Contents

Introduction

Cells were first described in 1665 by Robert Hooke. A cell is the smallest independent unit of life; they carry out the essential processes that make the organism a living thing. Cells share certain structural and functional unit of an organism.  Living cells are divided into two types prokaryotic and eukaryotic. This division is based on internal complexity.

Differences between plants and animals cells

Animals and plant cells are quite similar when you study them. They both contain:

  • Protoplasm.
  • A cell membrane
  • Cell membrane
  • Nucleus controlling the vital functions of the cells

Few differences that exist between plant and animals are very significant and reflect a difference in the functions of each cell. The main structural difference between plant and animal cells is that plant cells have chloroplasts, a cell wall and a vacuole, whereas animal cells do not.

Plant cell

The ultra structure of a plant cell is shown in figure 1.1. The centre of the cell is taken up by a large vacuole filled with a solution containing sugars and salts, the cell sap. The cell is bounded by the cell wall which is a plasma membrane. The cell wall is made up of the polysaccharide cellulose.

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Figure 1.1 the  structure of a plant cell

Chloroplasts

Chloroplasts are members of a family of organelles called . Chloroplasts are large, double membrane-bound structures (about 5 micrometers across) that contain , which absorbs sunlight. Additional membranes within the chloroplast contain the structures that actually carry out photosynthesis. Cells use sunlight as their energy source; the sunlight must be converted into energy inside the cell in a process called . Chloroplasts are the structures that perform this function.

Chloroplasts carry out energy conversion through a complex set of reactions similar to those performed by mitochondria in animals. ...

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