GENE EXPRESSION

Transcription 1. RNA polymerase unwinds DNA 2. RNA polymerase adds RNA nucleotides (A ↔ U, G ↔ C) 3. mRNA is formed! DNA reforms a double helix

Transcription recap… RNA polymerase makes RNA using DNA sequence RNA leaves the nucleus for the cytoplasm

Translation Ribosomes translate mRNA into an amino acid sequence Amino acids form proteins To a ribosome!

Codons Codons = 3 nucleotides in a row Ribosome recognizes a codon on mRNA and matches to the aniticodon on tRNA A C G anticodon amino acid

tRNA Transfer RNA transfers amino acids from the cytoplasm to a ribosome Anticodon = 3 nucleotides on one end of a tRNA Anticodons base pair with complementary bases on mRNA A C G anticodon amino acid

Codons Codon triplets code for 1 of 20 amino acids

1 “start” codon3 “stop” codons Codons

Steps of Translation 1.mRNA attaches to ribosome mRNA

Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA mRNA

Steps of Translation mRNA 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation mRNA 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation mRNA 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation mRNA 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation mRNA 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation mRNA 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation mRNA 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation mRNA 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation 2. tRNAs add amino acids based on how anticodons match to mRNA

Steps of Translation 3. Protein is released from ribosomes! Protein chain Stop codon

Steps of Translation Protein chain 3. Protein is released from ribosomes!

Summary DNA RNA PROTEIN (Transcription) (Translation)

Practice 1.DNA sequence: AAC TGA CTG ATT GCA TGC What is the complementary DNA sequence? What is the complementary RNA sequence? 2.DNA sequence: TAG CAT TGG GCA TCA CGA What is the complementary DNA sequence? What is the complementary RNA sequence? TTG ACT GAC TAA CGT ACG UUG ACU GAC UAA CGU ACG ATC GTA ACC CGT AGT GCT AUC GUA ACC CGU AGU GCU

Determine the amino acids for this strand of mRNA: AUG GCA AGU UCU UGA Practice Met – Ala – Ser – Ser – STOP

Determine the amino acids for this strand of mRNA: UGU AGA GAU CUC UAA Practice Cys – Arg – Asp – Leu – STOP