8. Eukaryotic vs Prokaryotic Cells
Eukaryotic Cell Prokaryotic Cells
Nucleus Present, double membraned Absent, only nucleoid region
Cell type Multi – or unicellular Always unicellular
Cell division Mitosis Binary fission
flagella large Small
Cell wall Simple in nature if present Present and complex
Lysosome Present Absent
Mitochondria Present Absent
Endoplasmic reticulum Present Absent
DNA linear Circular
Ribosomes Larger, linear Smaller, spherical
Reproduction Both sexual and asexual Asexual only
Plasmids Present Rare
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9. Nucleus
• Spherical or oval, most prominent feature.
• Cells may have one or more.
• Some cells lack nuclei e.g. RBCs.
• Double membrane (nuclear envelope) separates it from
cytoplasm.
• Outer membrane is continuous with RER.
• Small molecules and ions pass through nuclear pores.
• Large proteins and RNAs pass by active trpt.
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11. Nucleolus
•Spherical body producing ribosomes.
•Not enclosed in a membrane.
•Site of RNA synthesis, RNA and protein assembly in
ribosomal subunits.
•Disappear during cell division.
•Reorganize once cells are formed.
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12. Chromosomes
• Thread-like structures in the
nucleus.
•Not visible when cell not
dividing.
• Constriction divides
chromosome into:
i. p arm: short section
ii. q arm: long section.
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13. Chromosomes
•Made of DNA
coiled around
protein called
histone.
•DNA, proteins and
some RNAs form
chromatin.
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Linker DNA
14. Chromosomes
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Not entirely correct
Newly synthesized DNA is packed into
condensed chromatin fibers
Basic packing unit is nucleosome
(147 bp + 8 histones)
Five types of histones synthesized in S-
phase
-H1 (linker), -H2A, H2B, -H3,-H4
