Protein Synthesis Part 1: Transcription DNA to RNA

RNA Nucleic acid like DNA Polymer like DNA Monomers are called nucleotides like DNA Smaller than DNA (shorter & single stranded)

What is RNA made of? Like DNA, each nucleotide consists of 3 subunits 1) Phosphate 2) Sugar = RIBOSE (instead of the deoxyribose in DNA) 3) One of four bases

Ribonucleotide Bases A, C, G U instead of T BASES: C pairs with G A pairs with U U = Uracil (it replaces T)

Transcription 1st part of Protein Synthesis cell creates mRNA to carry information from DNA in nucleus to ribosome in cytoplasm DNA is too large to get out of nucleus needs RNA to carry the message with instructions!

Transcription, cont Transcription is the step during which a complementary mRNA strand is made from a specific region of the DNA molecule.

Transcription, cont An enzyme causes part of the DNA molecule to unwind/separate by breaking the hydrogen bonds between base pairs.

Transcription, cont DNA mRNA The exposed DNA bases attract their complementary RNA bases (thus the DNA acts as a template): mRNA DNA

Transcription, cont The enzyme helps the joining of nucleotides to form a strand of messenger RNA (mRNA). The enzyme leaves the DNA, and DNA closes to reform its double helix.

Transcription Ends mRNA leaves the nucleus through pores in the nuclear membrane. Transcription ends. Translation is next.

Central Dogma A gene is a section of DNA that codes for a protein. DNA is transcribed into mRNA mRNA is translated to protein (to be described next!)