Figure 5.11

• Fermentation releases energy from sugars or other organic molecules by oxidation.
• Pyruvate is metabolized to various compounds
•
O
2 is not required in fermentation.
• Does not use the
Krebs cycle or ETC
• Electrons removed from the substrate reduce
NAD+ to NADH.
• The final electron acceptor is an endogenous organic molecule.
• Produces only small amounts of ATP ( one or two ATP molecules for each molecule of starting material)
• ATP molecules are produced by substratelevel phosphorylation.

•
Alcohol fermentation acetaldehyde is reduced by NADH to produce ethanol .
– Product ethyl alcohol + CO
2
(gas)
• Lactic acid fermentation (homolactic)pyruvic acid is reduced by NADH to lactic acid.
– Product
- lactic acid only
•
Heterolactic fermentation
– Product lactic acid as well as other acids and alcohols.

Figure 5.18b

• Lipases hydrolyze lipids into glycerol and fatty acids.
• Fatty acids and other hydrocarbons are catabolized by beta-oxidation.
• Catabolic products can be further broken down in glycolysis and the
Krebs cycle.
(hydrolase)
Figure 5.20

Protein
Extracellular proteases
Amino acids
Deamination, decarboxylation, dehydrogenation
Organic acid Krebs cycle
Urea
Urease
NH
3
+ CO
2

Highly reduced complex molecules
Oxidized
NAD + NADH
Energy
ADP ATP

• Polysaccharide Biosynthesis
ADPG (adenosine diphosphoglucose).
UGPG (uridine diphosphoglucose)
UDPNAc ( UDP-N-acetylglucoseamine)
Figure 5.28

• Lipid Biosynthesis
– Lipids are synthesized from fatty acids and glycerol .
• Glycerol is derived from dihydroxyacetone phosphate.
• Fatty acids are built from acetyl CoA.
Figure 5.29

• Amino Acid and Protein Biosynthesis
• All amino acids can be synthesized either directly or indirectly from intermediates of carbohydrate metabolism, particularly from the Krebs cycle.
Figure 5.30a

• Purine and Pyrimidine Biosynthesis.
–
The sugars composing nucleotides are derived from either the pentose phosphate pathway or the Entner-Doudoroff pathway.
– Carbon and nitrogen atoms from certain amino acids form the backbones of the purines and pyrimidines
Figure 5.31

• Can readily go in either direction.
• Each direction may need special conditions.
NADH
AB
A + B
NAD+
[Product concentration]

• Anabolic and catabolic reactions are integrated through a group of common intermediates.
• Both anabolic and catabolic reactions also share some metabolic pathways, such as Krebs
• Such integrated metabolic pathways are referred to as amphibolic pathways .

• Energy from sunlight is used to convert carbon dioxide( CO
2 water (H
2 such as biosynthesis and respiration
) and
O) into organic materials to be used in cellular functions
•
Photo: Conversion of light energy into chemical energy (ATP)
– Light-dependent (light) reactions
•
Synthesis: Fixing carbon into organic molecules
–
Light-independent (dark) reaction, Calvin-Benson cycle
• Process is localized in chloroplasts (eukaryotes) or chlorosomes
(prokaryotes)

Cyclic
Photophosphorylation
- the electrons return to the chlorophyll
Noncyclic photophosphorylation -
The electrons are used to reduce
NADP + and form NADPH
-The electrons from:
H
2
O or H
2
S replace those lost from chlorophyll
(H
2
S)
( S )
Figure 5.24a

•
Oxygenic :
6CO
2
+ 12H
2
O +
Light energy

C
6
H
12
O
6
+ 6 O
2
+ 6H
2
O
•
Anoxygenic :
6CO
2
+ 12H
2
S +
Light energy

C
6
H
12
O
6
+ 12 S + 6 H
2
O

•
Photosynthesis: Fixing carbon ( CO
2
) into organic molecules
•
• Calvin-Benson cycle
• Use NADPH as cofactor
• Characteristic of:
Cianobacteria,
Green and Purple bacteria
Algae and Plants
Autotrophs: Carbon dioxide (CO
2
) is used as source of carbon
Figure 5.25

A Summary of Energy Production Mechanisms
Nutritional types of organisms by Sources of energy
Chemotrophs: Bond energy is released from a chemical compound
Phototrophs: Light is absorbed in photo receptors and transformed into chemical energy.

•
Chemotroph s - Organisms that use energy from organic chemicals
Glucose NAD +
ETC
Pyruvic acid NADH
ADP + P ATP
• Heterotrophs: Organic compounds are metabolized to get carbon for growth and development.
• Cannot fix carbon

• Use energy from inorganic chemicals
• Energy is used in the Calvin-Benson cycle to fix CO
2
2Fe 2+ NAD +
ETC
2Fe 3+ NADH
ADP + P ATP
2 H +
•
Chemoautotroph
–
Thiobacillus ferrooxidans

• Use
Energy from sunlight
Chlorophyll
ETC
Chlorophyll oxidized
ADP + P ATP
• Energy is used in the Calvin-Benson cycle to fix CO
2
–
Photoautotrophs
• Energy is used in anabolism (carbon from organic compounds) -
Photoheterotrophs

Nutritional type
Photoautotroph
Energy source
Light CO
2
Carbon source
Photoheterotroph
Chemoheterotroph
Light Organic compounds
Chemoautotroph Chemical CO
2
Chemical Organic compounds
Example
Oxygenic:
Cyanobacteria plants.
Anoxygenic: Green, purple bacteria.
Green, purple nonsulfur bacteria.
Iron-oxidizing bacteria.
Fermentative bacteria.
Animals, protozoa, fungi, bacteria.

Carbon cycle Nitrogen cycle
Sulphur cycle Phosphorus cycle

Bacillus subtilis
Staphylococcus aureus
Gram stain
Pseudomonas aeruginosa
Kelbsiella pneumonia
•
K. pneumonia and Ps. aeruginosa look alike through a microscope after Gram stain; so how can they be differentiated?
Different species produce different enzymes determine what type of metabolic reactions an organism can carry out
– Oxygen requirements
– Fermentation of different substrates (sugars)
– Enzymes of respiration
– Amino acid catabolizing enzymes

• Singlet oxygen: O
2 boosted to a higher-energy state
• Superoxide free radicals: O
2
–
• Peroxide anion: O
2
2–
• Hydroxyl radical (OH 
)

2

•Fermentation tests are used to determine the substrates the organism can metabolize by the products it generates.
Control tube S.epidermidis
S.aureus
E.coli
.
Medium: Carbohydrate Mannitol , inverted Durham tube
Products: Acid and gas.
Figure 5.23

Urease
NH
3
+ CO
2

•
A dichotomous key is a series of questions which leads to the identification of an item.
– a device on paper or computer that aids identification of a species or other type of entity.
• Dichotomous keys are used for the identification of organisms.
• A dichotomous key works by offering two alternatives at each juncture, and the choice of one of those alternatives determines the next step.

• Describe the chemical reactions of, and list some products of, fermentation.
• Describe how lipids and proteins undergo catabolism.
• Provide two examples of the use of biochemical tests to identify bacteria.
• Compare and contrast cyclic and noncyclic photophosphorylation.
• Compare and contrast the light-dependent and light-independent reactions of photosynthesis.
• Compare and contrast oxidative phosphorylation and photophosphorylation.
• Write a sentence to summarize energy production in cells.
• Categorize the various nutritional patterns among organisms according to carbon source and mechanisms of carbohydrate catabolism and ATP generation.
• Describe the major types of anabolism and their relationship to catabolism.
• Define amphibolic pathways