Download (3.1.1.5a) Nucleic Acids

(3.1.1.5a) Nucleic Acids
To understand the importance of nucleic acids, you must first understand the importance
of proteins. Proteins have to have a special shape in order to do their job. For example, proteins
that serve as enzymes have to have their active site, the groove that the substrate fits in. That
shape is determined by the order of the amino acids and the way their side chains cause them to
coil up. A cell has to be able to make all of its proteins in just the right amino acid arrangement,
for proteins are vital to a cell and if just one amino acid is incorrect, the whole shape of the
protein could be affected. Without the proper shape, the protein would not be able to do its job.
Nucleic acids are molecules in a cell that store a code. This code helps the cell arrange its
amino acids together in the correct order to make its proteins. The two types of nucleic acids are
DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA and
RNA molecules are made of nucleotides. Nucleotides get linked together to made DNA and
RNA like amino acids get linked together to make proteins.
A nucleotide is made of three parts, a sugar (ribose or deoxyribose), a phosphate group,
and a nitrogen base. In DNA, there are four different types of nitrogen bases. They are called
adenine, thymine, guanine, and cytosine. DNA is two strands of nucleotides, hooked together
and twisted into a ladder shape called a double helix. The two strands are held together by
complementary bases on opposite strands. Thymine has a shape that complements (fits together
like a puzzle) adenine. So every nucleotide that has a thymine nitrogen base, has a nucleotide
across from it that has adenine as its nitrogen base. Cytosine and guanine are also
complementary in shape.
RNA is a nucleic acid that is a single strand of nucleotides. Its job is to help use the code
in the DNA to make a cell’s proteins. DNA’s role is to store genetic information in the nucleus
of a cell. It also allows parents to pass on their genetic information to their offspring.
Matching
_____ 1. proteins
a. molecules that store a code
_____ 2. amino acids
b. ribonucleic acid
_____ 3. nucleic acids
c. deoxyribonucleic acid
_____ 4. DNA
d. building blocks of DNA and RNA
_____ 5. RNA
e. adenine, guanine, cytosine, thymine
_____ 6. nucleotides
f. building blocks of a protein
_____ 7. nitrogen bases
g. fit together like a puzzle
_____ 8. complementary bases
h. molecules built to have a special shape to do
_____ 9. double helix
their job
i. shape of a DNA molecule
True or False
_____ 1. Proteins have to have a special shape to do their job.
_____ 2. The shape of a protein is determined by the order of their nucleotides.
_____ 3. The shape of a protein is determined by the order of their amino acids.
_____ 4. If the arrangement of amino acids is changed, the shape of a protein may also change.
_____ 5. The code in DNA helps the cell arrange its amino acids together in the correct order to
make its proteins.
_____ 6. The two types of nucleic acids are DNA and RNA.
_____ 7. Amino acids are the building blocks of nucleic acids.
_____ 8. Nucleotides are the building blocks of nucleic acids.
_____ 9. A nucleotide is made of a sugar, a phosphate, and a nitrogen base.
_____ 10. There are three different nitrogen bases.
_____ 11. Adenine, thymine, guanine, and cytosine are the four different types of nitrogen
bases.
_____ 12. Thymine is complementary to guanine.
_____ 13. Thymine is complementary to adenine.
_____ 14. RNA is made of two strands of nucleotides.
_____ 15. A double helix is like a twisted ladder.
_____ 16. DNA’s shape is a double helix.
_____ 17. On a DNA molecule, cytosine would have a guanine across from it.
_____ 18. RNA’s job is to store genetic information in the nucleus of a cell.
_____ 19. DNA’s job is to allow parents to pass on their genetic information to their
offspring.
_____ 20. RNA’s job is to help use the code in the DNA to make a cell’s proteins.
Completing Sentences
proteins
DNA
adenine
thymine
nitrogen base
amino acids
RNA
guanine
sugar
double helix
nucleic acids
nucleotides
cytosine
phosphate group
1. The two types of nucleic acids are _____________ and _______________.
2. __________________________ are the building blocks of nucleic acids.
3. Each nucleotide is made of a __________________, a _________________________
and a _____________________________.
4. Two complementary bases are _______________ and ________________________.
5. Two other complementary bases are ____________________ and _______________.
6. The shape of a DNA molecule is called a ____________________________.
7. __________________________ are molecule that help the cell makes its proteins correctly.
8. _______________________ are vital to a cell, and they must be made to have a specific
shape to do their job.
9. The shape of a protein is determine by the sequence of its _____________________.
Answer the following.
1. Why must the amino acid arrangement be very specific in a protein?
2. What molecules allow a cell to make its proteins with the proper amino acid sequence?
3. What are two types of nucleic acids?
4. What are the building blocks of nucleic acids?
5. What are the three parts of a nucleotide?
6. What are the four types of nitrogen bases?
7. What is the shape of a DNA molecule?
8. How are RNA and DNA different?