DNA
Roles of DNA
1.
2.
Pop Quiz
1. What was the main goal of Griffith’s experiment?
What was the procedure?
What were the results?
2. What was the main goal of the experiment performed by Hershey and
Chase?
What was the procedure?
What were the results?
3. How did Watson and Crick use the discoveries of scientists before them to develop the alpha
helix model of DNA?
Discovery
Griffith’s Experiment (1928)
Avery (1944)
Chargaff (1949)
Hershey and Chase
Wilkins and Franklin (1952)
Nucleotides
A Closer look…
Watson, Crick, and the Double Helix
Nucleotides
A Closer look…
Base Pairing Rules
Human Genome Project
DNA Replication
http://www.mcb.harvard.edu/losick/images/trombonefinald.swf
http://www.pc.maricopa.edu/Biology/rcotter/BIO%20205/LessonBuilders/Chapter%209%20LB/DNAReplication.mpg
Protein Synthesis
Protein Synthesis
Protein Synthesis
Part I: Transcription
Part II: Translation
Gene Expression/Regulation in
Prokaryotes
Gene Expression in Eukaryotes
Homeotic Genes
Homeotic Genes/Homeobox
DNA Structure and Function
Watson and Crick
• An Englishman and an
American discovered
the structure of DNA in
1954.
• DNA is to small to see
so they had to build a
model using x-Rays and
chemical information
about Nitrogen bases
They Had Some Help
• Roselyn Franklin took this x-ray picture of DNA which
lead Watson and Crick to the double helix structure
of DNA but they failed to give her credit until much
later.
Double Helix
• DNA consists of two
strips, made of
sugars and
phosphates, twisted
around each other
and connected by
nitrogen bases.
• Looks like a spiral
staircase or a twisted
ladder.
Sugar Backbone
• The backbone of DNA is
made up of
Deoxyribose (Sugar)
molecules connected to
each other using
Phosphates
Nitrogen Bases
• DNA contains 4
nitrogen bases that
make up the “code”
for all living things.
A = Adenine
T = Thymine
G = Guanine
C = Cytosine
A always bonds to T
G always bonds to C
Nucleotide
• The combination of a sugar, phosphate and nitrogen
base is called a Nucleotide. These are the building
blocks of DNA.
Key Words for Protein Synthesis
• Gene- section of DNA that codes for a specific
protein.
• Messenger RNA (mRNA)- nucleic acid that
copies the DNA and takes it to the Ribosome.
• Ribosome- Organelle that builds proteins using
mRNA and tRNA.
• Transfer RNA (tRNA)- nucleic acid that
matches up codon to anticondon and drops off
amino acids in the correct order.
Key Words Continued
Codon- Group of three nitrogen bases found on
the mRNA that codes for a specific amino
acid.
Anticodon- Group of three nitrogen bases
found on the tRNA that matches up with the
codon and drops off the correct amino acid.
Amino Acid- Building blocks of proteins that are
placed in the correct order by matching codon
to anticodon along the length of a gene.
Steps to Protein Synthesis
Transcription
• DNA Opens one Gene
• One side of the DNA is copied by the mRNA
• mRNA travels outside the Nucleus to the Ribosome
Translation
• Ribosome attaches to the mRNA.
• tRNA matches up codon to anticodon and drops
off the correct amino acid
• A chain of amino acids is created which is a protein
Translation
Protein Synthesis Models
• https://www.youtube.com/watch?v=NJxobgkP
EAo&list=FLEezLUmpa3vfMmQGp1aPTQ&feature=mh_lolz
https://www.youtube.com/watch?v=u9dhO0iCLww&list=FLEezLUm-pa3vfMmQGp1aPTQ