Chapter 12: DNA

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Chapter 12 DNA RNA

• What do you already know about DNA?
• DNA Clearly Stated

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12.1 Three important functions of DNA

• Store genetic information stores genes
• Copy information copy genes prior to cell
  division
• Transmit the information pass genetic
  information along to next generation

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12.2 Structure of DNA

• DNA Deoxyribonucleic Acid
• A nucleotide is composed of
• Sugar (deoxyribose)
• Phosphate group
• Nitrogenous Base
• A nucleotide is the monomer of a DNA strand
  (polynucleotide)

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12.2 Structure of DNA

• DNA is a double-stranded helix
• James Watson and Francis Crick
• Worked out the three-dimensional structure of
  DNA, based on work (photos taken using x-ray
  crystallography) by Rosalind Franklin

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12.2 Structure of DNA

• The structure of DNA
• Consists of two polynucleotide strands wrapped
  around each other in a double helix (twisted
  ladder)

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12.2 Structure of DNA

• Hydrogen bonds (weak) between bases
• Hold the strands together
• Each base pairs with a complementary partner
• A with T, and G with C

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12-3 DNA Replication

• When does DNA replicate?
• DNA must copy before cell division (mitosis)
• How does it replicate?
• DNA is separated by helicase (enzyme)
• Nucleotides are added according to base pairing
  rules, using DNA polymerase (enzyme).

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12-3 DNA Replication

• DNA replication is semi-conservative
• The parent strand gives rise to two daughter
  strands.
• Each daughter strand is composed of one half the
  parent (old strand) and one half new.

Parental strand
Origin of replication
Daughter strand
Bubble
Two daughter DNA molecules
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12.3 DNA Replication

• DNA replication is a complex process
• The helical DNA molecule must untwist
• Each strand of the double helix is oriented in
  the opposite direction (antiparallel)

• DNA has three prime (3) and five prime (5)
  ends. Numbers refer to the position of the
  carbon atoms on ribose sugar.

DNA Replication Video
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Chapter 12 Protein SynthesisWhat is DNA?
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Chapter 13 Protein Synthesis - Overview

• The DNA of the gene is transcribed into RNA
• Which is translated into protein
• The flow of genetic information from DNA to RNA
  to Protein is called the CENTRAL DOGMA

DNA
Transcription
RNA
Translation
Protein
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Chapter 12 Protein Synthesis (Overview)
Central Dogma - FLOW IS FROM DNA TO RNA TO PROTEIN
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FLOW IS FROM DNA TO RNA TO PROTEIN
Chapter 13 Protein Synthesis (Overview)

• Genes on DNA are expressed through proteins,
  which provide the molecular basis for inherited
  traits
• A particular gene, is a linear sequence of many
  nucleotides
• Specifies a polypeptide (long protein made of
  amino acids)

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Chapter 12 Protein Synthesis (Overview)
Genes - discrete units of hereditary information
comprised of a nucleotide sequence found in a DNA
molecule.
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12.1 RNA

• Three Types of RNA
• Messenger RNA (mRNA) carries copies of genes
  (DNA) to the rest of the cell.
• Ribosomal RNA (rRNA) make up the ribosomes.
• Transfer RNA (tRNA) transfers the amino acids
  to the ribosomes as specified by the mRNA

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12-1 Messenger (mRNA)

• Three main differences between mRNA and DNA
• Ribose instead of deoxyribose
• mRNA is single stranded
• mRNA has uracil in place of thymine (U instead of
  T)

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• 12.1 TRANSCRIPTION The process of making mRNA
  from DNA
• Why do you need this process?
• Location of DNA? Nucleus
• Location of Ribosome? Cytoplasm
• mRNA takes code from DNA in the nucleus to the
  cytoplasm

Strand to be transcribed
DNA
Transcription
G
U
U
U
A
G
A
U
A
A
G
U
RNA
Startcondon
Stopcondon
Translation
Met
Lys
Phe
Polypeptide
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• Transcription produces genetic messages in the
  form of mRNA
• 12.1 In the nucleus, the DNA helix unzips
• And RNA polymerase lines up nucleotides along one
  strand of the DNA, following the base pairing
  rules
• As the single-stranded messenger RNA (mRNA) peels
  away from the gene
• The DNA strands rejoin

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C
C
A
A
T
T
A
U
T
C
G
T
U
G
A
C
A
U
C
C
A
C
C
A
G
A
T
T
G
G
A
T
Direction of transcription
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12-3 Protein Synthesis - Translation

• Translation is defined as going from mRNA to
  protein
• tRNA which have amino acids attached are going to
  the ribosome in the cytoplasm.
• What are amino acids? monomers of proteins
• Does the order of amino acids matter? Yes, they
  must be in order for the protein to fold
  correctly.

Amino acid attachment site
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Transfer RNA (tRNA) molecules serve as
interpreters during translation

• How does the correct tRNA (with amino acid
  attached) bind to the mRNA? The tRNA contains an
  anticodon which matches up with the mRNA sequence
  (codon).

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Amino acid attachment site
Amino acid attachment site
Hydrogen bond
RNA polynucleotide chain
Anticodon
Anticodon
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12.3 Translation

• Ribosomes build polypeptides (proteins)
• A ribosome consists of two subunits
• Each made up of proteins and a kind of RNA called
  ribosomal RNA
• Translation at Ribosome

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12.3 Translation

• The subunits of a ribosome
• Hold the tRNA and mRNA close together during
  translation

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Figure out the exact sequence of amino acids
needed

• Take the DNA and transcribe it into mRNA
• Example TAC ATA CTA GCG ACT
• mRNA
• Take the mRNA sequence and decode it using the
  codon chart.

AUG
UAU
GAU
CGC
UGA
AUG MET
UAU TYR
GAU ASP
CGC ARG
Animation
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13.3 Mutations

• Mutations heritable changes in genetic
  information (changes to the DNA sequence)
• Two types - gene and chromosomal mutations
• Mutations can be caused by chemical or physical
  agents (mutagens)
• Chemical pesticides, tobacco smoke,
  environmental pollutants
• Physical X-rays and ultraviolet light

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13.3 Mutations

• Gene mutations
• Point Mutation mutations that affect a single
  nucleotide
• Frameshift mutation shift the reading frame of
  the genetic message.
• Can change the entire protein so it doesnt work
• Gene Mutations Explained

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13.3 Mutations
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13.3 Chromosomal Mutations

• Chromosomal mutation mutation that changes the
  number or structure of chromosomes.

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13.3 Chromosomal Mutations

• Types of chromosomal mutations
• Deletion The loss of all or part of a
  chromosome
• Duplication A segment is repeated
• Inversion part of the chromosome is reverse
  from its usual direction.
• Translocation one chromosome breaks off an
  attaches to another chromosome.

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DNA Modeling

• Each person, Construct the DNA Strand Below
• Then, construct the complimentary strand to make
  a complete DNA molecule
• Ignore the color scheme below. Use
• Cytosine Blue Deoxyribose Sugar Black
  Pentagon
• Thymine Green Phosphate White Tubes
• Adenine Orange Ribose Sugar Purple Pentagon
• Guanine Yellow tRNA Purple Plastic
• Uracil Purple Amino Acid Black Plastic
• When you have constructed the complementary
  strand join the two strands together
• with Hydrogen bonds

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Transcription and Translation Modeling

• Each group will construct an mRNA strand from the
  DNA strand below
• Then, take your mRNA strand outside the nucleus
  to the ribosome
• Use the codons of mRNA and anticodons of tRNA to
  manufacture proteins
• Use the following model pieces
• Cytosine Blue Deoxyribose Sugar Black
  Pentagon
• Thymine Green Phosphate White Tubes
• Adenine Orange Ribose Sugar Purple Pentagon
• Guanine Yellow tRNA Purple Plastic
• Uracil Purple Amino Acid Black Plastic
• Peptide Bonds (between AAs) Grey Tubes
• When you have constructed the complementary
  strand join the two strands together
• with Hydrogen bonds

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Making a DNA Molecule

• Must Contain
• Deoxyribose Sugar Pentagon shape
• Phosphate Group Circle
• At least 6 base pairs (complimentary base pair
  must be interlocking)
• Label all parts of the DNA
• Question How could the structure of a DNA
  molecule allow it to carry information and
  replicate (make copies of itself).

Backbone
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HIV Images NPR Story Toddler
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DNA Structure Questions

• What pair of scientists are largely credited for
  discovering the shape of the DNA molecule?
• Name the scientist whose photographs helped solve
  the mystery of DNAs structure
• DNA is in the shape of a _______ _______.
• What are the sides of the DNA molecule made of?
  (2 things)
• What are the rungs of the ladder made of?
• What is the monomer of DNA?
• What holds nitrogenous bases together?

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DNA early scientists

• Scientist/Experiments
• What did Griffith call the phenomenon he observed
  in the mouse experiment?
• What did Hershey and Chase mark the bacteriophage
  with? What parts were marked?
• How did marking the bacteriophage assist in
  determining DNA was the transforming factor?

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Bryson Reading Discovery of DNA

• Section 1.
• Why is it surprising that the scientists working
  in England even discovered the structure of DNA?
• When did Watson start college and when did he get
  his Ph.D.?
• Section 2.
• Why was understanding the shape of DNA so
  important?
• What did Watson remark about that is surprising
  in his autobiography?

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Bryson Reading Discovery of DNA

• Section 3.
• How did Watson depict Rosie Franklin in his book
  The Double Helix?
• What did Rosie Franklin have that at the time was
  the best in the field?
• What method was Franklin using to capture DNA
• Section 4.
• How were women treated at Kings College?
• What did Franklin do to throw her colleagues off
  the trail?
• How did Watson and Crick eventually see
  Franklins photos?

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Central Dogma Questions

• The flow of genetic information is from ______ to
  ______ to ______.
• Why does DNA send a messenger out into the
  cytoplasm?
• The manufacture of mRNA from DNA is called
  _____________.
• What cellular organelle uses the DNA codes to
  manufacture proteins?
• How is DNA ultimately associated with our
  phenotype or outward appearance?

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Homework Chapter 13 Sections 13.3 and 13.4

• Section 13.3 Mutations 372-376
• Explain the difference between the three types of
  point mutations?
• How do point mutations differ from chromosomal
  mutations?
• Explain how mutations could be harmful or
  beneficial

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• Section 13.4 Gene Regulation and Expression
  377-383
• Describe how prokaryotes turn lac genes on and
  off (mention promoters, operators, lactose,
  repressor, and RNA polymersase)?
• How do eukaryotes regulate genes during
  transcription?
• What do homeotic genes like homeobox and hox
  genes have to do with development? What is the
  difference between homeobox and hox genes?

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Drawing a DNA Molecule

• Must Contain
• Deoxyribose Sugar Pentagon shape
• Phosphate Group Circle
• At least 6 base pairs (complimentary base pair
  must be interlocking)
• Label all parts of the DNA
• Question How does the structure of a DNA
  molecule allow it to carry information and
  replicate.
• Worth 20 Points

Backbone
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• Please complete the following
• The complementary DNA strand for
• GACTGAGGA
• The mRNA strand for
• GACTGAGGA
• Translate the mRNA sequence to amino acids
• CCAUUUACG
• Translate the mRNA codons to tRNA anticodons
• CCAUUUACG

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• Extra Credit
• Biology 1 pts each
• What is one part of the cell theory?
• What are the single units of a polymer called?
• Non Bio 2 pts
• Title and artist of these lyrics
• 3. Aww, he got the velcro!

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Mutations
FANTASY
REALITY
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Mutations
FANTASY
REALITY