animal cells
The cells that make up your body are typical animal cells. All cells have some features in common. You can see these features clearly in animal cells.
The nucleus
controls all the activities of the cell and is surrounded by the nuclear membrane. It contains the genes on the chromosomes that carry the instructions for making the proteins needed to build new cells or new organisms. The average diameter is around 10 um.
The cytoplasm
a liquid gel in which the organelles are suspended and where most of the chemical reactions needed for life take place.
The cell membrane
controls the passage of substances such as glucose and mineral ions into the cell, It also controls the movement of substances such as urea or hormones out of the cell.
The mitochondria
structures in the cytoplasm where aerobic respiration takes place, releasing energy for the cell. They are very small: 1-2 um in length and only 0.2-0.7 um in diameter.
The ribosomes
where protein synthesis takes place, making all the proteins needed in the cell.
Plant cells
Plants are very different organisms from animals. They make their own food by photosynthesis, They do not move their whole bodies about from one place to another. Plant cells are often rather bigger than animal cells - they range from 10 to 100 um in length.
cell wall
made of cellulose that strengthens the cell and gives it support.
Chloroplasts
are found in all the green parts of a plant. They are green because they contain the green substance chlorophyll. Chlorophyll absorbs light so the plant can make food by photosynthesis. Each chloroplast is around 3-5 um long. Root cells do not have chloroplasts because they are underground and do not photosynthesise.
A permanent vacuole
is a space in the cytoplasm filled with cell sap. This is important for keeping the cells rigid to support the plant.
Chloroplasts
are found in many plant cells but not all of them.
Key points
Animal cell features common to all cells - a nucleus, cytoplasm, cell membrane, mitochondria, and ribosomes. Plant and algal cells contain all the structures seen in animal cells as well as a cellulose cell wall. Many plant cells also contain chloroplasts and a permanent vacuole filled with sap.
