CPPS 325 FINAL EXAM QUESTIONS WITH CORRECT ANSWERS

CPPS325 FINALEXAM QUESTIONSWITH v v v v v




CORRECT ANSWERS 2025 v v v




What are the 5 well-known enzyme-linked cell surface receptors? - CORRECT ANSWER -
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1. Receptor Guanylyl Cyclase: produces cGMP v v v v




2. RTK: phosphorylate tyrosine residues leading to association of signalling molecules and cascade
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3. TK Associated Receptors: associate with proteins having TK activity
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4. Receptor Tyrosine Phosphates: Removes phosphate on tyrosine residues v v v v v v v




5. Receptor Serine/Threonine Kinases: phosphorylate specific Serine/Threonine residues on IC signallin g
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molecules
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How are RTK and TK Associated Receptors different? - CORRECT ANSWER -
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RTK phosphorylate tyrosine while associated receptors bind/find proteins with TK activity to initiate th e
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cascade of signalling.
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What is the reciprocal of RTK? - CORRECT ANSWER -
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Receptor Tyrosine Phosphatases. They take the phosphate off the tyrosine residues to inactivate signalli ng
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cascades.
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Ex. Transforming GF Beta superfamily of receptors, cell type dependent.
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What is the major mechanism for receptor signal transduction? - CORRECT ANSWER -
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Tyrosine kinase phosphorylation
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RTK vs. Serine/Threonine Phosphorylation ? - CORRECT ANSWERV-
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Tyrosine phosphorylation is rare (1%) relative to serine/threonine residue phosphorylation. Tyrosine ph
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osphorylation is the major mechanism of receptor signal transduction.
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What is the net effect of activated TKs? - CORRECT ANSWER -
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Tyrosine phosphorylation on target proteins.
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What do TK pathways mediate? - CORRECT ANSWERV-
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Cell growth (growth factors), differentiation, host defense, metabolic regulation, cell survival pathways (survival
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factors).
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What are amplifiers of the TK pathways? - CORRECT ANSWERV-PI3-K -> PIP3
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PLC -> DAG and InsP3&Ca2+
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What are RTK mediated actions in the cell? - CORRECT ANSWER -
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regulation of cell proliferation, differentiation, and cell motility, promotion of cell survival and modulat ion
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of cellular metabolism.
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TKs exist in either the cytosol or as transmembrane receptors, what are the differences in the two types
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? - CORRECT ANSWER -Cytosol receptors have an src N- terminal
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region. Cytosol has no membrane spanning domain.
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TM receptor has a single membrane spanning hydrophobic TM domain. Ex) Epidermal GF RTK. What is
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v src? - CORRECT ANSWER -Src is a non-
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, receptor TK, so it does not span a membrane. It is a tyrosine kinase. And although it is cytoplasmic T K
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it can still bind to activated RTKs.
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What is contact inhibition confluency? - CORRECT ANSWER -
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Stops Src domains signalling and therefore cells stop dividing.
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If there is an issue then cancer can result and mutation causes an inhibition of the stop signal so the ce lls
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keep growing and dividing.
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What are SH domains? - CORRECT ANSWER -
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Src homology domains. Src and other proteins that have src-
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homology domains can bing to activated RTKs.
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What are the different SH domains in proteins? - CORRECT ANSWER - There
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are SH1, SH2 and SH3 domains.
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What isSH1 domain characterized by? - CORRECT ANSWER -
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Catalytic domain of a protein, for example the receptor. and it has the kinase activity. It is responsible for
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phosphorylating tyrosine residues.
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What is SH2 domain characterized by? - CORRECT ANSWERV-
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Binds peptides with consensus (positional information on C- terminal
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side of the phosphorylated tyrosine).
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Very specific. v




Mediates protein- v




protein interactions in cellular signalling cascades. Very common in proteins outside the src family.
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What do SH2 and SH3 domains have as a common funciton? - CORRECT ANSWERV- They
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mediate protein-protein interactions in cellular signalling cascades.
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Very common in proteins outside the src family.
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What is SH3 domain characterized by? - CORRECT ANSWERV-Interacts with proline- rich
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peptide targets (minimal consensus). Mediate protien-
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protein interatctions in the cellular signalling cascade. Very common in proteins outside the src family.
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What are PTB domains? - CORRECT ANSWERV-(Phosphotyrosine binding domain)
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Bind to phosphorylated tyrosine. Functional equivalent of the SH2 domain, except for the positional inf
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vormational. Is not the C-terminus like SH2, but the N-terminus side of the phosphorylated tyrosine.
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shc is a PTB protein.
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What is the normal action that stops signalling for cell division in the src pathway? -
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CORRECT ANSWER -Contact Inhibition Confluency
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How do PTB and SH2 domains differ? - CORRECT ANSWERV- SH2
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domains binds consensus on the C-terminus.
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PTB domains binds the N-terminus. They
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both mediate cellular signalling.
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What is shc? - CORRECT ANSWER -PTB protein that docks at the N- terminus
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consensus docking site.
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