Biomedical Engineering Reference
In-Depth Information
ENDOPLASMIC
RETICULUM
NUCLEAR
ENVELOPE
NUCLEOLUS
GOLGI
APPARATUS
NUCLEOPLASM
PLUS DNA
VESICLE
GGGGI
MITOCHONDRIA
CENTRIOLE
ENDOPLASMIC
RETICULUM
GOLGI
APPARATUS
FIGURE 3.4
Animal cells are surrounded by a plasma membrane. They contain a membrane-bound region, the
nucleus, which contains DNA. The cytoplasm lies outside of the nucleus and contains several types of organelles
that perform specialized functions.
3.2.1 Plasma Membrane
The plasma membrane performs several functions for the cell. It gives mechanical
strength, provides structure, helps with movement, and controls the cell's volume and its
activities by regulating the movement of chemicals in and out of the cell. The plasma mem-
brane is composed of two layers of phospholipids interspersed with proteins and choles-
terol (Figure 3.5). The proteins in the plasma membranes of mammalian cells provide
PERIPHERAL PROTEIN
HYDROPHOBIC
TAIL
PHOSPHOLIPID
BILAYER
CHOLESTEROL
HYDROPHILIC HEAD
INTEGRAL PROTEIN
FIGURE 3.5
The plasma membrane surrounds all cells. It consists of a double layer of phospholipids inter-
spersed with proteins and cholesterol.
