, Cells and Cell Physiology
Cell Structure
Basic components:
a gel-like substance,
Cytoplasm
fundamental to the cell
Nucleus
Plasma separates the cell from the
membrane external environment
A. THE PLASMA MEMBRANE
-Delimits (encloses) the cell
-Composed of:
-Lipids (mainly phospholipids) – arranged in a double layer (bilayer structure)
-Proteins – float among the lipids, giving rise to the fluid mosaic structure
1. Phospholipids
Phospholipids have 2 ends:
One nonpolar end
One polar (charged) end
contains phosphorus made up of fatty acid chains
attracts water (hydrophilic) reacts with other nonpolar
comes into contact with the substances
water outside the cell repels water (hydrophobic)
In the bilayer structure, the
nonpolar ends face each
other, positioned in the
inner part of the membrane
REMEMBER
1. Some of the lipid molecules of the outer layer have carbohydrate molecules
attached to them, forming glycolipids
2. Besides phospholipids, the plasma membrane also contains a large amount of
cholesterol (it stabilizes the membrane lipids, reducing their fluidity)
Cell Structure
Basic components:
a gel-like substance,
Cytoplasm
fundamental to the cell
Nucleus
Plasma separates the cell from the
membrane external environment
A. THE PLASMA MEMBRANE
-Delimits (encloses) the cell
-Composed of:
-Lipids (mainly phospholipids) – arranged in a double layer (bilayer structure)
-Proteins – float among the lipids, giving rise to the fluid mosaic structure
1. Phospholipids
Phospholipids have 2 ends:
One nonpolar end
One polar (charged) end
contains phosphorus made up of fatty acid chains
attracts water (hydrophilic) reacts with other nonpolar
comes into contact with the substances
water outside the cell repels water (hydrophobic)
In the bilayer structure, the
nonpolar ends face each
other, positioned in the
inner part of the membrane
REMEMBER
1. Some of the lipid molecules of the outer layer have carbohydrate molecules
attached to them, forming glycolipids
2. Besides phospholipids, the plasma membrane also contains a large amount of
cholesterol (it stabilizes the membrane lipids, reducing their fluidity)
