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A Handbook of Biology

They are made of two subunits - 50S and 30S units. They together

form 70S prokaryotic ribosomes. (S= sedimentation coefficient; a

measure of density & size).

Function: Ribosomes are the site of translation (protein synthesis).

Several ribosomes may attach to a single mRNA to form a chain

called polyribosomes (polysome). Ribosomes translate the mRNA

into proteins.

7.

Inclusion Bodies

These are non-membranous structures which store reserve

material seen freely in the cytoplasm of prokaryotic cells. E.g.

phosphate granules, cyanophycean granules and glycogen

granules, gas vacuoles etc.

(NEET 2020)

Gas vacuoles are found in blue green and purple and green

photosynthetic bacteria.

ËÜKÅRÝØTÏÇ ÇËLLS

They have well organized membrane bound nucleus and organelles.

Presence of membranes gives clear compartmentalization of cytoplasm.

Their genetic material is organized into chromosomes.

They have complex locomotory & cytoskeletal structures.

Differences between Plant and animal cells

Plant cell

Animal cell

Centrioles are absent

Present

A large central vacuole

Many small vacuoles

Plastids are present

Absent

Cell wall present

Absent