D. Polarity and size.
<span>The size, polarity, and charge of a substance will determine whether or not the substance can cross the cell membrane by diffusion. The cholesterol was an example of a lipid, and is highly soluble in the nonpolar environment of the lipid bilayer. You saw, in the animation above, the cholesterol freely passing into the hydrophobic environment of the membrane. Cholesterol distributes freely in the membrane and then some fraction will dissolve in the aqueous environment of the cytoplasm. Water, on the other hand, while polar, is small enough to cross the membrane at a slow rate. Note that specialized transport proteins in certain cell membranes can provide a channel for the water, greatly increasing its rate of crossing the membrane. The lipid bilayer is much less permeable to the ion, because of its charge and larger size. As a general rule, charged molecules are much less permeable to the lipid bilayer.</span>
Answer:
Supportive connective tissue—bone and cartilage—provide structure and strength to the body and protect soft tissues. A few distinct cell types and densely packed fibers in a matrix characterize these tissues. In bone, the matrix is rigid and described as calcified because of the deposited calcium salts.
Explanation:
15
Each one of those letters represents a nucleotide. So to find out how many nucleotides are in the gene, just count them
However, keep in mind that this only represents 1/2 strands that make up DNA. If you are supposed to include the other strand, simply double 15, and there would be 30 nucleotides total. However, only 1 strand is actually required in order for protein synthesis to work, so I think it's just 15.
Answer:
Pinocytosis is the mechanism by which living cells consume liquid droplets. Endocytosis is the general mechanism by which cells ingest foreign substances and collect them in special membrane-bound vesicles within the cell. Pinocytosis is one form of endocytosis.
