How Cells Release Energy

1
How Cells Release Energy

• Glycolysis
• Cell Respiration
• Fermentation

2
Glycolysis

• Glucose breaking
• 10 reactions that break glucose into 2 molecules
  of pyruvic acid
• Occurs in the cytoplasm
• Energy yield 2 ATP

3
(No Transcript)
4
What is glucose?

• 6-carbon sugar (monosaccharide)
• Main source of energy for most cells
• What is pyruvic acid?
• 3-carbon sugar
• Starting matter for most biosynthetic pathways
• What is ATP?
• Adenosine Triphosphate
• Temporary energy storage molecule

5
Glucose Activation

• 1st half of glycolysis
• Phosphorylation by ATP allows enzyme to act on
  glucose and allows it to split into two PGAL
  (phosphoglyceraldehye) molecules.
• Energy expended as 2 ATP

6
2nd Half of Glycolysis

• 2 NAD reduced to NADH storing energy for later
  use.
• 4 ADP converted to ATP
• Net yield

7
2nd Half of Glycolysis

• 2 NAD reduced to NADH storing energy for later
  use.
• 4 ADP converted to ATP
• Net yield 2 ATP
• 2 molecules of Pyruvic acid (3 carbon sugar
  molecule)

8
Fermentation

• Anaerobic respiration occurs in the absence of
  oxygen.
• Oxidize NADH to NAD
• No yield of additional ATP very inefficient!
• 2 major pathways
• Alcoholic fermentation
• Lactic acid fermentation

9
Alcoholic Fermentation

• Carried out by yeast
• Used to make beer and bread
• Yeast coverts pyruvic acid to ethanol and CO2.

10
Lactic Acid Fermentation

• Bacteria
• Animal cells deprived of O2
• Common during periods of intense exercise
• May occur in cancer cells
• May occur in times of stress

11
Anaerobic Respiration

• Inorganic molecules act as electron acceptors.
• 3 common ones nitrate (NO3-) sulfate (SO42-)
  and Carbon dioxide (CO2)
• Carried out by bacteria called facultative
  anaerobes

12
Cell (aerobic) Respiration

• Requires oxygen to complete the breakdown of
  pyruvic acid
• Occurs in the mitochondria
• Provides an additional 34 ATP in animal cells
• 3 stages
• Acetyl CoA formation
• Krebs cycle
• Respiratory chain

13
Acetyl CoA Formation

• Pyruvic acid loses a molecule of CO2 as NAD is
  reduced to NADH.
• The molecule that remains is called Acetyl
  coenzyme
• This enters the Krebs cycle

14
Formation of Acetyl CoA
15
Krebs Cycle

• Process discovered by Sir Hans dolf Krebs
  English biochemist
• Continuing series of 8 reactions
• Also called Citric acid cycle
• CO2 produced as a by-product
• Energy storage compounds produced
• 6 NADH
• 2 FADH2
• 2 ATP

16
(No Transcript)
17
Total Energy Yield So Far

• From Glycolysis
• 2ATPs and 2 NADHs
• From Pyruvate - Acetyl CoA
• 2 NADHs
• From Krebs Cycle
• 2 ATPs, 6NADHs, and 2 FADH2s
• Where is all of the energy?

18
IT IS ALL LOCKED IN THE NADHS AND THE FADH2S!
19
The Electron Transport Chain

• What is the ETC? Where is it located?
• It is a series of electron carrier molecules,
  that transfer electrons to each other through a
  connected series of redox reactions.
• It is located within the inner membrane of the
  mitochondrion
• Electrons combine with free H ions and oxygen to
  produce H20
• So oxygen necessary to extract energy!

20
The Final Count

• For every NADH produced in the mitochondrion, how
  many ATPs are created?
• 3
• For every FADH2 produced, how many ATPs are
  created?
• 2
• For the 2 NADHs generated in glycolysis how many
  ATPs are created?
• 2

21

• 2 NADHs from glycolysis ----gt4-6 ATPs
• 8 NADHs from the mitochondrial matrix ----gt 24
  ATPs
• 2 FADH2s from KC -----gt

22

• 2 NADHs from glycolysis ----gt

23

• 2 NADHs from glycolysis ----gt4-6 ATPs
• 8 NADHs from the mitochondrial matrix ----gt

24

• 2 NADHs from glycolysis ----gt 4-6 ATPs
• 8 NADHs from the mitochondrial matrix ----gt 24
  ATPs
• 2 FADH2s from KC -----gt 4 ATPs
• Total ATPs

25

• 2 NADHs from glycolysis ----gt 4-6 ATPs
• 8 NADHs from the mitochondrial matrix ----gt 24
  ATPs
• 2 FADH2s from KC -----gt 4 ATPs
• Total ATPs 32- 36 ATPs
• ATPs from glycolysis

26

• 2 NADHs from glycolysis ----gt4-6 ATPs
• 8 NADHs from the mitochondrial matrix ----gt 24
  ATPs
• 2 FADH2s from KC -----gt 4 ATPs
• Total ATPs 32-34 ATPs
• ATPs from glycolysis 2 ATP
• ATPs from KC

27

• 2 NADHs from glycolysis ----gt4-6 ATPs
• 8 NADHs from the mitochondrial matrix ----gt 24
  ATPs
• 2 FADH2s from KC -----gt 4 ATPs
• Total ATPs 32-34 ATPs
• ATPs from glycolysis 2 ATP
• ATPs from KC 2 ATP
• GRAND TOTAL

28

• 2 NADHs from glycolysis ----gt4-6 ATPs
• 8 NADHs from the mitochondrial matrix ----gt 24
  ATPs
• 2 FADH2s from KC -----gt 4 ATPs
• Total ATPs 32-34 ATPs
• ATPs from glycolysis 2 ATP
• ATPs from KC 2 ATP
• GRAND TOTAL 36- 38 ATPs

29
The Equation of Respiration

• Glucose O2 CO2 H2O ATP
• The Equation of Fermentation
• Glucose Pyruvic acid Lactic acid or Alcohol
  CO2

30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)