Gene Expression

Indicates where the gene starts on the chromosome

• binds to promotor region - Helps RNA polymerase to bind to DNA strand

Converts double-stranded DNA to single strands by breaking hydrogen bonds Adds complementary RNA nucleotides to the 3’ end based on complementary base pairing rule

Transcription factor binds to promoter region: helps RNA polymerase to bind to DNA strand RNA polymerase unwinds double stranded DNA by breaking hydrogen bonds

RNA polymerase at complementary nucleotides to the three prime end

RNA polymerase Reaches termination sequence Releases the DNA (which reanneals) Releases primary RNA transcript

To create a primary RNA transcript

• Transcription • mRNA processing • Translation

Introns - NON coding regions Exons - CODING regions (want to keep)

Introns are removed Exons are joined together

To protect the gene Prevents gene from getting broken down in the cytoplasm

GGGGGG… Added to 5’ end

AAAAAAA…. Added to 3’ end

To produce the final RNA transcript • remove introns • add 5’ cap and poly-A tail

RNA acts as a template to make protein

5’ to 3’ 3 letters at a time (CODONS)

Codes for 1 amino acid Made up of three nitrogenous bases (AUG)

Free ribosomes • Cytoplasm • Make proteins for use inside the cell Bound ribosomes • Rough ER • Make proteins for use outside the cell

Redundant (many different codons can code for the same amino acid Not ambiguous - each codon can only code for one particular amino acid Non-overlapping Continuous

• Initiation • Elongation • Termination (Same as Transcription)

Ribosome attaches to start codon located on 5’ end Allows tRNA to read the start codon to bring amino acid (AUG, Methionine)

Carries an amino acid Reads codons of mRNA using anti-codons

codons anticodons

Hold everything together Hold mRNA, tRNA and polypeptide bonds