DNA Deoxyribonucleic Acid

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DNADeoxyribonucleic Acid

• Chapter 11
• Page 287

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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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DNA Structure

• The simple sugar is called deoxyribose.
• The phosphate group is made of phosphate and
  oxygen.
• There are four possibilities to Nitrogen bases
• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Thymine (T)

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DNA

• Nucleotides join together to form long chains.
• The phosphate group of one nucleotide joins
  together with the deoxyribose sugar of an
  adjacent nucleotide.
• The phosphate groups are thought of as the
  backbone of the chain
• The nitrogen bases are thought of as teeth coming
  off the structure.

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DNA Nitrogen bases

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

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Watson and Crick

• First people to propose that DNA is made of two
  chains of nucleotides joined together by the
  nitrogen bases
• They believed that the two strands are joined by
  complimentary bases
• A-T
• C-G
• They also proposed that DNA is put together like
  a zipper that is twisted.
• When something is twisted like a spring, it is
  called a helix.
• Because DNA has two strands it is called a Double
  Helix.

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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
• In English - E-A-R-T-H Is different than
  H-E-A-R-T
• They have the same letters, just a different
  order and mean different things.
• Can you think of any other words that you can do
  this with?
• The closer the order is to another order, the
  closer the relationship between the two organisms.

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Importance of Sequencing

• Scientists can use the sequencing to find out
  evolutionary history.
• For instance, gorillas and chimpanzees might have
  similar sequencing but chimpanzees and rose
  bushes would not be very similar.
• DNA sequencing can also be used to show whether
  two people are related or not.
• DNA sequencing can also be used to correlate
  someone to a crime scene.

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• END OF DAY 1

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DNA Replication

• DNA is copied this is called replication
• Without DNA replication, a new cell would only
  have half of its information.
• All organisms undergo DNA replication

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DNA Replication

• 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
• Would be replicated by matching T, with A, G with
  C
• A-T-C-G-G-C-A

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DNA Replication

• Remember The nitrogen bases are held together by
  hydrogen bonds
• There is an enzyme that goes to those hydrogen
  bonds and breaks them
• This causes the double helix structure to break
  apart or Unzip
• There are nucleotides that are floating around.
• These nucleotides are like puzzle pieces
• They each try to attach to the original
  nucleotide.

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DNA Replication

• The unzipping continues until the entire strand
  is done.
• The original DNA now has a complimentary strand.
• The result is two DNA molecules which is
  identical to the original.
• The end product is that there are two copies of
  the organisms genetic makeup.

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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 Replication

• 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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RNA

• There are three key differences between RNA and
  DNA
• RNA is single stranded only half of a zipper
  DNA is double stranded zipper
• RNA is made of the sugar Ribose DNA is made of
  deoxyribose
• RNA has Uracil instead of Thymine Both DNA and
  RNA have four nitrogen bases the difference is U
  vs T

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RNA

• RNA has the job of copying DNA
• The goal of RNA is to create proteins
• There are three 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

• Messenger RNA is responsible for uncoding the DNA
  and creating RNA (in a process called
  transcription) for mRNA, rRNA, and tRNA to read.
• Messenger RNA is responsible for bringing the
  information transcripted RNA to the cytoplasm.
• WHY in the cytoplasm?

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rRNA

• Ribosomal RNA are made of ribosomes.
• Where are ribosomes found?
• In the cytoplasm. They are not bound to any one
  organelle.
• rRNA attaches to the mRNA
• rRNA then begins to use the information from DNA
  that mRNA brought out.
• rRNA uses the information to set up the amino
  acids in the correct order.

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tRNA

• tRNA is the supplier
• tRNA gives amino acids to rRNA so that rRNA 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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END OF DAY 2
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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
• UAA 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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END OF DAY 3
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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 is called translation.
• This takes place at the ribosomes in the
  cytoplasm

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Translation

• When mRNA enters the cytoplasm, ribosomes attach
• For proteins to be made-20 different amino acids
  must be brought to the ribosomes.
• This is what tRNA does brings the amino acids
  to the mRNA strand

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Translation

• On the opposite side of the tRNA amino acid side
  is a set of three nucleotides that are the
  complement of the nucleotides codon.

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Translation

• These three nucleotides are called anticodons
  because they bond to the codon of the mRNA
• The tRNA is made of only the anticodon and the
  amino acid.

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Translation

• When a match is made- 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

• Translation VIDEO

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