Module 6: Nutrition

• what do cells need for growth?

  • energy
  • carbon
  • other nutrients
  • appropriate environmental conditions
• macronutrients (NCHOPS):

  • nitrogen
  • carbon
  • hydrogen
  • oxygen
  • phosphorus
  • sulfur
• how do cells get nitrogen?

  assimilated (amino acids, nitrate/ammonia) or N2 fixers
• how do cells get carbon?

  organic compounds, CO2 or methane
• micronutrients (SCIMP):

  • sodium
  • calcium
  • iron
  • magnesium
  • potassium
• micronutrients are essential ions needed in small amounts, all have separate transport
• sodium and calcium are not essential for all cells
• iron: many enzymes, especially e- transport
• magnesium: stabilize ribosomes, ATP dependent reactions
• potassium: main cellular cation
• trace elements are needed in very small quantities, help enzymes via coenzymes and cofactors
• trace elements and growth factors are organism specific
• example of spending energy to obtain trace elements: iron acquisition, build siderophores for 1 time use to bind and transport iron
• growth factors: small amounts of organic compounds needed by cells that can't make their own
• all microbes absorb macronutrients via transport proteins
• how do eukaryotes assimilate macronutrients?

  endocytosis
• what are the two ways macronutrients are absorbed into the membrane system?

  phagocytosis (solids) and pinocytosis (liquids)
• how do cells concentrate gas?

  proteins capture and bind (ex. hemoglobin and O2)
• how do cells break down polymers?

  secrete exoenzymes into environment
• how do microbes assimilate macronutrients?


  soluble nutrients (saprobes) or other cells (predators and parasites)
• macronutrient metabolism is used in nucleic acids, membranes, proteins and cell wall
• macronutrient metabolism:

  1. transport into cell (ex. nucleic acids)
  2. synthesize monomer (ex. DNA/RNA bases)
  3. synthesize polymer (ex. DNA/RNA)
  4. structural assembly (ex. chromosomes)
• what are the two types of energy source?

  1. chemotroph: chemical energy
  2. phototroph: light energy
• what are the two types of carbon source?

  1. autotroph: CO2
  2. heterotroph: organic compounds
• what are the two types of electron source?

  1. lithotroph: inorganic chemicals
  2. organotroph: organic chemicals