Question 1

Which of the following nucleotide bases is found only in DNA,not in RNA?

Accepted Answer

Thymine is found only in DNA, it is replaced by uracil in RNA.

Question 2

The ______ contain(s)the information for the structure of the protein.

Accepted Answer

Exons contain the coding regions of DNA that specify the sequence of amino acids in a protein.

Question 3

An intervening sequence of DNA that is not expressed is called a(n)

Accepted Answer

An intron is a non-coding segment of DNA that interrupts the coding sequence of a gene and is not expressed. Exons are segments of DNA that are expressed and code for a particular protein. Promoters are regions of DNA that help initiate transcription of a gene. A replicon is a unit of DNA replication. Therefore, the correct answer is B, intron.

Question 4

Which of the classes of RNA molecules carries the amino acids that are added to the growing polypeptide chain?

Accepted Answer

Transfer RNA (tRNA) carries amino acids to the ribosome during protein synthesis, where they are added to the growing polypeptide chain. Ribosomal RNA (rRNA) is a component of the ribosome itself, and messenger RNA (mRNA) carries the genetic information from the DNA to the ribosome. Primary mRNA transcript is the initial product of transcription that undergoes further processing to become functional mRNA. Ribozymes are RNA molecules that have catalytic activity.

Question 5

Which of the following nucleotide bases is found only in RNA,not in DNA?

Accepted Answer

Uracil is found only in RNA and replaces thymine, which is found only in DNA.

Question 6

In modern biochemical genetics,the flow of inherited information is from

Accepted Answer

In modern biochemical genetics, the flow of inherited information is from DNA to RNA to protein. This is known as the central dogma of molecular biology. Therefore, the correct option is B where the flow of information is from DNA to RNA to protein.

Question 7

Which is the process that synthesizes mRNA?

Accepted Answer

Transcription is the process by which DNA is used as a template to synthesize mRNA. It occurs in the nucleus of eukaryotic cells and involves RNA polymerase binding to a specific region of DNA called the promoter and then synthesizing a complementary strand of mRNA.

Question 8

Which is the process by which a protein is constructed in the cytoplasm of eukaryotic cells?

Accepted Answer

Translation is the process by which a protein is synthesized in the cytoplasm of eukaryotic cells. It involves the assembly of amino acids in a specific sequence determined by the mRNA template produced during transcription.

Question 9

Which of the classes of RNA molecules carries the genetic information from the nucleus as it is needed for the construction of a protein?

Accepted Answer

Messenger RNA (mRNA) carries genetic information from the nucleus to the ribosomes in the cytoplasm, where it is used as a template for protein synthesis. Ribosomal RNA (rRNA) and transfer RNA (tRNA) are also involved in protein synthesis, but do not carry genetic information from the nucleus. Primary mRNA transcript is the initial RNA molecule transcribed from DNA, which undergoes processing to become mature RNA. Mature RNA refers to the processed RNA molecule that is ready for translation, but it does not carry genetic information from the nucleus.

Question 10

Artificial RNA with a known base sequence was added to a medium containing bacterial ribosomes and a mixture of amino acids.By chemical identification of the resulting polypeptide,researchers could discover the

Accepted Answer

By observing the polypeptide that is synthesized by the bacterial ribosomes in the presence of the artificial RNA molecule, researchers can determine the codon that is specified by the sequence of the artificial RNA. The amino acid sequence of the resulting polypeptide can be used to infer the base sequence of the codons in the artificial RNA.

Question 11

During the process of transcription,the information in

Accepted Answer

During transcription, the information in DNA is converted into RNA information. This process involves the enzyme RNA polymerase synthesizing an RNA molecule that is complementary to a strand of DNA. The resulting RNA molecule carries the same information as the original DNA strand and can be used to produce a protein through the process of translation.

Question 12

The addition of a poly-A tail to mRNA occurs after which of the following?

Accepted Answer

The addition of a poly-A tail occurs after transcription, specifically during the processing of the newly synthesized mRNA molecule.

Question 13

Prior to protein synthesis,the DNA

Accepted Answer

Prior to protein synthesis, the DNA serves as a template for the production of mRNA through the process of transcription. The mRNA then carries the genetic information from DNA to the ribosomes, where it serves as a template for the production of proteins through the process of translation. Therefore, choice B is the correct answer.

Question 14

For translation to take place,which of the following would NOT be required to be present?

Accepted Answer

Translation is the process of protein synthesis where mRNA is decoded to produce a specific protein. The presence of mRNA, tRNA amino acid complex, rRNA, and ribosome is essential for translation to take place. However, DNA is not required for translation as it serves as the template for the synthesis of mRNA during transcription.

Question 15

The genetic code consists of ____ bases that stand for one codon.

Accepted Answer

The genetic code consists of a sequence of three nucleotide bases, or triplets, which are called codons. Each codon codes for a specific amino acid or a stop signal. Therefore, the genetic code is said to be triplet or three-base code.

Question 16

Which of the following is NOT part of gene expression?

Accepted Answer

Gene expression involves the process of using the information encoded in DNA to create functional molecules such as proteins. Transcription, translation, amino acids, and protein synthesis are all part of this process. Replication, on the other hand, is the process of copying DNA before cell division and is not directly related to gene expression.

Question 17

Which of the classes of RNA molecules is linked with proteins in forming the large and small subunits of a cytoplasmic structure?

Accepted Answer

Ribosomal RNA (rRNA) is the RNA molecule that is linked with proteins to form the large and small subunits of ribosomes, which are cytoplasmic structures involved in protein synthesis. Transfer RNA (tRNA) carries amino acids to the ribosome during protein synthesis and messenger RNA (mRNA) carries the genetic information from DNA to the ribosome to be translated into protein. Primary mRNA transcript refers to the initial RNA molecule transcribed from DNA, which undergoes processing to become mature mRNA. Ribozymes are RNA molecules that act as enzymes, catalyzing chemical reactions. None of these other classes of RNA are directly involved in forming ribosomal subunits.

Question 18

Which of the following is NOT true about RNA?

Accepted Answer

RNA does not typically form a helix like DNA does. Instead, it may fold or loop on itself in various ways depending on its function.

Question 19

Messenger RNA is produced in the

Accepted Answer

Messenger RNA is produced in the nucleus through the process of transcription, where DNA is used as a template to synthesize a complementary RNA strand. Once the mRNA molecule is produced, it can travel out of the nucleus and into the cytoplasm where it can be used by ribosomes for protein synthesis. Therefore, options A, B, D, and E are incorrect.

Question 20

The function of transfer RNA is to

Accepted Answer

Transfer RNA (tRNA) carries amino acids to ribosomes during protein synthesis. The tRNA has a specific sequence of three nucleotides, called an anticodon, that matches up with the codon on the messenger RNA (mRNA) which specifies a particular amino acid. The tRNA then transfers that amino acid to the growing protein chain.

Quiz 25: Dna Structure and Control of Gene Expression