14. The major components of a DNA molecular subunit are
a. a chromosome, deoxyribose, and double helix
b. a five-carbon sugar, phosphate group, and a nitrogen-containing base
c. adenine, guanine, cytosine, and thymine
d. all of the above
D?
16. During DNA replication, all of the following steps occur EXCEPT
a. enzymes proofread new strands for errors and correct them
b. the double helix is unwound by DNA polymerases
c. base-pairing rules determine which nucleotide is added to new strands
d. each strand of a DNA double helix is copied, forming two identical double helixes
17. When errors in nucleotide sequencing occur,
a. DNA polymerase replaces the incorrect nucleotide with the correct nucleotide
b. enzymes dissolve the incorrect nucleotide so DNA polymerase can add the correct one
c. purines replace pyrimidines in the DNA molecule
d. DNA polymerase proofreads for errors while another enzyme corrects it
Thanks
-MC
For 14 ...
Start by determining what the molecular subunits - the monomers - that make up DNA are.
Then look up what things make up such a monomer.
For question 14, the correct answer is option b. The major components of a DNA molecular subunit are a five-carbon sugar (deoxyribose), a phosphate group, and a nitrogen-containing base.
To arrive at this answer, you can break down the options and analyze them one by one:
Option a - a chromosome, deoxyribose, and double helix: While chromosomes are made up of DNA, they are not components of a DNA molecular subunit. Deoxyribose is the five-carbon sugar and is indeed a major component of a DNA molecular subunit, but the double helix is the overall structure formed by two DNA strands.
Option b - a five-carbon sugar, phosphate group, and a nitrogen-containing base: This is the correct answer. The five-carbon sugar (deoxyribose) is a major component, the phosphate group is essential for the backbone structure of DNA, and the nitrogen-containing bases (adenine, guanine, cytosine, and thymine) are the building blocks of the DNA molecule.
Option c - adenine, guanine, cytosine, and thymine: While these are indeed nitrogen-containing bases present in DNA, they do not represent the complete major components of a DNA molecular subunit. They are only part of the nitrogenous bases in DNA.
Option d - all of the above: This option includes options a, b, and c, but not all of the mentioned components are the major components of a DNA molecular subunit. Therefore, option d is incorrect.
For question 16, the correct answer is option d. Each strand of a DNA double helix is copied during DNA replication, forming two identical double helices.
To arrive at this answer, let's analyze the options:
Option a - enzymes proofread new strands for errors and correct them: This step, known as proofreading, is an essential part of DNA replication to ensure accurate copying of the DNA molecule.
Option b - the double helix is unwound by DNA polymerases: During DNA replication, the double helix does need to be unwound to expose the individual strands for replication. DNA polymerases are enzymes involved in DNA replication.
Option c - base-pairing rules determine which nucleotide is added to new strands: This is correct. The base-pairing rules (adenine with thymine, and guanine with cytosine) guide the addition of complementary nucleotides during DNA replication.
Option d - each strand of a DNA double helix is copied, forming two identical double helixes: This is incorrect. During DNA replication, each strand of the original DNA molecule serves as a template for the synthesis of a new complementary strand, resulting in two identical double helices.
For question 17, the correct answer is option a. When errors in nucleotide sequencing occur, DNA polymerase replaces the incorrect nucleotide with the correct nucleotide.
To arrive at this answer, let's analyze the options:
Option a - DNA polymerase replaces the incorrect nucleotide with the correct nucleotide: This is correct. DNA polymerase has the ability to remove the incorrect nucleotide and replace it with the correct one during DNA replication.
Option b - enzymes dissolve the incorrect nucleotide so DNA polymerase can add the correct one: This option is not correct. Enzymes do not dissolve incorrect nucleotides. They are responsible for various other aspects of DNA replication.
Option c - purines replace pyrimidines in the DNA molecule: This is incorrect. Purines (adenine and guanine) and pyrimidines (cytosine and thymine) are the two categories of nitrogenous bases found in DNA, and they do not replace each other in the DNA molecule.
Option d - DNA polymerase proofreads for errors while another enzyme corrects it: This is not entirely correct. DNA polymerase is responsible for both proofreading and correcting errors during DNA replication, without requiring the assistance of another enzyme.
14: If your momma asked you what DNA was made of...
16. What exactly does polymerase mean? What does an origin protein do? ((Broken Link Removed)
17. http://en.wikipedia.org/wiki/DNA_replication