1. CYTOLOGY & HISTOLOGY Lecture two
DR. ASHRAF SAID

2. Review
Of the first lecture

3. Concept 1
To study cells, biologists use microscopes and the tools of biochemistry

4. Isolating Organelles by Cell Fractionation
Takes cells apart and separates the major organelles from one another
The centrifuge
Is used to fractionate cells into their component parts

5. Concept 2
Eukaryotic cells have internal membranes that compartmentalize their functions
Two types of cells make up every organism
Prokaryotic
Eukaryotic

6. Comparing Prokaryotic and Eukaryotic Cells
All cells have several basic features in common
They are bounded by a plasma membrane They contain a semi-fluid substance called the cytosol
They contain chromosomes
They all have ribosomes
Eukaryotic cells
Contain a true nucleus, bounded by a membranous nuclear envelope
Are generally quite a bit bigger than prokaryotic cells
The logistics of carrying out cellular metabolism sets limits on the size of cells
Have extensive and elaborately arranged internal membranes, which form organelles
Prokaryotic cells
Do not contain a nucleus
Have their DNA located in a region called the nucleoid

7. Start
Of this lecture

8. Objectives of lecture two
A Panoramic View of the Pro/Eu-karyotic Cells
The Nucleus: Genetic Library of the Cell
Ribosomes: Protein Factories in the Cell

9. Concept 3
The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes

10. Intermediate filaments ENDOPLASMIC RETICULUM (ER)
A animal cell
Rough ER
Smooth ER
Centrosome
CYTOSKELETON
Microfilaments
Microtubules
Microvilli
Peroxisome
Lysosome
Golgi apparatus
Ribosomes
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
Nucleolus
Chromatin
NUCLEUS
Flagelium
Intermediate filaments
ENDOPLASMIC RETICULUM (ER)
Mitochondrion
Nuclear envelope
Plasma membrane
Figure 1.9

11. The Nucleus: Genetic Library of the Cell
Contains most of the genes in the eukaryotic cell

12. The nuclear envelope
Encloses the nucleus, separating its contents from the cytoplasm
Figure 1.10
Nucleus
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Rough ER
Pore
complex
Surface of nuclear envelope.
Pore complexes (TEM).
Nuclear lamina (TEM).
Close-up of nuclear
envelope
Ribosome
1 µm
0.25 µm

13. Ribosomes: Protein Factories in the Cell
Are particles made of ribosomal RNA and protein

14. Ribosomes Carry out protein synthesis Ribosomes Cytosol ER
Free ribosomes
Bound ribosomes
Large
subunit
Small
TEM showing ER and ribosomes
Diagram of a ribosome
0.5 µm ER
Endoplasmic reticulum (ER)
Figure 1.11

15. The endomembrane system
Concept 4
The endomembrane system regulates protein traffic and performs metabolic functions in the cell
The endomembrane system
Includes many different structures

16. The Endoplasmic Reticulum: Biosynthetic Factory
The endoplasmic reticulum (ER)
Accounts for more than half the total membrane in many eukaryotic cells

17. The ER membrane Is continuous with the nuclear envelope Figure 1.12
Smooth ER
Rough ER
ER lumen
Cisternae
Ribosomes
Transport vesicle
Transitional ER
200 µm
Nuclear
envelope
Figure 1.12

18. There are two distinct regions of ER
The ER membrane
There are two distinct regions of ER
Smooth ER, which lacks ribosomes
Rough ER, which contains ribosomes

19. Functions of ER The rough ER The smooth ER Rough Smooth
Has bound ribosomes
Produces proteins and membranes, which are distributed by transport vesicles
The smooth ER
Synthesizes lipids
Metabolizes carbohydrates
Stores calcium
Detoxifies poison

20. Tank you
End of first Lecture