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TLS Online TPP Program

#Question id: 12482

The Rb protein has been called the “master brake” of the cell cycle. How the Rb protein acts as a cell cycle brake?

#Unit 2. Cellular Organization
  1. Rb bound to E2F and function as transcriptional repressors because Rb recruits chromatin-modifying enzymes that promote deacetylation and methylation of specific histone lysines, causing chromatin to assume a condensed, transcriptionally inactive form.
  2. S phase CDKs and mitotic CDKs maintain Rb protein in the phosphorylated state throughout the S, G2, and early M phases.
  3. Rb bound to E2F and promotes ubiquitinylation of E2F and inhibits chromosomal segregation.
  4. Rb bound to E2F and promotes acetylation which prevents unloading of cohesins.
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TLS Online TPP Program

#Question id: 13196

#Unit 1. Molecules and their Interaction Relevant to Biology

 In The Mica Experiment Dnase I enzyme cleaves 
TLS Online TPP Program

#Question id: 13195

#Unit 1. Molecules and their Interaction Relevant to Biology

Who contributes to the stability of DNA helix structure?
A. Hydrogen bonding between bases
B. Hydrogen bonding between water and bases
C. Scattering interactions between bases
D. Stacking interactions between bases
CORRECT combination is
TLS Online TPP Program

#Question id: 13194

#Unit 1. Molecules and their Interaction Relevant to Biology

If we have the sequence 5’-ATGTC-3’ on one chain, the opposite chain must have the complementary sequence 
TLS Online TPP Program

#Question id: 13193

#Unit 1. Molecules and their Interaction Relevant to Biology

Data, collected from DNAs of a great many different species, led Chargaff to the following conclusions:
A. The base composition of DNA generally varies from one species to another.
B. DNA specimens isolated from different tissues of the same species have the different base composition.
C. The base composition of DNA in a given species changes with an organism’s age, nutritional state, or changing environment.
D. In all cellular DNAs, the sum of the purine residues equals the sum of the pyrimidine residues.
Which of the above statements are INCORRECT regarding Chargaff’s rule?
TLS Online TPP Program

#Question id: 10476

#Unit 1. Molecules and their Interaction Relevant to Biology

Following statements are regarding to gangliosides.

A. They are ceramides with attached oligosaccharides that include at least one sialic acid residue.

B. They are ceramides with attached oligosaccharides that include at least one phasphatidic acid residue.

C. Sialic acid gives gangliosides the negative charge at pH 7 that distinguishes them from globosides.

D. Gangliosides are primarily components of cell-surface membranes and constitute a significant fraction (6%) of brain lipids.

Which of the following combination is correct?
TLS Online TPP Program

#Question id: 10475

#Unit 1. Molecules and their Interaction Relevant to Biology

During the formation of a blood plasma protein The aromatic ring of vitamin K undergoes: