Elements, Molecules, and Bioelements

• Elements vs. Molecules

  • A chemical element is a pure chemical substance consisting of a single type of atom (Hydrogen, H2)
  • Molecules consist of an electrically neutral group of two or more atoms held together by chemical bonds

• Bacteria and Nutrients

  • Bacteria, like other living organisms, require certain nutrients for growth
  • Nutrients contain chemical elements
    • Constituents of cellular materials
    • Necessary for the activity of enzymes and transport system

Essential Bioelements

• Essential bio-elements constitute cellular materials and are necessary for the growth, maintenance, and reproduction of a living organism

Major Bioelements

• Bio-elements needed in relatively higher concentration (>10-4M)
• There are 12 major bio-elements

Minor Bioelements

• Are needed in small amounts
• Are critical to cell function

Elements and their functions

• Carbon (C)
  • Source is organic compounds, CO2.
  • It is a constituent of life
• Oxygen (O)
  • Source is CO2 O2, organic compounds, H₂Ō
  • It is a constituent of life
• Hydrogen (H)
  • Source is organic compounds, H₂O, H₂
  • It is a constituent of life
• Nitrogen (N)
  • Source is NH4+, NO3, N2, organic compounds
  • It is a constituent of life
• Sulfur (S)
  • Source is SO2-4, HS, SO, S₂O2-, organic sulfur compounds
  • Constituent of cysteine, methionine, thiamine, pyrophosphate, coenzyme A, biotin and a-lipoic acid
• Phosphorus (P)
  • Source is HPO2-4
  • Constituent of-nucleic acid, phospholipids, nucleotides
• Potassium (K)
  • Source is K+
  • Is the prinicpal inorganic cation in cells
  • Is a cofactor of some enzymes
• Magnesium (Mg)
  • Source is Mg2+
  • Is a cofactor of many enzymes
  • Is present in cell walls, membrane, ribosome, and phosphate esters
• Calcium (Ca)
  • Source is Ca2+
  • Is present in exoenzymes (amylases,proteases)
  • Present in cell wall
  • Ca-dipicolinate is an important component of endospores
• Iron (Fe)
  • Source is Fe2+, Fe3+
  • Is present in cytochromes, ferredoxins and other iron-sulfur proteins
  • Cofactor of some enzymes
• Sodium (Na)
  • Source is Na+
  • Involved in various transport processes
  • Required by halophilic, methanogenic bacteria
• Chloride (Cl)
  • Source is Cl-
  • Important inorganic anion
• Zinc (Zn)
  • Source is Zn2+
  • Present in alcohol dehydrogenase, alkaline phosphatase, aldolase
  • RNA and DNA polymerase
• Manganese (Mn)
  • Source is Mn2+
  • Present in bacterial and mitochondrial superoxide dismutase
  • Component of photosystem II in plants and cyanobacteria
  • Functions as cofactors of some enzymes
• Molybdenum (Mo)
  • Source is MoO2-4
  • Present in several enzymes that play an important role in nitrogen metabolism and formate oxidation
• Selenium (Se)
  • Source is SeO2-3
  • Present in glycine reductase and formate dehydrogenase
• Cobalt (Co)
  • Source is Co2+
  • Present in coenzyme B12 containing enzymes
• Copper (Cu)
  • Source is Cu2+
  • Present in enzymes
  • Transferring electrons from substrates to oxygen
  • Involved in denitrification (Denitrification is essentially the conversion of nitrate to nitrogen gas, carried out by bacteria in absence of oxygen)
• Nickel (Ni)
  • Source is Ni2+
  • Present in urease
  • Hydrogenase
  • Factor F430 in methanogenic bacteria
• Tungsten (W)
  • Source is WO2-4
  • Needed in some rare cases
  • Present in some formate dehydrogenase

Biomolecules

• Any molecule present in living organisms
• Includes large macromolecules such as proteins, polysaccharides, lipids, and nucleic acids
• Includes small molecules such as primary metabolites, secondary metabolites, and natural products
• Are complex, but are made up of simpler components

Biological Macromolecules

• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
• Life depends on these four types of organic macromolecules
• Proteins, nucleic acids, polysaccharides and lipids are the most abundant biomolecules

Basic Functions of Macromolecules

• Carbohydrates
  • Energy storage
  • Structure
  • Starch, Glycogen, Glucose, Sucrose, Cellulose
• Lipids
  • Long-term storage
  • Insulation
  • Protection
  • Lipid, fats, oils, waxes
• Nucleic acids
  • Inheritance
  • Blueprint for metabolism
  • DNA, RNA
• Proteins
  • Catalysts
  • Hormones
  • Structure
  • Proteins, Enzymes

Carbohydrates

• Contain carbon, hydrogen, and oxygen in a ratio of 1:2:1
• Account for less than 1% of body weight
• Used as an energy source
• Are called saccharides
• Sugars
  • Monosaccharides (monomers)
  • Disaccharides (Dimers)
  • Polysaccharides (polymers)

Lipids

• Contain carbon, hydrogen, and oxygen, but the ratio of C:H is 1:2 (much less O)
• May also contain other elements phosphorous, nitrogen, and sulfur
• Form essential structures in cells
• Important energy stores

Proteins

• Chains of amino acids linked together by peptide bonds
• Enzymes are proteins

Nucleic Acids

• Contain C, H, O, N, and P
• DNA and RNA are nucleic acids
• Nucleotides consist of:
  • Sugar
  • Phosphate group
  • Nitrogenous base
• Phospholipids are amphiphilic - they have polar heads and nonpolar tails.