Question

which is th structure and function unit of life plant or animal cell?​

Answer 1

The three main parts of the cell theory are: All living things are made of cells. The cell is the basic unit of structure and function in all living things. Cells only come from other pre-existing cells by cell division.

Answer 2

Answer:

The cell was first discovered in 1665 by an English scientist named Robert Hooke. While looking through a microscope, he observed tiny box-like objects in a slice of cork (bark from an oak tree) and named these boxes cells. Cells are the basic units of life, which make up all living things. This idea forms the basis of the Cell Theory.

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Cell Theory:

The three main parts of the cell theory are:

1. All living things are made of cells.
2. The cell is the basic unit of structure and function in all living things.
3. Cells only come from other pre-existing cells by cell division.

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While some organisms are single-celled, others are made up of many cells. These organisms are called multicellular (having many cells). Cells differ in their size and complexity.

Eukaryotes are organisms which are made up of large and complex cells, whereas prokaryotes are organisms which are made up of small and simple cells. Animals and plants are examples of eukaryotes (have eukaryotic cells) while bacteria are examples of prokaryotes (have prokaryotic cells).

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Plant Cell Structure and Function:

In spite of the differences in size and complexity, all cells are mostly composed of the same substances and they all carry out similar life functions. These include growth and metabolism and reproduction by cell division.

Cells are made up of subcellular structures that are responsible for different and specific functions. These structures are known as organelles. A number of these organelles are common to both animal and plant cells. This section will focus on those parts which plants have.

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Cell Structures (Cell Organelles):

• Cell Wall: This is the rigid outermost layer of a plant cell. It makes the cell stiff -providing the cell with mechanical support - and giving it protection. Animal cells do not have cell walls.
• Cell Membrane: This is a protective layer that surrounds every cell and separates it from its external environment. It is found just inside the cell wall and is made up of complex lipids (fats) and proteins.
• Cytoplasm: The cytoplasm is a thick, aqueous (water-based) solution in which the organelles are found. Substances such as salts, nutrients, minerals and enzymes (molecules involved in metabolism) are dissolved in the cytoplasm.
• Nucleus: The nucleus is the ‘control center’ of the cell. It contains Deoxyribonucleic acid (DNA), the genetic material that directs all the activities of the cell. Only eukaryotic cells have nuclei (plural for nucleus), prokaryotic cells do not. The nucleus is separated from the cytoplasm by a specialized membrane called the nuclear membrane
• Ribosomes: These are little round structures that produce proteins. They are found in the cytoplasm or attached to the endoplasmic reticulum.