Question

For each of the following sentences, select the best word or phrase from the list below to fill in the blanks. Not all words or phrases will be used; each word or phrase should be used only once.

An extracellular signal molecule can act to change a cell's behavior by acting through cell-surface __________________ that control intracellular signaling proteins. These intracellular signaling proteins ultimately change the activity of _________________ proteins that bring about cell responses. Intracellular signaling proteins can __________________ the signal received to evoke a strong response from just a few extracellular signal molecules. A cell that receives more than one extracellular signal at the same time can __________________ this information using intracellular signaling proteins. __________________ proteins can act as molecular switches, letting a cell know that a signal has been received. Enzymes that phosphorylate proteins, termed ___________, can also serve as molecular switches; the actions of these enzymes are countered by the activity of __________________.

a)acetylase
b)AMP-binding
c)amplify
d)autocrine
e)cleavage
f)convolute
g)decouple
h)decrease
i)effector
j)esterases
k)integrate
l)GMP-binding
m)GTP-binding
n)neurotransmitter
o)protein kinases
p)protein phosphatases
q)receptors
r)sterols

Answer 1

An extracellular signal molecule can act to change a cell's behavior by acting through cell-surface receptors that control intracellular signaling proteins. These intracellular signaling proteins ultimately change the activity of effector proteins that bring about cell responses. Intracellular signaling proteins can amplify the signal received to evoke a strong response from just a few extracellular signal molecules. A cell that receives more than one extracellular signal at the same time can integrate this information using intracellular signaling proteins. GTP-binding proteins can act as molecular switches, letting a cell know that a signal has been received. Enzymes that phosphorylate proteins, termed protein kinases, can also serve as molecular switches; the actions of these enzymes are countered by the activity of protein phosphatases.

Step-by-step explanation:

In cellular signaling, extracellular signal molecules bind to _receptors_, typically on the cell surface. These receptors then transmit signals to intracellular signaling proteins, such as _GTP-binding proteins_, which act as molecular switches. The intracellular signaling proteins can _amplify_ the signal, ensuring a robust cellular response.

Cells often receive multiple signals simultaneously. In such cases, intracellular signaling proteins play a crucial role in _integrating_ these signals. This integration allows the cell to coordinate and respond appropriately to complex environmental cues.

The actions of intracellular signaling proteins, especially those involving phosphorylation and dephosphorylation, are regulated by enzymes like _protein kinases_ and _protein phosphatases_. These enzymes serve as molecular switches, modulating cellular responses. The balance between kinase and phosphatase activity determines the cell's ultimate response to extracellular signals.