1. Which type of chromosome has no p arms? A) Submetacentric B) Acrocentric C) M
ID: 21970 • Letter: 1
Question
1. Which type of chromosome has no p arms?A) Submetacentric
B) Acrocentric
C) Metacentric
D) Telocentric
2.
You have isolated DNA for PCR and accidentally added topoisomerase instead of polymerase to your sample. What would you expect if you ran this DNA sample on a gel?
A) The DNA would show decreased supercoiling and have a lower electrophoretic mobility.
B) The DNA would show increased supercoiling and have a higher electrophoretic mobility.
C) The DNA would show decreased supercoiling, but electrophoretic mobility will be unaffected.
D) The DNA would show decreased supercoiling and have a higher electrophoretic mobility.
E) The DNA would show increased supercoiling and have a lower electrophoretic mobility.
3.
Methylation of nucleosome N-terminal tails typically leads to which of the following?
A) Activation of topoisomerase.
B) Relaxed packaging of the chromatin and increased transcription.
C) Tighter packaging of the chromatin and reduced transcription.
D) Increased amounts of euchromatin relative to heterochromatin.
E) Removal of the protein components of the chromatin from the DNA.
4.
What is meant by the 'beads on a string' model of chromatin?
A) The beads are molecules of DNA polymerase that attach to the DNA string.
B) The beads are the histones, and the string is the transcriptionally active DNA loops.
C) The beads are ribosomes, and the string is the mRNA that has been transcribed from active chromatin.
D) The beads are the heterochromatic regions that are tightly compacted, and the strings are euchromatic regions that are being actively transcribed.
E) The beads are the nucleosomes, and the string is the linker DNA.
5.
Where are chromosomes located in a bacterial cell?
A) Cytoplasm
B) Nucleolus
C) Nucleoid
D) Nucleus
E) Mitochondria
Explanation / Answer
1.Correct answer is:D) Telocentric
Reason: All except telocentric chromosomes have p arms.
2.Correct answer is: A)The DNA would show decreased supercoiling and have a lower electrophoretic mobility.
Reason:Topoisomerase will unwind the DNA and thus reduced its mobility.
3.Correct answer is:C) Tighter packaging of the chromatin and reduced transcription.
Reason:Methylation of N terminal tails bind the DNA tightly and pack it into chramatin as a result of which DNA is not easily accessible for transcription factors and RNA polymerase to bind and initiate transcription.
4.Correct answer is:E) The beads are the nucleosomes, and the string is the linker DNA.
Reason: Nucleosomes are arranged in form of beads and they are joined by linker DNA.
5.Correct answer is:C) Nucleoid
Reason: Nucleus is absent in bacteria and therefore chromosomes are located in nucleoid.
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