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What is a cell?

Cells are the basic structural and functional units of all living organisms. Most are far too small to see without a microscope - a typical animal cell is around 0.02 mm across. A cell is the smallest building block that makes up every living thing. Most are far too tiny to see without a microscope - an animal cell is about a fiftieth of a millimetre wide.

Parts every animal cell has

All animal cells share a set of sub-cellular structures, each with a specific role: Every animal cell has the same key parts, and each part has its own job:

• Nucleus - contains the genetic material (DNA) that controls the cell's activities.holds the DNA and acts like the control centre for the cell.
• Cytoplasm - a jelly-like medium where most chemical reactions take place.the jelly inside where most of the cell's reactions happen.
• Cell membrane - controls the passage of substances into and out of the cell.the thin skin that controls what goes in and out.
• Mitochondria - the site of aerobic respiration, releasing energy for the cell.where the cell releases energy it can use (respiration).
• Ribosomes - where protein synthesis occurs.where the cell makes proteins.

Plant cells have extras

Plant cells contain everything an animal cell has, plus three additional structures: Plant cells have all of the above, plus three extra parts:

• Cell wall - made of cellulose; strengthens the cell and gives it shape.a tough outer layer that keeps the cell strong and in shape.
• Permanent vacuole - a fluid-filled sac that helps keep the cell rigid.a big bag of liquid that keeps the cell firm.
• Chloroplasts - contain chlorophyll and are the site of photosynthesis.the green parts where the plant makes its own food (photosynthesis).