Chemistry of the Cell Next two lectures cover chapters 2 and 3 Know structure of cell Organelles and their function Figure 3.1, Table 3.1

The Cell Intracellular Extracellular plasma membrane

Elements C (carbon) H (hydrogen) O (oxygen) N (nitrogen) P (phosphorus) S (sulfur)

Elements C (carbon) H (hydrogen) O (oxygen) N (nitrogen) P (phosphorus) S (sulfur) organic compounds – lipids

Elements C (carbon) H (hydrogen) O (oxygen) N (nitrogen) P (phosphorus) S (sulfur) organic compounds – sugars

Elements C (carbon) H (hydrogen) O (oxygen) N (nitrogen) P (phosphorus) S (sulfur) organic compounds – amino acids – proteins

Elements C (carbon) H (hydrogen) O (oxygen) N (nitrogen) P (phosphorus) S (sulfur) – amino acids – proteins

Elements C (carbon) H (hydrogen) O (oxygen) N (nitrogen) P (phosphorus) S (sulfur) - ATP - Nucleic acids: DNA RNA - phospholipids

Molecules Water (H 2 O) is a simple molecule. Two hydrogens are covalently bonded to one oxygen. Polar covalent bond

The Cell Intracellular (67% of body’s water here) Extracellular ( 33% of water here) blood 20% interstitial fluid 80% plasma membrane

Ions H (hydrogen) H 2

Ions - Cations H + or H (Hydronium ion) Na + (sodium) Ca 2+ (calcium) K + (potassium) Mg 2+ (magnesium) NH4 + (ammonium) Fe 2+ (ferrous) Fe 3+ (ferric) Zn + (zinc) Ions

Ions - Anions Cl - (chloride) OH - (hydroxyl) PO 4 3- (phosphate) CO3 2- (carbonate) HCO 3 - (bicarbonate) SO 4 2- (sulfate) NO 3 - (nitrate) I - (iodide) Ions

Why? Harness energy from ion gradients sodium, hydronium ion Create nerve impulses sodium, potassium, calcium Messenger molecules calcium Muscle contractions calcium Ions – one of our essential parameters

Extracellular Intracellular Ca + Na + K+K+ K+K+ Ca + 3Na + 2K + Ca + Endoplasmic reticulum Sodium Potassium ATPase (or Pump) Energy (ATP)

H+H+ pH = 7.4 pH = 7.2 If the pH is lower within the cell, is the [H + ] higher or lower in the cell than outside? How is this difference maintained? H+H+ H+H+

Organic Compounds Lipids Proteins Carbohydrates Nucleic Acids The molecules that make up the structure of the cell

Lipids Organic compounds – predominately C & H Insoluble in water (hydrophobic) Includes: triacylglycerols (aka triglycerides) phospholipids cholesterol and steroids prostaglandins fat soluble vitamins

Triacylglycerol = TAG ThreeFatty acids (attached to something)

Triacylglycerol = TAG glycerol fatty acid linoleic acid = 18:2ω6 essential fatty acid unsaturated omega end carboxylic acid end What makes a fatty acid an acid?

Triacylglycerol = TAG saturated fatty acid palmitic = 16:0 + linoleic18:2 linolenic18:3

Phospholipids major component of cell membranes diacylglycerol with phosphate group attached glycerol backbone 2 fatty acids phosphate group If R group is choline than the phospholipid is called phosphotidylcholine (lecithin)

Phospholipids major component of cell membranes nonpolar and polar ends What happens if you dump a bunch of phospholipids into water? micelle formation

Cholesterol Why important?

Cholesterol Precursor to: vitamin D 3 bile salts steroids (hormones) Component of membranes All plant foods are cholesterol free.

Steroid Hormones glucocorticoids cortisol androgens estrogen testosterone progesterone DHEA pregnenolone mineralocorticoids aldosterone

Prostaglandins Made from fatty acids Short-lived, hormone like chemicals Three series with different physiological properties, classified depending on the fatty acid they are made from.

Prostaglandins Series 1 : PGE1 made from 20:3 ω6 Relaxes blood vessels Improves circulation Lowers blood pressure Series 2 : PGE2 made from arachidonic acid (20:4 ω6) Opposes PGE1 Series 3 : PG acid made from 20:5ω3 Blocks release of arachidonic acid

Fat Soluble Vitamins Vitamin A Vitamin E

Proteins The other main component of the cell membrane.

Functions of Protein Transport channels pumps carriers Communication receptors signaling molecules hormones “flags” Enzymes Structure Collagen, keratin, bone matrix, intracellular microtubules Antibodies Movement Muscle cells are 20% actin (protein)