Tag: nucleic acids

Questions Related to nucleic acids

Which of the following information transfers is catalyzed the reverse transcriptase?

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. RNA $\rightarrow$ RNA

  2. RNA $\rightarrow$ DNA

  3. DNA $\rightarrow$ DNA

  4. None of these

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Correct Option: C
Explanation:

Reverse transcriptase is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. A retrovirus is a type of RNA virus that inserts a copy of its genome into the DNA of a host cell that it invades thus changing the genome of that cell. Once inside the host cell cytoplasm, the virus uses its own reverse transcriptase enzyme to produce DNA from its RNA genome, the reverse of the usual pattern and thus retro (backward).

So, the correct option is ' RNA $\rightarrow$ DNA'.

Teminism is

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. Central dogma reverse

  2. Central dogma of molecular biology

  3. Circular flow of hereditary information

  4. Effect of cytoplasm on functioning of DNA

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Correct Option: A

Some RNA viruses carry a gene or an enzyme that uses viral RNA as a template in the synthesis of DNA. This enzyme is 

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. RNA replicase

  2. Reverse transcriptase

  3. Viral nuclease

  4. RNA polymerase

Show answer
Correct Option: B
Explanation:

Reverse transcriptase catalyzes the formation of double-stranded deoxyribonucleic acid (DNA) from a single-stranded ribonucleic acid (RNA) genome. It is called "reverse" transcriptase because it reverses the usual direction of information flow, from DNA to RNA. Reverse transcriptase enzymes can be found in viruses, which use reverse transcriptase to make more viruses.

So, the correct option is 'Reverse transcriptase'.

In cloning experiments, cDNA molecules can be obtained from an mRNA copy by

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. Polymerase chain reaction

  2. Reverse transcriptase

  3. Ribozyme

  4. DNA-RNA hybridization

Show answer
Correct Option: B
Explanation:

Complementary DNA (cDNA) is a DNA copy of a messenger RNA (mRNA) molecule produced by reverse transcriptase. cDNA is often used to clone eukaryotic genes in prokaryotes.  cDNA is also produced naturally by retroviruses (such as HIV) for integration into the host's genome.

So, the correct option is 'Reverse transcriptase'.

Choose the correct answers from the alternatives given :
The central dogma of molecular biology

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. states that DNA is a template for all RNA production

  2. pertains only to prokaryotes because humans are unique

  3. states that translation precedes transcription

  4. states that DNA is a template only for DNA replication

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Correct Option: A
Explanation:

During the transcription phase of the central dogma, DNA acts as the template for RNA synthesis. The RNA polymerase enzyme identifies the base on the DNA strand and adds a complementary base to the sequence. After transcription, translation of mRNA occurs that leads to the formation of the polypeptide sequence.

So, the correct option is 'states that DNA is a template for all RNA production'.

During transcription, the site of DNA molecule at which RNA polymerase binds is called

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. promoter

  2. regulator

  3. receptor

  4. enhancer

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Correct Option: A
Explanation:

The RNA polymerase enzyme binds to a specific site called promoter and initiates transcription. The promoter region determines which DNA strand is to be transcribed. Thus, a promoter region has RNA polymerase recognition site and RNA polymerase binding site.

The molecule needed to allow a cell to transfer genetic information from RNA to DNA, is

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. DNA polymerase

  2. RNA polymerase

  3. reverse transcriptase

  4. chlorophyll

Show answer
Correct Option: C
Explanation:

Reverse transcriptase is an enzyme used to generate complementary DNA from an RNA template, a process termed reverse transcription. Reverse transcriptase enzymes can be found in viruses, which use reverse transcriptase to make more viruses. 

So, the correct option is 'reverse transcriptase'.

Silencing of a gene could be achieved through the use of

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. RNAI only

  2. Antisense RNA only

  3. Both RNAi and antisense RNA

  4. None of the above

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Correct Option: C
Explanation:
RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate.
So, the correct answer is 'Both RNAi and antisense RNA'.

Which of the following is correct match of phenomenon and its explanation?

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. Central dogma$\rightarrow$ RNA$\rightarrow$ DNA $\rightarrow$ Protein$\rightarrow$ RNA

  2. Reverse transcription$\rightarrow$ PCR$\rightarrow$ DNA amplification

  3. Transcription$\rightarrow$ Formation of RNA and proteins

  4. RNA silencing$\rightarrow$ Use of dsRNA

Show answer
Correct Option: B
Explanation:
Reverse transcription polymerase chain reaction (RT-PCR) uses mRNA rather than DNA as the starting template. First, the enzyme reverse transcriptase uses the mRNA template to produce a complementary single-stranded DNA strand called cDNA in a process known as reverse transcription. Next, DNA polymerase is used to convert the single-stranded cDNA into double-stranded DNA. These DNA molecules can now be used as templates for a polymerase chain reaction ( PCR ) for DNA amplification.

Central dogma can be correctly represented as DNA→ DNA→ RNA → Protein. 
Transcription is the formation of RNA from DNA. 

So, the correct option is 'Reverse transcription→ PCR→ DNA amplification'.

In reverse transcription.......... is assembled on ..........

bio-chemistry nucleic acids central dogma transcription and gene expression molecular biology

  1. mRNA, DNA

  2. DNA, agar

  3. cDNA, mRNA

  4. DNA, enzymes

Show answer
Correct Option: C
Explanation:

Complementary DNA is DNA synthesized from a single-stranded mRNA template in a reaction catalyzed by the enzyme reverse transcriptase. This process is known as reverse transcription. cDNA is often used to clone eukaryotic genes in prokaryotes. Hence it can be said that in reverse transcription cDNA is assembled on mRNA. 

So, the correct option is 'cDNA, mRNA'.