University:
Sam Houston State University
Course:
BIOL 1406 | General Biology I
Academic year:

2022
Views:

84

Pages:

10
Author:

SpaceCadet101

Protein Synthesis OBJECTIVES • Explain the purpose and process of transcription and translation • Recognize that gene expression is a regulated process • Describe the roles of DNA and RNA in cell differentiation • Identify and illustrate changes in DNA and evaluate the significance of these changes WHAT IS PROTEIN SYNTHESIS? • Process whereby DNA encodes for the production of amino acids and proteins • Refers to a multi-step process, beginning with amino acid synthesis and transcription of nuclear DNA into messenger RNA, which is then used as input for translation WHY DO WE NEED IT? • We need proteins! • Proteins make up enzymes, hormones and components of cell membranes among many other things MRNA • Molecule of RNA that encodes a chemical "blueprint" for a protein product • Carries coding information to the sites of protein synthesis: the ribosomes • Read in a series of triplets called codons Example of a codon: AUG TRNA • Functions as an interpreter between nucleic acid and peptide sequences by picking up amino acids and matching them to the proper codons in mRNA • Each tRNA carries one amino acid that corresponds to an mRNA codon • The proper amino acid is joined to the tRNA by the enzyme aminoacyl-tRNA synthetase RIBOSOME • Composed of two subunits: a large and a small • Work bench for protein assembly STEP 1: TRANSCRIPTION • DNA unwinds and “unzips” • Enzymes match RNA nucleotides to unzipped nitrogen bases of the DNA and form one strand of mRNA • The strand of mRNA detaches and heads off out of the nucleus for a ribosome • DNA re-zips and twists back up again STEP 2: TRANSLATION • Small ribosomal subunit binds to the mRNA • Initiator tRNA binds to the binds with the start codon of mRNA • Large ribosomal subunit binds to the complex and starts the polypeptide chain • A second tRNA comes in and binds to the next mRNA codon • The ribosome advances down the line to the next codon, and the process continues • Rinse and repeat until a STOP codon is reached and a brand new polypeptide is released and ready to be used. OBJECTIVES • Explain the purpose and process of transcription and translation • Recognize that gene expression is a regulated process • Describe the roles of DNA and RNA in cell differentiation • Identify and illustrate changes in DNA and evaluate the significance of these changes