Which organelles do we need to know their functions of thoroughly? Thanks
Nucleus is the control centre of the cell, it contains the nucleolus which contains Proteins and DNA (deoxyribnucleic acid)
The Golgi apparatus is the Like the post office of a cell because it packages proteins which will later be transported by the ER.
the Ribosomes synthesise proteins.
Mitochondria produce energy for the cell by converting ATP (Tri phosphate) into ADP (Di phosphate) + energy
The vacuole contains water and some enzymes and can isolate treating compounds and waste products.
The cytosol is the fluid that holds the organelles.
Lysosomes recycle old organelles and waste.
Chloroplasts are found in plant cells, they contain the pigment chlorophyll and take energy from the sun in order to photosynthesise.
The Endoplasmic Reticulum (ER) is like a road for transporting things (particularly proteins) around the cell. Rough ER is called so because it is studded with Ribosomes.
It is also worth learning the difference between animal and plant cells and eukaryotic and prokaryotic cells.
I'm not sure all this is right though, just what I remember, so check wikipedia.