Organelles

Structure- 

• Largest organelle.
• When stained shows darkened patches-kromatin
• Surrounded by nuclear envelope
• Made of two membranes with fluid between them.
• Holes called nuclear pores- go through envelope.
• Allow relitively large moilecules to pass through
• Dense, spherical structure (nucleolous) inside nucleus. 

Function- 

• Houses nearly all cells genetic information. 
• Chromatin consists of DNA and proteins- instuctions for making proteins.
• Some proteins regulate cells acivities. 
• When cells divide chromatin condenses into visible chromosomes.
• Nucleolous makes RNA and ribosomes.
• These pass into cytoplasm and proteins are assembled at them. 

Structure- 

• Consists of series of flattened membrane bound sacs called cisternae.
• Continuous with outer nuclear membrane. 
• Rough endoplasmic reticulum is studded with ribosomes. 
• Smooth endoplasmic reticulum is not. 

Function-

• Rough ER transports proteins that were made on the attatched ribosomes. 
• Some of these proteins may be secreted from cell. 
• Some will be placed on cell surface membrane. 
• Smooth ER is involved in making lipids the cell needs. 

Structure-

• Stack of membrane bound flattened sacs. 

Function- 

• Recieves proteins from ER and modifies them 
• May add sugar molecules to them.
• Packages modified proteins into vesticles to be transported. 
• Some modified proteins may go to the surface of cell to be secreted 

Structure-

• May be spherical or sausage shaped.
• Two membranes seperated by fluid. 
• Inner membrane is highly folded to form cristae.
• Central part of mitochondria is matrix.

Function- 

• Where ATP is produced during respiration.

Structure- 

• Found only in plant cells and cells of some protoctists. 
• Two membranes seperated by fluid filled space. 
• Inner membrane is continuous with elaborate network of flattened membrane sacs called thylakoids.

Function-

• Site of photosynthesis in plant cells.
• Light energy is used to drive the reactions of photosynthesis.
• From this carbohydrate is made from water and carbon dioxide.

Structure- 

• Spherical sacs surrounded by single membrane.

Functions-

• Contain powerful digestive enzymes that break down materials. 

Structure- 

• Tiny organelles
• Some in cytoplasm and some are bound to ER.
• Each ribosome consists of two subunits. 

Function-

• Site of protein synthesis in the cell. 
• Act as assembly line where coded information (mRNA) from nucleus is used to assemble proteins from amino acids. 

Structure- 

• Small tubes of protein fibres (microtubules) 
• pair of them next to nucleus in animal cells and cells of some protocists. 

Function- 

• Take part in cell division
• Form fibres known as the spindle 
• Move chromosomes during nuclear division.