Question

What is cell. Explain brifely.

Answer 1

ÊLLØ'...!!

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⭕What is Cell?

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➖Cell is the structural and functional unit of life.

➖The cell is derived from Latin “ cella”, meaning "small room") .

➖Some organisms, such as bacteria, are unicellular, consisting of a single cell.

➖Other organisms, such as humans, are multicellular.

➖The largest known cell is an ostrich egg.

➖Each cell is at least somewhat self-contained and self-maintaining: it can take in nutrients, convert these nutrients into energy, carry out specialized functions, and reproduce as necessary.

➖Each cell stores its own set of instructions for carrying out each of these activities.

➖There are two types of cells:-

•eukaryotic cell

•prokaryotic cell

➖Prokaryotic cells are usually singletons

➖Eukaryotic cells are usually found in multi-cellular organisms.

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THÅÑKẞ...!!

Answer 2

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$\textbf{Cell}$ is the structural and functional unit of living organisms.

All living organisms are made up of cell. That's why cell is known as structural unit of life.

A single cell can perform all life functions with the help of it's components. Therefore it is known as functional unit of life.

→ Robert Hooke first discovered the cell in 1665.

He prepared a thin slice of cork and observed it under self made microscope. He saw some box like structures which he named as cell.

→ Anton Von Leeuwenhoek first saw the living cell and also first describe the living cell.

→ Cells can replicate independently.

→ It contain hereditary information due to presence of nucleus or nucleoid.

→ All organisms are made up of cells. Organisms with single cells are known as unicellular organisms. And organisms with multiple cells are known as multicellular organisms.

→ Cells size ranges from 1 - 100 μm.

→ Mycoplasmas, is the shortest cell (0.3 μm) and ostrich egg and nerve cells are the largest cell.

→ Cells are in different shapes. Their shape vary with their function. They may be cuboid, thread like, disc like etc.

→ Cells are of two types namely; Eukaryotic and Prokayotic cells.

» Eukaryotic cells :-

• These are generally large in size.

• Nuclear region is well defined and surrounded by a nuclear membrane.

• These are multicellular.

• Single chromosome are present.

• Member bound cell organelles are present such as mitochondria, endoplasmic reticulum, golgi appartus etc.

• DNA is linear.

• Cell divides by binary fission and budding.

• Ex :- Human beings, plants etc.

» Prokayotic cells :-

• These are smaller in size.

• Nuclear region is not well defined and not surrounded by a nuclear membrane.

• These are unicellular.

• More than one chromosomes are present in it.

• Membrane bound cell organelles are absent such as mitochondria, endoplasmic reticulum, golgi appartus etc.

• DNA is circular.

• Cell divides by mitosis and meiosis.

• Ex :- Bacteria, blue-green algae etc.

» Animal cell :-

• Cell wall absent.

• Centrosome present.

• Vacuoles are small and many.

» Plant Cell :-

• Cell wall present.

• Centrosome absent.

• Vacuole is large and single.

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