Protein Synthesis Transcription Translation Transcription - detail Animation – overview of transcription/translation http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a1.html Transcription - detail http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a2.html Translation - detail http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a3.html

Types of RNA mRNA tRNA rRNA

3 steps of transcription Promoter Region RNA Polymerase Primary Transcript is made from the coding strand of DNA Terminator Region Transcription Animation

RNA Processing mRNA has a short life span A cap is added A poly-A tail is added Protect enzymes from breaking down mRNA in the cytoplasm Introns Exons Splicing is the process of removing introns and rejoining cut ends

The Genetic Code (pg 237) Combine DNA nucleotides to code 20 different “words” (amino acids)

The Genetic Code

Translation Translation Animation – detailed: http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a3.html

Making a Protein DNA serves as a template in for making RNA in the nucleus RNA goes to the cytoplasm RNA attaches to the ribosome tRNA contains an anticodon that is complementary to the codon of the mRNA Amino acids are bonded together to make a polypeptide

THEDOGBITTHECAT THEDOGBITTHECAR Genetic Mutations THEDOGBITTHECAT THEDOGBITTHECAR THE DOG BIT THE CAT THE DOG BIT THE CAR POINT MUTATION: A change in a single base pair in DNA

Genetic Mutations

Genetic Mutations THEDOGBITTHECAT THE DOB ITT HEC AT If a single base is added or deleted from DNA, this is a FRAMESHIFT MUTATION, because it shifts the reading of codons by one base. A different sequence of codons and amino acids results.

Genetic Mutations

Normal Hemoglobin GGG CTT CTT TTT Sickled Hemoglobin GGG CAT CTT TTT DNA BASE SEQUENCES: Normal Hemoglobin GGG CTT CTT TTT Sickled Hemoglobin GGG CAT CTT TTT (Sickle-cell anemia) Point Mutation or Frameshift Mutation?

Sickle Cell Anemia POINT MUTATION OR FRAMESHIFT MUTATION?

The 20 Amino Acids General Structure (Variable or R group)

CODON BINGO!

VIRUSES Living or Not? No cells Tiny particles Replicate Evolve Do not carry out own metabolism Do not respond to environment Different structures http://www.newtown.k12.ct.us/~royalk/viruses.htm

How do viruses replicate? Lysogenic Infections Lytic Infections Host cell enzymes replicate viral DNA Viral genes transcribed and translated on host ribosomes Proteins reassemble into virus particles The cells lyses (splits)when there are many viruses in the host cell; they infect other cells Viral DNA inserts into cellular DNA Viral DNA is therefore copied when the host cell replicates No production of new viruses Stress to host can activate cell to enter into lytic cyle (example: starvation)

Protein structure Primary Secondary Tertiary Quaternary

Chromosome Structure DNA helix nucleosomes 30 nm solenoid

scaffold-associated condensed loops 30 nm solenoid chromatin loops scaffold-associated condensed loops

scaffold-associated condensed loops Chromatin 30 nm solenoid chromatin loops scaffold-associated condensed loops

scaffold-associated condensed loops metaphase chromosome

How nucleosomes affect transcription nucleosome particle in a 30nm fiber DNA wrapped around histone proteins two H2A two H2B two H3 two H4 histone octamer

How nucleosomes affect transcription + (+)-charged lysines of histone proteins interact with (-)-charged phosphates of DNA + DNA is tightly wrapped around histone octamer lysine Ac reversible acetylation of lysines neutralizes charges DNA decondenses from histone octamer N-O-C-CH 3 O || | H histone acetylation is correlated with transcriptional activity acetylated lysine

Transcription activators can promote histone acetylation TATA HRE nuclear hormone receptors histone acetylation TFIID TATA HAT Histone Acetyl Transferase co-Activator(s) coA

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