If a DNA double helix is gradually heated, which bonds in the molecule will break first (are the weakest)?
A. bonds between the nitrogenous bases
B. bonds between the bases and the sugars
C. bonds between the sugar and phosphate within a nucleotide
D. bonds between the sugar and phosphate of adjacent nucleotides
i feel like this is A but i just want to make sure.
its a. I checked
When does DNA replication happen?
A. during the G1 phase of the cell cycle
B. during the S phase of the cell cycle
C. during the G2 phase of the cell cycle
D. during the mitotic phase of the cell cycle
When does DNA replication happen?
A. during the G1 phase of the cell cycle
B. during the S phase of the cell cycle
C. during the G2 phase of the cell cycle
D. during the mitotic phase of the cell cycle
The answer is A.
To determine which bonds in a DNA double helix will break first when gradually heated, you need to consider the structure of DNA and the types of bonds involved.
The DNA molecule consists of two strands that are connected by hydrogen bonds between the nitrogenous bases. The four nitrogenous bases found in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). There are two types of base pairs: adenine always pairs with thymine (A-T), and cytosine always pairs with guanine (C-G).
Considering the options:
A. Bonds between the nitrogenous bases: These are hydrogen bonds, which are relatively weak compared to other types of chemical bonds. When DNA is heated, these bonds can break and separate the two strands.
B. Bonds between the bases and the sugars: These bonds form covalent bonds called glycosidic bonds. These bonds are stronger than hydrogen bonds and are not likely to break first during heating.
C. Bonds between the sugar and phosphate within a nucleotide: These bonds are also covalent bonds, forming the backbone of the DNA molecule. They are stronger than hydrogen bonds and are unlikely to break first.
D. Bonds between the sugar and phosphate of adjacent nucleotides: These bonds are also covalent bonds and are part of the backbone of DNA. Similar to option C, these bonds are strong and not likely to break first.
Based on the above analysis, option A is correct. Bonds between the nitrogenous bases (A-T and C-G) are the weakest in a DNA double helix and will break first when gradually heated.