Knockout mice have been genetically altered to knock out specific genes. How are these mice most often used in research?
A) to study DNA replication in the defective genes (those that have been altered)
B) to determine the role of proteins coded for by those genes that are knocked out
C) to examine defects in DNA structure in those regions that have been altered
D) to study the effect of radiation on DNA
Answer: B
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Which of the following is not a step in bacterial nucleotide excision repair (NER)?
A. The UvrA2UvrB complex creates a single-stranded bubble at the damage site to which UvrA subunits are tightly bound and the UvrB subunit dissociates. B. The UvrA2UvrB complex scanned the DNA for damage. C. Pol I fills the gap created by the removal of the damaged strand and the DNA is sealed by ligase. D. UvrC (exinuclease) nicks the damaged strand on one side of the damage randomly. E. UvrD (helicase) unwinds and releases the damaged strand.
The photosynthetic activity of cyanobacteria takes place in their:
A. thylakoids B. mitochondria C. pili D. vesicles E. vibrios
Examples of isotopes include:a
oxygen 8 and oxygen 16. b. carbon 12 and nitrogen 14. c. hydrogen 1 and helium 1. d. sodium 23 and potassium 23. e. carbon 12 and carbon 14.
What is meant by the "directionality" of the strands of a DNA molecule? Explain how this
directionality is ultimately responsible for Okazaki fragments. What will be an ideal response?