High School Biology : RNA

Study concepts, example questions & explanations for High School Biology

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Example Questions

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Example Question #1 : Rna Structure

Which nucleotide is present in RNA sequences, but not DNA sequences?

Possible Answers:

Thymine

Guanine

Adenine

Uracil

Correct answer:

Uracil

Explanation:

DNA sequences contain the following nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). Guanine and cytosine bases pair together, while adenine and thymine bases pair together. In RNA, thymine is replaced by uracil (U).

Example Question #1 : Understanding Differences With Dna

The following RNA sequence is reverse transcribed to generate cDNA (complementary DNA). What is the corresponding DNA sequence?

3'-AUCGGAUGCACA-5'

Possible Answers:

5'-TAGCCTACGTGT-3'

5'-ATCGGATGCACA-3'

5'-UAGCCUACGUGU-3'

5'-AUCGGAUGCACA-3'

Correct answer:

5'-TAGCCTACGTGT-3'

Explanation:

cDNA (and all DNA) sequences contain thymine (T) rather than uracil (U), which will form base pairs with adenine. Additionally, complementary DNA contains the "complement" of each RNA nucleotide. The resultant DNA will be oriented anti-parallel to the template RNA, and use complementary pairs of adenine-to-thymine and cytosine-to-guanine.

RNA: 3'-AUCGGAUGCACA-5'

DNA: 5'-TAGCCTACGTGT-3'

Example Question #1 : Rna Structure

Where is mature mRNA found in the cell?

Possible Answers:

In the mitochondria

In the nucleus

In the nucleolus 

In vesicles that are exocytosed by the cell

In the cytoplasm or in the endoplasmic reticulum

Correct answer:

In the cytoplasm or in the endoplasmic reticulum

Explanation:

RNA goes through modifications known as "post-transcriptional modification" before it becomes a mature mRNA molecule. By the time that it is mature, it is allowed to leave the nucleus to interact with the ribosomes for translation. Ribosomes are free-floating in the cytoplasm of a cell and also on the rough endoplasmic reticulum. These are the targets of the mature mRNA.

The nucleus contains heteronuclear RNA (htRNA) before it becomes mature mRNA. The nucleolus accepts rRNA and helps form ribosomes subunits.

Example Question #21 : Rna

There are several different types of RNA with different general structures and functions. What is common to all RNA molecules?

Possible Answers:

Nitrogenous bases

Thymine

A hairpin loop

A globular structure

Correct answer:

Nitrogenous bases

Explanation:

Each type of RNA is designed to complete a different function in the cell. Messenger RNA (mRNA) has a linear structure and provides the codon template for translation. Transfer RNA (tRNA) has a hairpin loop structure and carries amino acid residues to ribosomes for elongation of the polypeptide created from translation. Ribosomal RNA (rRNA) has a globular structure and forms an integral component of the ribosome subunits.

Despite their differences, all RNA molecules have the same backbone structure, which contains ribose sugars and phosphate groups, and the same nitrogenous bases: adenine, cytosine, guanine, and uracil.

Example Question #1 : Understanding Differences With Dna

How does RNA differ from DNA in eukaryotes?

I. RNA contains ribose 
II. RNA is found only in the cytoplasm
III. RNA uses bases A, C, U, G
IV. RNA is predominantly single-stranded 

Possible Answers:

I, III, and IV

I, II, III, and IV

I and IV

I and III

I and III

Correct answer:

I, III, and IV

Explanation:

RNA differs from DNA in that it contains a ribose instead of deoxyribose, uses uracil instead of thymine, and is not only found in the nucleus like DNA. In eukaryotes, RNA is transcribed in the nucleus, then it is exported into the cytoplasm where it binds to ribosomes during translation. RNA is indeed predominantly single-stranded.

Example Question #21 : Rna

Which of the following statements are true?

Possible Answers:

The 5-C sugar is exactly the same in both RNA and DNA.

RNA and DNA have no structural differences whatsoever.

DNA contains phosphates, while RNA does not.

RNA is double stranded, while DNA is single stranded.

RNA contains uracil, while DNA contains thymine.

Correct answer:

RNA contains uracil, while DNA contains thymine.

Explanation:

RNA is different than DNA in that it 1) is single stranded (DNA is double stranded), 2) contains uracil (DNA contains thymine instead), and 3) contains a ribose sugar (DNA contains a deoxyribose sugar). And since both DNA and RNA are made up of nucleotides, they will both contain phosphates.

Example Question #21 : Rna

Which of the following characteristics best describe RNA?  

I. It contains base pairs C, G, U, and A

II. It is double stranded

III. It stores hereditary information

IV. It is responsible for transcription of proteins

V. It is synthesized from DNA

Possible Answers:

I, II, and III

V only

I, IV, and V

III and IV

II, IV, and V

Correct answer:

I, IV, and V

Explanation:

RNA is composed of the sugar ribose and contains the nitrogenous bases C, G, U, and A.  RNA is single stranded and is essential for gene expression, transcription and translation of proteins.  RNA is synthesized by DNA; only DNA contains hereditary information.

Example Question #21 : Rna

Which DNA base is replaced by uracil in RNA? 

Possible Answers:

Thymine 

Cytosine 

Adenine 

Guanine 

Correct answer:

Thymine 

Explanation:

DNA is made up of Adenine, Thymine, Guanine, and Cytosine. RNA has these same bases, except in RNA, there is no Thymine. Instead, Uracil is found.  

Example Question #21 : Rna

DNA contains the following nitrogenous bases: adenine, guanine, thymine, and cytosine. RNA contains which of the following sets of nitrogenous bases?

Possible Answers:

Adenosine, guanine, cystine, and uracil

Adenine, guanine, cytosine, and uracil

Adenine, guanine, cystine, and thymine 

Adenine, guanine, cytosine, and uracil

Correct answer:

Adenine, guanine, cytosine, and uracil

Explanation:

Thymine is exclusively present in DNA. Uracil replaces thymine in RNA; thus, RNA contains the following four nitrogenous bases: adenine, guanine, cytosine, and uracil.

Example Question #21 : Rna

Which of the following is not a component of RNA?

Possible Answers:

Ribose

Adenine

Cytosine

Thymine

Correct answer:

Thymine

Explanation:

RNA’s nucleotide components consist of a phosphate group, ribose, and nitrogenous bases. RNA’s nitrogenous bases include the purines adenine and guanine, and the pyrimidines cytosine and uracil. Thymine is a pyrimidine found exclusively in DNA. 

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