Question

Some survival factors activate receptor tyrosine kinases upstream of the PI-3-kinase-Akt pathway. How does this pathway promote cell survival? Akt phosphorylates and inactivates an inhibitor of Tor. Akt phosphorylates and activates the antiapoptotic protein Bcl. Akt phosphorylates and inactivates the pro-apoptotic proteins Bax/Bak. O Akt phosphorylates and inhibits the Bcl2 inhibitor Bad.

Answer 1

ANSWER::

1..Akt phosphorylates and inhibit the Bcl2 inhibitor Bad

2..more than three

Explanation::

(1)PI-3 kinase pathway catalyses the formation of PI 3,4,5 triphosphate which acts as a docking site for various signal proteins such as AKt/PKB.

The Akt/PKB signaling pathways is one of the most critical pathways in regulation of cell survival. - The activation of Akt pathways normally provides the cells a signal for survival) through apoptotic stimulus , → AKT| PKB has direct effects on the apoptotic pathways which means this pathway promotes growth factor mediated cell survival and block the apoptosis As we know, apoptotis is a programm cell death In which damage call, mutated cells are destroyed by apoptotic factor such as Bid, Bad, Bik , bare etc. The proapoptotic factor helps in apoptosis and antiapoptotic factor helps in inhibiting apoptosis. → Antiapoptotic factors are Bcl-2. Bcl- XL etc. which inhibits apoptosis & helps in cell suviral. » The Akt | PKB pathways after Akt phospho- _rylation it directly inhibits the proapoptotic Bel-2 nelated protein Bad Bad is a member of BC-2 that binds to Bel-2 or Bel-A and inhibit anti- apoptotic potential > Bcl-2 family of proteine

But when BAD is phosphorylated on serine 136 by AKTIPKo it looses its proapototic activity and directs the cell survival. which means & phosphorylated BAD inhibits apoptosis.
(2) Mutation is sudden heritable changes which causes cancers.

Cancer is an uncontrolled cell growth which are caused due to distruption of cell cycle ....means normally cell cycle regulates by growth factor which inhibits the growth of damage ,mutated cells .and if it fails it results into cancer...

Normally it is supposed that 1to 10 mutation results into cancer but 2 mutation only causes uncontrolled , proliferation of cell which means it becomes tumor but more than 3 mutation results into metastasis ,malignant cancer.

Cancer are caused by mutation in protoncogene and tumor suppressor gene.In protoncogene mutation is causes cancer when it gains it's function and tumor suppressor gene causes cancer when loss of function mutation occur.Oncogene one mutation is for initiation of cancer ..but normal cell require more than three mutation for turning normal to cancer cells.