Protein Synthesis (to make proteins)

What is Protein Synthesis? Flow of Genetic Information: DNA RNA Protein DNA holds the code for protein synthesis but cannot leave the nucleus

Protein Synthesis is performed at the ribosomes in the cytoplasm The cell uses RNA to copy the code from DNA and bring it to the ribosomes

RNA – Ribonucelic Acid I. Nitrogenous Bases a. Adenine b. Cytosine c. Guanine d. Uracil I. Simple Sugar – a ribose rather than a deoxyribose II. Phosphate Groups

II. Structure a. A nucleic acid backbone b. single strand of nucleotides c. Sugar is ribose d. Contains uracil base instead of thymine

Difference between DNA and RNA  DNARNA  Double strandsingle strand  Deoxyriboseribose  Thymineuracil

III. Types of RNA Three types of RNA are used to make proteins a. mRNA – messenger RNA b. rRNA – ribosomal RNA c. tRNA – transfer RNA

IV. mRNA Function A. transcribe DNA code B. take code outside of nucleus to ribosome B. take code outside of nucleus to ribosome C. give instructions to ribosome on how to build protein C. give instructions to ribosome on how to build protein

How does DNA transfer info to RNA? A = U G = C T = A No T’s in RNA

V. tRNA Function  To deliver amino acids to the ribosome as it is building (synthesizing) protein

VI. rRNA Function  where translation of RNA to protein takes place  Ribosomes are made up of protein and ribosomal RNA (rRNA)

Remember: How many different amino acids are there? 20 Look at your notes - What makes each amino acid different from one another? R groups

VIII. The CODE!! A.James Watson and Francis Crick, with the help of Rosalind Franklin’s X-ray crystallography images unraveled the structure of DNA: B. The fact that bases paired led directly to a theory of how DNA codes for proteins. It took a few years to determine that the bases spell three- letter “words” called codons

mRNA Codons  3 letters on mRNA are called codons. These three letter codes are used to determine which Amino Acid is to be placed on the protein. Ex: TAC AUG = Start Codon (Methionine) AUG = Start Codon (Methionine) This is where you begin translation of DNA’s code given to mRNA

See the mRNA codon chart (slime green)  Write the codon for Proline here:  Glycine?  Which amino acid has the most codons?  Which amino acid has the fewest?  Start codon starts each protein  Three codons tell a ribosome to stop making a protein. List them here:

Transcription? - Copying the portion of DNA that carries the code for a protein. - Copying the portion of DNA that carries the code for a protein. yU&feature=related yU&feature=related mRNA Synthesis (Transcription begins with a promoter on DNA, site RNA polymerase binds to on DNA to begin transcription). -A mRNA is transcribed (built) using unwound DNA’s code as a template. -RNA nucleotides find their compliment. -RNA Polymerase is the enzyme that brings in the nucleotides

- Completed when reaches terminator sequence on DNA – ending transcription The original strand is used as the template.

Result: The resulting mRNA looks exactly like the template strand of DNA, with one important distinction each T is replace with a U. each T is replace with a U. ture=related ture=related Where does it go? Where does it go? The RNA releases from DNA and is then edited before leaving the nucleus

Practice Transcription 3 ‘ T A C G A T G C A T C G 5’ 5 ‘ A U G C U A C G U A G C 3’ DNA Strand RNA Strand

Translation -The process of interpreting mRNA to build a chain of amino acids that make up a protein. D38&feature=related D38&feature=related

How does it work? i. mRNA leaves the nucleus and heads to the cytoplasm where the ribosomes are located. Remember: Ribosomes are where translation will occur Each sequence of nucleotides is a codon (mRNA codon). Each codon codes for a specific amino acidEach sequence of nucleotides is a codon (mRNA codon). Each codon codes for a specific amino acid

ii. Amino acids are brought to the ribosome by tRNA. There are 20 different tRNA molecules, one for each type of amino acid.There are 20 different tRNA molecules, one for each type of amino acid. tRNA anticodon finds their complimentary codon on mRNA.tRNA anticodon finds their complimentary codon on mRNA.

Anticodon – 3 letters found to match the mRNA’s codon. –mRNA codon: UAA CGA GGC –tRNA anticodon: AUU GCU CCG

iii. Peptide bonds form between the amino acids forming a polypeptide. iV. Translation stops when a stop codon is reached. Video: Ne5mS2ls&feature=related Ne5mS2ls&feature=related Ne5mS2ls&feature=related

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