Page 44 - General and Inorganic Chemistry for Advanced Secondary Schools Students Book Form Five and Six

Biology for Secondary Schools

Prokaryotic cells (c) They reproduce by binary fission
The prokaryotic cell is a type of cell and sometimes by conjugation.
in which the nuclear materials are not (d) Mostly they are smaller in size
bound with a membrane. The cell is than eukaryotic cells.
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found in organisms called prokaryotes. (e) Some prokaryotes have whip-
Prokaryotes are single-celled organisms, like structure called flagella for
such as bacteria and blue-green bacteria. locomotion or hair-like structure

called pili for attachment.
The following are characteristics of (f) Have circular Deoxyribonucleic
prokaryotic cells: acid (DNA).
(a) They do not have true nucleus, as (g) Can be rod-shaped, spherical-
they lack membrane bound nucleus. shaped, spiral-shaped, or comma-
(b) They do not have membrane-bound shaped. Figure 3.1 shows various

organelles, such as mitochondria. shapes of prokaryotes.

(a) (b) (c) (d) (e)

Figure 3.1: Shapes of prokaryotes (a) spiral-shaped (b) spherical-shaped (c) rod-
shaped (d) comma-shaped (e) spirochaete-shaped

Eukaryotic cell (c) They contain specialised
These are types of cells whose membrane-bound organelles,

organelles are enclosed in a membrane. such as mitochondria and
The cells are found in organisms called chloroplasts.
eukaryotes. (d) They have linear DNA.

The following are the characteristics of Animal and plant cells
eukaryotic cells. Both animals and plants are made up of

(a) They have a membrane-bound eukaryotic cells. However, these cells
nucleus. differ in their structure and functions.
(b) They are generally larger and more
complex than prokaryotic cells.

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