Transcription and Translation

Structure of RNA

• Similar to DNA• 5 carbon sugar• Phosphate group• Nitrogenous base

• 3 main differences• Ribose sugar rather than deoxyribose• Single stranded rather than double stranded• Bases are Adenine, Uracil, Guanine, Cytosine

• Disposable copy of DNA

Types of RNA

• mRNA• The message of DNA to code for a gene

• tRNA• Used to bring amino acids together when creating proteins

• rRNA• Forms ribosomes, along with proteins

Transcription

• Production of RNA from DNA• Requires RNA polymerase• Function?

• Started by helicase proteins • Promoters • Regions of DNA that allows RNA polymerase to bind to it• Signal points for the beginning of a gene

After Transcription

• RNA produced requires editing before it is an active form• Introns: sequences of DNA found in eukaryotic genes• Must be removed from RNA before it can be used to produce proteins

• Exons: segments of DNA that code for proteins• Stay in DNA

• Both introns and exons are formed from DNA

Genetic Code

• Amino acids are joined together in long chains to form proteins (polypeptides) • Each combination of amino acids means the proteins have different

properties • Codon• Three nucleotides that code for a specific amino acid• mRNA is read 3 bases at a time, each 3 bases is one codon

• UCGCACGGU UCG-CAC-GGU Serine – Histidine – Glycine

Translation

• Turning mRNA into a protein • Requires ribosomes• Occurs in 3 steps• mRNA in cytoplasm attaches to a ribosome. mRNA moves through the

ribosome, each codon is read and a tRNA brings the matching amino acid and attaches them together. • Peptide bond is formed between amino acids to hold protein together. At the

same time, ribosome breaks the bond holding the amino acid to the tRNA then releases the tRNA. • Continues to grow until the ribosome reads a stop codon

Genes and Proteins

• Proteins control every physical characteristic• Genes control production of enzymes to produce skin pigment • Genes also control enzyme production that determines blood type

Activity

• Write a one paragraph summary of the lecture notes.