Page 35 - Biology_F5
P. 35
Biology for Advanced Level Secondary Schools
cellular membranes. It occurs in all cells, flattened, plate-like, compartments or
except in the prokaryotic cells and in cisternae (Figure 1.16). It is a modified
cells of certain eukaryotes, such as fungi smooth endoplasmic reticulum. The
and bryophytes. It also does not occur Golgi apparatus is associated with small,
in cells of mature sieve tubes of plants, spherical sac-like structures called Golgi
spermatozoa, and in red blood cells. vesicles. These contain various secretions
FOR ONLINE READING ONLY
such as hormones, mucus or enzymes, and
Structure of the Golgi bodies they are future lysosomes.
It is disc-shaped; consisting of central,
Incoming
transport vesicle
Cisternae
Lumen
Secretory vesicle
Newly forming
vesicle
Figure 1.16: Structure of the Golgi apparatus
Functions of the Golgi bodies Cytoskeleton
The functions of Golgi bodies include the A cytoskeleton is a complex network of
following: protein filaments and microtubules which
(a) They form lysosomes. exist in the cytoplasm of eukaryotic cells.
(b) They concentrate and pack
secretions, such as enzymes. It anchors proteins or organelles, such
(c) They are involved in transformation as nucleus to their fixed location. The
of spermatids into mature cytoskeleton consists of microtubules,
spermatozoa. microfilaments and intermediate filaments
(d) They are involved in formation of (Figure 1.17).
primary cell walls in plants.
Form Five Student’s Book
28