TAMU BIOL 213 - Cell Communication Part 1 (6 pages)

Previewing pages 1, 2 of 6 page document View the full content.
View Full Document

Cell Communication Part 1



Previewing pages 1, 2 of actual document.

View the full content.
View Full Document
View Full Document

Cell Communication Part 1

262 views


Lecture number:
22
Pages:
6
Type:
Lecture Note
School:
Texas A&M University
Course:
Biol 213 - Molecular Cell Biol
Edition:
1
Unformatted text preview:

BIOL 213 1st Edition Lecture 22 Outline of Last Lecture I Cytoskeleton II Intermediate filaments a Structure b Main functions c Two main different kinds i Cytoplasmic and nuclear lamins III Microtubules a Structure i Made of tubulin b Formed from centrosomes c Dynamic instability d Intracellular transport i Motor proteins dynein and kenisin e Mitosis IV Actin filaments a Structure b Growth occurs at both ends c Interaction with myosin to cause muscle contraction These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Outline of Current Lecture I Signal transduction a 5 different kinds of signaling II Response to signaling III Intracellular receptors a Ex nitric oxide and steroid hormones IV Cell surface receptors a 3 main kinds i Ion channels G protein coupled receptors enzyme linked receptors b Molecular switches Current Lecture I Signal transduction a This is the process of converting one form of signal into another b Signal molecules i These can be a lot of different things proteins peptides amino acids steroid hormones fatty acids sugars inorganic compounds gases c Different molecules can mimic or inhibit the signal i Agonist 1 Activates the pathway 2 They mimic the signal ii Antagonist 1 Blocks the pathway 2 They inhibit the signal d These signal molecules bind to receptor proteins to trigger a response e 5 different kinds of signaling i Endocrine 1 The signals travel through the blood all over the body ii Paracrine 1 These signals are released by one cell or a small group of cells and only affect the cells within the immediate vicinity iii Neuronal 1 Neurotransmitters are released by a neuron 2 The target cell is usually a muscle cell or another neuron iv Contact 1 The signal never leaves the signaling cell 2 It s on the surface of the signaling cell and the target cell has to be in direct contact with the signaling cell to get the message 3 The target cell membrane bound receptor has to bind to the signaling cell membrane bound signal v Autocrine 1 This is a specific form of paracrine 2 The signals released also affect the signaling cell 3 This is useful when the cells need to count themselves a A diffusible factor is released by a growing group of cells b The amount of factor represents the number of cells c When the cells detect enough of the signal factor they know that there are enough cells so they stop dividing II Response to signaling a In order to respond to a signal a cell has to have a specific receptor b Cell surface receptors i These are proteins on the surface of the cell that the signal molecule has to bind to 1 This binding will then be translated into a response on the inside of the cell ii The binding of a signal molecule causes movement of the transmembrane domains which initiates the cell s response 1 They can move apart from each other sometimes no more than the distance of the diameter of a hydrogen atom 2 They can shift in opposite directions relative to each other 3 They can cross c Intracellular receptors i The signal molecule actually diffuses across the cell membrane and into the cell to trigger a response 1 Signal molecules are small and hydrophobic so that they can diffuse across the membrane 2 Ex steroid hormones and gas ii Sometimes the signal molecule directly interacts with an enzyme iii Sometimes it binds to intracellular receptors d Can alter protein function or alter protein synthesis III IV i Altering protein function is fast ii Altering protein synthesis is slow 1 The cell has to go through the whole process of transcription and translation iii These both alter the cytoplasmic machinery which changes the cell s behavior e One signal can initiate several different cellular processes i Ex on signal can initiate a pathway that activates metabolic enzymes gene regulatory proteins and cytoskeletal proteins f One signal can initiate different processes in different cells i Ex the signal molecule acetylcholine ii It relaxes heart muscle cells iii It causes the release of amylase in salivary gland cells iv It causes contraction in skeletal muscle cells g Sometimes several signal molecules are needed to initiate one cellular response i If a cell doesn t receive all the necessary signals it usually goes through apoptosis because it means there s something wrong Intracellular receptors a Sometimes the signal molecule directly interacts with an enzyme i This provides a rapid response of only a few seconds to a few minutes ii Ex nitric oxide NO a gas and cGMP signaling to dilate blood vessels and relax heart muscles 1 Acetylcholine binds to a receptor in an endothelial cell membrane 2 This triggers the opening of an ion channel to let Ca2 flow into the cell 3 This activates nitric oxide synthase which turns the amino acid arginine into NO 4 NO binds to and activates the enzyme guanylyl cyclase 5 This enzyme turns GTP into cyclic GMP cGMP a small intracellular signal molecule 6 cGMP ultimately causes the muscle cells to relax b Sometimes it binds to intracellular receptors i These are usually involved in transcriptional regulation ii The receptor in the cytosol or nucleus is inactive until the signal binds to it iii Ex steroid hormones 1 These diffuse through the plasma membrane because they are small and hydrophobic and bind to an intracellular receptor 2 The receptor is activated when the steroid is bonded to it and can diffuse through the nuclear membrane to act as a transcription regulator Cell surface receptors a 3 basic types i Ion channel linked receptor 1 An open channel can let in thousands of ions which leads to amplification 2 These are seen in nerve terminals 3 These are a huge component of action potential ii G protein coupled receptors 1 The receptor protein is activated by the signal 2 This activates the G protein which will activate an enzyme to initiate the response iii Enzyme linked receptors 1 The receptor acts as an enzyme or directly activates an enzyme b Molecular switches i Involved in enzyme linked and G protein coupled receptors ii Molecular switches are protein receptors that are turned on and off by signal molecules iii Signaling by phosphorylation 1 A protein kinase phosphorylates the switch using the phosphate group of an ATP to activate it 2 A protein phosphatase clips off the phosphate group to inactivate the switch 3 The activity of the switch receptor depends on the balance of the activities of the protein kinase and


View Full Document

Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view Cell Communication Part 1 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Cell Communication Part 1 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?