1. The three stages of the cell communication?
2. What are the roles of protein kinases and phosphorylation in signal amplification?
3. What are the membrane receptors?
1. a) Reception : this is the first stage. outside of the cell to inside of the cell. receptor is in the membrane, taking in the signal molecules. the signal molecules are mostly water soluble. they are too large to travel thru membranes, they so uses receptors to get in the cell. receptor molecules are made of protein. they are flexible, depending on the signal molecule.
b) Signal Transduction : when the signal molecule moves to cytoplasm from the receptor. there is phosphorylation during this pathway. uses protein kinases which are enzymes that transfers phosphate groups from ATP to a protein.
c) Response : the signals coming from cytoplasm go to the nucleus. proteins turn specific genes on and off.
2. Protein kinases and phosphorylation in signal amplification :
A protein kinase is a kinase enzyme that modifies other proteins by chemically addingphosphate groups to them (phosphorylation). Phosphorylation usually results in a functional change of the target protein (substrate) by changing enzyme activity, cellular location, or association with other proteins. Up to 30% of all human proteins may be modified by kinase activity, and kinases are known to regulate the majority of cellular pathways, especially those involved in signal transduction.Tyrosine-specific protein kinases phosphorylate tyrosine amino acid residues, and like serine/threonine-specific kinases are used in signal transduction.
3. There are three membrane receptors. G Protein -Coupled Receptors, Receptor Tyrosine Kinases, and Ion Channel Receptors. These are located in the plasma membrane.
Video on cell communication :
Some facts about cell communication/signaling :
. Many signal transduction pathways include phosphorylation cascades, in which a series of protein kinases each add a phosphate group to the next one in line, activating it.
. Apoptosis, is a type of programmed cell death.
. Intracellular signals are the proteins in the nucleus or in the cytoplasm that can pass thru the membrane without the help of a receptors. ex. hormones.
. Reception may occur by direct contact, or by indirect contact.
. Two results, cytoplasmic regulation, or transcription regulation in the nucleus.
This chapter is about cell communication/ signaling. Cells communicate in order to respond to the environment, and to regulate themselves. Cells need to control cellular processes by signaling. There are three stages and each stage has its own work, and helpers such as enzymes, receptors, signals etc. There are two types of cellular responses, cytoplasmic regulation, and transcription regulation in the nucleus. It can cause a rearrangement of the cytoskeleton, or activation of new protein synthesis.
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