Chemistry of Microbes
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DESCRIPTIONLECTURES IN MICROBIOLOGY. Chemistry of Microbes. LESSON 2. Sofronio Agustin Professor. Topics. Fundamental Building Blocks Macromolecules The Cell. Fundamental Building Blocks. Atoms Elements Molecules and compounds. Atoms. Subatomic Particles Proton = positive charge - PowerPoint PPT Presentation
Chemistry of MicrobesLESSON 2LECTURES IN MICROBIOLOGYSofronio AgustinProfessor
Fundamental Building BlocksMacromoleculesThe Cell
Fundamental Building BlocksAtomsElementsMolecules and compounds
AtomsSubatomic ParticlesProton = positive chargeNeutron = neutralElectron = negative chargeAtomic number = no. of protons Atomic mass = no. of protons and neutrons
Models of Atomic StructureAtomic Structure
IsotopesAtoms with same number of protons but differ in number of neutrons are called isotopes.Example: 12C, 13C, and 14C are isotopes of carbon.Radioisotopes emit radiation in the form of alpha or beta or gamma rays or photons.
Major Elements of Life
Molecules and CompoundsMolecule = combination of two or more elements (e.g.H2)Compound = combination of two or more different elements (e.g. H2O) Molecules are held together by chemical bonds
Chemical BondsChemical bonds involve atoms sharing, donating or accepting electrons
Covalent BondingExamples of covalent bonding
Polar Covalent BondPolarity occurs when atoms electrons unequally due to differences in electronegativities. This is seen in water (H2O).
More electronegative atoms tend to pull electrons toward them creating a polar molecule.
Ionic BondingSodium chloride (table salt) is an example of ionic bonding, that is, electron transfer among atoms or redox reaction.
IonizationMolecules formed by ionic bonding breakup (ionization) when dissolved in water (solvent), producing separate positive (cation) and negative (anion) ions.
These ions conduct electricity and thus called electrolytes.
Hydrogen BondHydrogen bonding is formed between the partially positive (hydrogen) end of a polar molecule and the negative end of another (e.g. O2 or N2).
Example : Water molecules
pHpH measurement of the H+ ion concentration in a solution.General rule: Acidic = excess H+ ions in solutionBasic = excess OH- ions in solutionNeutral = equal amounts of H+ and OH- ions
The pH ScaleThe pH of an environment (exterior or interior of a cell) is important for living systems.
MoleculesMolecules important to life consist of inorganic and organic substances.
Inorganic either C or H maybe present (e,g, CO2, H2)Organic- C and H (hydrocarbons) are present (e.g. CH3)
Organic Molecules Carbon, a tetravalent atom, is an ideal element for life because it serves as the skeleton for macromolecules.
Functional groups (R) attached to these carbons confer unique properties to these macromolecules.
Classes of CarbohydratesMajor sugars (monosaccharides) in the cell are glucose, galactose and fructose. Several sugars bonded together are called polysaccharides.
Glycosidic BondSugars are bonded by special kind of covalent linkage called glycosidic bonds.
Water is released (dehydration) after the bond is formed.
PolysaccharidesPeptidoglycan in bacteria is an example of a polysaccharide.
FatsSynthesis and structure of a triglyceride (fat), a storage molecule.
PhospholipidsPhospholipids serve as a major structural component of cell membranes.
It is an amphiphatic molecule. Its phosphate head is hydrophilic and its fatty acid tail is hydrophobic.
Cholesterol: An Alcoholic SteroidCholesterols are associated with cell membranes of some cells such as those of eukaryotes.
ProteinsProteins are the predominant organic molecules in cells. Proteins consist of a series of amino acids (e.g. peptides, polypeptides)Peptide bonds link amino acids together.Examples: hormones, enzymes, antibodies, etc.
An amino acid has a central carbon, to which carboxylic, amino and R groups are attached.
Amino acid types vary according to the reactive (R) groups present.
The 20 Naturally Occurring Amino Acids
.A peptide bond (covalent) forms between the amino group on one amino acid and the carboxyl group on another amino acid with the accompanying loss of water.Peptide Bond
Levels of Structures of ProteinProteins take on a variety of shapes due to extensive folding of the molecule. This enable them to perform specific functions and interactions with other molecules.
Nucleic acidsDeoxyribonucleic acid (DNA)Ribonucleic acid (RNA)DNA contains genetic information and transfers it to RNARNA translates the DNA information into proteins
Nucleic Acid PolymersNucleic acids are polymers of repeating units called nucleotides.
The Sugars and Nitrogenous BasesThe pentose sugars and nitrogen bases determine whether a molecule will be DNA or RNA.
. The DNA configuration is a double helix similar to a spiral staircase
Sugar and phosphate backbones are held together by hydrogen bonds formed between nitrogenous bases.
The DNA Molecule
DNA : The Molecule of InheritanceDNA serves as a template for the synthesis of new DNA strands as well as mRNA, tRNA and rRNA.
DNA replication is an important step in cell reproduction.
The CellFundamental characteristics shared by all living organisms:ReproductionMetabolismMotility (Response to molecules)Protection and Storage (Cell wall or membrane) Nutrient transport