Transcription & Translation

Transcription & Translation

DNA Serves as the Genetic Code for PROTEIN SYNTHESIS

The Central Dogma Transcription Translation

DNA vs. RNA DNA • Double stranded • Deoxyribose sugar • Bases: C,G A,T RNA • Single stranded • Ribose sugar • Bases: C,G,A,U Both contain a sugar, phosphate, and base.

mRNA Long strand of RNA nucleotides that are formed complementary to one strand of DNA. Direct the synthesis of a specific protein

rRNA Associate with proteins to form ribosomes in the cytoplasm

tRNA Transports amino acids to the ribosome

Protein Synthesis: Transcription • Process by which genetic information encoded in DNA is copied onto messenger RNA (mRNA) • Occurs in the nucleus • DNA mRNA

Transcription

Transcription • mRNA forms base pairs with DNA • C-G • A-U

Protein Synthesis: Translation • Process by which information encoded in mRNA is used to assemble a protein at a ribosome • Occurs on a Ribosome in Cytoplasm • mRNA protein

Protein Synthesis: Translation

Translation • mRNA is on a ribosome • Every group of 3 mRNA bases encodes a single amino acid • Codon- coding triplet of mRNA bases • tRNA brings amino acids to the ribosome

tRNA • Transfer RNA • Bound to one amino acid on one end • Anticodon on the other end complements mRNA codon

Polypeptide Arg Met Phe Leu Ser Aminoacyl tRNA Gly P A UCU Ribosome E CCA 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAA 3’ mRNA Translation - Elongation

Polypeptide Met Phe Leu Ser Arg Gly P A Ribosome E CCA UCU 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAA 3’ mRNA Translation - Elongation Aminoacyl tRNA

Polypeptide Met Phe Leu Ser Arg Gly P A Ribosome E CCA UCU 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAA 3’ mRNA Translation - Elongation

Polypeptide Ala Met Phe Leu Ser Arg Aminoacyl tRNA Gly P A CGA Ribosome E CCA UCU 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAA 3’ mRNA Translation - Elongation

Polypeptide Met Phe Leu Ser Arg Ala Gly P A Ribosome E CCA UCU CGA 5’ GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAA 3’ mRNA Translation - Elongation

The Genetic Code

Protein Structure • Made up of amino acids • Individual amino acids are linked together by a peptide bond • 20 amino acids are arranged in different orders to make a variety of proteins

Gene Regulation • The ability to control which genes are transcribed in response to the environment.

Mutations A permanent change in a cell’s DNA

Point Mutation • Substitution – one base is exchanged for another. Missense- DNA code is altered so that it codes for the wrong amino acid Nonsense- DNA code is altered so that it codes for a stop codon.

Frame shift Mutation • Loss or gain of a nulceotide in the DNA sequence. This type of mutation changes the multiple of three codons from the point of the mutation.

Mutagens Substances that cause mutations Radiation Certain chemicals

Transcription & Translation