TLS Online TPP Program

#Question id: 7154


Cancer is believed to often arise from stem cells, rather than fully differentiated cells. Which of the following are consistent with this view?

#Unit 4. Cell Communication and Cell Signaling
  1. Stem cells are actively dividing and express few differentiated functions, so they may have fewer changes to undergo than do fully differentiated cells in becoming cancer cells.
  2. DNA replication is necessary for mutations to occur, and stem cells are replicating their DNA whereas differentiated cells are for the most part not replicating their DNA.
  3. Teratocarcinomas are tumors that arise from germ cells or embryonic stem (ES) cells, under certain circumstances, demonstrating that tumors can arise from stem cells without further mutation.
  4. All of the above are reasons that cancer cells may more readily arise from stem cells than from fully differentiated cells.
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TLS Online TPP Program

#Question id: 68

#Unit 1. Molecules and their Interaction Relevant to Biology

Match the following functional groups given in column I with their respective representatives given in column II.

COLUMN I               COLUMN II

1. Anhydride               a. RCOOR

2. Ether                       b. ROCOCH3

3. Acetyl                     c. ROR

4. Amido                     d. RCOOCOR

5. Ester                        e. RCONH2

TLS Online TPP Program

#Question id: 73

#Unit 1. Molecules and their Interaction Relevant to Biology

Match the Variation of Reaction Spontaneity (Sign of ΔG) given in Column I with the Signs of ΔH and ΔS given in column II.

COLUMN I

COLUMN II

 

 

 

  ΔH

ΔS

ΔG = ΔH – TΔS

1.

+

a. The reaction is both enthalpically and entropically opposed. It is nonspontaneous (endergonic) at all temperatures.

2.

 −

− 

b. The reaction is enthalpically opposed (endothermic) but entropically favored. It is spontaneous only at temperatures above T = ΔH/ΔS.

3.

+

+

c. The reaction is enthalpically favored but entropically opposed. It is spontaneous only at temperatures below T = ΔH/ΔS.

4.

+

d. The reaction is both enthalpically favored (exothermic) and entropically favored. It is spontaneous (exergonic) at all temperatures.

TLS Online TPP Program

#Question id: 674

#Unit 1. Molecules and their Interaction Relevant to Biology

Proline is not often found in a-helices of proteins because it

TLS Online TPP Program

#Question id: 1520

#Unit 1. Molecules and their Interaction Relevant to Biology

Following statements are regarding to enzymatic processing of benzo(a)pyrene to a more potent mutagen and carcinogen.

A. Liver enzymes, particularly P-450 enzymes, modify benzo(a)pyrene in a series of reactions, producing 7,8-diol-9,10-epoxide, a highly potent mutagenic species that reacts with DNA primarily at the N2 atom of a guanine base.

B. The adduct, (+)-trans-anti-B(a)P-N2-dG, causes polymerase to insert an A rather than a C opposite the modified G base. Next time the DNA is replicated, a T will be inserted opposite the A, and the mutation will be complete.

C. Potent mutagen majorly causes conversion of guanine (G) to thymine (T) bases, a transition mutation.

D. When this potent mutagen applied to cultured bronchial epithelial cells, activated benzo(a)pyrene induces many mutations, including activating mutations at codons 175, 248, and 273 of the p53 gene.

Which of the following statements are correct?

TLS Online TPP Program

#Question id: 835

#Unit 1. Molecules and their Interaction Relevant to Biology

The minor clefts and gullies on the sides of the funnel that will be false energy minima, it represents,

TLS Online TPP Program

#Question id: 837

#Unit 1. Molecules and their Interaction Relevant to Biology

Increasing order of free energy in unfolded to folded conformation of the proteins, the correct order is,