DNA is the Master Molecule of Life

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Chapter 7

• DNA is the Master Molecule of Life

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DNA

• The ___________ molecule
• Responsible for ___________________
• Two main qualities
• Holds ____________________________
• Can be _______________

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Discovery of DNA structure and function
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Early 1900s

• Scientists already knew about cellular structure,
  including the nucleus, DNA, and RNA
• A series of experiments revealed that DNA was
  responsible for _________________________________
  _________________
• DNA credited with _______________________________
  _____________________

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Early 1900s

• Question How is DNA able to control trait
  expression and transmission?
• Recall what you know about proteins
  _______________________________
• To answer the above question, scientists
  _________________________________________________
  _________________

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The Players

• ______________ at California Institute of
  Technology
• Knew helical secondary structure of proteins
• _____________________________ at Cambridge
  University
• Good interpreters of crystallography
• __________________________ at Kings College,
  Univ. of London
• Used x-ray crystallography to study structure

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Image by Maurice Wilkins Presented this image at
a conference Watson saw this image and wanted to
study with Wilkins at Kings College One of the
earliest attempts to see the structure of DNA
using x-ray crystallography
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Race to discover DNA structure

• Watson visited Wilkins, who shared
  ________________________________________________
  __
• Franklin was not ________________________________
  ____________________________________

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Race to discover DNA structure

• Franklins crystallography ______________________
  _______________________
• Watson and Crick ________________________________
  _____________________
• These papers were important for
  ________________________________________________
  _________________________________________________
  _________

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James Watson - 2005

• http//www.ted.com/talks/james_watson_on_how_he_di
  scovered_dna.html
• See 740 through 12 05

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DNA

• A nucleic acid formed from string of nucleotides
• Nucleotide
• A biological molecule composed of a phosphate
  group, a 5-carbon sugar, and a nitrogenous base

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REVIEW

• DNA is a nucleic acid, formed by chains of
  nucleotides
• Nucleotides are 3-part molecules
• 1 phosphate group
• 1 5-carbon sugar ring
• 1 nitrogenous base

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REVIEW Nitrogenous Bases
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Recall

• One of the differences between DNA and RNA (both
  nucleic acids) is that __________________________
  _____________
• These two strands are ___________________________
  _________________________________________________
  _______
• Both strands are copies of each other, but
  __________________________________

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3' and 5'

• Read ___________ and ______________
• Organic chemists number the carbon atoms in DNA
• 1'
• 5'
• 3'

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3' and 5'

• Designating each strand as either 3' or 5' allows
  _________________________________________________
  __________

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Base Pairs

• We are talking about the ________________________
  _________________________________________________
  ______
• Watson and Crick were correct
• Adenine _____________________________
• Guanine _____________________________
• This is the same across all organisms

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Base Pairs
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DNA to chromosomes?

• DNA does not exist by itself
• We know that DNA is found in the nucleus,
  _________________________________
• Due to the length of DNA, it must exist in an
  extremely ________________ form
• DNA exists in 46 pieces in humans
• DNA of human cells 9.84 ft (3 meters)

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DNA to chromosomes

• DNA existing in 46 pieces helps to make
  ________________________________
• Further squishing is needed to fit inside the
  cell
• ____________________help to coil and compact the
  DNA molecule

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DNA to chromosome

• The DNA double helix is wound tightly around a
  protein to form a ___________
• A little ball of protein with DNA around it
• These __________ are further coiled and compacted
  with additional proteins to form a
  _________________________
• __________________
• Pieces of DNA and their associated proteins

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We know the structure of DNA

• but how does this molecule and the information
  it contains related to traits and inheritance of
  traits?

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DNA and Genetic Information

• For inheritance to occur, a single cell must be
  able to ______________________
• The offspring are identical to the parents
  because
• The double helix design of DNA __________________
  ______________________

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Replicating DNA

• The DNA molecule ___________
• The copying mechanism ___________________________
  ____________
• The original strands ____________________________
  _________________________________________________
  _
• ________________ of the original molecule are
  formed

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Enzymes involved

• Several enzymes are involved with DNA replication
• We will focus on THREE

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DNA helicase

• The enzyme ______________________________________
  ________________
• The hydrogen bonds that join the nitrogenous
  bases are broken
• Results _________________________________________
  ____________________

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DNA polymerase

• The enzyme ______________________________________
  _________________________________________________
  _
• Two DNA polymerase molecules move at the same
  time
• Operates differently, depending on the
  __________________________________

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DNA polymerase

• IF reading from ___________
• DNA polymerase puts new strand together in the
  __________ direction
• _____________________ copying process
• ________________ strand

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DNA polymerase

• IF reading from ___________
• DNA polymerase puts new strand together in the
  __________ direction
• _________________ copying process
• Fragments of DNA are synthesized and then fused
  together
• _____________________________
• _______________ strand

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_________________

• The enzyme ______________________________________
  _________________________________________________
  ____

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Enzymes involved

• Several enzymes are involved with DNA replication
• We will focus on THREE

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Recall

• DNA provides the instructions for cellular
  activities

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DNA

• Provides directions for cellular activities
• Passes on these directions to offspring cells so
  they can survive
• Where are these instructions contained?

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DNA molecule

• Made up of chains of ________________
• There are ___________ different kinds of
  _________________ that occur in DNA
• _____________ are only different depending on
  their _________________
• The 5-carbon sugar and phosphate groups are
  identical in all nucleotides

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Proteins

• Biological molecules made up of chains of amino
  acids
• Important for cellular processes

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DNA ? Proteins

• Pairing of nitrogenous bases (base pairs) are the
  source of the instructions for making proteins
• There are only FOUR nitrogenous bases
• There are 20 different amino acids

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How is this possible?

• Proteins made up of 20 amino acids
• DNA made of up base pairs

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Code

• _______ nitrogenous bases code for _________amino
  acid
• This is the key to translating DNA language to
  protein language
• DNA
• Chains of ______________
• Speak with ____________________
• Proteins
• Chains of ______________
• Speak with ___________________

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New Terms

• ______________
• A segment of a DNA strand that carries the
  nucleotide code for one protein
• ______________________
• The entire nucleotide sequence for a cell or
  organism

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HOW does this translation occur?

• DNA nucleotides to Protein amino acids

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Different forms of RNA

• DNA has the instructions, but ___________________
  _______________________
• Three forms of ___________
• M_____________________________
• T_____________________________
• R_____________________________

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mRNA

• ___________________
• A single strand of nucleic acid
• The _____________________________________________
  __________________
• mRNA carries that information in DNA to
  ______________________

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tRNA

• ______________________
• An RNA molecule _________________________________
  _________________________________________________
  _______________________________________
• Uses amino acids from cytosol to build new
  proteins

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rRNA

• __________________________
• A ribonucleic acid found in ribosomes
• Ribozyme
• RNA molecules that function as biological
  catalysts

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Protein Synthesis
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Protein Synthesis

• A two-step process
• Transcription - _________________________________
  _________________________________________________
  ______________________________________________
• Translation - ___________________________________
  _________________________________________________
  ___________

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Recall

• Differences between DNA and RNA

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Nitrogenous Bases
DNA only
RNA only
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Transcription

• DNA is transcribed to messenger RNA inside the
  nucleus
• mRNA now has the same information contained in
  original DNA
• Thymine is replaced by ______________
• Three nucleotides still code for an amino acid
• Codon __________________________________________
  _______________________

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Transcription

• RNA polymerase
• An ______________________________________________
  ______________________
• Only ____________________________ molecule is
  used to make mRNA
• Responsible for _________________________________
  ____________________

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Transcription
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Protein Synthesis

• A two-step process
• Transcription - DNA copies the instructions for
  making proteins by making a Messenger RNA (mRNA)
  strand
• Translation - ___________________________________
  _______________________

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Translation

• mRNA instructions are used ______________________
  _____________________
• Requires a ________ and ____________ from the
  ____________
• Occurs outside of ___________________

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Translation

• mRNA has ________________ from DNA
• mRNA shares __________________________________
  to form amino acid chains
• tRNA brings _____________________________________
  ___________________
• ____________________ bond chains of amino acids
  together

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DNA and Protein Synthesis

• DNA directs the formation of proteins in the cell
  through a two-step process
• __________________
• ____________________
• _____________________ occurs in the nucleus and
  is where mRNA is formed from DNA by RNA
  polymerase
• ____________ occurs in the cytosol with the help
  of mRNA, tRNA, and ribosomes

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Why is protein synthesis important?
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DNA

• The same structure occurs _______________________
  _______________________
• The same nitrogenous bases ______________________
  _________________________________________________
  _______
• _____________ through DNA
• Recall, DNA is the ___________________

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DNA

• Studying DNA, genes, and the genomes of organisms
  _________________________________________________
  ________
• Degree of relatedness depends on length of the
  genome, the number of chromosomes, the traits
  shared across species,

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Gene Mutation

• A _______________________________________________
  _________________
• Can result in a _________________________________
  ______________________
• Caused by a variety of things
• Effects are varied
• No effect
• Deleterious effects
• Positive effects?

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____________________

• A lack of pigmentation
• Occurs in humans and other organisms
• Caused by a mutation at various parts in the
  genome

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Mutations

• May not always have an effect