Summary Structure of DNA (sugar-phosphate backbone, base pairs, double helix) RNA Structure (types, how is it different from DNA?) Transcription (RNA polymerase, 5’ cap, splicing, 3’ poly-A tail, export) Translation (Genetic code, reading frame, tRNA, start/stop codon, ribosomes) Protein Folding (pathway, chaperones)

First and Foremost: ATP

Basic Structure of DNA Backbone Base Pairs Bonding The Double Helix

Basic Structure of DNA The Double Helix

Basic Structure of DNA Side and Overhead View

Basic Structure of DNA The Backbone

Basic Structure of DNA The Base Pairs

Transcription RNA Structure Backbone Base Pairs 3-D Structure Types RNA Synthesis Initiation Elongation 5’ Cap Splicing 3’ End

Major differences between RNA and DNA 1.R, not D = ribose, not deoxyribose 2.Single stranded rather than double stranded 3.Uracil pairs with adenosine instead of thymine

Structure of RNA The Backbone

Structure of RNA Single Stranded– Can form base pairs

Structure of RNA The Base Pairs

Types of RNA mRNA “messenger”  codes for protein rRNA “ribosomal”  forms the ribosome, crucial for protein synthesis tRNA “transfer”  connects RNA with correct amino acid during translation snRNA “small nuclear”  splicing siRNA “small interfering”  technique for interfering with native mRNAs

Messenger RNA (mRNA) Coding strand of DNA Non-coding strand

Transcription Elongation

Transcription Initiation TATA box General Transcription Factors RNA Polymerase Phosphorylation  One way of controlling transcription is to change the availability or phosphorylation state of transcription factors

Enhancer/repressor genes are several kbp from the genes they control DNA bends frequently, allowing action at a distance

Gene Expression 3 ways to control expression before transcription

Transcription 5’ capping of new mRNA Why cap mRNA? Some theories…. 1.Stimulates translation: capped mRNA is translated more readily than uncapped 2.Provides protection against degradation by RNases that target loose 5’ ends 3.Transport out of nucleus

Transcription Creating the 3’ End Poly-Adenylation Poly-A Polymerase Poly-A binding proteins Ready for export Poly-A purposes: Same as capping

Transcription Splicing  Occurs during Elongation

After Transcription The Next Stage

Translation The Ribosome Transfer RNA Structure Selection and Attachment of Correct Amino Acid Genetic Code and Reading Frames Elongation Termination

Translation The Ribosome

Translation tRNA Structure

Translation Selection of Correct AA for tRNA

Translation Genetic Code: how the cell interprets triplets of bases Some point mutations are more dangerous than others!

Translation Start Codon

Translation Elongation

Translation Termination

Translation Reading Frames

Protein Structure Overview Chaperones

Protein structure: chains of amino acids

Protein structure: folding Primary: amino acid sequence Secondary: beta sheet or alpha helix (both can exist in different stretches of one protein) Tertiary: folded upon itself Quaternary: coassembly of several aa chains into a globular protein (optional)

Protein Folding Chaperones

Summary Structure of DNA (sugar-phosphate backbone, base pairs, double helix) RNA Structure (types, how is it different from DNA?) Transcription (RNA polymerase, 5’ cap, splicing, 3’ poly-A tail, export) Translation (Genetic code, reading frame, tRNA, start/stop codon, ribosomes) Protein Folding (pathway, chaperones)