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DNA vs. RNA Structure and
DNA Replication Notes
I. Functions of DNA = “Blueprint of Life”
• Storing Information
– Store the genes that code for basic instructions
for cells and cell parts, physical traits, diseases,
etc.
• Eye color, blood type, skin color, diabetes, etc.
• Copying Information
– Before a cell divides, it must make a copy of
every one of its genes
• Process called DNA replication
• Transmitting Information
– Genes are transmitted from one generation to the
next
• DNA must be carefully sorted and passed along during
mitosis and meiosis
II. Basics of DNA Structure
Nucleic Acid
DNA - stands for
deoxyribonucleic acid
Double Helix
Monomer is a nucleotide:
Phosphate
Sugar (Deoxyribose)
Nitrogen Bases
Adenine
Guanine
Cytosine
Thymine
NUCLEOTIDE IS THE
MONOMER!
DNA Structure (more details)
• Sugar/Phosphate “Backbone”
– Sides of ladder
– Covalent bond between
sugar and phosphate
• Nitrogen Bases in center
– Steps of ladder
– Hydrogen bond between
Nitrogen bases
• Double Helix
– Twisted ladder
• 2 rings = purines; 1 ring = pyrimidines
• Anti-parallel
– two strands of DNA run in opposite
directions
DNA is Anti-Parallel
The two strands
of DNA run in
opposite directions
This allows for the
bases to come in
contact at the
center of the
molecule
DNA -Complementary Base Pairing
A-T and C-G pairs are the
only ones physically
possible (Chargaff’s Rules)
Hydrogen bonds between
nitrogen bases
Adenine & Thymine
2 hydrogen bonds
Guanine and Cytosine
3 hydrogen bonds
LET’S PRACTICE!
Copy down the strand of DNA and write the
complementary base pairs
A
T
C
C
G
G
A
T
II. Basics of RNA Structure
Nucleic Acid
RNA - stands for
ribonucleic acid
Single Helix
Monomer is a nucleotide:
Phosphate
Sugar (Ribose)
Nitrogen Bases
Adenine
Guanine
Cytosine
Uracil
RNA Structure (more details)
• Sugar/Phosphate “Backbone”
– Sides of ladder
– Covalent bond between
sugar and phosphate
• Nitrogen Bases in center
– Steps of ladder
• Single Helix
• 2 rings = purines; 1 ring = pyrimidines
• 3 Types of RNA:
– mRNA – messenger
– rRNA – ribosomal
– tRNA - transfer
DNA Only
-Uses Thymine
RNA Only
Both
-Uses Uracil
-Uses A, G, C
-Single stranded
-Cannot leave the
nucleus
-type of
-Can leave the nucleus
nucleic acid
-Uses ribose sugar
-Uses deoxyribose sugar
-stores info
-Acts as blueprint for
protein production
-made of nucleotides
-Works in actual
protein production
-Double stranded