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Macromolecules of Life. Lecture 4. Cell Composition. Water - 70% Inorganic molecules Organic (carbon-containing) molecules Interaction of water with the other constituents of the cell is paramount. 02_26_Macromolecules.jpg. Uniqueness of Water. Water - H2 & 0 Polar molecule - H side is +
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Macromolecules of Life Lecture 4
Cell Composition • Water - 70% • Inorganic molecules • Organic (carbon-containing) molecules • Interaction of water with the other constituents of the cell is paramount
Uniqueness of Water • Water - H2 & 0 • Polar molecule - H side is + • Polar molecule - O side is - • Hydrogen bonding • Density at 4°C is key to life
Inorganic Molecules • Sodium • Potassium • Magnesium • Calcium • Phosphate • Chloride • Bicarbonate (HCO3-)
Organic Molecules • Most cellular organic molecules belong to the following classes • Carbohydrates • Lipids • Proteins • Nucleic Acids
Macromolecules • Proteins • Nucleic Acids • Carbohydrates Generally exist as macromolecules and constitute 80 + % of the dry weight of the cell.
02_17_disaccharide.jpg Animation of condensation reaction
Carbohydrates • Simple sugars & polysaccarides • Simple sugars are the cells preferred nutrient source • Polysaccarides used for storage and some structure • Cellular adhesion & intercellular transport
Carbohydrates cont… • Monosaccarides = simple sugar units • Glycosidic bonds • Oligosaccarides = short polymer • Polysaccarides = 100’s to 1000’s • Glycogen (animal) & Starch (plant) are storage forms of carbohydrates, both made of glucose • Cellulose (plant) structural role, also made of glucose
Lipids Have 3 major roles in cells Energy storage - • as triacylglycerols (fats) which due to the hydrophobic nature of their tails form droplets within the cytoplasm. • Yield upon hydrolysis 2X the energy per unit weight compared to carbohydrates. • Cell membranes - • Phospholipid form, which has just 2 fatty acids joined to a polar head group • Phospholipids are AMPHIPATHIC in nature. Key to membrane formation. • Cell signaling • Within cells and between cells as steroid hormones • Chemical messenger molecules
Nucleic Acids • DNA & RNA • Principle informational molecules of the cell. • DNA is normally the genetic material • RNA can be the genetic material, however more abundant as mRNA, rRNA, and tRNA. Other functions too.
Proteins • Most diverse of macromolecules • Functional and structural roles • Each cell contains several thousand AAs • ENZYMES • Polymers of 20 different amino acid sub-units. • Peptide bonds • Polypeptides - Linear molecules, sequence specific, with 3D configurations
