8 - Growth Factors and Signal Transduction Flashcards
How do growth factors affect cell division?
(proliferation) accelerates it = cell grows more aggressively
What are the 4 cell responses to signals? Which cells will respond to certain signals?
(SDDD) survive | differentiate | divide | die | only cells with the receptor of that signal
What is hypertrophy?
cells growing in size
What is the difference between cell growth and cell proliferation?
growth = increase size | proliferation = increase numbers/copies (multiply)
How can a cell grow independently?
allows access to a growth hormone that will activate division machinery
What is prolong ligand-induced signaling?
decrease degradation of pathway proteins, turn off negative regulators
What are the 5 ways a cell can achieve extrinsic factor (outside cell signaling) independence?
prolong ligand-induced signaling | increase sensitivity (respond to lower ligand levels) | express new receptors | signal in absence of ligand (induce mutations) | make own growth factors
Why would a tumor cell want to be independent of extrinsic factors?
the signal stimulation is not permanent = need more of it | signals are not always present = need to wait for it to come
What are autocrine loops and paracrine loops? Which ones do tumor cells most use?
autocrine (most used by tumors) = secrete own growth factors and stimulate self | paracrine = stimulate other cells, help others grow
What are cytokines?
proteins and peptides used as signaling compounds
What type of signal are tumor growth factors?
cytokines
What cellular responses do cytokines induce?
protein modification and gene activation
What is HER-ceptin?
targets breast cancer cells that express HER proteins via a signaling network
What enables a ligand-receptor interaction to give rise to multiple cellular responses/effects?
amplification in signaling pathway | a signal in the pathway will hit different types of proteins»_space;> different cellular effects/responses
What is phosphorylation of a protein?
adding a phosphate onto a protein = protein undergoes conformational change = either turns it on or off
On which 3 amino acids will a protein be phosphorylated?
tyrosine, serine, threonine
What enzyme adds a phosphate from ATP onto protein?
kinase
What enzyme takes a phosphate from a phosphorylated protein?
phosphatase = dephosphorylate
How does phosphorylation of a protein change the interaction within the amino acids of a protein?
phosphate = highly negative = can cause major repulsion = can open up active sites
What effect does the signaling pathway have on tumor suppressors or proto-oncogenes?
can activate or deactivate them
What is the effect of a mutation in the p53 gene?
it is unable to activate genes that encode for the protein needed to stall cell division = this protein is not made = cell division not stalled
What type of gene (tumor suppressor or proto-oncogene) is the Ras gene?
proto-oncogene
What is the effect of a mutation in the Ras gene?
it will send out growth signals in the cell on its own without a signal stimulating receptor = cell replicates excessively
What are the 6 types of proteins encoded by proto-oncogenes?
growth factors and its receptors | protein kinases and those that activate it | cell cycle proteins | apoptotic proteins | transcription factors
