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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
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 (H2O) is a simple molecule.
Two hydrogens are covalently bonded to one oxygen.
OHH
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)
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
Ions - Anions
Cl- (chloride) OH- (hydroxyl) PO4
3- (phosphate)
CO32- (carbonate) HCO3
- (bicarbonate)
SO42- (sulfate)
NO3- (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+
Na+
Ca+
3Na+
2K+
Ca+Ca+
Endoplasmic reticulum
Sodium Potassium ATPase (or Pump)
Energy (ATP)
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+
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
H2C
O
O
O
O
Triacylglycerol = TAG
H2C
HC
H2C
OH
OH
OH
glycerol
fatty acidlinoleic acid = 18:2ω6essential fatty acidunsaturated
HO
Oomega end
carboxylic acid end
What makes a fatty acid an acid?
Triacylglycerol = TAGH2C
HC
H2C
OH
OH
OH
O
H2C
O
HC
H2C
O
O R1O
O
saturated fatty acidpalmitic = 16:0
HO
O
HO
O
HO
O
+ linoleic18:2
linolenic18:3
Phospholipids
R1OH2C
O
CH2O
CH R2O
O
O
P
O-
OR3H3C
N+
H3C
H2C
CH3
H2C
Choline
• major component of cell membranes• diacylglycerol with phosphate group attached
glycerol backbone
2 fattyacids
phosphategroup
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 bunchof 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
beta-carotene
CH2OH
Retinol
HO
OR
R
Tocopherol
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)
