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Nutritional Strategies and Nutrient Acquisition

Nutritional Strategies and Nutrient Acquisition. Nutritional Strategies (Types) Required Resources Nutritional Types Nutrition Acquisition Passive transport Active transport “Scavenging”. Resources for All Life:.

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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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