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DNA and RNA Replication
Unit 6
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Something to think about..
When a species reproduces, there is genetic continuity maintained from one generation to the next. WHAT is responsible for this continuity? HOW does this continuity happen?
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What is DNA? DNA = DeoxyriboNucleic Acid
Genetic material present in ALL organisms Different for each individual Found in nucleus Polymer- nucleic acids Monomer = nucleotides What three ‘parts’ are nucleotides made of? a. Phosphate group b. Sugar c. nitrogen base (A,T,C,G)
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Nucleotides Monomer made of the following 3 parts:
1. a 5-Carbon sugar group (deoxyribose) 2. a phosphate group 3. a nitrogen base – 4 different possibilities! (5 Carbon sugar)
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4 Nitrogen Bases “Pure As Gold” Purines Pyrimidines Adenine, Guanine
Cytosine, Thymine A, G C, T 2 carbon rings 1 carbon ring “Pure As Gold”
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Nitrogen Base Pairing Adenine ALWAYS pairs with Thymine
2 hydrogen bonds Cytosine ALWAYS pairs with Guanine 3 hydrogen bonds “AT C-G”
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DNA Code The order of the 4 nitrogen bases is what causes each individual’s DNA to be unique! Pictured below are small segments of DNA from three organisms, how do they compare? Plant Mammal Bacteria
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DNA Code If we looked at the total DNA of each of the below organisms, which would have DNA with the least amount of base pairs? Why? Plant Mammal Bacteria
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Structure of DNA Double Helix
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Double Helix Which 2 scientists are credited with the discovery of the structure of DNA? James Watson & Francis Crick (1953) Double Helix Nobel Prize for Medicine in 1962
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Structure of DNA Double Stranded
“Backbone” = alternating phosphates and sugars (deoxyriboses) Middle Portion = bases A-T (bonded by 2 H-bonds) C-G (bonded by 3 H-bonds) In 3D: forms twisted ladder (spiral staircase)
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Double Helix
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On the diagram on the right, circle 1 nucleotide
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DNA Replication DNA copying Why? 4 Steps
in order for genetic material to be passed on to the next generation and to preserve genetic continuity 4 Steps
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DNA Replication “Unzip DNA twisted ladder” (HELICASE)
Break H bonds between bases
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DNA Replication Match correct nucleotides according to base pair rules (DNA POLYMERASE) There are free floating nucleotides in nucleus Remember: A-T, G-C
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DNA Replication Bonding-hydrogen bonds form between bases; and phosphates bond to sugar molecules to form the ‘backbone’ of DNA Bonding continues until 2 new strands have completely formed RESULT = 2 copies of the original DNA molecule
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DNA Replication Pink = parent strand Blue = daughter strands
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DNA Replication DNA Replication Simulation
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