Answer: The correct answer for the fill in the blank is osmosis.
Osmosis is defined as the movement of solvent (like water) from a region where the concentration of solute is lower to a region where the concentration of solute is higher though a semipermeable membrane.
In other words, it is the water movement from an area where its ( water ) concentration is higher to an area where its concentration is lower.
This process does not require any energy as water is moving along the concentration gradient.
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:
E2F transcription factors
Explanation:
The E2F transcription factors (TFs) encode intracellular factors associated with the control of the cell cycle. E2F are TFs that bind to promoter consensus sequences in order to activate transcription. These TFs control the expression of target genes involved in cell proliferation including, among others, genes for DNA replication and mitotic activation. Moreover, the E2F proteins also may act as a link between cell fate and the cell cycle. The retinoblastoma (Rb) is a protein that modulates the activity of the E2F family of TFs, and it has been shown that the Rb/E2F pathway is a key molecular mechanism associated with cell proliferation.
So he doesn't fall and drown
The correct answer would be:
<em>Cycles.</em>
