Answer:
E) Improve membrane fluidity
Explanation:
Cholesterol constitutes the basic structural element of the skeleton of cell membranes. Without their reinforcement, the membranes would become extremely fluid and lose their consistency. Cholesterol is found in the esterified membranes in its hydroxyl group (OH): with fatty acids, mainly oleic and linoleic, or as cholesterol sulfate. The cholesterol-sulfate polar group is disposed on one of the faces of the membrane that interacts with other polar groups in that area, while its bulky hydrophobic portion is embedded between the apolar parts of the lipids that form the membrane skeleton and They fulfill many other functions, among which the reduction in the permeability of protons and sodium ions, and their participation in signal transmission. Cholesterol is also essential in phagocytosis processes carried out by cells to capture many nutrients and, in general, for the function of cleaning up organic waste produced by macrophages.
The membranes must have a fluid structure so that the integrated proteins can move "horizontally" to interact with their ligands and with other proteins. The fluidity is given by unsaturated fat. With the excess of saturated fat, the membranes become rigid, but only with the necessary unsaturated fat the membranes are extremely fluid and very sensitive to temperature changes. Cholesterol stabilizes the structure of the membranes; In order for them to have the correct structure, they must have the correct proportions of saturated, unsaturated fats and cholesterol. The membranes produced in the laboratory without cholesterol are unstable to temperature changes, drastically modifying their fluidity against the small temperature changes that occur in the physiological range.
In addition to its functions in cell membranes, cholesterol is an important product that metabolism uses as a raw material to make other compounds:
*Bile salts
*Sex hormones
*Hormones of the adrenal cortex (corticosteroids)
*Vitamin D (Calciferol)
Answer:
he Taeniae coil
Explanation:
The mesocolic,free and omental taeniae are collectively known as TAENIAE.
They are the 3 ribbon of smooth muscle of the ascending,transverse, descending and the sigmoid colon. Anatomically their longitudinal contractions give the <u>natural</u> bulges(HAUSTRAL) in the colon.
The Haustral helps in translocation of chyme to the next haustral, and aiding the mixing of chyme for water absorption in the colon,
The coil of these smooth muscles is under the parasympathetic nervous system through Sacral nerve (of the spinal cord) innervation.
Answer:
- multiple pathways
- ligands/signaling molecules
- inorganic phosphate
- inactive relay proteins
Explanation:
Receptor Tyrosine Kinase:
- Receptor tyrosine kinase (RTK) is the largest class of enzyme linked cell surface receptors.
- When a growth factor or a ligand binds to two neighboring RTK receptors, the two receptors bind together and form a dimer.
- This change in the conformation of the RTKs activates the associated tyrosine kinase enzymes.
- Tyrosine kinases break down ATP to ADP and phosphorylate the RTKs. Cross phosphorylation between the receptors helps activate multiple tyrosine kinases on the neighboring RTK.
- Once phosphorylated, the cytoplasmic ends of the RTKs are available for docking by relay proteins or signaling molecules with an SH-2 domain.
The term “water stress" describes the suffering in a region caused by the water scarcity (the lack of fresh water resources) in that area. Overconsumption, growing population , institutional or financial issues are also factor that contribute to water scarcity. Precipitation differences is not one of them. Correct answer: C
the suns mass affects the planets in the solar system by giving different amount of heat to different distances
