Following statements are regarding to the apoptosis which is induced by trophic factors.

A. The presence of specific trophic factors (e.g., NGF) leads to activation of their cognate receptor tyrosine kinases (e.g., TrkA) and activation of the PKB pathway.

B. DNA damage or ultraviolet irradiation leads to induction of synthesis of the BH3-only Puma protein. Puma binds to Bak and Bax as well as to Bcl-2, allowing Bak and Bax to form oligomeric pores.

C. Removal of a cell from its substratum disrupts integrin signaling, leading to release of the BH3-only Bim protein from the cytoskeleton.

D. Binding of extracellular death signals, such as tumor necrosis factor and Fas ligand, to their receptors oligomerizes an associated protein (FADD), which in turn triggers the caspase cascade, leading to cell murder by apoptosis.

Which of the following pathway does not belong to the trophic factor inducing apoptotic pathway?

#Question id: 4272

#Unit 3. Fundamental Processes

There are two classes of release factors for translation termination. Choose correct statements

A. Class I release factors recognize the stop codons and trigger hydrolysis of the peptide chain from the tRNA in the P-site.

B. Prokaryotes have two class I release factors called RF1 and RF2. RF1 recognizes the stop codon UGA, UAA and RF2 recognizes the stop codon UAG and UAA.

C. In eukaryotic cells, there is a single class I release factor called eRF1 that recognizes all three stop codons.

D. Class II release factors stimulate the dissociation of the ribosome after release of the polypeptide chain.

#Question id: 4273

#Unit 3. Fundamental Processes

80S initiation complex includes

#Question id: 4274

#Unit 3. Fundamental Processes

One mechanism that contributes to the fidelity of codon recognition involves the 16S rRNA other than initiation. Which of the following statements are correct in this phenomenon?

A. Codon recognition involves two adjacent uracil residues in the 16S rRNA component

B. The adjacent residues in the 16S rRNA do not discriminate between G:C or A:U base pairs and recognize either as correct

C. Even a single mismatch in the codon–anticodon base pairing alters the position of EF-Tu, reducing its ability to interact with the factor-binding center 16s rRNA, leads to a dramatic reduction in EF-Tu GTPase activity

D. Pyrophasphatic editing is key mechanism to ensure fidelity

#Question id: 4275

#Unit 3. Fundamental Processes

CCA-adding enzymes add a specific sequence without a template because

#Question id: 4276

#Unit 3. Fundamental Processes

Which of the following post-translational modifications of proteins occur(s) in the lumen of the endoplasmic reticulum?

a. glycosylation                       b. formation of disulfide bonds

c. conformational folding and formation of quaternary structure

d. proteolytic cleavage                        e. aldol condensation of sugars

#Question id: 4277

#Unit 3. Fundamental Processes

N-linked oligosaccharides in glycoproteins