discovery of cells - jufiles – ملفات الجامعات...
TRANSCRIPT
Discovery of Cells
The first scientist to look at cells under a microscope was the English scientist Robert Hooke
Common feature in all cell:
Plasma membrane :the border of cell and function to regulate passage of materials into and out of cell
Nucleus :region contain genetic material
Cytoplasm :the components enclosed by the plasma membrane
Two Cell types
Prokaryotic Cells do not have an organized nucleus
surrounded by an envelope and are relatively small (1-10 um)
compose two domains Eubacteria and Archaebacteria
Eukaryotic Cells are much larger and have an organized
nucleus enclosed by a nuclear envelope
Eukarya forms 4 kingdoms :the animals ,plants ,protists
and fungi
Common ancestor
Archaea Eubacteria Eukaryota
Protista Kingdom Fungi
Kingdom Plant
Kingdom Animal
Eubacteria (Prokaryotes)
Three fundamental bacterial cell shapes
Cocci
Bacilli
Spirilli
Exe 4-1
bacteria in yoghurt
Yogurt is a nutrient-rich culture of lactic acid bacteria such as lactobacillus
These bacteria live on lactose (milk sugar) and converts milk to yogurt
To observe bacteria in yogurt the following procedure is employed
Place a very small amount of yogurt on slides by using tooth pick , spread yogurt by using other slide (smear)
Add one drop of methylene blue to the yogurt and place the cover slip
Observed under microscope
Exe 4-2
Cyanobacteria
Photosynthetic prokaryotes
Live in aquatic environment
E.x : Anabaena
Is filamentous organism and each filament is composed of long chains of greenish cells
Exe 4-3
Eukaryotic cells
The nucleus is separated from the rest of the protoplasm by a double membrane (nuclear envelope)
Human cheek cells (animal cell)
The lining inside your mouth is composed of many cell layers that serve to protect your body by forming a barrier
Exe 4-4
Human skin cells (animal cells) Exe 4-5
Microscope
Onion epidermal cells
The onion is an underground ,storage structure made up of thickened modified leaves called scales.
Go To Work…….