Cell:
The cell is the fundamental, structural and functional unit of all living beings.
Prokaryotic cell:
In lower organisms like the bacteria and blue-green algae, the nuclear membrane is absent. As such, the nuclear material is in direct contact with the cytoplasm. Such cells are called prokaryotic cells.
Eukaryotic cell:
In higher organisms the nuclear material is enclosed or bounded by a membrane.
Cellsize:
Size of a particular cell is dependent on the surface area/ volume relationship. A small cell is more efficient than a large cell. The largest cell in the world is ostrich’s egg.
The smallest cells are those of Mycoplasma gallisepticum, an organism intermediate between viruses and bacteria.
The largest human cell is ovum. The smallest human cell is red blood cell. The longest cell is the nerve cell. In elephant, it has been found to measure about 1 m.
Cell shapes:
Cells exhibit varied shape to perform different tasks, e.g., the nerve cells are long to carry messages from one part of the body to another.
Microscope:
A microscope is an instrument used to magnify objects, i.e., increase the size of images.
Protoplasm:
The living part of a cell which consist of cytoplasm, nucleus and other living bodies. It is a transparent semifluid granular substance that loses its transparency on heating. The largest component of protoplasm is water, minerals salts and elements of oxygen, carbon, hydrogen and nitrogen in the form of proteins, fats and carbohydrates.
Nucleoplasm:
The portion of protoplasm that occurs in the nucleus is called the nucleoplasm.
Cell membrane:
The cell membrane controls the entry and exit of materials allowing certain substances through, but preventing the passage of others, such a membrane is described as a selectively permeable membrane.
Cell wall:
Cell wall is a rigid, differentially permeable non-living boundary wall present outside the cell membrane in plant cells. The cell wall provides and maintains the shape of these cells and serves as protective barrier. It may be made of cellulose or chitin.
Cytoplasm:
Cytoplasm is a fluid jelly, transparent substance. It is a collective term for the cytosol and the organelles suspended within the cytosol. The cytoplasm shows the distinct regions - (i) ectoplasm and (ii) endoplasm. The outer non-granular, transparent thin layer is known as ectoplasm and the inner viscous portion where cell organelles are located is called endoplasm. The cytoplasm is composed of the matrix, the organelles and non-living inclusions like vacuoles and granules.
Cytosol:
The cytosol is the liquid found inside cells. It constitutes most of the intracellular fluid (ICF). It is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into many compartments.
The cell is the fundamental, structural and functional unit of all living beings.
Prokaryotic cell:
In lower organisms like the bacteria and blue-green algae, the nuclear membrane is absent. As such, the nuclear material is in direct contact with the cytoplasm. Such cells are called prokaryotic cells.
Eukaryotic cell:
In higher organisms the nuclear material is enclosed or bounded by a membrane.
Cellsize:
Size of a particular cell is dependent on the surface area/ volume relationship. A small cell is more efficient than a large cell. The largest cell in the world is ostrich’s egg.
The smallest cells are those of Mycoplasma gallisepticum, an organism intermediate between viruses and bacteria.
The largest human cell is ovum. The smallest human cell is red blood cell. The longest cell is the nerve cell. In elephant, it has been found to measure about 1 m.
Cell shapes:
Cells exhibit varied shape to perform different tasks, e.g., the nerve cells are long to carry messages from one part of the body to another.
- Human red blood cells are circular and biconcave, to transport oxygen.
- White blood cells are amoeboid that can squeeze out through capillary walls.
- Guard cells of stomatal pore in the leaves are bean—shaped to open and close the pore.
Microscope:
A microscope is an instrument used to magnify objects, i.e., increase the size of images.
Protoplasm:
The living part of a cell which consist of cytoplasm, nucleus and other living bodies. It is a transparent semifluid granular substance that loses its transparency on heating. The largest component of protoplasm is water, minerals salts and elements of oxygen, carbon, hydrogen and nitrogen in the form of proteins, fats and carbohydrates.
Nucleoplasm:
The portion of protoplasm that occurs in the nucleus is called the nucleoplasm.
Cell membrane:
The cell membrane controls the entry and exit of materials allowing certain substances through, but preventing the passage of others, such a membrane is described as a selectively permeable membrane.
Cell wall:
Cell wall is a rigid, differentially permeable non-living boundary wall present outside the cell membrane in plant cells. The cell wall provides and maintains the shape of these cells and serves as protective barrier. It may be made of cellulose or chitin.
Cytoplasm:
Cytoplasm is a fluid jelly, transparent substance. It is a collective term for the cytosol and the organelles suspended within the cytosol. The cytoplasm shows the distinct regions - (i) ectoplasm and (ii) endoplasm. The outer non-granular, transparent thin layer is known as ectoplasm and the inner viscous portion where cell organelles are located is called endoplasm. The cytoplasm is composed of the matrix, the organelles and non-living inclusions like vacuoles and granules.
Cytosol:
The cytosol is the liquid found inside cells. It constitutes most of the intracellular fluid (ICF). It is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into many compartments.
Nucleus:
The nucleus is the most obvious organelle in any eukaryotic cell. It is enclosed in a double membrane and communicates with surrounding cytosol via numerous nuclear pores. Within the nucleus is the DNA responsible for providing the cells with its unique characteristics. The DNA is similar in every cell of the body, but depending on the specific cell type, some genes may be turned on or off — that’s why a liver cell is different from a muscle cell, and a muscle cell is different from a fat cell. All cells have nucleus, except sieve tubes in plants and the mature mammalian red blood cells.
Nucleolus:
The prominent structure in the nucleus. The nucleolus produces ribosomes, which move out of the nucleus and take positions on the rough endoplasmic reticulum.
Chromatin fibers:
Chromatin fibres are very fine thread - like coiled filaments. At the time of cell divisions, the chromatin becomes thick and ribbon - like and are known as chromosomes. The chromosomes bear genes, which are composed of DNA and histones. Genes are responsible for transmission of hereditary characteristics.
DNA:
DNA or deoxyribonucleic acid is a helically twisted double chain poly-deoxyribonucleotide macromolecule.
Endoplasmic reticulum:
Endoplasmic reticulum is a complex tubular membrane system which almost fills up the intracellular cavity. Some tubes are studded with spherical bodies called ribosomes. These are called rough endoplasmic reticulum. Those that do not bear ribosomes are called smooth endoplasmic reticulum. Rough ER is the site of protein synthesis. Smooth ER takes part in secretion of lipids.
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