DNA Deoxyribonucleic Acid

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DNADeoxyribonucleic Acid
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DNA Structure
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What is DNA?

• The information that determines an organisms
  traits.
• DNA produces proteins which gives it The power
• Many things contain and are made of proteins.
• Skin, hair, bones, etc are made of proteins.

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What is DNA? Contd

• Enzymes are special proteins.
• Enzymes control chemical reactions needed for
  life.
• DNA contains all the information for making all
  and any proteins for human life.

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DNA Structure

• DNA is made of repeating subunits called
  nucleotides.
• Nucleotides have three parts
• Simple sugar
• Phosphate group
• Nitrogen base

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1 Nucleotide
Phosphate Group
Nitrogen Base
Sugar (Deoxyribose)
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DNA Structure

• The simple sugar is called deoxyribose.
• The phosphate group is made of phosphate and
  oxygen.

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DNA Structure

• Four possible Nitrogen Bases
• Thymine (T)
• Adenine (A)
• Cytosine (C)
• Guanine (G)

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DNA
Backbone

• Nucleotides join together to form long chains.
• The phosphate group of one nucleotide joins
  together with the deoxyribose sugar of an
  adjacent nucleotide.

Teeth
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DNA

• Nitrogen bases pair up
• Adenine Thymine (A-T)
• Cytosine Guanine
• (C-G)
• Complementary bases

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Watson Crick, 1953

• Proposed DNA is put together like a twisted
  zipper
• DNA 2 chains of nucleotides joined by nitrogen
  bases

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Watson Crick, 1953Double Helix

• Double DNA has two strands
• Helix twisted like a spring, spiral

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Importance of Sequencing

• The sequence of the four different nucleotides
  determines what organism is created.
• For instance T-A-A-G-C-A is different than
  A-G-C-A-A-G
• Another example E-A-R-T-H is different than
• H-E-A-R-T

vs.
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Importance of Sequencing

• The more similar the order of nucleotides are,
  the closer the relationship between 2 organisms

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DNA Replication
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DNA Replication

• Replication to copy
• Process of copying DNA in the chromosomes
• Without DNA replication, a new cell would only
  have half of its information.

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DNA Replication

• DNA Replication Video

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DNA Replication 2

• Replication VIDEO

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DNA Replication

• Because of the pairing- if you have one strand,
  it is easy to predict the replicated strand.
• T-A-G-C-C-G-T
• Remember A goes with T, C goes with G
• A-T-C-G-G-C-A

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DNA Replication

• Remember The nitrogen bases are held together by
  hydrogen bonds
• An enzyme goes to those hydrogen bonds and breaks
  them Double Helix Unzips

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DNA Replication
Step 1 Separate the two DNA strands
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DNA Replication
Step 2 Original DNA strands act as templates
complementary nucleotides fill in.
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DNA Replication
Step 3 Nucleotides connected and a new
sugar-phosphate backbone is formed.
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DNA Replication
Each new DNA molecule consists of one original
strand and one new strand
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So now what??
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DNA to Protein

• DNA encodes the instructions for making proteins.
  
• Remember proteins make up your bones, skin, etc.
• Enzymes are special proteins
• Enzymes control all chemical reactions in an
  organism

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DNA to Protein

• Proteins are made up of many amino acids
• The order of nucleotides in each gene has
  information on how to make the string of amino
  acids which is a protein.
• ESTIMATE Each cell contains about 800,000 genes

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We need to figure out how to get from DNA to
Proteins!
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RNA

• What is it?
• What does it do?

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RNA vs. DNA

• RNA
• Single Stranded- only half of a zipper
• Contains the sugar Ribose
• Contains the nitrogen bases
• Adenine
• Uracil
• Guanine
• Cytosine

• DNA
• Double Stranded- double helix
• Contains the sugar Deoxyribose
• Contains the nitrogen bases
• Adenine
• Thymine
• Guanine
• Cytosine

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RNA

• Its job Copying DNA
• Its goal To create proteins
• There are 3 types, each with a different job
• mRNA Messenger RNA copies DNA to take it out in
  the cytoplasm
• rRNA Ribosomal RNA works on matching mRNA - to
  create the amino acids in the correct order
• tRNA Transfer RNA gives amino acids to rRNA to
  produce the protein.

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mRNA

• Brings information (in the form of an RNA strand)
  from the DNA in the nucleus to the cytoplasm

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rRNA

• Ribosomes are made of rRNA
• Where are ribosomes found?
• Cytoplasm
• rRNA attaches to the mRNA and uses its
  information to set up the amino acids in the
  correct order

Ribosome
mRNA
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tRNA
Amino Acid

• The supplier
• Brings amino acids to the ribosome so that it can
  assemble the protein

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Review Questions

• How does information from the DNA get to the
  cytoplasm?
• How does the zipper get unzipped in DNA
  replication?
• Who does the work in getting the amino acids to
  the worker?
• What is the formal name of the worker

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Transcription
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Transcription

• Transcriptions purpose is to create a single
  stranded RNA molecule rather than a double
  stranded DNA molecule.
• This is needed to allow the single stranded RNA
  to be taken out of the nucleus by the mRNA to the
  cytoplasm.

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Transcription

• Transcription Tutorial / SHOW
• Transcription mRNA VIDEO

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Genetic Code with mRNA

• In order to take the DNA and create a mRNA, there
  are special codes used.
• In mRNA, three nitrogen bases together form a
  code this is called a codon.
• Looking ahead
• this code is matched with an amino acid.
• A string of amino acids form a protein.

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Genetic Code with mRNA

• Some codons code for information other than amino
  acids
• UAG is an example of a stop codon.
• AUG is an example of a start codon.
• NOTE For every one codon, there is only ONE
  amino acid that can join.

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Transcription Pictures
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Transcription Pics
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How does this work in the cell?
mRNA COPIES DNA INTO CYTOPLASM
NUCLEUS
DNA
rRNA USES PLAN FROM mRNA TO PUT AMINO ACIDS IN
ORDER TO MAKE PROTEINS
AMINO ACIDS TRANSPORTED BY tRNA
RIBOSOME
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Translation
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Translation From mRNA to Protein

• The process of changing the information from an
  order of nitrogen bases in mRNA into the order of
  amino acids
• Occurs at the ribosomes in the cytoplasm

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Translation

• When mRNA enters the cytoplasm, ribosomes attach
• 20 different amino acids must be brought to the
  ribosomes for proteins to be made
• tRNA brings the amino acids to the mRNA strand

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Translation
Amino Acid

• On the opposite side of the tRNA amino acid side
  is a set of three nucleotides that are the
  complement of the nucleotides codon
• This is called an Anticodon

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Translation

• When a match is made between codons and
  anticodons- a temporary bond is formed.
• This places the amino acid in the correct
  position to enable it to bond with the next amino
  acid

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Translation

• The next tRNA bonds to its codon and then the
  two amino acids bond together.
• The first amino acid then releases itself from
  the mRNA

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Translation

• This continues until a stop codon is reached.
• Amino acid chains then become proteins when they
  are freed from the ribosome and twist and curl
  into complex three-dimensional shapes.

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Translation
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Translation

• Translation VIDEO

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