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Unit 8: Nucleic
Acid
The Genetic Material
DNA
• Deoxyribose nucleic
acid  type of nucleic acid
• DNA function
– to hold genetic code
– Genetic code = genetic
instructions to make
proteins
• DNA is found in nucleus of
eukaryotic cells
Bases:
Adenine
Thymine
Guanine
Cytosine
RNA
• Single stranded
• Found outside of
nucleus to make
proteins.
Bases:
Adenine
Cytosine
Uracil
Guanine
Searching for Genetic Material
• Gregor Mendel
(1866):
– discovered that inherited
traits are determined by
discrete units, or 'genes,’ passed on from the parents.
• Freidrich
Miescher(1868):
– discovered DNA
– Isolated something new
from the nuclei of
eukaryotic cells
• Later called DNA!!!
Discovering the structure of
Photo 51
DNA
Rosalind Franklin
(1952)
•Obtained sharp X-ray photographs
of DNA (Photo 51)
•Watson and Crick used her data 
revealed its helical shape
•Watson and Crick went on to
win Nobel Prize (1962) for their
DNA model
How did PHOTO 51
reveal DNA’s helical
shape?
• X-rays passing through a helix
diffract at angles perpendicular to
helix making an "X" pattern, which
favors an equal diameter "helix".
Discovering the structure of DNA
James Watson & Francis Crick
(1953)
•Discovered double helix structure
•Solved the three-dimensional structure
of the DNA molecule
Watson Constructing Bair Pairs movie
http://www.hhmi.org/biointeractive/dna/animations.html
DNA replication
• Replication – making a copy of DNA
before the cell divides (Mitosis).
• DNA polymerase – enzyme that joins
individual nucleotides to produce a new
copy of DNA
Steps to DNA replication
1. Enzyme (helicase) unzips the DNA.
2. DNA polymerase (enzyme) matches
the correct nucleotide to each side of
the unzipped DNA.
3. DNA polymerase – proofreads their
replication to make sure they did not
make any mistakes.
RNA synthesis
Ribose nucleic acid
• Transcription - RNA polymerase copies
only one strand of the DNA in order to
make the single-stranded RNA.
Protein Synthesis
• Translation – reading RNA in order to
get the correct amino acid.
• Codon – group of 3 bases.
• Amino acids are added for every three
bases to build a protein.
• https://www.youtube.com/watch?v=1YD
TOcAVJrE
Purines
• Adenine & Guanine
• Double ringed
Pyrimidines
• Cytosine, Thymine, Uracil
• Single-ringed
Cell Energy:
• Cells usable source of energy is called ATP
• ATP stands for adenosine triphosphate
Adenine
Ribose
3 Phosphate groups
• ADP stands for adenosine diphosphate
Adenine
Ribose
2 Phosphate groups
• All energy is stored in the bonds of compounds—
breaking the bond releases the energy
• When the cell has energy available it can store this
energy by adding a phosphate group to ADP, producing
ATP
• ATP is converted into ADP by breaking the bond between
the second and third phosphate groups and releasing
energy for cellular processes.
• https://www.youtube.com/watch?v=00jb
G_cfGuQ