Molecular Biology

Step 1: Understanding blunt ends.
Blunt ends are formed when both strands of the DNA are cut at the same position, without any overhang.
Some restriction enzymes cut DNA to produce blunt ends.
Step 2: Identifying EcoRV.
EcoRV is a restriction enzyme that cuts DNA to produce blunt ends.
It cleaves the DNA at specific recognition sites without leaving overhanging bases.
Step 3: Reviewing other options.
HindIII: This enzyme cuts to produce sticky ends with overhangs.
SalI: This enzyme also creates sticky ends, not blunt ends.
XhoI: This is another enzyme that creates sticky ends.

Thus, the correct answer is (C) EcoRV.

Step 1: Understanding the charge of DNA.
DNA molecules carry a negative charge due to the phosphate groups present in the backbone of the DNA.
This negative charge is crucial for many of the processes in molecular biology, such as gel electrophoresis, where DNA moves towards the positive electrode.
Step 2: Reviewing other options.
Neutral: DNA is not neutral; it is negatively charged due to the phosphate group.
Positively charged: DNA is not positively charged.
Either positively or negatively charged depending on size: DNA is always negatively charged, irrespective of its size.

Thus, the correct answer is (A) Negatively charged.