IGCSE Science/Section 2: Structures and functions in living organisms/Cell structure

From Wikibooks, open books for an open world
Jump to navigation Jump to search
The organelles of an animal cell
The organelles of a plant cell

Cell organelles: Small structure having definite shape and performing specific functions

They are embedded in the cytoplasm, These structures are called cell organelles. Most cells have these organelles:

Name Function
Nucleus It regulates all important activities of the cell and plays an important part during cell division.
Cytoplasm a place for chemical reactions to happen, and it contains enzymes which speed up these reactions
Cell membrane It allows only certain substances to pass through small pores on it and protects the inner cell contents.
Mitochondria It perform cellular respiration, referred as powerhouse of the cell.

Plants cells have:

Name Function
Cellulose cell wall It gives a definite shapes to the cell , allows all substances to pass through it and protect the inner cell contents called protoplasm.
Plastids They are of 3 types:

i)Chloroplast- It can trap solar energy and covert it into chemical energy in the form of food through the process of photosynthesis. ii)Chromoplast-It contains coloured(red, yellow, orange)pigments that impart colour to flowers and fruits. iii)Leucoplast-It is colourless pigment that store food in the form of starch, proteins and fats.

Vacuole It stores sugar ,mineral and water in the form of cell sap and maintain the shape of cell.

Yeast cells have:

Name Function
Chitin cell wall to keep the structure of the cell
Vacuole to store nutrients and food

Animal cells only have the basic organelles, but plants have all the basic organelles and some more: a cell wall, chloroplasts and a vacuole:

Diagram showing the parts of animal and plants cells. Plant-only organelles are shown in green.
Diagram showing the parts of animal and plants cells. Plant-only organelles are shown in green.