Answer:
Membrane Lipid Rafts.
Explanation:
They are present in all cells and have been implicated in a variety of sorting and signaling processes. They are rich in cholesterol, sphingomyelin, and glycosylphosphatidylinositol (GPI)-anchored proteins; have more ordered acyl side chains; and are thicker than nonraft bilayer domains.
Answer:
The answer is A.
Explanation:
B) Nucleotides and amino acids can act as extracellular signal molecules:
ATP is made of adenosine (a type of nucleotide) and used in cell signalling called "purigenic signalling" and amino acids are also used as signal molecules.
C) Some signal molecules are transmembrane proteins:
Transmembrane acts as receptors for smaller signal molecules so this can also be accepted as true.
D) Some signal molecules can bind directly to intracellular proteins that bind DNA and regulate gene transcription:
That is also true, some of the hormones can cross lipid membrane of the cells and bind directly to the intracellular (inside-of-a-cell) proteins.
Lastly; dissolved gasses such as nitric oxide can activate proteins such as guanylyl cyclase so this choice is <u>false</u>.
D) cell membrane is the anwser
B. It's less dense. Ice floats<span> because it is about 9% less dense than liquid water.</span>