Cell to cell communication -Cell Biology and Genetics- UPASS PDF

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Cell to cell review practice questions from UPass with answers...

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PIP2

Is a phospholipid in the plasma membrane that is cleaved to form two different second messengers IP3 Is a second messenger formed, along with DAG, when a phospholipid in the membrane is cleaved DAG Is a second messenger formed, along with IP3, when a phospholipid in the membrane is cleaved Camp Is a second messenger formed from ATP Cell signalling

When histamine binds to a histamine receptor, the specific cellular response that results is determined by the following factors:     

the type of histamine receptor the type of cell in which the receptor is located the enzyme that is activated by the G protein associated with the receptor the types of second messengers involved in the signal transduction pathway the proteins activated by the second messengers

Signaling molecules can trigger a multitude of cellular responses, which may ultimately affect the transcription of genes, the activity of proteins, or cell growth and division. The cleavage of glycogen by glycogen phosphorylase releases _____. Epinephrine acts as a signal molecule that attaches to _____ proteins

Glucose-1-phosphate

Which if these is activated by calcium ions?

Calmodulin, is a calcium-binding protien.

G-protein-linked receptor

Kinases are enzymes that phosphorylate other molecules. Tyrosine-kinase receptors consist of two polypeptides that join when activated by a signal molecule. Phospholipase C catalyzes the formation of IP3. Ion channels are found on both the plasma membrane and the endoplasmic reticulum

Calcium binds to calmodulin A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to _____ receptors.

G-protein-linked

Steroid hormones are chemical signaling molecules. Because they are usually small and hydrophobic, steroid hormones can readily pass through a cell’s plasma membrane. The receptors for steroid hormones are usually located in the cytoplasm of target cells.

Both G protein-coupled receptors and receptor tyrosine kinases are transmembrane receptors that have a binding domain located on the extracellular side of the plasma membrane. The binding of a signaling molecule to these receptors is the first step in a signaling pathway. However, what happens after a signaling molecule binds is different for each receptor. An activated G protein-coupled receptor activates a G protein inside the cell, which involves the release of GDP and the binding of GTP. The activated G protein then activates an associated enzyme, leading to a cellular response. Receptor tyrosine kinases form dimers after binding signaling molecules. The tyrosines are then phosphorylated, fully activating the receptor. Each phosphorylated tyrosine can bind a relay protein, each of which can trigger a transduction pathway. In this way, a single signaling-molecule binding event can trigger multiple signal transduction pathways and thus multiple cellular responses.

When histamine encounters a target cell, it binds extracellularly to the H1 receptor, causing a change in the shape of the receptor. This change in shape allows the G protein to bind to the H1 receptor, causing a GTP molecule to displace a GDP molecule and activating the G protein. The active G protein dissociates from the H1 receptor and binds to the enzyme phospholipase C, activating it. The

active phospholipase C triggers a cellular response. The G protein then functions as a GTPase and hydrolyzes the GTP to GDP. The G protein dissociates from the enzyme and is inactive again and

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