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TLS Online TPP Program

#Question id: 27628

Choose the incorrect statement of the following

#Unit 1. Molecules and their Interaction Relevant to Biology
  1. Right-handed helical conformation has 3.6 residues per turn with height of 5.4A
  2. The diameter of a typical α helix is about 22 Å, which matches the 22 Å wide and 6–8 Å deep minor groove of B-form DNA

  3. If the α helix lies parallel to the direction of the major groove, the straight α helix can contact 4–6 bp before the bases curve out of the plane of the amino acids in the α helix.

  4. The α helices have rotation of 100 degree per amino acid

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TLS Online TPP Program

#Question id: 33477

#Unit 2. Cellular Organization

Finding: Ancestry have similar organizations with conservation of the positions (of at least some) of the introns.

Example: The globin and DHFR genes are examples of a genes that share a common ancestor
TLS Online TPP Program

#Question id: 33478

#Unit 2. Cellular Organization

Find true and false statements
A. Comparisons of related genes in different species show that the sequences of the corresponding exons are usually conserved
B. when two genes are related, the relationship between their exons is closer than the relationship between their introns.
C. The sequences of the introns are much less similar.
D. Introns evolve much more rapidly than exons because of the lack of selective pressure to produce a polypeptide with a useful sequence.
TLS Online TPP Program

#Question id: 33479

#Unit 2. Cellular Organization
TLS Online TPP Program

#Question id: 33480

#Unit 2. Cellular Organization

Finding: The overall degree of divergence between two homologous exons in related genes corresponds to the differences between the polypeptides.

Reason: Overall degree of divergence between two homologous exons is mostly a result of base substitutions.
TLS Online TPP Program

#Question id: 33481

#Unit 2. Cellular Organization

A. In homologous introns, the pattern of divergence involves both changes in length.
B. Divergence in introns is due to deletions and insertions and base substitutions. 
C. Introns are slowly evolve while exons much more rapidly 
D. When a gene is compared among different species, there are instances where its exons are homologous but its introns have diverged so much that very little homology is retained.
TLS Online TPP Program

#Question id: 33482

#Unit 2. Cellular Organization

Find true and false statements
A. In general, mutations occur at the same rate in both exons and introns, 
B. Exon mutations are eliminated more effectively by selection.
C. Introns may more freely accumulate point substitutions and other changes.