Question

Which of the statement is true?

If a double-stranded DNA molecule of 125 million base pairs were scaled to the size of a human hair, it would have a diameter of 0.003 inches and be 1 mile long. If this scaled-up DNA molecule were condensed and compacted into a chromosome, into which of the objects below could that chromosome fit?

A. a tennis ball

B. a bathtub

C. a pencil eraser

D. a soda (pop) can

E. a basketball

Answer 1

ANSWER: Option A is correct

EXPLANATION: As by visualizing the answer provided here we have to apply our general thinking. We know that the nucleotide sequences present inside the DNA which contains the information. This whole structure is present inside the nucleus.

generally we call Nucleus as brain of cell because all the genetic information is present inside this nucleus. By seeing the structure of any plant or animal cell we see a circular double membrane bounded structure(in eukaryotes) condensed structure of chromosome is found packed inside the nucleus. As the nucleus can be visualized(by microscope) as a circular structure which is very thick so we can compair it with tennis ball.

Steps in DNA coiling:

Protein(histone) + DNA= NUCLEOSOME(long thread)--- condense further form--- chromatin thread(microscopelly clearly visualized  at interphase stage during cell cycle )--------condense further and form----chromosome(visualized in metaphase )....... further it is packed inside the nucleus in telophase stage as nuclear membrane is reappeared (earlier the nuclear membrane disappear during late prophase after formation of chromosome) ---- so it appear as a round tennis ball like structure..