Protein Synthesis Transcription Translation DNA m RNA ribosome

Protein Synthesis: Transcription & Translation DNA > m. RNA > ribosome > protein

Protein Synthesis Overview • Two processes are required: – 1. – 2.

Transcription: DNA > m. RNA

Transcription: -

• Steps of Transcription 1. DNA strands unwind & separate 2. DNA strand containing a specific gene serves as a template strand 3. RNA nucleotides are matched to complimentary DNA bases 4. m. RNA molecule is complete and DNA rewinds

• The bases of m. RNA pair with DNA bases but RNA replaces T with U DNA A T G C • DNA: • m. RNA: RNA U A C G CTG TAC GGA ---> Transcription GAC AUG CCU template strand

Transcription • m. RNA leaves the nucleus

Translation: m. RNA > protein • Process of making proteins from info on m. RNA – m. RNA travels out of nucleus to the ribosome, which “reads” the m. RNA as a series of 3 letter words called codons

• Codon: Codon 3 -base code on m. RNA that codes for a specific amino acid – Ex. CGU = alanine GUU = valine • The sequence of bases in DNA tell m. RNA what order amino acids must join together to make a particular protein.

Codons found in m. RNA Third Base First Base Second Base

• Transfer RNA (t. RNA) matches up with each codon and transfers the correct amino acid • Each t. RNA molecule has 3 unpaired bases called the anticodon that is complementary to one m. RNA codon.

• Each amino acid is added to a growing chain of amino acids • Protein = peptide bonds connecting amino acids – Many different types of proteins exist because the number and sequence of amino acids can be different

Second Base m. RNA: AUG AAA AGU UGU CUG GUU UAA A. A: Met - Lys – Ser - Cys – Leu – Val - Stop ___________________ Third Base Practice translating m. RNA into amino acids: First Base Codons found in m. RNA

How DNA determines proteins • DNA molecules serve as templates for making messenger RNA molecules • Messenger RNA molecules move to ribosomes • Transfer RNA molecules bring amino acids to the ribosome • Polypeptides (proteins) are formed as ribosomes move along the messenger RNA strand

Gene Expression • DNA in all of your body cells is the same! – Ex: DNA in your eye cells is the same DNA that is in your skin cells. • Different types of cells express different genes. – Ex: Your eyes may be green, while your skin is brown. • Specialization of cells is due to different patterns of gene expression, rather than different genes themselves. – Liver cells express different genes than blood cells

• DNA: • • TAC TCC AGC GCA ACT ----Transcription----> m. RNA: AUG AGG UCG CGU UGA ----Translation---> A. A. : met arg ser arg stop

Learning Goals • 1. Summarize the overall process of protein synthesis including the “central dogma rule”. • 2. Describe Transcription in detail including where it takes places and the roles of introns and exons. • 3. Describe Translation in detail including where it takes place, codons, anti-codons, t. RNA, amino acids, and protein • 4. Explain how gene expression works.