Biology Forums - Study Force

When chromosomes fail to segregate properly, it can result in:
 
  A. sister chromatids that are no longer identical.
  B. gene conversion.
  C. aneuploidy.
  D. mating type conversion.
  E. recombination.

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Which of the following is a difference between the solenoid and zigzag models for the formation of the 30 nm filament?
 
  A. Most of the evidence to date supports the solenoid model, while the zigzag model is unlikely to occur in cells.
  B. Linker DNA is at the center of the filament in the zigzag model, and on the outside of the filament in the solenoid model.
  C. The solenoid model is a one-start helix and the zigzag model is a two-start helix.
  D. The helical pitch in the solenoid model is higher than the helical pitch in the zigzag model.
  E. The zigzag model occurs in higher eukaryotes such as humans, while the solenoid model occurs in lower eukaryotes such as yeast.

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Which of the following is true of the leucine-zipper structural motif?
 
  A. It contains several evenly spaced leucine residues that make specific DNA contacts.
  B. It is made up of a single alpha-helix.
  C. It is often used to mediate protein-protein interactions.
  D. It is only found in bacterial proteins.

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Which of the following is not a role for methylation?
 
  A. Methylation can protect bacterial RNA from restriction enzymes that are used to destroy viral DNA.
   B. Methylation of DNA can act as an inhibitor of gene expression.
   C. Methylation of DNA can enhance binding of certain proteins.
   D. Methylation is important in directing mismatch repair to repair the correct DNA strand.
   E. Methylation in eukaryotes can affect the formation of Z-DNA.

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Which of the following structural motifs found in transcriptional regulators is the least likely to require an inverted repeat for binding to DNA?
 
  A. helix-turn-helix
  B. homeodomain
  C. leucine zipper
  D. zinc finger

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