Cells are the basic unit of life. Organelles are sub-cellular structures that form parts of the cell. Examples of organelles include nucleus, mitochondria, ribosomes, vacuoles, cytoplasm, cell surface membrane, rough endoplasmic reticulum, smooth endoplasmic reticulum, golgi apparatus and chloroplast.
Plant cells and animal cells differ in terms of the number and size of vacuole(s) present, presence and absence of cellulose cell wall and also presence and absence of chloroplasts.
Microscopes are equipment used to observe cells. The two types of microscopes discussed here are light microscope and electron microscope. Light microscope has a lower resolution and can observe fewer details while electron microscope has a greater resolution and can observe more details.
Organelles that are visible under both the light microscope and electron microscope include cellulose cell wall, chloroplasts, cytoplasm, nucleus and cell surface membrane. Organelles that are only visible under the electron microscope are ribosomes, rough endoplasmic reticulum, smooth endoplasmic reticulum, golgi apparatus and mitochondria.
Proteins manufactured in ribosomes are packaged at rough endoplasmic reticulum in the form of vesicles and may be transported to golgi apparatus for addition of carbohydrate chains to form glycoproteins. Glycoproteins are then packaged into vesicles where they fuse with the cell surface membrane to release glycoproteins out of the cell. This transport and movement of proteins within the cell is known as protein trafficking.
Cells may have unique adaptations to perform specific functions. Examples of specialised cells include red blood cells, root hair cells and xylem vessels.
To further maximise efficiency, cells group and organise into tissues, organs and organ systems.