AP Biology : DNA and RNA Structure
Study concepts, example questions & explanations for AP Biology
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Example Questions
Example Question #51 : Dna, Rna, And Proteins
Which of the following is not a component of nucleic acids?
Phosphate group
Guanine
Adenine
Tyrosine
Sugar
Tyrosine
Nucleic acids are made up of nitrogenous bases and a sugar-phosphate backbone. The sugar will vary depending on if it is an RNA or DNA molecule that's being discussed. RNA has ribose while DNA has deoxyribose. The nitrogenous bases are guanine, adenine, thymine, cytosine and uracil. Tyrosine is an amino acid, therefore not involved in the composition of nucleic acids.
Example Question #52 : Dna, Rna, And Proteins
What are the three major components that make up a nucleotide in DNA?
Glucose, ribose, and nitrogenous base
Phosphate, deoxyribose, and nitrogenous base
Protein unit, deoxyribose, and nitrogenous base
Phosphate, ribose, and nitrogenous base
Phosphate, deoxyribose, and nitrogenous base
The three major components of a nucleotide in DNA are phosphate, deoxyribose, and one of the four nitrogenous bases. The phosphate and deoxyribose alternate along the backbone, and the nitrogenous base codes for the type of protein made in transcription and translation.
Example Question #21 : Understanding Nucleotides And Base Pairs
What is the nitrogenous base that adenine bonds to in the DNA strand?
Thymine
Uracil
Cytosine
Guanine
Thymine
In the DNA strand, adenine bonds to thymine. It does not bond to the other bases in DNA. In RNA, adenine bonds to uracil.
Example Question #21 : Understanding Nucleotides And Base Pairs
In the DNA strand, with which nitrogenous base does guanine pair?
Cytosine
Uracil
Adenine
Thymine
Cytosine
In the DNA strand, guanine bonds to cytosine. It does not bond to the other nitrogenous bases. Guanine and cytosine form three hydrogen bonds to keep complementary strands of DNA together.
Example Question #51 : Dna And Rna Structure
What is one of the primary differences between the purines and pyrimidines of DNA?
Purines consist of a single ring, whereas pyrimidines consist of two rings
The purines bond to the phosphates on the DNA backbone, whereas the pyrimidines bond to sugar
Purines have a lipid chain, whereas pyrimidines do not
Purines consist of two rings, whereas pyrimidines consist of one ring
Purines consist of two rings, whereas pyrimidines consist of one ring
One of the primary differences between purines and pyrimidines is that purines consist of two rings, whereas the pyrimidines consist of one ring. One way to help remember the differences between purines and pyrimidines is that pyrimidines are like pyramids: sharp. Sharp things CUT (Cytosine Uracil Thymine). Note that uracil is only present in RNA, while thymine is only present in DNA. All nitrogenous bases bond to the sugar in the DNA backbone. The sugar is also connected to a phosphate group via a phosphodiester bond.
Example Question #52 : Dna And Rna Structure
Which of the following nitrogenous bases are purines?
Thymine and uracil
Thymine and guanine
Cytosine and adenine
Guanine and adenine
Adenine and thymine
Guanine and adenine
Purines are adenine and guanine, while pyrimidines are cytosine, thymine, and uracil.
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