The Molecules of Life
Part 4: Nucleic Acids
Friday, June 12, 15
Nucleic Acids
★
Building blocks of nucleic acids are nucleotides
Nucleotide consists of a 5-carbon sugar, a phosphate group,
and nitrogenous base group
★
★
Function as energy storage molecules (ATP, NADH, FADH)
In nucleic acids (DNA, RNA, mtDNA) sequence of joined
nucleotides encodes genetic information
★
Friday, June 12, 15
DNA is an example of a nucleic acid
DNA (deoxyribonucleic acid) - polymer of nucleotides
★ Each contains sugar deoxyribose, phosphate group, and one of
4 nitrogenous bases:
★
adenine (A)
guanine (G) cytosine (C) thymine (T)
★ Adenine
and guanine have double-ring structure - purines
★ Cytosine and thymine have single-ring structure - pyrimidines
cytosine
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thymine
DNA is an example of a nucleic acid
DNA - typically double-stranded molecule that’s twisted into
helical shape (double helix) (i.e. ATGAC).
★ Two strands held together by hydrogen bonds
★
Genetic information is coded in sequence of nitrogenous bases
(i.e. ATGAC)
★
deoxyribose
nitrogenous bases
phosphate group
Friday, June 12, 15
RNA is another example of a nucleic acid
★
RNA (ribonucleic acid) - polymer of nucleotides
Each contain sugar ribose, phosphate group, and one of 4
nitrogenous bases
★ Adenine, guanine & cytosine are same as in DNA , but thymine
is replaced by uracil in RNA
★ Like thymine, uracil is a pyrimidine
★
Friday, June 12, 15
thymine
uracil
in DNA only
in RNA only
RNA is another example of a nucleic acid
★
RNA (ribonucleic acid) - polymer of nucleotides
Each contain sugar ribose, phosphate group , and one of 4
nitrogenous bases
★ Adenine, guanine & cytosine are same as in DNA , but thymine
is replaced by uracil in RNA
★ Like thymine, uracil is a pyrimidine
★
★
Function of RNA is related to protein synthesis
★
RNA - single-stranded molecule that comes in 3 forms: thesis.
Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
Friday, June 12, 15
Nucleic Acids
What makes nucleic acids different from all other molecules is
ability to self-replicate (copy themselves)
★
★ Allows
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genetic information in a cell to “outlive” cell itself
DNA
RNA
Building
Blocks
Polymer of
nucleotides
polymer of
nucleotides
Nucleotide
nitrogenous base
Deoxyribose sugar
phosphate group
Nitrogenous Base
Ribose Sugar
Phosphate Group
Nitrogenous
Bases
Adenine, cytosine,
Thymine, Guanine
Adenine, cytosine,
guanine, uracil
Structure
double stranded
helix
H-bonds hold two
strands together
Single stranded
Friday, June 12, 15