dna protein synthesis. dna structure rosalind franklin took diffraction x-ray photographs of dna...

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

http://www.youtube.com/watch?v=nHM4UUVHPQM