this reaction occurs inside
  the mitochondrial matrix

24
Krebs Cycle

• Acetyl CoA enters the Krebs cycle, a biochemical
  pathway that also takes place in the
  mitochondrial matrix
• Each turn of the Krebs cycle generates 3 NADH, 1
  FADH2, 1 ATP, and 2 CO2 molecules
• Because you produced 2 pyruvic acid molecules
  through glycolysis the Krebs cycle has to go
  around 2 times leaving you with
• 6 NADH, 2 FADH2, 2 ATP, and 4 CO2 molecules

25
Stage 2 Krebs Cycle
26
Electron Transport Chain

• NADH and FADH2 donate electrons to the electron
  transport chain, which lines the inner
  mitochondrial membrane
• Electrons are passed from molecule to molecule in
  the transport chain in a series of redox reactions

27
Electron Transport Chain

• As electrons pass along the electron transport
  chain, protons donated by NADH and FADH2 are
  pumped into the space between the inner and outer
  mitochondrial membranes
• This pumping creates a concentration gradient of
  protons across the inner mitochondrial membrane
• As protons move down their gradient and back into
  the mitochondrial matrix, ATP synthase uses the
  energy released by their movement to make ATP

28
Stage 3 Electron Transport Chain
29
Products of Aerobic Respiration

• During aerobic respiration, oxygen accepts both
  protons and electrons from the electron transport
  chain
• As a result, oxygen is converted to water

30
Aerobic Respiration

• Aerobic respiration can produce up to 38 ATP
  molecules from the oxidation of a single molecule
  of glucose
• This means that up to 66 of the energy released
  by the oxidation of glucose can be transferred to
  ATP
• However, the most eukaryotic cells produce only
  about 36 ATP molecules per molecule of glucose

31
Aerobic Respiration
32
Anaerobic Fermentation

• Lactic Acid Alcoholic Fermentation

33
Fermentation

• Fermentation is a set of anaerobic pathways in
  which pyruvic acid is converted into other
  organic molecules in the cytosol
• Fermentation DOES NOT produce ATP, but it does
  regenerate NAD, which helps keep glycolysis
  operating

34
Lactic Acid Fermentation

• In lactic acid fermentation, an enzyme converts
  pyruvic acid into lactic acid

35
Lactic Acid Fermentation
36
Lactic Acid Fermentation

• Lactic Acid involves the transfer of 2 H 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.
• 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.

37
Alcohol Fermentation

• In alcoholic fermentation, other enzymes convert
  pyruvic acid into ethyl alcohol and CO2

38
Alcoholic Fermentation
39
Alcohol Fermentation

• 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, and
  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.