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Macronutrients and Micronutrients

• Macronutrients (Macroelements): Essential elements highlighted in yellow and pink on the periodic table. Commonly recognized as required for biological functions.

• Micronutrients: Include other essential elements found on the periodic table that may not be classified as macronutrients but still play crucial roles in biological systems.

Biological Functions of Nutrients

• Important for enzyme functions and various biochemical processes.

• Iron: Necessary for nitrogenase enzymes which aid in nitrogen fixation. Sometimes considered a macronutrient depending on the organism's needs.

• Molybdenum: Co-factor in nitrogenase; essential for certain enzymatic reactions in nitrogen fixation.

• Boron and others: Essential for quorum sensing in bacteria, enabling communication and collective behaviors like biofilm formation.

Concept of Essential Elements

• Despite being small in quantity, essential elements have significant impacts on growth and metabolism of organisms.

• The absence of even a single element can inhibit an organism's development, such as ammonia production in nitrogen fixation, undermining growth.

Growth Factors

• Definition: Organic molecules essential for cell growth but separated from actual elements on the periodic table.

• Examples include vitamins like folic acid, biotin, and vitamin K.

• These compounds can either be synthesized by the cell or taken up from the environment.

• Folic Acid: Especially important for fetal development; deficiency can cause conditions like spina bifida.

• Microbes also require growth factors for proper metabolic functions.

Metabolism

• Importance of Nutrient Uptake: Bacterial cells must acquire macronutrients to function and perform metabolic processes, including energy production and biomass synthesis.

• Metabolism encompasses all biochemical reactions, including catabolic pathways for breakdown and energy release and anabolic pathways for building cellular structures.

Key Components of Metabolism

• Energy Sources: Cells need organic/inorganic substrates like glucose to perform metabolic conversions.

• Catabolic Pathways: Involve breaking down molecules to release energy, such as glycolysis and the citric acid cycle.

• Energy Storage Forms: Long-term storage molecules like glycogen (polymer of glucose) can release glucose for catabolism when needed.

Phosphorylation Types

• Substrate-Level Phosphorylation: Direct transfer of phosphate from a high-energy substrate to ADP to form ATP. Common in glycolysis and fermentation.

• Oxidative Phosphorylation: Occurs in respiration, involving an electron transport chain and ATP synthase. This process requires an electron acceptor (oxygen in aerobic respiration).

• Photophosphorylation: Similar to oxidative phosphorylation but driven by light energy, used in photosynthesis.

Enzymes in Metabolism

• Kinases: Enzymes that catalyze the addition of a phosphate group to a substrate (e.g., hexokinase).

• Dehydrogenases: Facilitate redox reactions, transferring electrons (e.g., isocitrate dehydrogenase in the citric acid cycle).

• Synthases: Enzymes that join two molecules together (e.g., ATP synthase).

Glycolysis Overview

• Glycolysis breaks down glucose (6-carbon sugar) into two 3-carbon pyruvate molecules, conserving all carbons initially.

• Starts with the input of ATP for phosphorylation. Ends with a net gain of ATP and NADH.

• Glucose is ultimately transformed into energy-rich intermediates which subsequently produce ATP through substrate-level phosphorylation.

Fermentation and Respiration

• Fermentation occurs in the absence of an electron acceptor, allowing for the recycling of NADH back to NAD+ through the production of waste products like alcohol or acids.

• Facultative Organisms: Can perform both fermentation and respiration depending on oxygen availability. Obligate aerobes rely solely on respiration.

• Variety of substrates can be fermented, making many organic compounds usable as energy sources.

Practical Implications

• Knowledge of metabolism and enzyme functions is crucial for understanding microbial behavior, growth requirements, and industrial applications (e.g., brewing, waste treatment).

• Recognition of the vital role of micronutrients and growth factors in cellular health and development.