• Fermentation releases energy from sugars or other
• Pyruvate is metabolized to various compounds •
O 2 is not required
• Does not use the
• Electrons removed from the substrate
reduce NAD+ to NADH.
• The final electron acceptor is an endogenous
• Produces only small amounts of ATP (
one or two ATP
molecules for each molecule of starting material) • ATP molecules are produced by
substrate level phosphorylation.
Alcohol fermentation -
acetaldehyde is reduced by NADH to
– Product ethyl alcohol + CO 2
Lactic acid fermentation (homolactic)-
pyruvic acid is reduced by NADH to
– Product - lactic acid only
fermentation – Product lactic acid as well as other acids and alcohols.
• Lipases hydrolyze
into • Fatty acids and other hydrocarbons are catabolized by
• Catabolic products can be further broken down in
Deamination, decarboxylation, dehydrogenation
Urea Urease NH 3 + CO 2
Highly reduced complex molecules Oxidized NAD + NADH
• Polysaccharide Biosynthesis
ADPG (adenosine diphosphoglucose).
UGPG (uridine diphosphoglucose) UDPNAc ( UDP-N-acetylglucoseamine)
• Lipid Biosynthesis – Lipids are synthesized from
• Glycerol is derived from dihydroxyacetone phosphate.
• Fatty acids are built from acetyl CoA.
• 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.
• 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.
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
Energy from sunlight
is used to convert carbon dioxide( CO 2 ) and water (H 2 O) into organic materials to be used in cellular functions such as biosynthesis and respiration •
Conversion of light energy Light-dependent
into chemical energy (ATP) (light) reactions •
Fixing carbon Light-independent
into organic molecules (dark) reaction, Calvin-Benson cycle • Process is localized in
- the electrons return to the chlorophyll
Noncyclic photophosphorylation -
The electrons are used to reduce NADP + and form NADPH -The electrons from: -
H 2 O
H 2 S
chlorophyll replace those lost from
(H 2 S)
) Figure 5.24a
6CO 2 + 12H 2 O + Light energy C 6 H 12 O 6 +
6 O 2
+ 6H 2 O
6CO 2 + 12H 2 S + Light energy C 6 H 12 O 6 +
+ 6 H 2 O
• • •
Photosynthesis: Fixing carbon Calvin-Benson cycle
• Use NADPH as cofactor (
CO 2 )
into organic molecules • Characteristic of: -
Green and Purple bacteria Algae
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: Phototrophs:
Bond energy is released from a chemical compound Light is absorbed in photo receptors and transformed into chemical energy.
s - Organisms that use energy from organic chemicals Glucose NAD + ETC • Pyruvic acid NADH ADP + P ATP
Organic compounds are metabolized to get carbon for growth and development.
• Cannot fix carbon
• Use energy from
• Energy is used in the Calvin-Benson cycle
to fix CO 2
2Fe 2+ NAD + ETC 2Fe 3+ NADH ADP + P ATP 2 H + •
Energy from sunlight
Chlorophyll ETC Chlorophyll oxidized ADP + P ATP • Energy is used in the Calvin-Benson cycle to fix CO 2 –
• Energy is used in anabolism (carbon from organic compounds) -
Light CO 2
Photoheterotroph Chemoautotroph Chemoheterotroph Light Organic compounds Chemical CO 2 Chemical Organic compounds
Oxygenic: Cyanobacteria plants.
Anoxygenic: Green, purple bacteria.
Green, purple nonsulfur 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
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 )
•Fermentation tests are used to determine the substrates the organism can metabolize by the products it generates.
Control tube S.epidermidis
, inverted Durham tube Products: Acid and gas.
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.
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