Download Microbial Metabolism

Microbial Metabolism
Microbial Metabolism
• The sum of all chemical
reactions within a living
organism
–Catabolism
–Anabolism
Catabolism
Destructive metabolism;
the breaking down in living
organisms of more complex
substances into simpler ones,
with the release of energy
(opposed to anabolism)
Catabolism
• Complex substances into
simple ones, releases
energy
Glucose
CO2 + H2O + Energy
Catabolism
Peptide
Protein
Single
amino acids
Energy
Anabolism
Constructive metabolism; the
synthesis in living organisms
of more complex substances
from simpler ones, spending
energy (opposed to
catabolism )
Anabolism
• Simple substances into
complex ones, spend energy
Amino acids + Energy
Proteins
Anabolism
Peptide
Enzyme
Energy
Single
amino acids
Protein
Enzymes
• Speed up chemical reactions
– Increase frequency of
collision
–Orient molecules
–Lower activation energy
–Low temperatures
Enzymes (cont.)
• Very efficient
–Reactions occur 10 billion
times faster than without
enzyme
–Enzyme does not change
during reaction
Substrate
• Substance that the enzyme
acts on (i.e.. Sucrose)
sucrose + sucrase=glucose &
fructose
substrate+enzyme=product(s)
Enzyme structure
• three-dimensional shape
(thousands of shapes)
• lock and key
complementary
Enzyme structure
Substrate
Enzyme
Product
Processing
Active site
Turnover number
• Maximum number of
substrate molecules that one
enzyme can process per
second
• 1 to 10,000, but may be as
high as 500,000
Enzyme cellular control
• Repression
• Induction
Repression
• Mechanism that inhibits the
synthesis of an enzyme
when the specific-end
product is present in
abundance, or the substrate
is absent
Induction
• Mechanism that promotes
the synthesis of an enzyme
when the specific-end
product is present in low
concentration, or absent,
and the substrate is present
Repression/induction
Lactose present
B-galactosidase
Glucose and galactose
(end products) high
concentration
Concentration
End-product and enzyme
b-galactosidase
(enzyme)
Glucose and
galactose
(end products)
Time
Concentration
Substrate and enzyme
B-galactosidase
Lactose (substrate)
Time
Concentration
Substrate and enzyme
B-galactosidase
Lactose (substrate)
Time
Cofactors
• Metal ions (Fe, Cu, Mg, Zn, Ca
and Co)
–Bridge between substrate and
enzyme
• Coenzymes
–Derived from vitamins (Bvitamins)
–Electron carriers (NAD+ &
NADP+)
Factors Influencing
Enzymatic Activity
• Temperature
• pH
• Inhibitors
– Cyanide, arsenic, mercury
Energy Production
• Adenosine triphosphate (ATP)
– Cell’s energy carrier
•Mitochondria (eucaryotes)
•Plasma membrane
(bacteria)
Respiration in
eucaryotes
Mitochondria
Cell membrane
Respiration in
procaryotes
(bacteria)
Oxidation-Reduction
(Redox reactions)
• Highly reduced compounds
(many Hydrogens) are high
in energy (glucose)
• Highly oxidized compounds
are low in energy (CO2)
Oxidation-Reduction
(Redox reactions) (cont.)
• Glucose (C6H12O6),
reduced, high energy
• CO2, oxidized, low energy
Glucose
– Respiration (O2 or
inorganic substances as
electron acceptors)
– Fermentation (organic
substances as electron
acceptors)
Glycolysis
• First step in carbohydrate
catabolism in both,
respiration and
fermentation
• Does not require oxygen
• 10 different reactions
(enzymes)
Glycolysis
Glucose -C-C-C-C-C-C Oxidation
Pyruvic
acid
-C-C-C- -C-C-C -
Glycolysis (cont.)
• ATPs’ produced
• ATPs’ consumed
4
2
2
Aerobic Respiration
• O2 required
Pyruvic acid C-C-C (2)
Oxidation
Krebs cycle
6CO2 + 6H2O + 38 ATP (pro)
36 ATP (eu)
Anaerobic respiration
• Electron acceptor is an inorganic
substance other than O2 (number
of ATPs varies)
NO3 ---> NO2
SO4 ---> H2S
CO3 ---> CH4
Fermentation
• e acceptor is an organic
substance (pyruvate)
• Products
–Energy
–Lactic acid
–Alcohol
Fermentation
Glucose
2 Lactic acid
2 ATP