Question

regarding genetics. can someone help and explain WHY the answer is chosen for the question

18. What is the purpose of using a blender in the Hershey & Chase experiment to identify the identity of genetic material? A) Break the conjugation bridge B) Lyse the infected cells C) Displace the bacteriophage material that has not been injected into the bacterial cell D) Resuspend all the cells and particles that have fallen to the bottom of the culture E) Displace dsDNA that is attached to the surface of competent cells 19. Bacteriophage P1 normally packages 2 of DNA in its capsid. Which of the following markers are most likely to be co-transduced? A) Two markers 0.2 minutes apart B) Two markers 0.5 minutes apart C) Two markers 2 minutes apart D) Two markers 5 minutes apart E) All markers will be equally likely to be co-transduced 20. Which of the following is not part of the genome of a biological entity? A) Circular double stranded DNA chromosome of a bacterial cell B) Linear double-stranded DNA chromosome of a eukaryotic cell C) Circular double-stranded F plasmid DNA D) single stranded chromosome of a virus E) single stranded RNA of a eukaryotic cell 21. What did the results of the Dnase I experiment with chromatin isolated from rat nuclei indicated regarding nucleosomes in eukaryotes (circle all that apply)? A) Nucleosomes only cover the centromere and telomere regions of a chromosome B) A nucleosome contains about 200 bp of DNA C) Nucleosomes form on both RNA and DNA D) Nucleosomes are distributed evenly along the DNA of the chromosomes E) Nucleosomes only form on negatively supercoiled DNA 22. Which of the following will result in transformation of a strain of S. pneumoniae to IS? (circle all that apply) A) Addition of a DNA extract from IIIS cells to competent IR cells B) Addition of a DNA extract from III cells plus DNase to competent IR cells C) Addition of a DNA extract from IIIS cells plus RNase to competent IIR cells D) Addition of a DNA extract from IIS cells plus protease to competent IIR cells E) Addition of heat-killed Ils cells to competent IR cells 23. Which of the following will produce negatively supercoiled DNA? (circle all that apply) A) DNA topoisomerase I added to double stranded DNA B) DNA topoisomerase Il added to double stranded DNA C) double-stranded DNA with 7 base-pairs pertum D) double-stranded DNA with 10 base-pairs pertum E) double-stranded DNA with 13 base-pairs per turn

Answer 1

You have asked multiple questions here. As per Chegg Q&A Guidelines, I am answering the first question i.e. Question 18.

Hershey and Chase's experiment was the experiment that was used to identify the nature of the genetic material as to whether it is DNA or protein.

For the purpose, phages were cultured in either radioactive phosphorous or sulfur medium. Phosphorous was incorporated into DNA while sulfur was incorporated into protein. The phages were then allowed to infect the host cell.

This was then followed by separating the bacteriophages from the bacterial cells that they were infecting. The pelleted cells were then checked for the radioactivity of phosphorous and sulfur.

Hence, the correct answer is C.