Transcript Microbial Metabolism

Microbial Metabolism
Chapter 5
Metabolism
A.
B.
Metabolism: Is the
sum of all chemical
reactions in the
body.
metabolism is
divided into two
types of classes:
catabolism and
anabolism.
• Catabolism is the chemical
reactions that break down
large compounds and release
energy.
• Anabolism is the chemical
reactions that require energy to
build large compound
• Catabolic reactions furnish the
energy needed to drive
anabolic reactions.
– . Energy harvested from
catabolic reactions are stored
in ATP molecules. ATP
molecules are used to drive
many anabolic reactions.
Oxidation Reduction
Energy is often transferred from one molecule to another
by oxidationreduction reactions.
1.Energy is transferred when electrons from a molecule
being oxidized are shifted to a molecule being reduced.
a. Oxidation is the removal of electrons
b. Reduction is the gaining of electrons
c. Oxidation and reduction always occur together.
d. Most microorganisms oxidize carbohydrates
as their primary source of energy.
cellular respiration
1.Cellular respiration oxidizes glucose to
reduce NAD+ to NADH (NADH is an
electron carrier)
2. Cellular respiration has three stages,
glycolysis, krebs and electron transport.
Glycolysis
Glycolysis is an oxidation
reduction reaction.
1. Glucose is oxidized to 2
Pyruvic acids.
2. 2NAD+ are reduced to 2
NADH.
3. produce 2 ATP by
substrate level
phosphorolation
4. Occurs in the cytoplasm
of both procaryotes and
eucaryotes
Preparatory step
• Preparatory step for
Krebs cycle:
• Both pyruvic acid
molecules from glycolysis
are oxidized into two
acetyl CO-A.
• 2 NAD+ are reduced
yielding two NADH
• Prep step occurs in the
Mitochondria.
Krebs cycle
• Oxidation of 1 acetyl co-A
to carbon dioxide produces
– 1 molecule of ATP
– 3 NADH
– 1 FADH
• Occurs in the cytoplasm in
procaryotes
• Occurs in the mitochondria
in eucaryotes
Electron Transport
• Converts the energy in NADH and FADH
molecules into a hydrogen gradient in the
mitochondria
Electron Transport
– Occurs in the plasma membrane of prokaryotes and
in the inner mitochondrial membrane in eukaryotes.
– The hydrogen gradient built up in the mitochondria is
responsible for the production of the most of the ATP
in the cell.
Electron Transport
Production of ATP
H+ ions pass through ATP synthase stimulating it to
produce ATP from ADP
D
ATP yield from procaryotic respiration
1. Each NADH produces enough H+ to account for the
production of 3 ATPs. Each FADH is worth 2 ATPs
a
glycolysis = 8 ATP (6 from 2 NADH and 2 produced
during glycolysis)
b. Preparatory Step in which pyruvic acid is converted
into Acetyl Co-A = 6 ATP (from 2 NADH)
c. Krebs cycle = 18 ATP (from 6 NADH) + 4 ATP (from 2
FADH) + 2 ATP produced in the cycle.
d. Total = 38 ATP in procaryotes
e. In eukaryotes it cost the cell 2 ATP to get the 2
molecules of NADH produced in glycolysis into the
mitochondria.
III
F erm enta tion . O rg an ism s p rodu ce A T P in th e a bsence o f
o x yg en .
A.
Fermentation produces ATP through glycolysis.
1.
Fermentation does not use the krebs cycle or the electron
transport.
2.
NADH is used to reduce pyruvic acid to either lactic acid or
alcohol.
a.
NADH is converted back to NAD+
Fermintation