#module 2.1

(Singular: Mitochondrion) Structure: They are either spherical, rod-shaped or branched, and are typically 2-5 micrometers long. They are surrounded by two membranes with a fluid-filled space between them. The inner membrane is highly folded into cristae. The inner part part of the Mitochondrion is a fluid filled matrix.

Function: Mitochondria are the site of ATP production during aerobic respiration. They are self-replicating so more can be made if the cells energy needs increase. They are abundant in cells where much metabolic activity takes place, for example in liver cells and at synapses between neurones where neurotransmitter is synthesised and released.

(Also called ‘Golgi body’) Structure: This consists of a stack of membrane-bound flattened sacs. Secretory vesicles bring materials to and from the Golgi apparatus.

Functions: Proteins are modified. This can be done by adding sugar molecules to make glycoproteins, adding lipid molecules to make lipoproteins, and being folded into their 3D shape. The proteins are packaged into vesicles that are pinched off and then either stored in the cell or moved to plasma membrane in order to be incorporated into the plans membrane, or exported outside the cell.

Structure: This is a system of membranes that contain fluid-filled cavities (cisternae) that are continuous with the nuclear envelope. There are no ribosomes on its surface.

Structure: It’s a system of membranes that contain fluid-filled cavities, known as cisternae, that are continuously with the nuclear membrane. It is coated with ribosomes.

Structure: The nucleus is surrounded by a double membrane known as the nuclear envelope. There are pores in the nuclear envelope. The nucleolus does not have a membrane around it, and contains RNA.

Function: The nuclear envelope separates the contents of thr nucleus from the rest of the cell. In some regions the outer and inner nuclear membranes fuse together. At these points, some dissolved substances and ribosomes can pass through. The pore enable larger substances, like mRNA, to leave the nucleus. The nucleolus is where ribosomes are made. Chromosomes contain the organisms genes. The nucleus stores the organisms genome,is in control of the cell, transmits genetic information, and provides the instructions for protein synthesis.

Advantages: Very high resolution and magnification