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DNA
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Nucleic Acids DNA and RNA are examples Deoxyribonucleic acid
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Nucleic Acids A gene is a section of DNA that provides the code to make a protein.
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Nucleic Acids Built from monomers of nucleotides
Consists of a phosphate group, a sugar molecule, and a nitrogenous base
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Nitrogenous bases Purines – double ring -adenine, guanine
A=T C=G Purines – double ring -adenine, guanine Pyrimidines – single ring thymine, cytosine
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Tight helical fiber (30-nm diameter)
Huge molecule over 3 billion base pairs per cell Condenses by wrapping/coiling around histones -called a chromosome Linker DNA double helix (2-nm diameter) “Beads on a string” Tight helical fiber (30-nm diameter) Metaphase chromosome Histones Nucleosome (10-nm diameter) Supercoil (300-nm diameter) 700 nm Figure 11.2a-0 DNA packing in a eukaryotic chromosome
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How did we discover DNA is the genetic material?
In a group or individually, read through page 182 and figure 10.1B (183) What did Fredrick Griffith discover? What did Alfred Hershey and Martha Chase discover? What was their experiment?
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Hershey Chase Animation
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Batch 1: Radioactive protein labeled in yellow
Phage Bacterium Radioactive protein DNA Empty protein shell Phage DNA Centrifuge Pellet Batch 1: Radioactive protein labeled in yellow Radioactive DNA The radioactivity is in the pellet. The radioactivity is in the liquid. Batch 2: Radioactive DNA labeled in green Figure 10.1b-0 The Hershey-Chase experiment
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How was the double helix discovered?
Read pages 186 and 187
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Thymine (T) Cytosine (C) Adenine (A) Guanine (G) Pyrimidines Purines
Figure 10.2b-0 The nitrogenous bases of DNA
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Recall: The experiment from Hershey and Chase (1952) demonstrated DNA is the passed from parents to offspring, but what is its structure? Phage Bacterium Radioactive protein DNA Empty protein shell Phage DNA Centrifuge Pellet Batch 1: Radioactive protein labeled in yellow Radioactive DNA The radioactivity is in the pellet. The radioactivity is in the liquid. Batch 2: Radioactive DNA labeled in green Figure 10.1b-0 The Hershey-Chase experiment
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Discovering the Structure of DNA
Watson and Crick were the first to discover the structure of DNA. Used data x-ray crystallography data from Wilkins and Franklin without their permission
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Earliest Model of DNA
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Make our own models Two simple steps Label the nitrogenous bases
Fold it
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DNA We know the structure of DNA, and that more than 3 billion base pairs are in each cell, what about new cells?
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DNA Replication Depends on specific base pairs adenine – thymine
guanine – cytosine If this is one half of DNA, what would the other half be?
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DNA Replication Semiconservative model
The two DNA strands separate (parent strands). Each parent strand then becomes a template for a new, complementary strand (daughter strand) forming two new daughter molecules of DNA Each new DNA helix has one old strand with one new strand.
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Daughter DNA molecules
Figure 10.4b A T G C A T Parental DNA molecule A T T A C G G C T Daughter strand Parental strand A C C G G G C T G C T T C A A G Figure 10.4b The untwisting and replication of DNA A G T A C C A G T A T A T A G Daughter DNA molecules T C
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DNA Replication Over a dozen enzymes and other proteins needed to replicate DNA DNA polymerase – adds nucleotides one at a time to the strand Other enzymes “proofread” and fix mistakes
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DNA Replication Replication occurs at multiple points at the same time
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DNA Replication Carbons are labeled The direction DNA polymerase moves is determined by the sugar phosphate backbone There is a 5’ end and a 3’ end Nucleotides are added onto the 3’ end, moving towards the 5’ end
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DNA polymerase molecule 3′
This daughter strand is synthesized continuously 5′ Parental DNA 5′ 3′ Replication fork This daughter strand is synthesized in pieces 3′ 5′ 5′ Figure 10.5c How daughter DNA strands are synthesized 3′ DNA ligase Overall direction of replication
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Recall A gene is a section of DNA that provides the code to make a protein. Genes carry different information on them Human Genome mapped it out – ethical questions
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https://www. youtube. com/watch
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Parent molecule Daughter molecules
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Parent strand Daughter strand
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Daughter DNA molecules
Parental DNA molecule A T T A C G G Daughter strand C T Parental strand A C C G G G C T G C T C A A T G Figure 10.4b The untwisting and replication of DNA A G T A C C A G T A T A T A G Daughter DNA molecules T C
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Hypothetical DNA If this is the parent strand? What is the daughter strand? A - T - C - G -
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What was the main enzyme in DNA replication
What was the main enzyme in DNA replication? What was unique as a result of the sugar phosphate backbone?
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DNA polymerase molecule 3′
This daughter strand is synthesized continuously 5′ Parental DNA 5′ 3′ Replication fork This daughter strand is synthesized in pieces 3′ 5′ 5′ Figure 10.5c How daughter DNA strands are synthesized 3′ DNA ligase Overall direction of replication
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3’ 5’
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After DNA replicates, the cell divides
Looking at that after break. Why is DNA Critical?
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Transcription and Translation
DNA is transcribed into RNA RNA is translated into protein DNA NUCLEUS CYTOPLASM RNA Transcription Translation Protein
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DNA Ingredientes: 2 1 / 4 tazas de harina para todo uso
1 cucharadita de bicarbonato de soda 1 cucharadita de sal 1 taza (2 palos) de mantequilla, suavizada 3 / 4 taza de azúcar granulada 3 / 4 taza de azúcar morena 1 cucharadita de extracto de vainilla 2 huevos grandes 2 tazas (12 oz. Pkg.) TELEPEAJE CASA NESTLÉ ® ® semi-dulce de chocolate bocados 1 taza de nueces picadas
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RNA Ingredients: To 2 1/4 cups all-purpose flour
1 teaspoon baking soda 1 teaspoon salt 1 cup (2 sticks) butter, softened 3/4 cup granulated sugar 3/4 cup brown sugar 1 teaspoon vanilla extract 2 large eggs 2 cups (12 oz. Pkg.) NESTLÉ TOLL HOUSE ® ® semi-sweet chocolate morsels 1 cup chopped walnuts
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Protein
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Transcription Sections of DNA called genes are used
RNA polymerase attaches to the DNA at a ‘promoter’ site It moves along the gene forming a new RNA strand using the base pair rules
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Transcription DNA Base pairs
A-T G-C There is no thymine in RNA, a different nucleotide Uracil is used RNA Base pairs A-U G-C
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DNA Transcription RNA Codon Translation Polypeptide Amino acid
A A A C C G G C A A A A Transcription RNA U U U G G C C G U U U U Codon Translation Figure Transcription and translation of codons (partial) Polypeptide Amino acid
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Genetic Code The genetic code is the amino acid translations of each of the nucleotide triplets. Three nucleotides specify one amino acid
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Second base of RNA codon U C A G
Figure 10.8a Second base of RNA codon U C A G UUU UCU UAU UGU U C A G Phe Tyr Cys UUC UCC UAC UGC U Ser UUA UCA UAA Stop UGA Stop Leu UUG UCG UAG Stop UGG Trp CUU CCU CAU CGU U C A G His CUC CCC CAC CGC C Leu Pro Arg CUA CCA CAA CGA Gln First base of RNA codon Third base of RNA codon CUG CCG CAG CGG AUU ACU AAU AGU U C A G Ser Asn AUC lle ACC AAC AGC A Thr Figure 10.8a The genetic code used to translate RNA codons to amino acids AUA ACA AAA AGA Arg Lys AUG Met or start ACG AAG AGG GUU GCU GAU GGU U C A G Asp GUC GCC GAC GGC G Val Ala Gly GUA GCA GAA GGA Glu GUG GCG GAG GGG
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Try it DNA: T A C A A T C G T A C G (one strand) RNA: Amino Acid:
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