So how do we get from DNA to Protein? This is the: Central Dogma of Molecular Biology DNA RNA Protein Transcription Translation

How Proteins are Made Ribonucleic Acid (RNA) – a type of nucleic acid involved in protein synthesis.

How Proteins are Made PROTEINS ARE MADE BY DECODING THE INFORMATION IN DNA DNA codes for the formation of RNA in the nucleus of the cell.  RNA is short for another kind of nucleic acid called ribonucleic acid.   RNA is very similar in structure to DNA except for three small differences.   These differences include the fact that RNA is a single stranded molecule, and it lacks the base thymine (T) as it is replaced by the base uracil (U), and its five carbon sugar ribose has one more oxygen atom than the sugar deoxyribose in DNA.    Three are different types of RNA exist, mRNA or messenger RNA, tRNA or transfer RNA, and rRNA or ribosomal RNA. 

How Proteins are Made PROTEINS ARE MADE BY DECODING THE INFORMATION IN DNA Uracil – a nitrogen-containing base of RNA, complementary to adenine when RNA base pairs with the DNA.

How Proteins are Made PROTEINS ARE MADE BY DECODING THE INFORMATION IN DNA Transcription - stage of protein synthesis in which the information in DNA for making protein is transferred to an RNA molecule. http://www.fed.cuhk.edu.hk/~johnson/teaching/genetics/animations/transcription.htm

How Proteins are Made PROTEINS ARE MADE BY DECODING THE INFORMATION IN DNA Translation – stage of gene expression in which the information in mRNA (messenger RNA) is used to make a protein. http://gslc.genetics.utah.edu/units/basics/transcribe/ This mRNA codon is then carried from the nucleus out to the ribosome.  Messenger RNA attaches to another kind of RNA called tRNA (transfer RNA).  Transfer RNA attaches to amino acids and carries them to the ribosome.    This assembly of amino acids due to the code provided to RNA by the original DNA molecule is what produces proteins for the cell.  Remember a protein is a long molecule formed from amino acid subunits.

Protein: The stuff of your body Proteins are organic compounds made up of chains of amino acids. There are 20 amino acids commonly used in your body. Most of your body structure is made of some type of protein. The rest of your body is made of other materials that are made by proteins (enzymes).

All 20 Amino Acids

How Proteins are Made PROTEINS ARE MADE BY DECODING THE INFORMATION IN DNA Gene Expression – the two–stage processing of information encoded in DNA to produce proteins.

How Proteins are Made TRANSCRIPTION TRANSFERS INFORMATION FROM DNA TO RNA RNA Polymerase – enzyme that adds and links complementary RNA nucleotides during transcription.

How Proteins are Made TRANSCRIPTION TRANSFERS INFORMATION FROM DNA TO RNA RNA polymerase binds to a segment of DNA where a certain gene sequence is located. It unwinds the DNA helix and exposes the DNA nucleotides. It next creates a strand of mRNA by linking nucleotides together that complement the coding strand of DNA. The mRNA will be used to make a specific protein that was encoded in the DNA.

How Proteins are Made THE GENETIC CODE IS WRITTEN IN THREE-NUCLEOTIDE “WORDS” Messenger RNA – a RNA copy of a gene used as a blueprint for the making of a protein during translation. The mRNA that was transcribed in the nucleus will be transported out of the cell nucleus into the cytoplasm where it most likely will rendezvous with a ribosome attached to the endoplasmic reticulum. Translation of the mRNA molecule will occur there.

How Proteins are Made THE GENETIC CODE IS WRITTEN IN THREE-NUCLEOTIDE “WORDS” Codons – a three-nucleotide sequence in DNA or mRNA that encodes for an amino acid or signifies a stop signal. http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html#

Universal for all organisms How Proteins are Made Universal for all organisms THE GENETIC CODE IS WRITTEN IN THREE-NUCLEOTIDE “WORDS” Genetic Code – a sequence of nucleotides that specifies the amino acid sequence for a protein. http://library.thinkquest.org/20465/g_DNATranscription.html

How Proteins are Made MANY RNA’S ARE USED TO MAKE PROTEIN Transfer RNA – a RNA molecule that temporarily carries a specific amino acid to a ribosome during translation.

How Proteins are Made MANY RNA’S ARE USED TO MAKE PROTEIN Anticodon - a three-nucleotide sequence on tRNA (transfer RNA) that recognizes a complementary codon on mRNA. http://www.lewport.wnyric.org/jwanamaker/animations/Protein%20Synthesis%20-%20long.html

How Proteins are Made MANY RNA’S ARE USED TO MAKE PROTEIN The translation of mRNA into a protein is achieved by the use of a ribosome and tRNA. The tRNA carries or transfers individual amino acids to the site of translation. The type of amino acid brought to the sight of protein synthesis is determined by the codons that are embedded in the sequence of DNA, which is transcribe into mRNA. Amino Acids will be linked together by dehydration synthesis to form a protein. http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html

Protein Synthesis (Translation) MANY RNA’S ARE USED TO MAKE PROTEIN Ribosomal RNA – a type of RNA molecule that plays a structural role in ribosomes. http://www.biostudio.com/demo_freeman_protein_synthesis.htm

How Proteins are Made MANY RNA’S ARE USED TO MAKE PROTEIN The anticodon region on the tRNA will match up to a specific codon on the mRNA based on base-paring rules. An amino acid will temporarily attach to a site that is far removed from Anticodon region on tRNA.

How Proteins are Made PROTEIN SYNTHESIS IN PROKARYOTES IS CONTROLLED BY “ON-OFF” SWITCHES Lac Operon – a gene system with a promoter, an operator gene, and three structural genes that control lactose metabolism. Operator – region of DNA that controls RNA polymerase’s access to a set of genes with related functions. Operon – a segment of DNA that controls gene regulation in a set of genes with related functions in prokaryotes. Repressor – a protein that binds to the operator in an operon to switch off transcription. Honors

Honors http://www.csam.montclair.edu/%7Esmalley/LacOperon.mov

Gene Expression in Eukaryotes vs. Prokaryotes http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html#

How Proteins are Made GENES IN EUKARYOTES OFTEN HAVE INTERVENING DNA Introns – are segments of mRNA transcribed from eukaryotic DNA but are removed before translation of mRNA into a protein occurs. Exons – are a sequence of nucleotides on a gene that gets transcribed and translated. http://www.sumanasinc.com/webcontent/anisamples/molecularbiology/mRNAsplicing.html

How Proteins are Made GENES IN EUKARYOTES OFTEN HAVE INTERVENING DNA In Eukaryotes there are long segments of nucleotides in some genes that have no coding information. These segments are called introns. Think of it as an intervening sequence or an interruption in the gene. The other segments that will be expressed or transcribed and that are translated into protein are called exons. http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter15/animations.html#

How Proteins are Made MUTATIONS CAN RESULT IN A NONFUNCTIONAL PROTEIN Point Mutations – mutation in which one or just a few nucleotides in a gene are changed.

How Proteins are Made Mutations fall in several categories ... MUTATIONS CAN RESULT IN A NONFUNCTIONAL PROTEIN Mutations fall in several categories ... ... Point mutations are small (but significant) changes often in a single nucleotide base. Deletions remove information from the gene. A deletion could be as small as a single base or as large as the gene itself. Insertions occur when extra DNA is added into an existing gene. Frame shift mutations result from either addition or deletion of one or two nucleotide bases. When this occurs the "reading frame" is changed so that all the codons read after the mutation are incorrect, even though the bases themselves may be still present.