Cell Biology and Structure

Nebenkern consists of mitochondrial sheath.

Ribosomes are the centre of protein synthesis in bacteria (and all cells). They are the molecular machines that read messenger RNA (mRNA) and assemble amino acids into polypeptide chains according to the genetic code. Bacteria have 70S ribosomes.

Neurocan core protein is a protein that in humans is encoded by the NCAN gene. Neurocan is a chondroitin sulphate proteoglycan consisting of neurocan and chondroitin sulphate. It is thought to be involved in the modulation of cell adhesion and migration.

DNA (Deoxyribonucleic Acid) is present in chromosomes, which are located in the nucleus of eukaryotic cells. Chromosomes carry genetic information. Option B is correct.

Egg pro-nucleus with cytoplasm is present at animal pole.

Polar bodies are haploid.

A relatively rigid cell wall outside the cell surface membrane has pores containing fine threads known as plasmodesmata, which link the cytoplasm of neighbouring cell through the cell walls.

Differential centrifugation—The separation of mixtures such as cellular particles in a medium at various centrifugal forces to separate particles of different density, size and shape from each other.

A fibroblast is a type of cell that synthesises the extracellular matrix and collagen, the structural framework (stroma) for animal tissues and plays a critical role in wound healing. Fibroblasts are the most common cells of connective tissue in animals.

Osteoblasts are bone cells that are responsible for the formation of new bone. The osteoblasts are much smaller; they only have one nucleus. Osteoblasts also work in groups to form new bone. Osteoblasts are important because it allows the bones to be made, remodeled and repaired.

Sieve tube is an organised and differentiated cellular structure having cytoplasm without any nucleus. However, nucleus is present in young cells, but mature sieve tube element lacks nucleus. Its functions are controlled by the nucleus of companion cells.

Regeneration is specifically carried out by specialized cells (often called neoblasts in planaria or stem cells in other organisms) that can dedifferentiate, proliferate, and redifferentiate into needed cell types. Broken cells are damaged beyond function, all cells lack regenerative capacity, and differentiated cells have limited ability to change fates.

Neuron has a branched structure.

The surface of influenza virus particles is studded with hemagglutinin spikes. It can cause attachment of the virus to specific mucoprotein receptors on the surface of host cells.

The Enter-Doudoroff pathway is an alternative pathway of glucose metabolisms. It is found in aerobic and anaerobic prokaryotes (especially in Gram negative bacteria) but not found in eukaryotes.