1.
Rna is synthesized on a DNA template in a process called_______, which utilized the enzyme ___________.
Correct Answer
C. Transcription, RNA Polymerase
Explanation
RNA is synthesized on a DNA template in a process called transcription, which utilizes the enzyme RNA polymerase. Transcription is the process by which the DNA sequence is copied into RNA. RNA polymerase is the enzyme responsible for catalyzing the formation of RNA from the DNA template. This process is essential for gene expression and the production of different types of RNA molecules, such as messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).
2.
Given the following DNA strand, which of the following is its complementary mRNA? ACTCGATTACGATACGA
Correct Answer
D. UGAGCUAAUGCUAUGCU
Explanation
The correct answer is UGAGCUAAUGCUAUGCU. To find the complementary mRNA strand, we need to replace each DNA base with its complementary RNA base. In DNA, A pairs with T and C pairs with G. In RNA, A pairs with U and C pairs with G. Therefore, the complementary mRNA strand for the given DNA strand ACTCGATTACGATACGA is UGAGCUAAUGCUAUGCU.
3.
Which of the following is not used during translation?
Correct Answer
A. DNA
Explanation
During translation, the process by which proteins are synthesized, DNA is not directly involved. DNA carries the genetic information in the form of genes, but it is transcribed into mRNA before it can be used in translation. mRNA carries the genetic code from the DNA to the ribosomes where protein synthesis occurs. tRNA brings the amino acids to the ribosomes based on the codons on the mRNA. rRNA is a component of the ribosomes and plays a structural role in protein synthesis. Therefore, DNA is not used directly during translation.
4.
What kind of chemical bond is found between paired bases of the DNA double helix?
Correct Answer
B. Hydrogen
Explanation
Hydrogen bonds are the type of chemical bond found between paired bases of the DNA double helix. These bonds form between the nitrogenous bases (adenine, thymine, cytosine, and guanine) and hold the two strands of DNA together. Hydrogen bonds are relatively weak compared to covalent bonds, allowing the DNA strands to separate during replication and transcription processes. The hydrogen bonds play a crucial role in maintaining the structure and stability of the DNA molecule.
5.
Which of the following separates the DNA strands during replication?
Correct Answer
A. Helicase
Explanation
Helicase is responsible for separating the DNA strands during replication. It is an enzyme that unwinds the double helix structure of DNA by breaking the hydrogen bonds between the base pairs. This unwinding creates a replication fork, allowing DNA polymerase to access and copy each strand. Helicase moves along the DNA molecule, separating the strands and creating two templates for DNA replication. Therefore, helicase is the correct answer as it plays a crucial role in the replication process by separating the DNA strands.
6.
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
Correct Answer
C. Join Okazaki fragments together
Explanation
DNA ligase plays a crucial role in the elongation of the lagging strand during DNA replication by joining Okazaki fragments together. The lagging strand is synthesized in short fragments called Okazaki fragments, and DNA ligase seals the gaps between these fragments by catalyzing the formation of phosphodiester bonds. This process ensures the continuous synthesis of the lagging strand and the completion of DNA replication.
7.
The leading and lagging strands differ in that
Correct Answer
A. The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.
Explanation
The leading and lagging strands differ in their synthesis direction. The leading strand is synthesized in the same direction as the movement of the replication fork, while the lagging strand is synthesized in the opposite direction.
8.
The nitrogenous base adenine is found in all members of which group?
Correct Answer
C. ATP, RNA, and DNA
Explanation
The nitrogenous base adenine is found in ATP, RNA, and DNA. Adenine is one of the four nitrogenous bases that make up the building blocks of nucleic acids, which include RNA and DNA. Adenine pairs with thymine in DNA and with uracil in RNA, forming the base pairs that make up the genetic code. Adenine is also a component of ATP, which is a molecule that stores and transfers energy in cells. Therefore, the correct answer is ATP, RNA, and DNA.
9.
RNA polymerase moves in which direction along the DNA?
Correct Answer
B. 5' --> 3'
Explanation
RNA polymerase moves in the 5' to 3' direction along the DNA. This is because RNA polymerase synthesizes RNA by adding nucleotides to the 3' end of the growing RNA strand. Therefore, it needs to move in the 5' to 3' direction along the DNA template in order to properly synthesize RNA.
10.
Which of the following help to stabilize mRNA by inhibiting its degradation?
Correct Answer
D. 5' cap & poly (A) tail
Explanation
The 5' cap and poly (A) tail are both modifications that are added to the mRNA molecule after transcription. The 5' cap is a modified guanine nucleotide that is added to the 5' end of the mRNA, while the poly (A) tail is a string of adenine nucleotides that is added to the 3' end of the mRNA. These modifications help to protect the mRNA from degradation by enzymes in the cell. The 5' cap and poly (A) tail also play a role in the export of the mRNA from the nucleus to the cytoplasm and in the initiation of translation. Thus, the 5' cap and poly (A) tail help to stabilize the mRNA molecule and ensure its proper function.
11.
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
Correct Answer
A. AAA
Explanation
The correct answer is AAA because the anticodon on the tRNA molecule is complementary to the codon on the mRNA molecule. Since the given codon in the DNA sequence is AAA, the anticodon on the tRNA that binds to it will also be AAA.
12.
This can inhibit transcription by blocking the RNA polymerase.
Correct Answer
D. Repressor
Explanation
A repressor is a regulatory protein that binds to a specific DNA sequence called an operator, preventing the transcription of genes. In this context, the presence of a repressor can inhibit transcription by blocking the RNA polymerase, the enzyme responsible for synthesizing RNA from a DNA template. Therefore, the correct answer is repressor.
13.
Purines and Pyrimidine's are:
Correct Answer
A. Nitrogen bases that form hydrogen bonds between one another
Explanation
Purines and pyrimidines are nitrogen bases that form hydrogen bonds between one another. This is an important characteristic as it allows the two strands of DNA to come together and form a stable double helix structure. The purines (adenine and guanine) and pyrimidines (cytosine and thymine) form specific base pairs, with adenine always pairing with thymine and guanine always pairing with cytosine. These hydrogen bonds between the nitrogen bases play a crucial role in maintaining the integrity and stability of the DNA molecule.
14.
A possible sequence of nucleotides in the template stand of DNA that would code for the polypeptide sequence "phe-leu-ile-val" would be
Correct Answer
C. AAA-GAA-TAA-CAA
Explanation
The given polypeptide sequence "phe-leu-ile-val" can be coded by the DNA sequence "AAA-GAA-TAA-CAA". In DNA, each three nucleotides (called a codon) corresponds to one amino acid in the polypeptide chain. The codons "AAA", "GAA", "TAA", and "CAA" correspond to the amino acids phenylalanine (phe), leucine (leu), isoleucine (ile), and valine (val) respectively. Therefore, the DNA sequence "AAA-GAA-TAA-CAA" would code for the polypeptide sequence "phe-leu-ile-val".
15.
What amino acid sequence will be generated, based on the following mRNA codon sequence?5' - AUG-UCU-UCG-UUA-UCC-UUG - 3'
Correct Answer
C. MET-SER-SER-LEU-SER-LEU
Explanation
The given mRNA codon sequence is "AUG-UCU-UCG-UUA-UCC-UUG". Each codon codes for a specific amino acid. The codon "AUG" codes for the amino acid methionine (MET). The codons "UCU", "UCG", and "UCC" all code for the amino acid serine (SER). The codon "UUA" codes for the amino acid leucine (LEU). Finally, the codon "UUG" also codes for the amino acid leucine (LEU). Therefore, the correct amino acid sequence generated by the given mRNA codon sequence is "MET-SER-SER-LEU-SER-LEU".