Protein Synthesis

The Kentucky Fried Caper

Protein Synthesis

× DNA carries the information needed to create proteins but does not create them itself

× DNA information is first converted into an RNA strand and then RNA can help to create proteins within our body× These proteins is what

determines a gene’s expression

THe Difference between the two

DNA vs. RNA

Protein Synthesis

× There are two processes that are involved in a gene resulting in a specific phenotype× Transcription- the transfer of genetic

information from DNA to RNA× Translation- the RNA strand is read and

creates a specific amino acid sequence× The amino acid sequence determines

the protein created× How it happens

Transcription

DNA segment acts as a template for the production of an RNA molecule

Step 1:

× An enzyme called RNA polymerase binds to a promoter (TATAAAA)

× A promoter is the beginning segment of a specific segment of a DNA molecule

× RNA polymerase opens the DNA helix so that it can create a complementary RNA strand

× This strand is called mRNA (messenger RNA)

Note me: The Promoter

TATA Box× Contained within the promoter× DNA sequence of 5’ TATAAAA 3’× 25 nucleotides before the transcription starting

point.× The DNA strand opens shortly after the TATA box.

TranscriptionFor example: the DNA segment TAC will be converted into the RNA strands AUG

× TAC is the codon and AUG is the anticodon× Later these three bases form amino acids× The amino acid AUG will form is Methionine

(START)

TranscriptionStep 2:

× mRNA is processed and then allowed to leave the nucleus and enter the cytoplasm

Translation

× Translation is the 2nd step in protein synthesis where a gene leads to the creation of a protein

× Translation requires:× Enzymes× mRNA× tRNA× rRNA

Translation

× A sequence of DNA bases creates a variety of different three base sets

× Bases form segments of 3 in order to create the most different combinations of the 4 bases

Translation

Triplet Code

× 3 base sequence is called a codon× One codon will create one amino acid

× 64 total combinations× 61 codons will create a specific amino acid× 3 create stop or start codons× Several combinations of bases create the

same amino acid× The order of amino acids determines the

protein

Translation

× 3 Steps involved in Translation:

Step 1: Chain Initiation

× The mRNA reaches the rRNA× tRNA molecule carries amino acids to

the rRNA and binds to the start codon on the mRNA

Translation

Step2: Elongation (building the polypeptide chain)

× More tRNA brings more amino acids according to the codons on the mRNA

Three Steps of Translation

Translation

Step 3: Termination

× tRNA stops bringing amino acids once it reaches a stop codon on the mRNA

Translation

Step 3: Termination

× tRNA stops bringing amino acids once it reaches a stop codon on the mRNA

More Vocabulary

Polypeptide ChainThe polypeptide chain, or amino acid chain, is then formed into a proteinproteins are needed for gene expression

More Vocabulary

The ProteinThe amino acid chain that forms is very flexible. Different areas of the protein will fold in different ways creating distinct shapes

Why is this important?

× Protein synthesis needs to be accurate so that you have actively functioning proteins

× Proteins carry functions within cells that influence the way our body works (ex. Transport proteins inside cell membranes)

× If the amino acid chain is produced in the wrong order it can cause a faulty gene or mutations

× A gene mutation is a change in the sequence of bases that make up the gene