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Nutritional Strategies and Nutrient Acquisition

Explore the various nutritional strategies and nutrient acquisition processes crucial for sustaining life. Learn about major elements, trace elements, growth factors, types of transport mechanisms, and the role of energy, electrons, and carbon in cellular processes.

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Nutritional Strategies and Nutrient Acquisition

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  1. Nutritional Strategies and Nutrient Acquisition • Nutritional Strategies (Types) • Required Resources • Nutritional Types • Nutrition Acquisition • Passive transport • Active transport • “Scavenging”

  2. Resources for All Life: • Energy: cells need to do the work of membrane transport, biosynthesis, and mechanical processes. • Electrons: anabolic reactions (biosynthesis) require reducing power (adding e-). • Major Elements (macronutrients):Carbon, Nitrogen, Phosphorous in varying proportions (e.g. C:N:P ratio of eukaryote algae ≈ 106:16:1; bacteria ≈ 100:25:1; fungi ≈ 400:20:1). These, along with O, H and S, are all supplied in organic or inorganic form. In lesser amounts are Fe, Mg, Ca, K, and Na, which are mostly supplied as inorganic forms. • Trace Elements (micronutrients): Mn, Zn, Co, Cu, Mo, & Ni. • Growth Factors: essential amino acids, vitamins, and nucleoside bases are needed for growth but cannot be made by many organisms; some are sources of macro- and micro- nutrients

  3. Major Nutritional Types: (see Table 5.2)Energy→ Electrons → Carbon • Photolithoautotrophy • Photoorganoheterotrophy • Chemolithoautotrophy • Chemoorganoheterotrophy

  4. Both follow a concentration gradient, high to low; therefore reversible. • Passively through membrane lipids or porins; rate increase linear. • Facilitated by selective transporters; rate increase with [S] then plateaus at “saturation”. Transport Types:Passive DiffusionFacilitated Diffusion

  5. Against concentration gradient requires energy. • “Primary” transporters directly use ATP for energy. • May require solute binding proteins to scavenge solute. Transport Types:Primary Active Transport ATP-Binding Cassette Transporter (ABC transporter)

  6. Transport Types:Secondary Active Transport • Solute transport against a concentration gradient. • Secondary transporter couples solute with a flow of protons or other ions along strong concentration gradients; energy source. • Mechanism may be antiport or symport.

  7. Transport Types:Group Translocation • Solute can transport against concentration gradient. • Solute is modified during transport and energy released. • Often a high energy P-group gets translocated in a cascading sequence toward a lower energy state. • e.g. phosphoenolpyruvate (PEP): sugar phosphotransferase system (PTS). • PST is involved in chemotaxis.

  8. “Send out the scavengers!”Siderophores • Iron bioavailability is low; “rust never sleeps”. • Bacteria release these scavenger molecules to facilitate iron transport. • Multiple siderophores complex an iron molecule. • Siderophores can be species specific.

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