Gene Expression From genotype to phenotype

From Gene to Protein DNA In Genes Transcription RNA is created Translation Amino Acids are sequenced into a protein. Proteins are physical expression of gene =phenotype A gene is a specific sequence of a DNA molecule that codes for a protein.

TRANSLATION TRANSCRIPTION RNA PROCESSING

Structure of RNA  Formed from nucleotide subunits  Singled Stranded  Uracil instead of Thymine  Sugar is ribose  Look familiar?

Transcription  RNA polymerase pries the DNA strands apart and hooks together the RNA nucleotides  RNA synthesis follows the same base- pairing rules as DNA, except uracil substitutes for thymine Watch it in action!

Elongation RNA polymerase Nontemplate strand of DNA RNA nucleotides 3 end Direction of transcription (“downstream”) Template strand of DNA Newly made RNA Promoter Codon Terminator Codon

Transcription produces three types of RNA Ribosomal RNA (brown) makes up ribosomes.rRNA Messenger RNA (pink): provides templatemRNA Transfer RNA (green): transfers amino acids to ribosometRNA

Codons  Specific sequence of three nucleotides on the mRNA.  Used to code for amino acids.  The Genetic Code Chart is based on codons.

Translation  Changing from the language of nucleotides, to the language of amino acids. Codon (mRNA) UUU Translation Amino Acid Phenylalanine

Codon sequence ties to specific amino acids Second letter UCAG First letter (5’ end) U C A G Third letter (3’ end) UCAGUCAG UCAGUCAG UCAGUCAG UCAGUCAG = Stop Codon = Start Codon

Translation happens with the help of tRNA  Each tRNA has: – anti-codon –Attached amino acid  Example: –Amino Acid: Leucine –Codon (mRNA): CUU –Anti-codon (tRNA): GAA Anti- codon

Translation Stage 1: Initiation 1. Small ribosomal subunit binds AUG sequence AUG codon signals start of sequence AUG codon signals start of sequence AUG codes for methionine (Met) AUG codes for methionine (Met) 2. Large subunit then binds

Translation Stage 2: Elongation Watch it!

Translation Stage 3: Termination  Ribosome reaches a stop codon on mRNA.  New protein is released from ribosome.  Ribosome subunits disconnect.

RNA splicing Most eukaryotic genes and their RNA transcripts (mRNA) have long noncoding stretches of nucleotides that lie between coding regions Most eukaryotic genes and their RNA transcripts (mRNA) have long noncoding stretches of nucleotides that lie between coding regions Noncoding regions are called introns Noncoding regions are called introns The other regions are called exons because they are expressed The other regions are called exons because they are expressed translated into amino acid sequences translated into amino acid sequences RNA splicing removes introns and joins exons (spliceosome) RNA splicing removes introns and joins exons (spliceosome) creating an mRNA molecule with a continuous coding sequence creating an mRNA molecule with a continuous coding sequence

RNA splicing 5 ExonIntronExonIntronExon3 Pre-mRNA Coding segment Introns cut out and exons spliced together  Cap Poly-A tail 5 3 UTR Exon = expressed Intron = spliced out

Mutations –Base substitution mutations –Base insertion or deletions  One or two nucleotide pairs are inserted into or deleted from the molecule  Frameshift mutation

Mutations

The Jamba Juice Analogy For protein synthesis

Products Jamba Juice Product Various flavored Smoothies! Cell Product Cell Product Various proteins

Nucleus of the operation. Locked inside this building are the recipes for all Jamba Juice smoothies. Recipes =??Building = ?? Jamba Juice Corporate Headquarters, Emeryville, CA

Transcribing the recipes mRNA

Jamba Juice Stores rRNA/ribosomes

Transport of materials to stores tRNA

Jamba Juice Mixologists Mixologists are the A and P sites in the ribosome – Translates recipe (codons) to fruit ingredients (amino acids)

Jamba Juice Smoothie Combines fruits (amino acids) into a smoothie (protein).