Cell Biology and Structure

Cancer is characterized by uncontrolled growth and division of cells. Abnormal and persistent cell division localized in a particular region is called benign tumour. Tumour cells may be carried by blood steam or lymph or penetrate directly to other parts of the tissue resulting in dangerous malignant tumour. The spread of cancerous cells to distant sites is termed as metastasis. 

Growth is an irreversible process seen at all organizational levels. It consist of cell growth. Growth is the result of the excess of the anabolic (synthetic) over the catabolic (destructive) processes in the organism. 

Semi-autonomous organelles are organelles with DNA. In eukaryotic cells, mitochondrion and chloroplast are semi-autonomous organelles.

Electron microscope is a microscope with high magnification and resolution, employing electron beams in the place of light and using electron lenses. It is used to visualise plasma membrane.

Microtubules are a component of the cytoskeleton found throughout the cytoplasm. In eukaryotes, microtubules are long and hollow cylinders made up of polymerised α- and β-tubulin dimers.

A contractile vacuole (CV) is a sub-cellular structure (organelle) involved in osmoregulation. It is found predominantly in protists and in unicellular algae.

A vacuole is a membrane-bound organelle which is present in all plant and fungal cells. A vacuole is surrounded by a membrane called the tonoplast.

The glycocalyx is a glycoprotein-polysaccharide covering that surrounds the cell membranes of some bacteria, epithelia and other cells.

The thickness of the plasma membrane is 70-100 A.

Chloroplast is a double membrane cell organelle found in plants.

One of the key organelles involved in digestion and waste removal is the lysosome. Lysosome has one membrane or single membrane.

This protoplasm is of a living plant or bacterial cell whose cell wall has been removed.

A microbody is a type of organelle that is found in the cells of plants, protozoa and animals. Organelles in the microbody family include peroxisomes, glyoxysomes, glycosomes and hydrogenosomes. In vertebrates, microbodies are especially prevalent in the liver and kidney organs.

The mature red blood cell contains no internal membranous structures. The mature cell has no nucleus and no organelles. As red blood cells develop and mature in bone marrow, the nucleus and organelles completely deteriorate.

The cell wall forms outside the plasma membrane initially as a thin primary cell wall. Thereafter, the primary cell wall may thicken or a more durable secondary cell wall can form between the primary cell wall and plasma membrane. All the above given structures have primary cell wall.