Cell Division And Cell Cycle

Diksha Bhatla

Cell Division And Cell Cycle

25 May 2022

Introduction

Mitosis and Meosis

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Introduction

All organisms are made of cells or aggregates of cells. Cells vary in their shape, size, and activities/functions. Based on the presence or absence of a membrane-bound nucleus and other organelles, cells and hence organisms can be named eukaryotic or prokaryotic.

A typical eukaryotic cell consists of a cell membrane, nucleus, and cytoplasm. Plant cells have a cell wall outside the cell membrane. The plasma membrane is selectively permeable and facilitates the transport of several molecules.

The endomembrane system includes ER, Golgi complex, lysosomes, and vacuoles. All the cell organelles perform different but specific functions. Centrosomes and centriole form the basal body of cilia and flagella that facilitate locomotion. In animal cells, centrioles also form spindle apparatus during cell division. The nucleus contains nucleoli and chromatin networks. It not only controls the activities of organelles but also plays a major role in heredity.

The endoplasmic reticulum contains tubules or cisternae. They are of two types: rough and smooth. ER helps in the transport of substances, and the synthesis of proteins, lipoproteins, and glycogen.

The Golgi body is a membranous organelle composed of flattened sacs. The secretions of cells are packed in them and transported from the cell.

Lysosomes are single membrane structures containing enzymes for the digestion of all types of macromolecules.

Ribosomes are involved in protein synthesis. These occur freely in the cytoplasm or are associated with ER.

Mitochondria help in oxidative phosphorylation and generation of adenosine triphosphate. They are bound by a double membrane; the outer membrane is smooth and the inner one folds into several cristae.

Plastids are pigment-containing organelles found in plant cells only. In-plant cells, chloroplasts are responsible for trapping light energy essential for photosynthesis. The grana, in the plastid, is the site of light reactions and the stroma of dark reactions. The green-colored plastids are chloroplasts, which contain chlorophyll, whereas the other coloured plastids are chromoplasts, which may contain pigments like carotene and xanthophyll.

The nucleus is enclosed by a nuclear envelope, a double membrane structure with nuclear pores. The inner membrane encloses the nucleoplasm and the chromatin material. Thus, the cell is the structural and functional unit of life.

Mitosis and Meosis

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Cell Division And Cell Cycle

Cell Division And Cell Cycle

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Introduction

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