Eukaryotic Cell

THE nucleus

It is the most prominent feature.It contains the organisms hereditary material and controls the cells activities 

 Nuclear envelope:

• ·      Double membrane that surrounds the nucleus
• ·      Outer membrane is continuous with the endoplasmic reticulum of the cell
• ·      Has ribosomes on its surface
• ·      Controls the entry and exit of materials in the nucleus and  Contains the reactions taking place within the nucleus 

Nuclear pores

• ·      Allows the passage of large molecules out the nucleus

 Nucleoplasm

• ·      Granular, jelly like material that makes up the bulk of the nucleus

 Chromosomes

• ·      Consists of protein bound linear DNA 

Nucleolus

• ·      Small spherical region within the nucleoplasm
• ·      Manufactures ribosomal RNA  and Assembles ribosomes
• ·      May be more than one nucleolus in the nucleus

 FUNCTIONS:

• ·      Act as a control center, through the production of mRNA and tRNA and protein synthesis.
• ·      Retain the genetic material of the cells – form of DNA and Chromosomes
• ·      Manufacture ribosomal RNA and Ribosomes
• . 

The Mitochondrian

Rod shaped and made up of:

Double membrane

• ·      Surrounds organelle
• ·      Controls entry and exit of material
• ·      The inner two membranes is folded to form extensions – CRISTAE

Cristae

• ·      Extensions of inner membrane
•       In some species – extend across the whole width of the mitochondria – provides a large surface area for the attachment of enzymes and other proteins involved in respiration

Matrix

• ·     Makes up the remainder of the mitochondria
• ·      Contains proteins, lipids, ribosomes
• ·      Contains DNA which allows mitochondria to control production of their own proteins.
• ·      Respiration enzymes are found in the matrix

FUNCTIONS

• ·      Sites of aerobic stages of respiration – responsible for the production of ATP
• ·      Number and size of mito and number of cristae is high in cells that have a high level of metabolic activity and require a lot of ATP

E.G

• ·      Muscle and epithelial cells
• ·      Epithelial cells require a lot of ATP in the absorbance of substances in the intestines by active transport.

mitochondria

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