Protein Synthesis

DNA Replication Before a cell divides, all the DNA must be copied During Interphase of the Cell Cycle, the DNA replicates or makes a copy of itself DNA Replication will produce 2 IDENTICAL new complementary strands following the rules of base pairing: A-T, G-C

Practice – DNA Replication G T A C C T A G G C T A A A C T G A ________________________________ T T A G C A T A C G G G T C A G A __________________________________

Protein Synthesis Cell DNA mRNA Protein (chain of Amino acids) Transcription Protein (chain of Amino acids) Translation Ribosome

DNA and Protein Synthesis DNA contains the genetic information or genes to make proteins Proteins are chains of amino acids linked together These proteins determine the physical traits of an organism and control cellular functions.

What is a Gene? A gene is a certain length or piece of DNA on a chromosome A gene is made of 2 parts: 1. Exon – the expressed parts of the DNA sequence or part that is used to make a protein 2. Intron – the intervening, not expressed or used Parts are cut, put together and then used to make RNA and proteins

How to make a Protein… Step 1: Use DNA to make a messenger RNA molecule - Transcription Step 2: Decode that messenger RNA to see which amino acids are needed to make a protein – Translation Flow of Information: DNA RNA Proteins

Protein Synthesis Step 1: Transcription DNA unzips Messenger RNA (or mRNA) is made from DNA using base pairs RNA is different from DNA: RNA is single stranded, not double stranded Instead of deoxyribose, it has ribose instead of Thymine, it uses Uracil (and UA) 3) mRNA carries the genetic code from the nucleus to the ribosome in the cytoplasm

Protein Synthesis: Transcription

Eukaryotic Transcription DNA Cytoplasm Nucleus Nuclear pores RNA Transcription G AAAAAA RNA Processing mRNA Export G AAAAAA

Practice – Transcription DNA- G T A C C T A G G C T A A A C T G A mRNA ______________________________ DNA - T T A G C A T A C G G G T C A G A mRNA _______________________________

Codons Codon: is a group of three bases that code for a specific amino acid ex: AAA = Lysine The codons code for 20 amino acids Just like the alphabet has 26 letters to make all the words we know, the 20 amino acids make all the different proteins found in living organisms The codons are the template for protein synthesis, which takes place on the ribosomes (rRNA) in the cytoplasm

Protein Synthesis: Translation In the cytoplasm, mRNA attaches to the rRNA (ribosomal RNA) and starts reading the codons tRNA (transfer RNA) – carries amino acids to the ribosome and attaches them together to make a growing protein chain When protein production is complete, the ribosome releases the protein chain, and the protein folds into a 3D shape – the shape of the protein dictates is job or where it is used

DNA and Protein Synthesis – Codons and amino acids Name the Amino Acid: UAU CCG AGU GCA Tyrosine Proline Serine Alanine

Protein Synthesis: Translation

Translation - Initiation fMet UAC A E Large subunit P GAG...CU-AUG--UUC--CUU--AGU--GGU--AGA--GCU--GUA--UGA-AT GCA...TAAAAAA 5’ mRNA 3’ Small subunit

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

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

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

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

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