Cellular Respiration

1
Cellular Respiration

• How Cells Convert Energy
• or
• How Cells Manage to Keep Staying Alive

2
Cellular Respiration An Overview

• Cellular Respiration is nothing more than an
  energy conversion process
• It converts energy in the form of glucose into
  energy in the form of ATP
• The process, when done at its greatest
  efficiency, requires oxygen
• The products are carbon dioxide and water

3
Cellular Respiration An Analogy

• Cellular Respiration is analogous to Money
  Conversion.
• Analogy When you travel to France you arrive in
  Paris and your dollars are useless, they need to
  be converted into Euros. You must go to a bank
  and exchange your money. After the conversion,
  the amount of money you have is still the same,
  it is just in a new form that is useful to you in
  France.
• In living systems energy is generally transferred
  between cells in a chemical form called glucose,
  a monosaccharide carbohydrate. This is the way
  cells like to exchange energy between themselves.
  However, once in the cell, glucose is useless,
  just like dollars in France. So the cell converts
  the glucose into something it can use- ATP.

4
Cellular Respiration Simplified

• There is one goal to Cellular Respiration Making
  ATP
• Beginning Energy Source Glucose
• Ending Energy Source ATP

5
Cellular Respiration A Drama in Three Parts

• Cellular Respiration is a process that occurs in
  cells, it can be thought of as a play that has
  three acts.
• Act One Glycolysis
• Act Two Krebs Cycle
• Act Three Electron Transport Chain and Oxidative
  Phosphorylation

6
Cellular Respiration Overview
7
Location of the Action

• Location
• Cytoplasm (cytosol)
• Metabolic Pathway
• Glycolysis
• Carbon Processing
• Conversion of 1 glucose (6 carbon molecule) into
  2 pyruvates (3 carbon molecules)

• Location
• Mitochondria
• Metabolic Pathways
• Krebs Cycle
• Electron Transport and Oxidative Phosphorylation
• Carbon Processing
• Conversion of 1 pyruvate (3 carbon molecule) into
  3 carbon dioxides (1 carbon molecules). This
  whole process is done twice for every molecule of
  glucose.

8
Act One Glycolysis

• Glycolysis word derivation
• Glyco Glucose
• Lysis To Split
• To split glucose
• Glucose enters the cytoplasm of the cell and
  glycolysis occurs in the cytoplasm
• Glycolysis begins with 1 glucose (6 carbon
  molecule) and ends with 2 pyruvates (3 carbon
  molecules)
• It is a 10 step process (You do not need to know
  the details)
• It occurs in 2 phases
• Energy Investment Phase
• Energy Payoff Phase (this phase is passed through
  twice for every one molecule of glucose)

9
Glycolysis Energy Investment Phase

• In this first phase of glycolysis, glucose, a 6
  carbon sugar, is split in half and becomes two 3
  carbon molecules.
• This phase requires an energy investment of 2
  ATPs for each molecule of glucose
• Glyceraldehyde Phosphate is the 3 carbon molecule
  that continues into the next phase.
• The numbers like Glucose 6-phosphate, refer to
  the number of the carbon to which the phosphate
  group is bound.
• The 6 carbon sugars are shown here as simplified
  linear structures to indicate the location of the
  phosphate groups. In reality are ringed
  structures.

10
Glycolysis Energy Payoff Phase

• In this second phase of glycolysis, the 3 carbon
  sugars are modified in a series of steps such
  that 2 ATP molecules are produced
• One NADH molecule is also produced
• The final molecule in the pathway is pyruvate, a
  3 carbon sugar
• This phase of glycolysis MUST occur twice for
  every one molecule of glucose (a 6 carbon sugar)

11
Glycolysis Net ATP

• Initial Molecule 1 glucose (6 carbon)
• Final Molecule 2 pyruvates (3 carbon)
• Energy Investment Phase -2 ATP
• Energy Payoff Phase 2ATP (x2) 4 ATP
• Net 2 ATP

12
Total Energy Conversion in Glycolysis

• At the end of glycolysis all the energy that was
  originally in glucose is now in three different
  kinds of molecules- ATP, NADH, Pyruvate. The
  total energy count at the end of the process is
• 2 ATP
• NADH x 2 2 NADH
• 2 Pyruvate