Module 5: Microbial Metabolism Flashcards
Metabolism and its 3 Components
- series of biochemical reactions by which the cell breaks down or biosynthesizes various metabolites
(i) Cell Nutrition
(ii) Metabolic Pathways
(iii) Biosynthesis of biomolecules
Macronutrients (sources of carbon and nitrogen)
Nutrients required in large amounts
- carbon and nitrogen
- most microbes obtain organic compounds from CO2; prokaryotes require organic compounds as sources of carbon
- sources of nitrogen (NH3, NO2, N2)
Micronutrients definition and 2 examples
Nutrients required in small amounts
- trace metals & growth factors
- trace metals: cofactors of certain enzymes and cellular respiration (iron)
- growth factor: organic micronutrients (e.g. vitamins)
SIDEROPHORES (iron maiden)
Small, high-affinity iron-chelating compounds that are secreted by microorganisms such as bacteria and fungi. They help the organism accumulate iron.
3 Types of Active Transport
- Simple Transport
- consists of only a transmembrane transport protein; co-transported by H+ - Group Translocation
- chemical modification of the transported substance driven by phosphoenolpyruvate - ABC transport System
- ATP-binding cassette; periplasmic binding proteins are involved and energy comes from ATP
SYMPORT vs ANTIPORT
SYMPORT: solute and proton are co-transported in one direction (simple transporters)
ANTIPORT: solute and proton are transported in opposite directions
Where are ABC transport systems present in?
- Gram positive Bacteria and Archaea
3 Components of ABC transport system (SAT)
- Substrate-binding protein
- Transmembrane transporter
- ATP-hydrolyzing protein
Metabolic Couping
An essential mechanism that concentrates on the transfer of energy that is released from an exergonic pathway to provide energy needed for an endergonic pathway.
PHOTOTROPHS vs CHEMOTROPHS
Phototrophs: obtain energy for metabolism from light
Chemotrophs: obtain energy for metabolism from chemical reactions
CHEMOORGANOTROPHS vs CHEMOLITHOTROPHS
Chemoorganotrophs: obtain energy and reducing power from organic molecules
Chemolithotrophs: obtain energy and reducing power from inorganic molecules
Where does E. Coli get its energy from?
From organic compounds; CHEMOORGANOTROPHS
Fermentation definition
Form of anaerobic catabolism in which organic compounds both donate electrons and accept electrons, and redox balance is achieved without the need for external electron acceptors
Fermentation Cycle
Organic Compound –[REDOX]–> Energy-rich compound –[SUBSTRATE-LEVEL PHOSPHORYLATION]–> Oxidized Compound –[REDOX]–> Fermentation Product
Lactic Acid Fermentation
Glucose + 2 ADP + 2 Pi –> 2 Lactate + 2 ATP
Fermentative Diversity (Clostridium and Fermentative Anaerobes)
- Some microorganisms convert polysaccharides to fermentable glucose
- Some fermentations allow for additional ATP synthesis
- Clostridium species ferment amino acids and others ferment purines and pyrimidines
- Fermentative anaerobes ferment aromatic compounds
Fermentation-Respiration Switch
- Capable of both fermentation-respiration
- Energy available from glucose molecule is much greater if it is respired to CO2 then if it is fermented; yeast cells prefer respiration in O2 presence
- Saccharomyces cerevisiae can both ferment and respire
Respiration
form of aerobic or anaerobic catabolism in which an organic or inorganic electron donor is oxidized with O2 (aerobic) or some other compound (anaerobic) functioning as electron acceptors
Electron Acceptors in Anaerobic Respiration
- CO2
- Sulfate
- Ferric iron
- Nitrate
2 Types of Phototrophy based on starting material
- Photoheterotrophy
- organic compound –> cell material - Photoautotrophy
- CO2 –> cell material
+ electrons from H2O (oxygenic) or H2S (anoxygenic)
Glucose synthesis (ANABOLISM)
Glucogeogenesis
Pentose Sugar synthesis (ANABOLISM)
Pentoses for nucleic acid synthesis are formed by removal of carbon atom from a hexose through PENTOSE PHOSPHATE PATHWAY
3 Types of Sugar synthesis
- Formation of uridine diphosphogluclose (for nucleic acids)
- Citric Acid Cycle
- Pentose Phosphate Pathway (PPP; DNA and RNA)
Formation of Alanine Family
Glycolysis –> Pyruvate –> Alanine Family
Formation of Serine Family
Glycolysis –> 3-Phosphoglycerate –> Serine Family
Formation of Aromatic Family
Glycolysis –> Chorismate + Pentose Phosphate Pathway –> Aromatic Family
Formation of Glutamate family
Citric Acid cycle –> alpha-Ketoglutarate –> Glutamate family
Formation of Aspartate Family
Citric Acid Cycle –> Oxaloacetate –> Aspartate Family
What Amino Acids are formed from Citric Acid Cycle and Glycolysis?
GLYCOLYSIS:
1. Alanine Family
2. Serine Family
3. Aromatic Family
Citric Acid Cycle:
1. Glutamate Family
2. Aspartate Family
Nucleotide Synthesis (2 PURINE and 2 PYRIMIDINE biosynthesis)
PURINE:
1. Purine Skeleton
2. Inosinic Acid
PYRIMIDINE:
1. Orotic Acid
2. Uridylate
Fatty Acid Synthesis
Fatty acids are synthesized from malonyl-ACP
Electron Acceptors in Anaerobic Respiration
- CO2
- Sulfate
- Ferric iron
- Nitrate
Lipid Synthesis
Lipid is formed when fatty acids attach to glycerol
–> only lipids of bacteria and Eukarya contain fatty acids
Another Name for Glycolysis
Embden-Meyerhof-Pathway
2 Metabolic Pathways after Glycolysis
- Glyoxylate Cycle (C2 electron donor; ANABOLIC & fatty acids to carbohydrates)
- The glyoxylic cycle is an anabolic pathway that occurs in plants, bacteria, fungi, and protists. - Citric Acid Cycle / Tricarboxylic Acid Cycle / Krebs Cycle (C4 or C6 electron donor; CATABOLIC)
Products of Krebs Cycle from 1 Glucose Molecule
6 CO2
8 NADH
2 FADH2
Total ATP produced from Glycolysis, Link Reaction and Krebs Cycle for 1 Glucose molecule
Glycolysis: 8 ATP (2 ATP and 2 NADH:6 ATP)
Link Reaction: 6 (2 NADH:6 ATP)
Krebs Cycle: 24 ATP (2 ATP and 6 NADH: 18 ATP and 2 FADH2:4 ATP)
= 38 ATP
Oxygenic photosynthesis
oxidation of water to PRODUCE molecular O2
Anoxygenic Photosynthesis
Oxygen is NOT PRODUCED
Photosynthetic Systems in Bacteria (6)
CHAG PF
- Cyanobacteria
- Heliobacteria
- Acidobacteria
- Green Sulfur Bacteria
- Purple Bacteria
- Filamentous Anoxygenic Phototrophs [FAP] (Green nonsulfur bacteria)
What photosynthetic systems in bacteria use water as an electron donor?
Green plants
Algae
Cyanobacteria
Which bacteria are oxygenic and which are anoxygenic? What substances do they use as electron donors?
OXYGENIC:
- Cyanobacteria
- Water
ANOXYGENIC:
- Purple bacteria
- Green sulfur bacteria
- H2S, SO42-, S0
Define Photocomplexes
pigments attached to proteins within membranes
Reaction center
Complex macromolecular structure of a photosynthetic system that acts as the main site for the energy conversion of light
Light-Harvesting / Antenna Pigments
Aid in the absorption of light and funnels energy into the reaction center
Chlorosome and what photosynthetic systems is it found in (3)?
Structures for capturing energy from low light intensities
- Anoxygenic green sulfur bacteria
- Green nonsulfur bacteria
- Photosynthetic Acidobacteria
