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A neuron receives signals from neighboring cells through branched, cellular extensions called dendrites.The neuron then propagates an electrical signal down a specialized axon extension from the basal pole to the synapse, where neurotransmitters are released to propagate the signal to another neuron or effector cell (e.g., muscle or gland).
A polar organelle is a structure at a specialised region of the bacterial polar membrane that is associated with the flagellar apparatus. [ 1 ] [ 2 ] This flagellum-associated structure can easily be distinguished from the other membrane regions in ultrathin sections of embedded bacteria by electron microscopy when the cell membrane is ...
Semidiagrammatic. z.p. Zona pellucida. p.gl. Polar bodies. a. Two-cell stage. b. Four-cell stage. c. Eight-cell stage. d, e. Morula stage. A polar body is a small haploid cell that is formed at the same time as an egg cell during oogenesis, but generally does not have the ability to be fertilized. It is named from its polar position in the egg.
Polarized membranes are key cellular components that aid in facilitating compartmentalization, cell-to-cell communication, and signaling. Cells actively utilize polarized membranes to form and maintain electrochemical gradients and regulate both intracellular and extracellular environments.
Polar microtubules interdigitate at the spindle midzone and push the spindle poles apart via motor proteins. Astral microtubules anchor the spindle poles to the cell membrane. Microtubule polymerization is nucleated at the microtubule organizing center .
The second mechanism of unequal cleavage involves the production of an enucleate, membrane bound, cytoplasmic protrusion, called a polar lobe. [8] This polar lobe forms at the vegetal pole during cleavage, and then gets shunted to the D blastomere. [7] [8] The polar lobe contains vegetal cytoplasm, which becomes inherited by the future D ...
Thus the inside of the bilayer sheet is a non-polar region sandwiched between the two polar sheets. [ 2 ] Although phospholipids are the principal constituents of biological membranes, [ 3 ] there are other constituents, such as cholesterol and glycolipids , which are also included in these structures and give them different physical and ...
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...