Cell Biology and Structure

It is a system of highly branching membranes, which almost fills the space inside the cell membrane. Some of the branches of endoplasmic reticulum are connected to the plasma membrane while some of them are connected to the nuclear membrane. An examination of endoplasmic reticulum under the electron microscope reveals two types of membranes. Being highly coiled in nature, it provides an increased surface area for various enzyme catalyzed reactions.

Mitochondria are tiny structures that occur in varying shapes cylindrical, spherical, oval, rod shaped etc.. They are found distributed all over the cytoplasm. Each mitochondrion is bound by a double membrane. The outer membrane is smooth and straight, while the inner membrane is thrown into numerous folds called cristae. Thus, the surface area of inner membrane is much higher than that of outer membrane. The cristae bear numerous, minute, regularly spaced particles called elementary particles or oxysomes.

A ribosome is a component of a biological cell that creates proteins from all amino acids and rRNA representing the protein. Ribosomes are made from complexes of rRNAs and proteins. Ribosomes are divided into two subunits. The smaller subunit binds to the mRNA, while the larger subunit binds to the tRNA and the amino acids.

Each mitochondrion is bound by a double membrane. The outer membrane is smooth and straight, while the inner membrane is thrown into numerous folds called cristae. Thus, the surface area of inner membrane is much higher than the outer membrane. The cristae bear numerous, minute, regularly spaced particles called elementary particles or oxysomes. Mitochondria are able to change shape and even move to the areas where considerable activity is taking place. This is facilitated by cytoplasmic streaming movement.They are known as the powerhouse and ATP mill of the cell.

Each mitochondrion is bound by a double membrane. The outer membrane is smooth and straight, while the inner membrane is thrown into numerous folds called cristae. Mitochondria represents the sites of aerobic respiration in a cell. They use molecular oxygen to oxidize glucose into carbon dioxide and water. Oxidation releases energy in the form of molecules of adenosine triphosphate (ATP), which are stored and released in the cell. Hence, mitochondria are described as minute powerhouses of the cell.

Mitochondria are tiny structures that occur in varying shapes cylindrical, spherical, oval, rod shaped etc.. Each mitochondrion is bound by a double membrane. The outer membrane is smooth and straight, while the inner membrane is formed into numerous folds called cristae. The number of mitochondria in a cell varies considerably and depends on the nature of the cell. Cells with very high-energy requirements possess very large number of mitochondria. A human liver cell for example may have more than 1000 mitochondria. So also the flight muscle cells in insects. Mitochondria are absent in mature human RBC.

The centrosome is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell as well as a regulator of cell-cycle progression. It was discovered by Edouard Van Beneden in 1883. The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells.Doubling of a centrosome is similar to the DNA replication in two respects: the semi-conservative nature of the process and the action of cdk2 as a regulator of the process.

Each mitochondrion is bound by a double membrane. The outer membrane is smooth and straight, while the inner membrane is thrown into numerous folds called cristae. Thus, the surface area of inner membrane is much higher than the outer membrane. Mitochondria represent the sites of aerobic respiration in a cell. They use molecular oxygen to oxidize glucose into carbon dioxide and water. Oxidation releases energy in the form of molecules of adenosine triphosphate (ATP), which are stored and released in the cell. Hence, mitochondria are described as minute power houses of the cell as well as storage batteries of the cell.

Each mitochondrion is bound by a double membrane. The outer membrane is smooth and straight, while the inner membrane is thrown into numerous folds called cristae. Thus, the surface area of inner membrane is much higher than the outer membrane. Mitochondria represent the sites of aerobic respiration in a cell. They use molecular oxygen to oxidize glucose into carbon dioxide and water. Oxidation releases energy in the form of molecules of adenosine triphosphate (ATP), which are stored and released in the cell. Hence, mitochondria are described as minute powerhouses of the cell.

Golgi Complex is represented by several structures like membranes, vesicles and granules. It appears as a central stack of flattened inter communicating sacs called cisternae in a parallel arrangement along with tubules and vesicles. The cisternae are continuously being formed at one end and bud off as vesicles at the other end of the stack. In plant cells, cisternae are 15 to 20 in number and form discrete structures called dictyosomes. In animals they are 3 to 7 in number.

Golgi Complex is represented by several structures like membranes, vesicles and granules. It appears as a central stack of flattened inter communicating sacs called cisternae in a parallel arrangement along with tubules and vesicles. The cisternae are continuously being formed at one end and bud off as vesicles at the other end of the stack. In plant cells, cisternae are 15 to 20 in number and form discrete structures called dictyosomes. In animals they are 3 to 7 in number.

It consists of nucleoplasm surrounded by a nuclear membrane. The nuclear membrance is perforated and the pores are called nuclear pores or nucleopores. The nuclear membrance is a double unit membrane enclosing a perinuclear space. The nucleoplasm possesses chromatin reticulum and 1 or 2 darkly stained bodies called nucleoli (sing-nucleolus).

It consists of nucleoplasm surrounded by a nuclear membrane. The nuclear membrance is perforated and the pores are called nuclear pores or nucleopores. The nucleoplasm possesses chromatin reticulum and 1 or 2 darkly stained bodies called nucleoli (sing-nucleolus). The chromatin reticulum is made up of DNA which is the genetic material and  associated histone proteins. The nucleoplasm consists of more than 90% proteins, RNA and phospholipids.