2: DNA Structure

Students answer questions about DNA composition, base pairing rules, nucleotide components, and double-helix complementarity.

LibreTexts reference: Chapter 2: DNA Structure and Sequences

True/False Statements About DNA Structure (BIOL 351)

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT WeBWorK PGML

Click to show True/False Statements About DNA Structure (BIOL 351) example problem

Which one of the following statements is FALSE about the structure of DNA?

• A. the helix is made of nucleotides
• B. the two strands of DNA are anti-parallel
• C. the DNA bases for each strand face the inside of the helix
• D. the phosphate groups are on the outside of the DNA double helix
• E. the backbone contains only phosphate and nucleobase

Check Answer

 

True/False Statements About DNA Structure

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT WeBWorK PGML

Click to show True/False Statements About DNA Structure example problem

Which one of the following statements is FALSE about the structure of DNA?

• A. the DNA double helix has ten nucleotides between each turn
• B. purine bases pair up with pyrimidine bases
• C. the DNA bases for each strand face the inside of the helix
• D. DNA exists as a parallel double helix
• E. G-C base pairs have three hydrogen bonds, whereas A-T base pairs only have two hydrogen bonds

Check Answer

 

True/False Statements About DNA Melting Temperature (Tm)

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT WeBWorK PGML

Click to show True/False Statements About DNA Melting Temperature (Tm) example problem

Which one of the following statements is TRUE concerning melting temperature (T_m) of DNA?

• A. The melting temperature (T_m) of a DNA strand goes down (decreases)
  when the amount of nucleobases with amino groups, adenine (A) + cytosine (C), increases.
• B. The melting temperature (T_m) of a DNA strand goes up (increases)
  when the cytosine (C) (C) + guanine (G) (G) base pairing content increases.
• C. The melting temperature (T_m) of a DNA strand goes up (increases)
  when the adenine (A) + thymine (T) base pairing content increases.
• D. The melting temperature (T_m) of a DNA strand goes down (decreases)
  when the amount of nucleobases with ketone groups, guanine (G) + thymine (T), increases.
• E. The melting temperature (T_m) of a DNA strand goes down (decreases)
  when the amount of pyrimidine nucleobases, cytosine (C) + thymine (T), increases.

Check Answer

 

True/False Statements About Factors That Increase DNA Melting Temperature (Tm)

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT WeBWorK PGML

Click to show True/False Statements About Factors That Increase DNA Melting Temperature (Tm) example problem

Which one of the following will INCREASE the melting temperature (T_m) of a DNA strand?

• A. decrease the amount of cytosine (C) + guanine (G) base pairing
• B. decrease the amount of adenine (A) (A) + thymine (T) (T) base pairing
• C. increase the amount of pyrimidine nucleobases, cytosine (C) + thymine (T)
• D. increase the amount of nucleobases with amino groups adenine (A) + cytosine (C)
• E. decrease the amount of nucleobases with ketone groups, guanine (G) + thymine (T)

Check Answer

 

True/False Statements About Factors That Decrease DNA Melting Temperature (Tm)

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT WeBWorK PGML

Click to show True/False Statements About Factors That Decrease DNA Melting Temperature (Tm) example problem

Which one of the following will DECREASE the melting temperature (T_m) of a DNA strand?

• A. increase the amount of nucleobases with ketone groups, guanine (G) + thymine (T)
• B. increase the amount of purine nucleobases, adenine (A) + guanine (G)
• C. decrease the amount of adenine (A) + thymine (T) base pairing
• D. decrease the amount of pyrimidine nucleobases, cytosine (C) + thymine (T)
• E. decrease the amount of cytosine (C) (C) + guanine (G) (G) base pairing

Check Answer

 

True/False Statements About Nucleotide Components

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT WeBWorK PGML

Click to show True/False Statements About Nucleotide Components example problem

Which one of the following is NOT one of the three (3) major components of a DNA or RNA nucleotide?

• A. ribose
• B. serine
• C. phosphate group
• D. purines and pyrimidines

Check Answer

 

True/False Statements About RNA and DNA Differences (BIOL 301)

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT WeBWorK PGML

Click to show True/False Statements About RNA and DNA Differences (BIOL 301) example problem

Which one of the following statements is TRUE concerning differences between RNA and DNA?

• A. RNA is usually single-stranded (simplex), whereas DNA is usually double-stranded (duplex)
• B. uracil in DNA takes the place of thymine in RNA
• C. DNA nucleotides are missing the 4′ hydroxide (-OH) group compared to RNA
• D. RNA is made of nucleotides, DNA is made of amino acids
• E. DNA has a sugar-phosphate backbone, RNA does not

Check Answer

 

True/False Statements About RNA and DNA Differences

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT WeBWorK PGML

Click to show True/False Statements About RNA and DNA Differences example problem

Which one of the following statements is FALSE concerning differences between RNA and DNA?

• A. Both double-stranded DNA and double-stranded RNA have major and minor grooves
• B. RNA has a regular consistent structure, whereas DNA adopts a wide variety of tertiary structures
• C. RNA is usually single-stranded (simplex), whereas DNA is usually double-stranded (duplex)
• D. the RNA sugar is ribose, DNA has a different sugar
• E. thymine in DNA takes the place of uracil in RNA

Check Answer

 

DNA Base Composition Using Chargaff's Rules (5 Choices)

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT

Click to show DNA Base Composition Using Chargaff's Rules (5 Choices) example problem

According to Chargaff's rules concerning the base pairing composition in double-stranded DNA, consider a sample where the percentage composition of 8% is thymine.
What are the percentages of the other three bases?

• A. adenine (A): 8% — cytosine (C): 42% — guanine (G): 42%
• B. adenine (A): 25% — cytosine (C): 42% — guanine (G): 25%
• C. adenine (A): 42% — cytosine (C): 8% — guanine (G): 42%
• D. adenine (A): 42% — cytosine (C): 42% — guanine (G): 8%
• E. adenine (A): 42% — cytosine (C): 25% — guanine (G): 25%

Check Answer

 

Complementary DNA Sequences Without Direction Labels

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT

Click to show Complementary DNA Sequences Without Direction Labels example problem

DNA is organized as a double helix where two strands run in opposite, or anti-parallel, directions. The ends of these strands are referred to as 5′ (five prime) and 3′ (three prime) ends. The strands are held together by hydrogen bonds between complementary base pairs. Specifically, adenine (A) forms a pair with thymine (T), and guanine (G) pairs with cytosine (C). This base pairing is critical for the stability of the DNA molecule and is central to processes like DNA replication and transcription.

 

T

T

T

,

C

T

G

,

A

G

G

Which one of the following DNA sequences is complementary to the direction-less DNA sequence shown above?

• A.  

  C

  T

  T

  ,

  T

  T

  G

  ,

  A

  G

  G

• B.  

  A

  A

  A

  ,

  G

  A

  C

  ,

  T

  C

  C

• C.  

  G

  G

  A

  ,

  G

  T

  C

  ,

  T

  T

  T

• D.  

  T

  T

  T

  ,

  C

  G

  G

  ,

  A

  G

  T

• E.  

  A

  A

  A

  ,

  G

  G

  G

  ,

  A

  G

  T

Check Answer

 

5' and 3' Complementary DNA Sequences

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT

Click to show 5' and 3' Complementary DNA Sequences example problem

DNA is organized as a double helix where two strands run in opposite, or anti-parallel, directions. The ends of these strands are referred to as 5′ (five prime) and 3′ (three prime) ends. The strands are held together by hydrogen bonds between complementary base pairs. Specifically, adenine (A) forms a pair with thymine (T), and guanine (G) pairs with cytosine (C). This base pairing is critical for the stability of the DNA molecule and is central to processes like DNA replication and transcription.

 

3′–

G

C

T

,

A

G

A

,

T

G

T

–5′

Which one of the following sequences below is complementary to the DNA sequence shown above?

Hint: pay close attention to the 5′ and 3′ directions of the strand.

• A.  

  5′–

  G

  C

  T

  ,

  A

  G

  A

  ,

  T

  G

  T

  –3′

• B.  

  5′–

  A

  C

  A

  ,

  T

  C

  T

  ,

  A

  G

  C

  –3′

• C.  

  5′–

  T

  G

  T

  ,

  A

  C

  T

  ,

  A

  C

  A

  –3′

• D.  

  5′–

  T

  G

  T

  ,

  A

  G

  A

  ,

  T

  C

  G

  –3′

• E.  

  5′–

  C

  G

  A

  ,

  T

  C

  T

  ,

  A

  C

  A

  –3′

Check Answer

 

DNA Melting Temperature Extremes from Sequence (12 Bases)

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT

Click to show DNA Melting Temperature Extremes from Sequence (12 Bases) example problem

Which one of the following DNA sequences below will have the LOWEST melting point (T_m).

Hint: I tried to make this question pretty easy and it does not require a calculator.

• A.

  5′–

  A

  A

  C

  ,

  C

  G

  T

  ,

  G

  C

  C

  ,

  G

  G

  T

  –3′

  3′–

  T

  T

  G

  ,

  G

  C

  A

  ,

  C

  G

  G

  ,

  C

  C

  A

  –5′

• B.

  5′–

  G

  C

  A

  ,

  G

  C

  G

  ,

  C

  G

  G

  ,

  A

  G

  G

  –3′

  3′–

  C

  G

  T

  ,

  C

  G

  C

  ,

  G

  C

  C

  ,

  T

  C

  C

  –5′

• C.

  5′–

  C

  C

  A

  ,

  G

  T

  C

  ,

  G

  C

  C

  ,

  T

  C

  G

  –3′

  3′–

  G

  G

  T

  ,

  C

  A

  G

  ,

  C

  G

  G

  ,

  A

  G

  C

  –5′

• D.

  5′–

  A

  A

  T

  ,

  C

  A

  C

  ,

  T

  T

  C

  ,

  C

  A

  T

  –3′

  3′–

  T

  T

  A

  ,

  G

  T

  G

  ,

  A

  A

  G

  ,

  G

  T

  A

  –5′

Check Answer

 

Palindromic DNA Sequence Completion

Blackboard Learn TXT Blackboard Ultra QTI v2.1 Canvas/ADAPT QTI v1.2 Human-Readable TXT

Click to show Palindromic DNA Sequence Completion example problem

The following numbered sequences only contains half of a palindromic sequence.
Match the correct lettered sequence that would finish and replace the 'N's in the sequence to make them palindromes.
Letters will be used exactly once.

	Your Choice	Prompt
	Drop Your Choice Here	1.   5′–  N   N   N   G  –3′
	Drop Your Choice Here	2.   5′–  G   C   C   ,   N   N   N  –3′
	Drop Your Choice Here	3.   5′–  C   G   G   C   ,   N   N   N   G  –3′
	Drop Your Choice Here	4.   5′–  C   N   N   N  –3′

Drag one of the choices below:

• A.  

  C

  G

  G

• B.  

  C

  C

  G

• C.  

  G

  C

  C

• D.  

  G

  G

  C

Check Answer Reset Game