Cell Biology and Structure

These proteins transport specific substances from one part of body to the others. Most familiar is haemoglobin of red blood cells (erythrocytes or RBCs) of vertebrates. Serum albumin transports fatty acids in blood from fatty tissues to other tissues. Transferrin protein transports iron, and certain other proteins transport steroid hormones, drugs, toxins, etc. in blood. Transport proteins of plasma membrane transport materials across the membrane. For instance, glucose and amino acids enter into all cells through membrane transport proteins.

Passage cells are found in root endodermis. They are thin walled cells just opposite to protoxylem patches that help in passage of water from cortex to xylem.

A tylosis is a bladder-like distension of a parenchyma cells into the lumen of adjacent vessels in wood.

Centrosome is not present in the ovum as centrosome is required for cell division, which is not required in the ovum.

Most of the steps of pentose phosphate pathway take place in plastids in plants.

Nucleus is absent in mature sieve tubes. They use the nucleus of companion cells for metabolic regulation.

In some yeasts, when buds do not separate from the parent cell, they form a chain of cells that resembles a mycelium, known as pseudomycelium.

The tonoplast is the specialized cytoplasmic membrane that surrounds the vacuole in plant cells, regulating the movement of ions and molecules.

Leucoplasts are non-pigmented plastids found in plant cells that function primarily for the storage of starch, lipids, or proteins.

Genes are specific segments of DNA that are organized and packaged into structures called chromosomes within the cell nucleus.

Lysosomes are single-membrane-bound organelles containing digestive enzymes. Mitochondria, chloroplasts, and the nucleus are all double-membrane-bound organelles.

A gland is a group of cells or an organ that synthesizes and secretes substances such as hormones or enzymes.

Fibroblasts are the most common type of cell in connective tissue; they produce the extracellular matrix and collagen fibers.

Meristematic cells are undifferentiated plant cells that are actively dividing, allowing for growth in length and girth.

Chondrocytes are the only cells found in healthy cartilage; they produce and maintain the cartilaginous matrix.