Do Now

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Do Now

• What is DNA?
• Why is it important?
• Who helped to discover DNA and its structure?
• Draw a picture of what you think DNA looks like.

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DNA

• The Molecule of Life

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Objectives

• To explain the structure of DNA
• To identify the different types of bases and
  which pair with which.
• To list the scientists involved in discovering
  DNA.

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DNA fun facts - true or false?

• Your DNA is 99.9 similar to your classmates
• Identical twins have the same fingerprints
• Identical twins have the same DNA
• You share 50 of your DNA with a banana
• DNA is only found in some of your cells
• DNA and RNA are structurally the same
• A mutation in your DNA can turn you into a zombie
• You eat DNA everyday
• DNA lab techniques are used to solve crime
• The first cloned mammal was a cat.

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DNA cookbook for you!
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All your cells have same cookbook (DNA) but
following different recipes (GENES)
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DNA

• What do the letters stand for?
• DEOXYRIBONUCLEIC ACID
• Where is it found?
• In the nucleus (or nuclear region in prokaryotes)
• What is it used for?
• Blueprints of your genes/traits

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DNA Structure

• DNA often is compared to a twisted ladder.
  (double helix)
• Rails of the ladder are represented by the
  alternating deoxyribose(sugar) and phosphate.
• The pairs of bases (cytosineguanine or
  thymineadenine) form the steps.
• (Is this a monomer, or polymer?)

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What is DNA Made of?

• Repeating units of nucleotides

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DNA STRUCTURE

• Nucleotides
• 5 carbon sugar (Deoxyribose)
• Phosphate Group
• Nitrogen base

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DNA has four different nitrogenous bases

• Cytosine   C
• Thymine   T
• Adenine   A   
• Guanine   G

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Nitrogenous Bases

• Purines
• Double ring structure
• Adenine and Guanine
• Pyrimidines
• Single ring structure
• Thymine, Cytosine, Uracil

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Nitrogenous Bases
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Erwin Chargaff

• Chargaffs rule
• C G
• T A

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What does DNA mean?

• Every three letters codon DNA word
• Each codon represents one amino acids
• Amino acids make up proteins! YOU!

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Draw in the complimentary sequence

• ATGCTAATTCGCATCG

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Two Stranded DNA - discussion

• Remember, DNA has two strands that fit together
  something like a zipper.
• The teeth are the nitrogenous bases but why do
  they stick together?

  
 
  
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Hydrogen Bonds

• The bases attract each other because of
  hydrogen bonds.
• Hydrogen bonds are weak but there are millions
  and millions of them in a  single molecule of
  DNA.

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Label the parts of the DNA molecule
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Rosiland Franklin
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Rosiland Franklin

• X-ray Diffraction use of photo 51
• X-ray diffraction data helped solve the structure
  of DNA
• Indicated that DNA was a double helix

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X-Ray Crystallography
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Watson and Crick
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Watson and Crick

• Built a model of the double helix that conformed
  to the others research
• two outside strands consist of alternating sugar
  and phosphate molecules
• cytosine and guanine bases pair to each other by
  three hydrogen bonds
• thymine and adenine bases pair to each other
  by two hydrogen bonds

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• Structure Worksheet!

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Do Now

• How does DNA get into EVERY cell of our bodies?
• Is it the same in every cell?
• What is RNA?
• How is it different from DNA?

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Objectives

• To understand how DNA is replicated.
• To compare and contrast DNA vs. RNA.

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DNA Replication

• Allows cells to get an exact copy of DNA.

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Steps to Replication

• 1- The two DNA strands unwind and separate.

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Steps to Replication

• 2- Nucleotides in the area around the DNA match
  up base by base with the nucleotides on each
  TEMPLATE DNA strand.
• All of the Cs pair with the Gs and all of the
  As pair with the Ts.

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Steps to Replication

• 3- Each new molecule has one strand of new DNA
  and one from the original strand.

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Replication Animation

• http//www.johnkyrk.com/DNAreplication.html

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What is DNA responsible for again?
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Protein synthesis

• DNA cookbook for making you protein!
• Proteins made in ribosomes (CHEF)

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Examples of proteins

• Insulin

• Melanin

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RNA is needed to make proteins!

• What is RNA?
• Ribonucleic Acid
• How is it different from DNA?
• Single Stranded
• Indefinite shape
• Uses uracil
• Contains Ribose

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Types of RNA

• Messenger RNA (mRNA)- (like a secretary!)
• Located in both the nucleus and the cytoplasm
• Brings genetic code from DNA to the ribosome to
  make protein

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Types of RNA

• Ribosomal (rRNA)
• Located within the ribosome
• Helps make the structure of the ribosome

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Types of RNA

• Transfer (tRNA)
• Located in the cytoplasm
• Brings amino acids to ribosome to build proteins.

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DNA?RNA?Protein

• Transcription
• Occurs in nucleus
• Create mRNA from DNA
• Translation
• Occurs in cytoplasm
• Takes mRNA and makes proteins with the help of
  tRNA.

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• DNA vs. RNA worksheet!

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Do Now

• What are the 3 types of RNA?
• What is the purpose of each of them?
• What are the names of the two processes involved
  in making proteins?

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Objectives

• To understand how mRNA is made.
• To determine how proteins are made through the
  process of translation.

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Transcription

• Only individual genes are transcribed, not a
  whole DNA molecule.
• What is the first step to making a protein?

  
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Transcription

• Step 1 DNA molecule unwinds and separates just
  like in replication.

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Transcription

• Step 2 RNA nucleotides match up with their
  complimentary bases on the template strand.
• Practice Write the complimentary mRNA strand
  from this DNA
• ATCGATGGCAAGCTA

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Transcription

• Step 3 mRNA detaches once entire gene is done
  and the DNA recoils.
• Many copies of RNA can be made from the same
  gene in a short period of time.

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Translation

• What happens in translation?
• Where does this happen?

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Translation

• Step 1 Translation begins when a ribosome
  attaches to the beginning end of an mRNA
  molecule.
• Translation MUST START AT THE LETTERS AUG.
• Every 3 letters on the mRNA is called a Codon
  that codes for a specific amino acid.

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• CODON BINGO!!

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Translation

• Step 2 A tRNA molecule carrying an amino acid
  matches up to a complementary codon in the mRNA
  on the ribosome.
• tRNA molecules contain Anticodons which are 3
  bases on the tRNA.

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Translation

• Step 3 The ribosome attaches one amino acid to
  another as it moves along the mRNA molecule.
• Amino acids are attached by PEPTIDE BONDS.

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Translation

• Step 4 The tRNA molecules are released after the
  amino acids they carry are attached to the
  growing chain of amino acids.

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Translation

• Step 5 The ribosome completes the translation
  when it reaches a stop codon. The newly made
  protein molecules in the form of a chain of amino
  acids, is released.

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Practice!

• Translate this mRNA sequence.
• Remember to start and stop at the right
  places!!
• TCACTAUGCGGACGGACATTATCG

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• Translation Practice Worksheet!