Hormone activity

Question 1

how does each of the above hormones exert its influence?

Answer 1

Each of the above hormones (described as the ligand) exerts its influence by combining with a specific receptor.

Question 2

what does the interaction between the two lead to?

Answer 2

The interaction between the two leads to secondary changes in the receptor or in a molecule adjacent to it.

Question 3

where are the receptors for lipid soluble hormones located?

Answer 3

The receptors for lipid soluble hormones are located inside target cells.

Question 4

what are the receptors for water soluble hormones part of?

Answer 4

The receptors for water soluble hormones are part of the plasma membrane of target cells.

Question 5

which hormones diffuse from blood and through what?

Answer 5

Lipid soluble hormones (lipophilic), including steroid hormones and thyroid hormones, diffuse from blood through interstitial fluid and through the lipid bilayer of the plasma membrane into the target cell.

Question 6

where do the hormones bind to/where are activated receptors located?

Answer 6

The hormones bind then to and activated receptors located within the cytosol or nucleus.

Question 7

what does the activated receptor-hormone complex alter? What does it do?

Answer 7

The activated receptor-hormone complex alters gene expression. It turns specific genes of the nuclear DNA in or off.

Question 8

what do we call this type of receptors?

Answer 8

This type of receptors is called intracellular receptors.

Question 9

which hormones can’t diffuse through the lipid bilayer of the plasma and binds to receptors inside target cells?

Answer 9

Water soluble hormones (hydrophilic), including amine, peptide, protein, and eicosanoid hormones, cannot diffuse through the lipid bilayer of the plasma and binds to receptors inside target cells.

Question 10

what do they bind to instead?

Answer 10

Instead, they bind to receptors on the target-cell surface.

Question 11

describe these receptors

Answer 11

The receptors are integral transmembrane proteins in the plasma membrane.

Question 12

what do the hormones act as?

Answer 12

The hormone acts as the first messenger.

Question 13

what does the hormone-receptor complex activate?

Answer 13

The hormone-receptor complex activates a membrane protein called a G-protein.

Question 14

what does the activated G-protein activate in turn?

Answer 14

The activated G-protein in turn activates adenylyl cyclase.

Question 15

what does this enzyme convert ATP into?

Answer 15

This enzyme converts ATP into cyclic AMP (second messenger).

Question 16

what does the first messenger cause?

Answer 16

the first messenger causes production of a second messenger inside the cell.

Question 17

what does cyclic AMP activate?

Answer 17

Cyclic AMP activates one or more protein kinases.

Question 18

what is a protein kinase?

Answer 18

A protein kinase is an enzyme that phosphorylates other cellular proteins.

Question 19

how does phosphorylation work?

Answer 19

Phosphorylation activates some proteins and inactivates other, rather like turning a switch on or off.

Question 20

after a brief period, what is the enzyme that inactivates cAMP called?

Answer 20

After a brief period, an enzyme called phosphodiesterase inactivates cAMP.

Question 21

What happens to the cell’s response? What is the exception?

Answer 21

The cell’s response is turned off unless new hormone molecules continue to bind to their extracellular receptors in the plasma membrane.