Monday, 29 October 2012

Microscopic preparations of animal and plant cells

Living things are made of cells. Cells are the smallests units of life. They undergo the three vital functions: nutrition, interaction and reproduction. We have studied prokaryotic and eukaryotic cells. Prokaryotic cells are the most primitive. Scientists believe that the first cells to exist on Earth were prokaryotic. They don't have a nucleus and their genetic material is dispersed in the cytoplasm. Prokaryotic cells exist today as bacteria. Cells evolved and protected their genetic material in a nucleus. These are eukaryotic cells.
Cells have three main parts: cell membrane, nucleus and cytoplasm. In the cytoplasm there are other organelles like vacuoles, mitochondria, chloroplasts. We have also studied the differences between animal and plant cells. Plant cells have a cell wall, chloroplasts and a big vacuole.
We have made microscopic preparations of cells and observed them with the microscope.

Do you recognise these cells? How did we obtain these cells? What can you say about their shape? What parts can you see? Where is the nucleus located?
These are human cheek cells. Maybe yours!

 We have made microscopic preparations of plant cells.

These are onion cells. They have a polyhedral shape and if you look carefully you can see that the nuclei are not in the centre. They are located to one side of the cell. Do you know why?

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