LAB 6
DNA AND RNA STRUCTURE AND FUNCTION
Objective: To learn the composition, structure and location of DNA and RNA and to describe the
basic function of each
A. DNA Structure
Deoxyribonucleic acid is a double-stranded molecule composed of carbon, oxygen, hydrogen and nitrogen. It is
constructed from structural units called nucleotides, which consist of a nitrogen-containing base, a pentose sugar
(deoxyribose) and a phosphate group.
Read about the structure of DNA in the chemistry chapter of your book. Label the various structures on the DNA
molecule below and answer the following questions
1
2
4
5
3
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QUESTIONS
1.
______________________ and ____________________are large two-ring bases called purines. The smaller,
single-ring bases known as pyrimidines are ____________________ and _____________________ ,as well as,
another base found in RNA called _______________________.
2.
The two sides of the DNA molecule is composed of alternating _____________________and
_______________________ molecules.
3.
The rungs of the DNA ladder is composed of _____________________ pairs that are bonded together by a
______________________________.
4.
The entire DNA molecule is coiled into a spiral called a _______________________.
5.
Bonding of the nitrogenous bases is specific, each bonding only to a complementary partner. Thymine will
always bond to ____________________ while guanine bonds to ______________________. In RNA, adenine
bonds to ____________________ instead of thymine.
6.
Typically, DNA is found in the ________________________ of the cell. It is additionally found in organelles
called_____________________.
7.
What are the main functions of DNA? (Give at least 2)
8.
The genetic code of an organism is determined by the nitrogenous base sequence of a DNA molecule. A
segment of DNA that carries the code or instructions for the construction of polypeptide is called a
______________________.
9.
Prior to cell division, the DNA in the nucleus must _______________________ to ensure the cell being
produced has an identical copy of DNA.
B. RNA Structure
Ribonucleic acid is composed of the same elements as DNA. It is also constructed from nucleotides, however, the
pentose sugar in the RNA nucleotide is ribose.
Read about RNA in the chemistry chapter of your text and answer the following questions:
QUESTIONS
1.
Name three structural differences between DNA and RNA.
2.
Where is RNA typically found in the cell?
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3.
What is the function of RNA?
4.
Give the full names of each of the following types of RNA. Briefly describe the function of each:
a.
rRNA 
b.
mRNA 
c.
tRNA 
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