Please sign in and get a piece of
paper
Draw a picture of DNA
Draw a picture of a nucleotide
DNA
• DNA’s shape is a double helix
• Sides of ladder (Backbone) = Deoxyribose Sugars and
Phosphates
• Rungs of ladder (middle) = Nitrogen Bases
• The two strands are held together by HYDROGEN bonds
• A binds to T
• C binds with G
DNA Nucleotides:
Subunits that make up DNA
– 3 Parts:
1. Phosphate group
2. 5 Carbon Sugar (Deoxyribose)
3. Nitrogen-Base (ATGC)
PBS!!!
Base Pairing
• Nitrogen Bases are held together by weak
hydrogen bonds.
• Nitrogen Bases:
Adenine, Thymine, Guanine, Cytosine
–A with T (Apple in the Tree)
–C with G(Car in the Garage)
YOUR TURN! (2min)
• WHAT ARE THE COMPLIMENTARY NITROGEN
BASES TO THE FOLLOWING DNA SEGMENTS?
• 1. TTACGGCTA
4. CGCTACCGA
• 2. ACTGGCTAT
5. GGTCACAAT
• 3. GACTGGACT
Describe how DNA replicates itself
2 min
DNA Replication
•
•
Process of DNA copying itself
Steps
• DNA Unzips (Hydrogen bonds break)
• Each side acts as a template
• New DNA nucleotides are added according to base-pairing rules
• Two new molecules of DNA result – each with one old and one new
strand. (semiconservative)
• Happens in INTERPHASE (s phase) (before mitosis or meiosis)
Create a T chart for DNA and RNA
DNA
Both
RNA
DNA and RNA
• How do we go from DNA to the traits that we
see each day?
Protein Synthesis
•
•
•
•
•
Remember, genes are made of DNA and are in the nucleus
Genes (DNA) contain the instruction for making a protein
In transcription, DNA is used to make mRNA in the nucleus
mRNA then leaves the nucleus and goes to the ribosome
In translation, tRNA then brings amino acids in the proper
order to make the protein on the ribosome.
DNA  mRNA  protein
Made of amino acids
Transcription
• mRNA is synthesized from the DNA code
• Occurs in the nucleus
Translation
• Converting RNA to proteins
• Occurs in the cytoplasm
PROTEIN SYNTHESIS
DNA
RNA
PROTEIN
• DNA is in nucleus
• GENES (made of DNA) hold code for protein
• mRNA is made in nucleus
• TRANSCRIPTION
• Remember base pairing rules
• mRNA goes to ribosome
• 3 bases on mRNA is a codon – each codon codes for one amino acid
• tRNA brings the right amino acid to the mRNA
• Anticodon on tRNA base pairs with codon on mRNA
Can you IDENTIFY the parts?
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
DNA
mRNA
Nucleus
Cytoplasm
Ribosome
Codon
Anticodon
tRNA
Amino acid
Protein (polypeptide)
READING THE CODON CHART
• Be sure to use
mRNA
• You won’t have
to memorize this!
• What amino acid
is coded for by
the DNA
ATA GAG
First convert DNA to mRNA
ATA GAG
UAU CUC
UAU = tyr
CUC = Leu
• Using a codon chart:
Let’s Practice:
• Which of these changes to the DNA triplet 3’ GCT
5’ will affect the protein produced?
A. GTT
C. TCC
B. TCT
D. GCA
Now you practice by completing the following
chart:
DNA
mRNA
tRNA
Amino Acid
TCA
GGA
TAA
Methionine
UAA
TTT
AAA
Lysine
YOU ARE ALMOST FINISHED!!!!!!!
YOUR EXIT TICKET FOR THE LESSON IS TO SYNTHESIZE
YOUR OWN PROTEIN!:
1.Create 3 DNA codons
2. Show the complementary mRNA strand
3. Show the complementary tRNA strand
4. Write the corresponding amino acid for each codon.