copyright cmassengale PROTEIN SYNTHESIS copyright cmassengale
copyright cmassengale I.DNA and Genes copyright cmassengale
copyright cmassengale DNA DNA contains genes, sequences of nucleotide bases These Genes code for polypeptides (proteins) Proteins are used to build cells and do much of the work inside cells copyright cmassengale
copyright cmassengale Genes & Proteins Proteins are made of amino acids linked together by peptide bonds 20 different amino acids exist copyright cmassengale
copyright cmassengale Polypeptides Amino acid chains are called polypeptides copyright cmassengale
copyright cmassengale DNA Begins the Process DNA is found inside the nucleus Proteins, however, are made in the cytoplasm of cells by organelles called ribosomes Ribosomes may be free in the cytoplasm or attached to the surface of rough ER copyright cmassengale
copyright cmassengale Starting with DNA DNA ‘s code must be copied by the mRNA (transcription) In the cytoplasm, this code must be read so amino acids can be assembled to make polypeptides (proteins) This process is called PROTEIN SYNTHESIS copyright cmassengale
copyright cmassengale II. RNA copyright cmassengale
RNA is the BLUEPRINT of the Master Plan Roles of RNA and DNA DNA is the MASTER PLAN RNA is the BLUEPRINT of the Master Plan copyright cmassengale
copyright cmassengale RNA Differs from DNA RNA has a sugar ribose DNA has a sugar deoxyribose copyright cmassengale
copyright cmassengale Other Differences RNA contains the base uracil (U) DNA has thymine (T) RNA molecule is single-stranded DNA is double-stranded DNA copyright cmassengale
copyright cmassengale Structure of RNA Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded. copyright cmassengale
copyright cmassengale . Three Types of RNA Messenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomes Ribosomal RNA (rRNA), along with protein, makes up the ribosomes Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized copyright cmassengale
copyright cmassengale Messenger RNA Long Straight chain of Nucleotides Made in the Nucleus Copies DNA & leaves through nuclear pores Contains the Nitrogen Bases A, G, C, U ( no T ) copyright cmassengale
copyright cmassengale Messenger RNA (mRNA) Carries the information for a specific protein Made up of 500 to 1000 nucleotides long Sequence of 3 bases called codon AUG – methionine or start codon UAA, UAG, or UGA – stop codons copyright cmassengale
copyright cmassengale The Genetic Code A codon designates an amino acid An amino acid may have more than one codon There are 20 amino acids, but 64 possible codons Some codons tell the ribosome to stop translating copyright cmassengale
copyright cmassengale The Genetic Code Use the code by reading from the center to the outside Example: AUG codes for Methionine copyright cmassengale
copyright cmassengale Name the Amino Acids GGG? UCA? CAU? GCA? AAA? copyright cmassengale
Remember the Complementary Bases On DNA: A-T C-G On RNA: A-U copyright cmassengale
copyright cmassengale Transfer RNA (tRNA) Single stranded molecule with attachment site at one end for an amino acid Opposite end has three nucleotide bases called the anticodon copyright cmassengale
copyright cmassengale Transfer RNA amino acid attachment site U A C anticodon copyright cmassengale
copyright cmassengale Codons and Anticodons The 3 bases of an anticodon are complementary to the 3 bases of a codon Example: Codon ACU Anticodon UGA UGA ACU copyright cmassengale
III. Transcription and Translation copyright cmassengale
Pathway to Making a Protein DNA mRNA tRNA (ribosomes) Protein copyright cmassengale
copyright cmassengale Protein Synthesis The production or synthesis of polypeptide chains (proteins) Two phases: Transcription & Translation mRNA must be processed before it leaves the nucleus of eukaryotic cells copyright cmassengale
copyright cmassengale DNA RNA Protein Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein Eukaryotic Cell copyright cmassengale
copyright cmassengale Transcription The process of copying the sequence of one strand of DNA, the template strand mRNA copies the template strand Requires the enzyme RNA Polymerase copyright cmassengale
copyright cmassengale Template Strand copyright cmassengale
copyright cmassengale Question: What would be the complementary mRNA strand for the following DNA sequence? DNA GCGTATG copyright cmassengale
copyright cmassengale Answer: DNA GCGTATG mRNA CGCAUAC copyright cmassengale
copyright cmassengale Transcription During transcription, RNA polymerase binds to DNA and separates the DNA strands RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA copyright cmassengale
copyright cmassengale RNA Polymerase copyright cmassengale
copyright cmassengale mRNA Transcription mRNA leaves the nucleus through its pores and goes to the ribosomes copyright cmassengale
copyright cmassengale Translation Translation is the process of decoding the mRNA into a polypeptide chain Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins copyright cmassengale
copyright cmassengale Translation Translation is the process of __________________ _______ read mRNA three bases or ______ at a time and construct the proteins A chain of polypeptides is a _______ (w/a _____ & _____ code). copyright cmassengale
copyright cmassengale Transcription Transcription occurs when DNA acts as a template for mRNA synthesis. Translation occurs when the sequence of the mRNA codons determines the sequence of amino acids in a protein. Translation copyright cmassengale
copyright cmassengale Ribosomes Large subunit P Site A Site mRNA A U G C Small subunit copyright cmassengale
copyright cmassengale peptide bonds 4-tRNA G C U aa4 aa1 aa2 aa3 2-tRNA 3-tRNA G A U G A A A U G C U A C U U C G A A C U mRNA copyright cmassengale
copyright cmassengale peptide bonds 4-tRNA G C U aa4 aa1 aa2 aa3 2-tRNA G A U (leaves) 3-tRNA G A A A U G C U A C U U C G A A C U mRNA Ribosomes move over one codon copyright cmassengale
copyright cmassengale peptide bonds U G A 5-tRNA aa5 aa1 aa2 aa4 aa3 3-tRNA 4-tRNA G A A G C U G C U A C U U C G A A C U mRNA copyright cmassengale
copyright cmassengale peptide bonds U G A 5-tRNA aa5 aa1 aa2 aa3 aa4 3-tRNA G A A 4-tRNA G C U G C U A C U U C G A A C U mRNA Ribosomes move over one codon copyright cmassengale
copyright cmassengale aa5 aa4 aa199 Termination aa3 primary structure of a protein aa200 aa2 aa1 terminator or stop codon 200-tRNA A C U C A U G U U U A G mRNA copyright cmassengale
End Product –The Protein! The end products of protein synthesis is a primary structure of a protein A sequence of amino acid bonded together by peptide bonds aa1 aa2 aa3 aa4 aa5 aa200 aa199 copyright cmassengale
copyright cmassengale Messenger RNA (mRNA) A U G C mRNA start codon codon 2 codon 3 codon 4 codon 5 codon 6 codon 7 codon 1 methionine glycine serine isoleucine alanine stop codon protein Primary structure of a protein peptide bonds copyright cmassengale