Eukaryotic cells
Introduction

Topic 1 Cell theory

Topic 2 Prokaryotic cells

Topic 3 Eukaryotic cells

Topic 4 Cell Division

Topic 5 Cell membranes


What are eukaryotic cells?
Animal, plant, fungi and protista cells are examples of eukaryotic cells. They are cells with membranes around organelles ( nucleus ). All the different organelles of a cell are called utrastructures and this includes: nucleus, golgi apparatus, ribosomes, mitochondria, ER, lysosomes, plasma membrane and cell wall.

Nucleus: It controls all cell activities and genetic information ( DNA ). The nucleus and the cytoplasm is called the protoplast.The nucleus is divided into 4 different parts which are the nuclear envelope, nuclear pores, nucleoles and heterochromatin.

Golgi apparatus: this is a series of membranes, bond sacs, which transport and store the proteins made in the ribosomes.

Ribosomes: Very small organelles made of equal amounts of protein and RNA. They are the sities of protein synthesis and they are mainly found in the ER ( endoplasmic reticulum ). Their size is of 80s in eukayotic cells.

Lysosomes: Spherical sacs ( suicide sacs ). Contain digestive enzymes, concerned with the breaking down of molecules. They contain digestive enzymes.

Mitochondria: this is where aerobic respiration takes place. It is a double membrane. Inside the mitochondria there is the matrix, DNA, phosphate granules and ribosomes.

ER: a system of flattened, membrane bounded sacs called cisternal, forming tubes and sheet. Sometimes it has ribosomes attached to it ( rough ER ) but if it doesn't it is called smoth ER.

Cell surface membrane: also called plasma membrane, it controls exchange between the cell and its enviroment. It is partially permeable.


This is an example of a typical animal and plant cell.

Difference between Prokaryotic and Ukaryotic cells:
>>Prokaryotic cells:

5-10 micrones

no nucleus ( naked DNA )

ribosomes 70s

DNA is not supported by histone protein.

>>Eukaryotic cells:

50-100 micrones

nucleus with DNA (chromosomes)

ribosomes 80s

DNA supported by histone protein