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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
Extracellular
Intracellular
plasma membrane
Elements
 C (carbon)
 H (hydrogen)
 O (oxygen)
 N (nitrogen)
 P (phosphorus)
 S (sulfur)
Elements
 C (carbon)
organic compounds
– lipids
 H (hydrogen)
 O (oxygen)
 N (nitrogen)
 P (phosphorus)
 S (sulfur)
Elements
 C (carbon)
organic compounds
– sugars
 H (hydrogen)
 O (oxygen)
 N (nitrogen)
 P (phosphorus)
 S (sulfur)
Elements
 C (carbon)
organic compounds
– amino acids
– proteins
 H (hydrogen)
 O (oxygen)
 N (nitrogen)
 P (phosphorus)
 S (sulfur)
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 (H2O) is a simple molecule.
 Two hydrogens are covalently bonded to
one oxygen.
Polar covalent bond
O
H
H
The Cell
Extracellular
(33% of water here)
blood 20%
interstitial fluid 80%
Intracellular
(67% of body’s water here)
plasma membrane
Ions
 H (hydrogen)
 H2
Ions - Cations









H+ or H30+ (Hydronium ion)
Na+ (sodium)
Ca2+ (calcium)
K+ (potassium)
Mg2+ (magnesium)
NH4+ (ammonium)
Fe2+ (ferrous)
Fe3+ (ferric)
Zn+ (zinc)
Ions - Anions
 Cl- (chloride)
 OH- (hydroxyl)
 PO43- (phosphate)
 CO32- (carbonate)
 HCO3- (bicarbonate)
 SO42- (sulfate)
 NO3- (nitrate)
 I- (iodide)
Ions –
one of our essential parameters
 Why?
 Harness energy from ion gradients

sodium, hydronium ion
 Create

nerve impulses
sodium, potassium, calcium
 Messenger

calcium
 Muscle

molecules
contractions
calcium
Extracellular
Sodium Potassium ATPase (or Pump)
3Na+
K+
2K+
Energy (ATP)
Na+
Na+
K+
Ca+
Endoplasmic reticulum
Ca+
Ca+
Intracellular
Ca+
pH = 7.4
If the pH is lower within the cell, is the [H+]
higher or lower in the cell than outside?
How is this difference maintained?
pH = 7.2
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
Three
Fatty acids (attached to something)
O
H2C
O
HC
O
O
H2C
O
O
Triacylglycerol = TAG
H2C
HC
H2C
OH
OH
glycerol
OH
What makes a fatty acid an acid?
HO
O
carboxylic
acid end
fatty acid
linoleic acid = 18:2ω6
essential fatty acid
unsaturated
omega end
Triacylglycerol = TAG
saturated fatty acid
palmitic = 16:0
HO
H2C
OH
O
HC
OH
+
linoleic18:2
HO
O
H2C
OH
linolenic18:3
HO
O
O
H2C
O
HC
O
O
H2C
R1
O
O
Phospholipids
• major component of cell membranes
• diacylglycerol with phosphate group attached
O
H2C
O
R1
O
CH
O
H3C
+
N
H3C
CH3
H2
C
H2
C
R3
O
Choline
phosphate
If R group is choline
group
than the phospholipid is
called phosphotidylcholine (lecithin)
P
O
O
R2
CH2
O-
glycerol
backbone
2 fatty
acids
Phospholipids
• major component of cell membranes
• nonpolar and polar ends
What happens if you dump a bunch
of phospholipids into water?
micelle formation
Cholesterol
HO
Why important?
Cholesterol
 Precursor to:
 vitamin
D3
 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 20:3ω6
 Relaxes blood vessels
 Improves circulation
 Lowers blood pressure
 Series 2 : PGE2 made from arachidonic acid (20:4ω6)
 Opposes PGE1
 Series 3 : PG acid made from 20:5ω3
 Blocks release of arachidonic acid
Fat Soluble Vitamins
CH2OH
Vitamin A
Retinol
beta-carotene
R
Tocopherol
HO
R
O
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)