A phylogenetic tree is shown for the three domains of life (Eukarya, Archaea, and Bacteria). The tree branches in two directions from the first point, labeled Common ancestor of all life. One branch leads in the direction of Eukarya and Archaea, and the other branch leads to Bacteria. The branch leading to Eukarya and Archaea divide, one branch leading to each domain. The branch leading to Eukarya divides into four branches. One leads to Euglenozoans, and the other three lead to branching points. The first leads to Forams in one direction, and another branching point in the other that leads to Diatoms and Ciliates. The second branching point leads to Red algae in one direction, and a branching point that leads to green algae and land plants in the other direction. The third branching point leads to amoebas in one direction, and a branching point that leads to fungi and animals in the other direction. Land plants, Fungi and Animals are all highlighted.

Cyanobacteria were once called blue-green algae because they are photosynthetic. According to the phylogeny shown, the cyanobacteria are more closely related to gram-positive bacteria than to ________.

#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