Identify the statements which hold true for DNA in E. coli
A. DNA is organised in nucleoid region
B. The length of E. coli DNA is 1.36 metres
C. DNA is not scattered throughout the cell
D. DNA is organised in large loops.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A, C and D only
A. DNA is organised in nucleoid region — Correct. The DNA is held in a region called the nucleoid, as E. coli has no defined nucleus.
B. The length of E. coli DNA is 1.36 metres — Incorrect. NCERT gives 1.36 mm; 1.36 metres would be a thousand times too long.
C. DNA is not scattered throughout the cell — Correct. The negatively charged DNA is held together with positively charged proteins.
D. DNA is organised in large loops. — Correct. In the nucleoid the DNA is held with proteins as large loops.
NCERT Extract:
Packaging of DNA Helix – “… In prokaryotes, such as, E. coli, though they do not have a defined nucleus, the DNA is not scattered throughout the cell. DNA (being negatively charged) is held with some proteins (that have positive charges) in a region termed as ‘nucleoid’. The DNA in nucleoid is organised in large loops held by proteins.”