Nonsteroid hormones cannot cross the plasma membrane of cells, yet still have the ability to influence cell activity. Explain how this is possible
What will be an ideal response?
For most nonsteroid hormones, binding to the cell surface receptor is just the beginning of the cell changes that follow. These hormones tend to rely on second messengers — chemical agents that carry the message provided by the hormone (the first messenger). The second messenger typically activates a cascade of enzyme-driven pathways, which ultimately lead to a change in cell activity.
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Synaptic integration refers to
A. the summing of multiple excitatory or inhibitory influences in a postsynaptic neuron. B. the fusing of presynaptic and postsynaptic membranes. C. the binding of Ca2+ions to secretory vesicles in presynaptic neurons. D. the binding of secretory vesicles to the presynaptic neuron membrane. E. the enzymatic degradation of neurotransmitters in the synaptic cleft.
Probes can come from a variety of sources, such as ____________________
a. single-stranded RNA templates b. histones from other species c. artificially engineered gene sequences d. related genes from other species e. unrelated genes from other species
Explain how tonicity affects water uptake at the roots.
__________ is rapid diversification into new species
that occupy novel niches. Fill in the blank(s) with the appropriate word(s).