Golgi Appartus?body

It consists of a stack of membranes that make up flatterned sacs called cisternae, with small rounded hollow structures called vesicles.

Similar structure to SER but more compact.

The functions of the Golgi body are to;

• Add carbohydrates to protiens to form glycoproteins.
• Produce Secretery enzymes, such as those secreted by the pancreas.
• Transport, modify and store lipids.
• Form Lysosomes.
• Sorts and packages proteins and lipids and sends them to other parts of the cell.

The Golgi body is very well developed in secretary cells because of these functions.

Ribosomes

Ribosomes are the smallest organelles. They measure apporx. 22nm in diameter.

They can only be viewed through an elcron microscope.

They are attached to most of the Endoplasmic reticulum.

They consist of two parts, the smaller and larger summit.

Ribosomes are the site of protein synthesis.

Ribosomes can also be found free in the cytoplasm.

They are made of Ribosomic Nucleic Acid (RNA) and protein.

Endoplasmic Reticulum (ER)

The ER is an elaborate system of membranes found throughout the cell, forming a cytoplasmic skeleton.

It is an extension od the outer nuclear membrane, with which it is continuous.

The membranes form a series of sheets which enclose flatterned sacs called Cisternae.

Where the ER is lined with ribosomes it is calles rough ER

The RER is concerned with protien syntheisis.

Where the ER lacks ribosomes it is called smooth ER

SER provide a surface area for chemical reactions and provides a pathway for transport of materials through the cell.

Lysosomes

Lysosomes digest materials consumed by the cell from the environment.

Useful chemicals are absorbed into the cytoplasm and any debris is egested by the cell by a process called Exocytosis.

It also digests worn out or damaged organelles through a process called Autophagy.

Lysosmes are spherical bodies about 0.1 to 1.0μm in diameter.

They contain around 50 enzymes, mostly hydrolases, in an acid solution.

Lysosome isolate the enzyemes from the rest of the cell to stop it self digesting.

Once the cell dies, the lysosomes are responsible for completly breaking down the cell through Autolysis.

Mitochondria

Most of the reactions for Aerobic respiration happens in the mitochondria.

Mitochondria are self replicating

They can be spherical or elongated and are usually 5μm by 0.2μm.

The mitochondria consits of two membranes; the inner and outer membrane. The inner membrane form cristae which increase surface area for the attachtment of enzymes involved in respiration.

The fluid contained within the mitochondria is called the matrix.

Mitochondria are located in the cytoplasm of all eukaryotic cells.

Nucleus

Its shape, size, position and chemical composition vary from cell to cell.

It posses many large nuclear pores, typically 3000 per nucleus.

Is bounded by a double membrane, called the nuclear envelope.

It contains a granular jelly-like material called the nucleoplasm.

It contains a nucleolus which manufactures rRNA and assembles ribosomes.

Chromatin is found in the nucleoplasm.