receptor enzymes

Question 1

What happens when an extracellular messenger cannot enter a target cell?

Answer 1

t acts through a series of intracellular signaling pathways, such as protein kinases, which lead to phosphorylation of proteins and a subsequent cellular response.

Question 2

What is phosphorylation in the context of cell signaling?

Answer 2

: Phosphorylation is the process where protein kinases add a phosphate group to a protein, causing a change in the protein’s shape and function. This change helps in carrying out the cellular response dictated by the first messenger.

Question 3

Why is phosphorylation sometimes not enough for signal transduction?

Answer 3

r: Phosphorylation of a single protein may not be sufficient to trigger the desired cellular response. Often, protein kinases function in a cascade, where multiple proteins are phosphorylated in a chain reaction to pass the signal along to designated proteins.

Question 4

What is a kinase cascade, and why is it important?

Answer 4

A kinase cascade is a series of phosphorylation events where one protein kinase activates another in sequence. This cascade amplifies the signal, allowing the cell to respond effectively to the original extracellular messenger.

Question 5

What are the two main pathways for activating protein kinases?

Answer 5

The two main pathways for activating protein kinases are the Tyrosine Kinase Pathway and the Second Messenger Pathway.

Question 6

when the extracelllular messanger reaches the receptor what happens

Answer 6

the receptor has a enzyme attached to the internal surface
the ligand binds causing a change in enzyme shape
the enzyme becomes active and catylyses a specific chemical reaction such as phosphorylation
downstream molecules become active and change activity of the cell

Question 7

How does the Tyrosine Kinase Pathway work?

Answer 7

he receptor itself acts as an enzyme, known as a receptor-enzyme, with a protein kinase site on the cytoplasmic portion.
1.When a signaling molecule binds to the receptor, it activates the enzyme(tyronsine kinase)
2.ligand binds and activates TKTK phosphorylate proteins to activate them
3.the active proteins change cellular activity