Cytology or cell biology is the scientific study of the physiological properties, structure, organelles, interactions with the external environment, life cycle, division and death of cells . This study is done at the microscopic and molecular levels.
Knowledge of the components of cells and the way they function is fundamental and important for all biological sciences. In particular, a detailed understanding of the similarities and differences between different types of cells is important in the fields of cytology, molecular biology, and biomedical.
Movement of proteins
Different types of proteins are sent to different and specific part of the cell. A major division of cell biology examines the molecular mechanisms by which proteins are transported to different locations in the cell or the mechanisms by which proteins are synthesized within cells.
- Active transport and Passive transport – Movement of molecules into and out of cells.
- Autophagy – The process whereby cells “eat” their own internal components or microbial invaders.
- Adhesion – Holding together cells and tissues.
- Reproduction – Made possible by the combination of sperm made in the testiculi (contained in some male cells’ nuclei) and the egg made in the ovary (contained in the nucleus of a female cell). When the sperm breaks through the hard outer shell of the egg a new cell embryo is formed, which, in humans, grows to full size in 9 months.
- Cell fusion : Chemotaxis, contraction, cilia and flagella.
- Cell signaling – Regulation of cell behavior by signals from outside.
- DNA reconstruction and cell death
- Metabolism : Glycolysis, Respiration, Photosynthesis
- Transcription and mRNA splicing – gene expression.
- Active transport and passive transport – the movement of molecules in and out of cells.
- Autophagy – the process by which cells “eat” their own internal components or microbial invaders.
- Adhesion – the holding of cells and tissues together.
- Reproduction – made possible by the combination of the testis (contained in the nucleus of some male cells) and the egg (contained in the nucleus of a female cell) made in the ovary. When the sperm breaks through the hard outer shell of the egg, a new cell embryo is formed, which, in humans, grows to full size in 9 months.
Cell Semen: Chemotaxis, contraction, cilia and flagella.
- Cell signaling – regulation of cell behavior by signals from outside.
- DNA restart and cell death
- Metabolism: glycolysis, respiration, photosynthesis
- Transcription and mRNA Splicing Gene Expression Outcomes
The body of every animal or plant higher than Protozoa , bacteria and virus is made up of small cells. Cells are so small that they cannot be seen without a microscope. The bigger the animal, the more cells it is made up of. There is some difference between the cells of animals and plants, but in general they have the same structure. There is also a difference in the cells of different animals. The size and properties of cells of different organs of the same animal are also characteristic, such as the structure of liver and kidney cells of any mammal is not the same. Their functions are also different. Despite this variation, the imaginary simple cell can be described.
Cells are made up of two main parts:
(1) Cytoplasm , and
Vegetative cells have a wall of cellulose around them, but such a wall is not found in animals. There are some organelles in the cytoplasm which will be described later.
Every sexually reproducing organism starts its life from the cell stage itself. The cell is the egg and its continuous division gives rise to many cells. The process of cell division continues till the time the animal is well developed.
During cell division, centromeres are visible, but they are often not visible in the resting nucleus. The nucleus is surrounded by a covering on all sides. The cytoplasm is a polyphasic colliod, but it differs from ordinary buds in that it is organized. There are many substances in the cytoplasm which do not perform any function in its structure, but they have great importance in the life of the cell.
A microscope can be used to observe cells . Other types of microscopes are used, including optical microscopes, transmission electron microscopes, scanning electron microscopes, fluorescent microscopes, and confocal microscopes.
Each division of a cell is preceded by a division of its nucleus. Nuclear division is a random phenomenon, which can be divided into several stages. These conditions are as follows:
In the early stage, thin threads are visible inside the nucleus, which are called nucleus. These nuclei gradually become shorter and thicker due to spiralization. By the time of middle age, they become many times smaller and thicker than before. Some more important changes take place within the cell by the time of the intermediate stage. The envelope of the nucleus is destroyed and a spindle apparatus is formed in its place. The cells of most animals, which have the ability to divide, have a special apparatus called the centrosome and in which there is a granule called centriole.