How genes on a chromosome determine what proteins to make Making Protein How genes on a chromosome determine what proteins to make

The Language of Nucleotides The sequence of the nucleotide bases are like a language The only letters in this language are A T C and G All words in this language are made up of three letters

How many words can you spell if English had only 4 letters? D N E O

20 possible ‘words’ for ATCG Every ‘word’ is an amino acid Some words are like a period at the end of a sentence.

Transcription The same as replication EXCEPT the sequence is copied to messenger RNA (mRNA) A pairs with Uracil (U) instead of T SINGLE strand. NOT double strand.

Transcription

Transcribe the following sequence from DNA into mRNA G-C-A-T-T-A-C-G-A C-G-U-A-A-U-G-C-U

Practice G-C-C-A-T-A C-T-A-C-G-A T-C-T-A-G-A A-T-T-G-A-C

mRNA ‘words’ Words are called codons Every three letters is 1 codon Codons are matched with anticodons to make proteins

Translation (reading the sequence) Translation build proteins (the last of the central dogma DNA – RNA – Proteins)

Three types of RNA Transfer RNA (tRNA) Ribosomal RNA (rRNA) Messenger RNA (mRNA)

Sequence of events Amino acid attaches to tRNA tRNA carries amino acid to rRNA rRNA ‘sits’ on top of mRNA and reads the sequence tRNA anticodons match with mRNA strand Protein is formed by the matching Translation stops when ‘stop codon’ appears

Practice C-C-A-T-T-C DNA sequence