RNA StructureandFunction Transcription Translation

RNA versus DNA

The Sugar Ribose

Four RNA Bases AdenineUracil Guanine Cytosine

Types of RNA

mRNA mRNA = messenger RNA Represents the sequence of codons (mRNA language) from the DNA strand. Brings the sequence to the ribosomes (site of protein synthesis) in the cytoplasm. Provides the sequence for the synthesis of specific protein from the amino acids (found in cytoplasm).

rRNA rRNA = ribosomal RNA Function: forms a complex with various proteins and make a structure called ribosome, and this complex reads the coded sequence in mRNA to link amino acids together into particular proteins.

Transfer RNA tRNA brings the amino acids to the ribosomes

The Central Dogma of Life. replication

Transcription RNA DNA Transcription is the process by which RNA is built from a template of DNA

Transcription

Transcription The mRNA sequence leaves the nucleus and enters the cytoplasm to be “read”. Translation

Translation Translation Translation is the process by which protein is made from an mRNA template

Codons 4 different bases make up RNA RNA is read in groups of three called a triplet One triplet is called a CODON Each CODON represents a specific amino acids Amino acids build proteins

Codons

Why Three Bases per Codon? 4 1 = 4 A one base code: 4 1 = 4 combinations 4 2 = 16 A two base code: 4 2 = 16 combinations 4 3 = 64 A three base code: 4 3 = 64 combinations There are twenty amino acids, so a three- base code is the minimum required.

Making a protein mRNA from nucleus travels through the cytoplasm to the ribosome On the mRNA, a start codon: AUG signals the beginning of a protein tRNA delivers specific amino acids and creates a polypeptide chainpolypeptide chain A release factor ends the processprocess

Protein Synthesis