Biochemistry & Cell Biology PHR213 / Lecture – 02

Chemical foundation of the cell

Small molecules

Macromolecules

Molecules participating in chemical and physical reactions of cell

Water, salts, ions and trace elements

Molecular interactions

Water• 70-80% of total cell mass is water• Water interacts with polar molecule / charged ions• Hydrophilic/polar biomolecules are soluble in water• Hydrophobic/non-polar biomolecules are insoluble in water• High boiling point, provides temperature stability • High heat of vaporization, excellent coolant• Water ionizes in hydroxide ion (OH-) and hydrogen ion (H+)

Chemical foundation of the cell

Chemical foundation of the cell

Salts, ions and trace elements

Sodium – Na+Potassium – K+

Chloride – Cl-maintaining osmotic pressure

Magnesium (Mg2+) cofactor for > enzymatic reactions

Calcium component of blood and body fluid

Chemical foundation of the cell

Salts, ions and trace elements

Iron (Fe2+/Fe3+)hemoglobin, cytochromes,

peroxidases

Manganese > bone formation, free radical defense systemsCopper > component of many enzymesCobalt > part of vitamin B12Selenium > cofactor for enzymesNickel > important in intra-uterine developmentMolybdenum > cofactor for enzymesZinc > a messenger, a cofactor

Chemical foundation of the cell

Molecular interactions

Covalent interactions Non-covalent interactions

Ionic bonds Hydrogen bonds

Van der Waals attractions

Hydrophobic interactions

Chemical foundation of the cell

Chemical foundation of the cell

Building blocks of the cell

• Proteins – Amino acids, peptide bonds • Nucleic acids – Phosphodiester bonds• Polysaccharides – Glycosidic bonds

Chemical foundation of the cell

Building blocks of the cell

Amino acid

Chemical foundation of the cell

Building blocks of the cell

Peptide bond = bond between two amino acids in protein chains

Chemical foundation of the cell

Building blocks of the cell

• DNA, RNA• Nucleotides

Phosphodiester bonds = Bonds between twonucleotides

Chemical foundation of the cell

Building blocks of the cell

Chemical foundation of the cell

Building blocks of the cell

Heterocyclic nitrogenous bases in DNA/RNA

Glycosidic bond = Bondsbetween a carbohydratemolecule to another molecule(carbohydrate / non-carbohydrate)

Chemical foundation of the cell

Building blocks of the cell

Thank you

Mohammad Ahad A Khan, PhDAssistant Professor, Department of Pharmaceutical SciencesNorth South University, Bangladesh Room: SAC 1013email: mohammad.khan03@northsouth.eduCell: +880 17 0386 4707