Transcript Hein and Arena - University of Wisconsin–Eau Claire

Chapter Outline
14.1 Nucleic Acid Building Blocks
14.2 Nucleoside di- and
Triphosphates, Cyclic Nucleotides
14.3 Polynucleotides
14.4 DNA Structure
14.7 DNA Replication
14.8 RNA
14.9 Translation
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14.1: Nucleic Acid Building Blocks
•
•
Nucleic acids consist of nucleotide residues.
Each nucleotide is put together from three building
blocks:
1) phosphoric acid
2) a monosaccharide
3) an organic base
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Two types of
Bases:
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Nucleosides:
A
G
C
U
In
RNA
A
G
C
T
In
DNA
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Nucleotides:
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14.2: Nucleoside di- and Triphosphates, Cyclic Nucleotides
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Dinucleotides
O-
NH2
-
O P O
N
N
O
H 2C
N
O
N
O
-
NH2
O P O
N
N
O
H2C
O
N
N
O
-
O P O
O-
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14.3: Polynucleotides in DNA:
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Polynucleotides in RNA:
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14.4 DNA Structure
The structure of DNA is understood in terms of three
levels of structure:
1) primary (sequence of nucleotide residues)
2) secondary
3) tertiary
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Secondary Structure
• In DNA, secondary structure pertains to the helix
formed by the interaction of two DNA strands.
• In the most commonly found form of DNA, two
single strands lie side by side in an antiparallel
arrangement, with one running 5’ to 3’ and the
other running 3’ to 5’.
• The two DNA strands are held to one another by
base pairing, hydrogen bonding between the
bases attached to the sugar-phosphate
backbone.
• This base pairing is complementary, which
means that A forms hydrogen bonds with T and
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G forms hydrogen bonds with C.
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Base Pairing:
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DNA Replication:
• When DNA is replicated, each strand of the double
helix serves as a template for the manufacture of a new
strand of DNA.
• In each of the daughter DNA strands, one strand from
the parent DNA is present.
• This is called semiconservative replication.
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14.8: RNA differs from DNA in that:
1) It contains a different monosaccharide residue
2) It contains the bases A, G, C, and U instead of A, G, C, and T
3) It exists as a single strand instead of a double strand
The first step in using the information stored in DNA to
produce proteins is transcription - using DNA as a template to
make RNA.
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Three Types of RNA
1)
2)
3)
Transfer RNA (tRNA) are the smallest of the three types
(73-93 nucleotide residues), and they carry the correct amino
acid to the site of protein synthesis.
Messenger RNA (mRNA) are of variable size, depending
on the protein to be manufactured, and carry the information
that specifies which protein should be made. This message is
carried as a sequence of nucleotides that is complementary
to the template strand of DNA.
Ribosomal RNAs (rRNA) are relatively long RNA strands
(hundreds or thousands of nucleotide residues) that combine
with proteins to form ribosomes, the multisubunit complexes
in which protein synthesis takes place.
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14.9: Translation
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