00:01
Lipid -soluble signaling molecules cross the membranes of all cells but only affect target cells because a, only the target cells have the correct dna segment.
00:11
B, the intracellular receptors are only in the target cells.
00:15
C, only the target cells have the enzymes to break down the signaling molecule.
00:21
Or d, only the target cells allow the signaling molecule to initiate a phosphorylation cascade.
00:27
First of all, d, a phosphorylation cascade doesn't happen for lipid soluble signals.
00:35
So hormones can be split into two main groups, water soluble and lipid soluble.
00:40
So the lipid soluble ones enter the cell because they can diffuse across the lipid bilayer, whereas water soluble, like protein hormones, cannot enter the cell, so they activate a cell surface receptor.
00:59
And that starts the cascade.
01:02
So it's the water -soluble hormones that start a phosphorylation cascade, lipid -soluble ones enter, bind to a receptor, and that receptor typically will then affect which genes are switched on and off.
01:16
Okay, what else do we have? so, a, all the cells are going to have the same dna, because all of your cells, minor scammates, eggs and sperm, have the same genetic material...
