Molecular Biology Of DNA Replication Process Quiz

1.

The first DNA polymerase was discovered by _______.

A.

Kornberg
B.

Chargaff
C.

Watson and Crick
D.

Mullis
E.

Brittney Spears

Correct Answer
A. Kornberg

Explanation
Kornberg is the correct answer because he was the scientist who discovered the first DNA polymerase. He won the Nobel Prize in Physiology or Medicine in 1959 for his work on the enzymatic synthesis of DNA. His discovery paved the way for further understanding of DNA replication and the development of techniques such as polymerase chain reaction (PCR).

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2.

When double-stranded DNA is heated to 94-95ºC, it becomes single-stranded due to the hydrogen bonds breaking. This process is called _______.

Correct Answer
denaturation, melting, denaturing

Explanation
When double-stranded DNA is heated to high temperatures (94-95ºC), the hydrogen bonds between the two strands break, causing the DNA to separate into two single strands. This process is known as denaturation, melting, or denaturing.

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3.

When single-stranded DNA is cooled to below 60ºC, it becomes double stranded due specific base pairing. This process is called _______.

Correct Answer
annealing, hybridization, renaturing, hybridizing

Explanation
When single-stranded DNA is cooled to below 60ºC, it undergoes a process called annealing, hybridization, renaturing, or hybridizing. During this process, the complementary bases of the single-stranded DNA molecule pair up with each other to form a double-stranded DNA molecule. This is a crucial step in many molecular biology techniques, such as PCR and DNA sequencing, as it allows for the specific binding of DNA strands and the amplification or analysis of specific DNA sequences.

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4.

In Meselson and Stahl's experiment, _______ generation(s) after cells were transferred from heavy-nitrogen medium to light nitrogen medium, all of the DNA was of hybrid density. (Type in a number.)(I believe we didn't cover this one this year, 2010).

Correct Answer
1, one

Explanation
In Meselson and Stahl's experiment, after one generation, all of the DNA was of hybrid density. This suggests that DNA replication is a semi-conservative process, where each new DNA molecule consists of one strand from the original DNA molecule and one newly synthesized strand. This result supports the hypothesis proposed by Watson and Crick regarding the mechanism of DNA replication.

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5.

In Meselson and Stahl's experiment, _______ generation(s) after cells were transferred from heavy-nitrogen medium to light nitrogen medium, half of the DNA was of hybrid density. (Type in a number.)(I believe we didn't cover this one this year, 2010).

Correct Answer
2, two

Explanation
In Meselson and Stahl's experiment, after two generations of cell division, half of the DNA was of hybrid density. This means that one strand of the DNA molecule was made of the original heavy nitrogen isotope, while the other strand was made of the lighter nitrogen isotope. This result supported the semi-conservative model of DNA replication, where each new DNA molecule consists of one old strand and one newly synthesized strand.

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6.

In 1958, Meselson and Stahl proved that DNA replication was _______.

Correct Answer
semiconservative, semi-conservative, semi conservative

Explanation
Meselson and Stahl's experiment in 1958 provided evidence that DNA replication is semiconservative. This means that during replication, each new DNA molecule consists of one strand from the original DNA molecule and one newly synthesized strand. This disproved the other two options, which suggest conservative or dispersive replication, where the original DNA molecule would remain intact or be randomly distributed among the new molecules, respectively.

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2

7.

DNA polymerase adds a nucleotide to the ___'-OH (hydroxyl) of a primer DNA molecule. (Type in a number)

Correct Answer
3

Explanation
DNA polymerase adds a nucleotide to the 3'-OH (hydroxyl) of a primer DNA molecule. This is because DNA polymerase synthesizes DNA in the 5' to 3' direction, meaning that it adds nucleotides to the 3' end of the growing DNA strand. The 3'-OH group of the primer DNA molecule provides the necessary hydroxyl group for the formation of a phosphodiester bond with the incoming nucleotide, allowing for DNA synthesis to occur.

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1

8.

The main replication polymerase of E. coli is DNA polymerase ____. (We didn't cover this one this year, 2010).

Correct Answer
III, 3, three

Explanation
The main replication polymerase of E. coli is DNA polymerase III. This enzyme is responsible for synthesizing new DNA strands during replication. It is a complex enzyme made up of multiple subunits and is highly processive, meaning it can catalyze the addition of many nucleotides in a row without dissociating from the DNA template. DNA polymerase III is essential for accurate and efficient DNA replication in E. coli.

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9.

The enzyme that breaks the hydrogen bonds at the replication fork is called _______.

Correct Answer
DNA helicase, helicase

Explanation
DNA helicase is the enzyme responsible for breaking the hydrogen bonds between the two DNA strands at the replication fork. It does this by using energy from ATP to unwind the double helix and separate the strands. Helicase is another term used to refer to DNA helicase, emphasizing its role in unwinding the DNA strands during replication.

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10.

The protein that binds to single-stranded DNA to keep it from kinking up is abbreviated with the three letters ______.

Correct Answer
SSB

Explanation
The protein that binds to single-stranded DNA to prevent it from forming secondary structures or kinking up is known as SSB, which stands for Single-Stranded DNA Binding protein. SSB plays a crucial role in DNA replication, repair, and recombination by stabilizing and protecting single-stranded DNA. It coats the DNA strand, preventing it from folding back on itself and maintaining its single-stranded state, which is essential for various cellular processes.

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11.

The short RNA molecule made at the beginning of an Okazaki fragment is called an RNA _______.

Correct Answer
primer

Explanation
The short RNA molecule made at the beginning of an Okazaki fragment is called an RNA primer. This primer is necessary for DNA replication as it provides a starting point for the DNA polymerase enzyme to bind and begin synthesizing the complementary DNA strand. The RNA primer is later removed and replaced with DNA nucleotides, completing the formation of the Okazaki fragment.

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1

12.

Okazaki fragments are needed for replication on the ______ strand.

Correct Answer
lagging, discontinuous

Explanation
Okazaki fragments are short DNA fragments that are synthesized on the lagging strand during DNA replication. The lagging strand is synthesized in the opposite direction of the replication fork, resulting in the need for Okazaki fragments to be synthesized in short, discontinuous segments. Therefore, Okazaki fragments are necessary for replication on the lagging strand, which is synthesized discontinuously.

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1

13.

A reverse transcriptase that is involved in replication of the tips of eukaryotic chromosomes is the enzyme _______.

Correct Answer
telomerase

Explanation
Telomerase is the correct answer because it is an enzyme that plays a crucial role in the replication of the tips of eukaryotic chromosomes, known as telomeres. Telomerase helps to maintain the length and stability of telomeres by adding repetitive DNA sequences to the ends of chromosomes. This prevents the loss of genetic material during DNA replication and ensures the proper functioning of cells. Therefore, telomerase is essential for the replication and maintenance of eukaryotic chromosomes.

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14.

The end of a eukaryotic chromosome is called the _______.

Correct Answer
telomere

Explanation
A telomere is the end of a eukaryotic chromosome. It consists of repetitive DNA sequences that protect the chromosome from degradation or fusion with neighboring chromosomes. Telomeres play a crucial role in maintaining the stability and integrity of the chromosome during cell division. As cells divide, telomeres gradually shorten, eventually leading to cell senescence or apoptosis. Therefore, telomeres are essential for preserving the genetic information and ensuring the proper functioning of cells.

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