dna protein synthesis. dna structure rosalind franklin took diffraction x-ray photographs of dna...
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DNAProtein Synthesis
DNA StructureDNA Structure
• Rosalind Franklin took diffraction x-ray photographs of DNA crystals
• In the 1950’s, Watson & Crick built the first model of DNA using Franklin’s x-rays
Rosalind Franklin Frances Crick & James Watson
X-ray diffraction photograph of DNA, 1953
Proposed double helix model 1953
Cell
What is DNA?What is DNA?• DNA, or deoxyribonucleic acid, is the genetic
instruction set.
• It is composed of a linear sequence of units called nucleotides.
• There are four different kinds of nucleotides (designated by the letters A, G, C, & T; sometimes called “bases”).
• An individual DNA strand (or chromosome) may consist of 100,000’s of nucleotides.
• The sequence of the nucleotides of a DNA strand determines the genetic code.
DNA
Polymers made up of individual nucleotides
Nucleotides contain• Phosphate group• Five carbon sugar• Ring shaped nitrogen base
DNA contains information for almost all cell activities
DNA
Nitrogen Base
ADENINE (A) THYMINE (T)
Chargaff’s RuleChargaff’s Rule
GUANINE (G)
CYTOSINE (C)
DNA is Double StrandedDNA is Double StrandedDNA is Double StrandedDNA is Double Stranded
16
Question:
• What would be the complementary DNA strand for the following DNA sequence?
DNA 5’-CGTATG-3DNA 5’-CGTATG-3’’
copyright cmassengale
17
Answer:Answer:
DNA 5’-CGTATG-3’DNA 5’-CGTATG-3’
DNA 3’-GCATAC-5’DNA 3’-GCATAC-5’
copyright cmassengale
Gene Gene ExpressionExpression
Transcription
Translation
RNRNAA
Contrasting RNA with Contrasting RNA with DNADNA
Single-stranded Ribose Bases
AdenineUracilGuanineCytosine
Double-stranded Deoxyribose Bases
AdenineThymineGuanineCytosine
RNA DNA
Three Kinds of RNA
• mRNA (Messenger RNA)• rRNA (Ribosomal RNA)• tRNA (Transfer RNA)
Ribosome
tRNAtRNA
TranscriptiTranscriptionon
DNA Sense Strand
mRNA
Transcription
DNA Sense Strand
mRNA Transcript
TranscriptionTranscription
TranslationTranslationAmino Acid
tRNA
mRNA
Codon
Anticodon
TranslatiTranslationon
TranslatiTranslationon
TranslatiTranslationon
TranslatiTranslationon
TranslatiTranslationon
TranslatiTranslationon
TranslatiTranslationon
Stop codon
AA
1
AAAA
U A GA U C
2
AA
Complete protein
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