Phospholipids have phosphate group heads that are hydrophilic while the fatty acid tails are hydrophobic.
They are able to form cell membrane as they automatically arrange themselves in the required pattern in water because of these properties.To form membranes, these line up next to each other with their heads on the outside of the cell and their tails on the inside. A second layer of phospholipids also forms with heads on the inside of the cell and tails facing away.
In this way a double layer is formed with phosphate group heads on the outside, and fatty acid tails on the inside. This double layer, called a lipid bi-layer, forms the main part of the cell membrane.
The cell is called the structural and functional unit of life as all living organisms are made up of cells.
Answer:
The correct order of events is:
C) Nicotine binds to the transmembrane protein that normally binds the neurotransmitter acetylcholine.
A) The acetylcholine receptor is an ion channel, and when a ligand binds, the ion channel opens.
B) An influx of ions carries the signal to the reward areas of the brain.
D) The signal causes release of dopamine in the brain, which causes good feelings.
E) Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).
Explanation:
Nicotine acts on acetyl cholinergic receptors that are located in membranes of the midbrain neurons. Nicotine can activate those receptors or block them more efficiently than acetylcholine. Stimulation of nicotinic receptors leads to an increase in ions flow that reaches the brain and causes dopamine release in the nucleus accumbens through axonal prolongations of the dopaminergic pathway. This response is responsible for the smoker´s recompense sensation.
The dopaminergic pathway is the most important way in the process of nicotine dependence and addiction to the drug.
Answer:
In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them underpin all biology.
Five common abiotic factors in the enviroment are atmosphere, chemical elements, sunlight/temperature, wind and water.
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Explanation:
