32. Which of the following is TRUE about Apoptosis? It causes cell membranes to

Question

32. Which of the following is TRUE about Apoptosis?

It causes cell membranes to leak

It causes inflammation

It is considered a 'sloppy' process

It plays an important role in tumor suppression

33. Which of the following enzymes are central to the apoptotic process?

phosphatases

caspases

kinases

polymerases

34. All of the following are TRUE about caspases EXCEPT:

they cleave proteins at aspartate residues

they are only active in the intrinsic pathway

they exist as procaspases prior to activation

they can activate each other

Explanation / Answer

32) It plays an important role in tumor suppression.

Apoptosis suppression in cancer involves elusion of immune observation. Tumor cells can acquire resistance to apoptosis by the expression of anti-apoptotic proteins such as Bcl 2 or mutation of pro-apoptotic proteins such as Bax. The expression of both Bcl-2 and Bax is regulated by the p53 tumor suppressor gene. The ataxia telangiectasia-mutated gene (ATM) has involved in tumorigenesis via the ATM/p53 signaling pathway . The ATM gene encodes a protein kinase that acts as a tumor suppressor.

33) caspases   caspases are play important role in apoptosis. This is dependable with the major functions of the two protease families: execution of apoptosis for caspases and intracellular protein turnover within lysosomes for cathepsins. Caspases become visible to be a full-time work in apoptosis. They also play a central role in the execution phase of apoptosis, and the caspases (cysteine aspartate-specific proteases), a family of cysteine proteases, are of major importance and carrying out a range of cellular functions. The role of these enzymes in programmed cell death.

34) they are only active in the intrinsic pathway, because caspases active in both intrinsic and extrinsic pathway

Intrinsic apoptopic pathway: During times of cellular stress ,activated, initiator caspases such as Caspase 9 will cleave and activate other executioner caspases. This leads to degradation of cellular components for apoptosis and in extrinsic apoptopic pathway: The caspase cascade is also activated by extracellular ligands, via cell surface Death Receptors. This is done by the formation of a multiprotein Death Inducing Signalling Complex (DISC) that recruits and activates a pro-caspase, this activates the death domains at the cytoplasmic tail of the receptor. The adaptor protein FADD (Fas-Associated protein with Death Domain) will recruit (by DED or Death domain-Death domain interaction). The other end of the adaptor contains a DED domain for pro-caspase recruitment. This FasR, FADD and pro-Caspase 8 form DISC where Caspase-8 is activated.

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