Question

“Multicellular organisms can only exist due to cell signalling pathways”. Critically discuss this statement supporting your arguments with specific and relevant examples.

Answer 1

cell signelling is an important process in biological life.It allows cells to perceive and respond to the extracellular environment allowing development, growth, immunity, etc and the errors in cell signaling may cause in cancer growth, diabetes.The Cell signaling governs basic cellular activities and coordinates cell actions through a complex coordination of responses to cellular microenvironment.The signelling molecules can be lipids, phospholipids, amino acids, monoamines, proteins, glycoproteins, or gases. Signaling molecules binding surface receptors are generally large and hydrophilic.

There are three major stages in cell signelling pathways,they are:

• reception, whereby the signal molecule binds the receptor.
• Then, signal transduction, which is where the chemical signal results in a series of enzyme activations.
• Finally, the response, which is the resulting cellular responses.

In multicellular organisms,There are four basic categories of chemical signaling ,they are:

paracrine signaling, autocrine signaling, endocrine signaling, and signaling by direct contact.

Paracrine signaling is a form or cell-to-cell communication in which a cell produces a signal to induce changes in nearby cells, altering the behaviour of those cells.An example of paracrine signals is the chemical transmitted from nerve to muscle that causes the muscle to contract.

form of cell signaling in which a cell secretes a hormone or chemical messenger (called the autocrine agent) that binds to autocrine receptors on that same cell, leading to changes in the cell is called as autocrine signaling.FOr example; the cytokine interleukin-1 in monocytes. When interleukin-1 is produced in response to external stimuli, it can bind to cell-surface receptors on the same cell that produced it.

endocrine signaling occurs when endocrine cells release hormones that act on distant target cells in the body. Endocrine signaling can be distinguished from two other types of signaling: neural signaling and paracrine signaling.Well-known examples of peptide hormones include insulin, glucagon, and the hormones produced by the pituitary gland (growth hormone, follicle-stimulating hormone, prolactin, and others).

In neural signelling, Neurons send what are known as electrochemical signals. Once a neuron has been stimulated by some sort of stimulus, it generates an electric potential that travels down the length of the cell. This is the 'electro' part of electrochemical.

Signelling by direct contact:Cells communicate with each other via direct contact (juxtacrine signaling), over short distances (paracrine signaling), or over large distances and/or scales (endocrine signaling). One cell will happen to produce more of a cell surface protein that activates the Notch receptor on the adjacent cell.

recognition markers are important in embryo develop as they signal adjacent cells to specialize for a specific tissue type and/or inhibit specialization. The mating types recognition in yeast previously mentioned is an example of direct contact signaling.