Name: _____________________________________________________ Date:______________

 

Structure of DNA and RNA

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are two of the cellís most important molecules. These nucleic acids have a complex three-dimensional structure that enables them to direct protein synthesis in the cell.

Study the structure of the DNA and RNA molecules shown below. Fill in the missing labels. Then complete the chart and answer the questions.

Name

Type of Sugar

Types of nitrogen bases

Number of nucleotide strands

DNA

 

 

 

 

RNA

 

 

 

 

 

1.      The two DNA strands twist around each other. The is best described as a ___________________

__________________________.

 

2.       The repeating units of _____________________________ and ___________________________ make the backbone of DNA and RNA.

 

3.      In a DNA molecule, the nitrogen bases of one strand attach to the nitrogen bases of the other by following  _____________________________________ rule. The bases are held together by

 

_____________________________________________.

 

4.      A strand of DNA contains the following bases A-T-C-G-A-C-T. What will be the bases on the complementary DNA strand? ______________________________________.What will be the

 

bases on the complementary RNA strand? _________________________________________

 

5.      Part of the DNA molecule shown above is starting to unwind. What two cellular activities could this be the start of? _____________________________________________________________

Carefully read each term or phrase in the left-hand column of the following table. If the term or phrase applies to DNA, place a check mark in the column labeled DNA. If it applies to RNA, place a; check mark in the column labeled RNA.I f it applies to both nucleic acids, place a check mark in both columns.

 

 

DNA

RNA

 

DNA

RNA

Nucleotides

 

 

 

Double Helix

 

 

Deoxyribose as the sugar

 

 

Made during replication

 

 

 

Ribose as the sugar

 

 

Made during transcription

 

 

 

Single-stranded

 

 

Exact copy

 

 

 

Double-stranded

 

 

Acts as a messenger

 

 

 

Has nitrogenous bases

 

 

More than one form

 

 

 

Thymine

 

 

Found in the nucleus

 

 

 

Uracil

 

 

Leaves the nucleus

 

 

 

Template for synthesis of nucleic acids

 

 

Does not leave the nucleus