Upload
johnathan-benson
View
216
Download
0
Embed Size (px)
Citation preview
Cellular Respiration Part 2Glycolysis - Pages 93 to 95
Overview: Cellular Respiration
•Cellular Respiration takes place in three steps:▫Glycolysis – initial breakdown of glucose;
very little direct energy production; takes place in cytoplasm
▫Krebs Cycle – finishes the breakdown of glucose; very little direct energy production; takes place in the matrix of the mitochondria
▫Oxidative Phosphorylation – major energy producing process; takes place in the cristea of the mitochondria
Fig. 9-6-3
Mitochondrion
Substrate-levelphosphorylatio
n
ATP
Cytosol
Glucose Pyruvate
Glycolysis
Electronscarried
via NADH
Substrate-levelphosphorylatio
n
ATP
Electrons carried
via NADH andFADH2
Oxidativephosphorylatio
n
ATP
Citric
acidcycle
Oxidativephosphorylation
:electron transport
andchemiosmosis
Glycolysis
•Glycolysis (“splitting of sugar”) breaks down glucose into two molecules of pyruvate
•Glycolysis occurs in the cytoplasm and has two major phases:▫Energy investment phase▫Energy payoff phase
Fig. 9-8
Energy investment phase
Glucose
2 ADP + 2
P 2 ATP used
formed
4 ATP
Energy payoff phase
4 ADP + 4 P
2 NAD+ + 4 e– + 4 H+
2 NADH
2 Pyruvate
2 Pyruvate GlucoseNet
4 ATP formed – 2 ATP used
2 ATP
2 NAD+ + 4 e– + 4 H+
2 NADH + 2 H+
Glycolysis
•Takes place in the cytoplasm
•Believed to be the oldest metabolic process – shared by all organism
•ATP produced during the process via substrate level phosphorylation
Glycolysis – summarized in words• 2 molecules of ATP are used to start the process –
phosphorylating (energizing) the 6 carbon molecule– unstable 6C
• Unstable 6 C splits into to 3 C called G3P
• Oxidation of 2-3C (G3P) and reduction of 2 NAD+ to 2NADH releases enough energy to phosphorylate the 3C molecule
• Phosphates removed from 2-3C molecules in substrate level phosphorylation to produce 4 ATP; end with pyruvate
Glycolysis Summary• Reactants
▫Glucose, 2ATP and 2NAD+• Products
▫Pyruvate, 4 ATP, and 2 NADH• Net gain of ATP
▫2 ATP• Do you need to know all of the intermediates
in the process?▫NO – understand that it occurs in several steps,
each step involves different enzymes & results in a different carbon compound