DNA Transcription: one gene on DNA translated into mRNA.

1. A specific section of DNA unwinds, exposing one gene.
2. Along 1 strand, complementary RNA bases bond.
3. Adjacent nucleotides form covalent bonds and build RNA backbone, RNA polymerase.
4. RNA is released by DNA reforms double helix.

RNA is converted DNA’s message to protein. Made of a chain of nucleotides, RNA is based on a single-stranded and short, contains sugar ribosome, Uracil. There are three types of RNA: Messenger RNA which carries DNA’s message to the ribosome. Ribosomal RNA makes up part of the ribosome, and Transfer RNA carries amino acids to the ribosome.

1. Describe the process of translation: initiation, elongation, and termination.

Translation is mRNA carries a message to a ribosome. Ribosome reads mRNA and links amino acids together, as instructed.

1. Initiation: mRNA binds to the small ribosome subunit, then the 2 ribosome subunit, then the 2 ribosome subunits bind together. The ribosome holds the mRNA and reads the start codon.

2. Elongation: ribosome holds mRNA and allows complimentary tRNA to attach to binding sites. mRNA has 3 letter code called “codon”, tRNA has complimentary 3 letter code called “anticodon”. Each of the 64 possible codons is specific to one of the 20 amino acids. In addition, tRNA binds to “p” site, another tRNA binds to “A” site binding causes change binds to neighbouring amino acid. “Empty” tRNA leaves ribosome. The ribosome moves along mRNA, now the second tRNA is at “p” site and new tRNA binds to mRNA codon at “A” site.

3. Termination: The ribosome reads a stop codon. There is no complimentary tRNA for a stop codon. This will cause the ribosome to release the mRNA, tRNA, and polypeptide strand. The elongation cycle continues until mRNA “reads” a stop codon. “3 letter word” which does not have a matching tRNA. No new Amino acids are added to the chain, so the ribosome dissociates into its 2 subunits and the polypeptide is released.