General Histology Dr. Ashraf Shamia Al Azhar University Gaza Uplode by Lama K El Banna

1. The Cell
Prepared By :
Dr.Ashraf Y. Shamia
Al-Azhar University –Gaza
Dr.Haydar Abd El-Shafi Faculty of Dentistry

2. • Anatomy at the microscopic level
(microanatomy)
• Cells---tissues---organs---organ systems
• 1015
cells in the human body
• 200+ cell types in the body

3. • All organisms are composed of one or
more cells.
• Cells are the smallest living units of all
living organisms.
• Cells arise only by division of a previously
existing cell.

4. • Robert Hooke – first to see and identify
cork “cells.”

6. • single circular molecule of DNA in prokaryotes
• double helix located in nucleus in eukaryotes
– nuclear envelope (double membrane
• Cytoplasm fills cell interior –
• sugars, amino acids,
• proteins - organelles
• Plasma membrane encloses
• the cell – phospholipid bilayer

7. • Nucleus – large membrane-enclosed
structure that contains the cell’s genetic
information.
• Prokaryotes – cells that do not contain
nuclei. (Bacteria)
• Eukaryotes – cells that contain nuclei. (All
other organisms)

9. • Most cells are relatively small because as
size increases, volume increases much
more rapidly.
– longer diffusion time

10. 1.Inside the Nucleus
2.Ribosomes.
3.Endoplasmic Reticulum (ER)
4.Golgi Apparatus.
5.Lysosomes.
6. Vacuoles
7.Mitochondria.
8.Chloroplast.
9.Cytoskeleton.
10.Cell Boundaries.
11.Cell Membrane.

11. • Nuclear Envelope – membrane that
surrounds the nucleus.
• Chromatin – consists of DNA wrapped
around proteins. “Ball of string”
• Chromosomes – condensed string-like
structure that forms from DNA just before
the cell divides.
• Nucleolus – structure within the nucleus
that makes ribosome's.

12. Inside the Nucleus
Nuclear
Envelope
Chromatin
Nucleolus

13. • Ribosomes – made of RNA and protein.
Make Proteins!

14. Ribosomes
Ribosome

15. • Endoplasmic reticulum –
internal membrane system
of the cell.
– Lipids, proteins, and other
products are made here.
– Rough ER – has ribosomes
– Smooth ER – no ribosomes

16. Endoplasmic
Reticulum (ER)
Rough ER
Smooth
ER

17. • Golgi Apparatus – modifies, sorts, and
packages proteins.

18. Golgi Apparatus
Golgi Apparatus

19. • Lysosomes – small organelles filled with
enzymes.
– Digest molecules to be used by the cell.

20. • Vacuoles – store materials.

21. Vacuoles
Vacuoles

22. • Mitochondria – organelle that converts
chemical energy stored in food into
compounds that are more convenient for
the cell to use.
– “Powerhouse of the Cell!”

23. Mitochondria
Mitochondria
7-2

24. • Chloroplasts – organelles that capture
energy from sunlight and convert it into
chemical energy. (Photosynthesis)
– Found only in plants.
7-2

25. Chloroplasts
Chloroplast
7-2

26. • Cytoskeleton – helps cell to maintain
shape, move, and move organelles.
• Centrioles – help organize cell division.
Not found in plants.
7-2

27. Cytoskeleton

28. • Cell membrane – thin, flexible membrane
that surrounds the cell.
• Cell walls – rigid layer around the
membrane found only in bacteria, fungi
and plants.

29. • Controls what enters/leaves cell, provides
support/protection.
• Lipid Bilayer – double-layered sheet of
phospholipids.
Two layers!