* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Protein Synthsis
Protein moonlighting wikipedia , lookup
Promoter (genetics) wikipedia , lookup
Non-coding DNA wikipedia , lookup
Western blot wikipedia , lookup
RNA interference wikipedia , lookup
Ribosomally synthesized and post-translationally modified peptides wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
Molecular evolution wikipedia , lookup
RNA silencing wikipedia , lookup
Peptide synthesis wikipedia , lookup
List of types of proteins wikipedia , lookup
Protein adsorption wikipedia , lookup
Eukaryotic transcription wikipedia , lookup
Protein (nutrient) wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Polyadenylation wikipedia , lookup
RNA polymerase II holoenzyme wikipedia , lookup
Silencer (genetics) wikipedia , lookup
Two-hybrid screening wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Transcriptional regulation wikipedia , lookup
Protein structure prediction wikipedia , lookup
Point mutation wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Bottromycin wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Proteolysis wikipedia , lookup
Biochemistry wikipedia , lookup
Non-coding RNA wikipedia , lookup
Gene expression wikipedia , lookup
Messenger RNA wikipedia , lookup
Expanded genetic code wikipedia , lookup
Protein Synthesis Central Dogma Central Dogma Information flows from DNA to RNA to proteins Replication copies DNA Transcription converts a DNA message into an intermediate molecule called RNA Translation interprets an RNA message into a string of amino acids, called a polypeptide. A single polypeptide or many polypeptides working together make a protein. Transcription When DNA converts into an intermediate molecule called RNA. RNA is necessary to make proteins. Transcription Replication and transcription occur in the nucleus. Translation will occur in the cytoplasm Transcription is the process of copying a sequence of DNA to produce a complimentary strand of RNA It is catalyzed by RNA polymerase. Bonds nucleotides together in a chain to make a new RNA molecule. Transcription 1. RNA polymerases recognize the transcription “start” site of a gene. RNA polymerase begins to unwind a segment of DNA. 2. RNA polymerase, using one strand of DNA as a template, strings together a complimentary strand of RNA nucleotides. The growing RNA strand hangs freely as it is transcribed, and the DNA strand zips back together. 3. Once the entire gene has been transcribed, the RNA strand detaches completely from the DNA. mRNA Carries DNA’s Instructions RNA acts as an intermediate link between DNA in the nucleus and protein synthesis in the cytoplasm. RNA is like a temporary copy of DNA that is used and then destroyed Protein Synthesis takes 3 different types of RNA Messenger RNA (mRNA) Intermediate message that is translated into a protein. Ribosomal RNA (rRNA) Forms part of ribosomes, a cell’s protein factory. Transfer RNA (tRNA) Brings amino acids from the cytoplasm to a ribosome to help make a growing protein. The transcription process is cool! Transcription enables a cell to adjust to changing demands. Say you are trapped by an ANGRY bear! Your body needs adrenaline (a hormone/protein) to run FAST! Transcription allows your body to make a lot of adrenaline very quickly Translation Translation is the process that converts, or translates, an mRNA message into a polypeptide. One or more polypeptides make a protein. RNA uses adenine, uracil, guanine, cytosine to code for 20 amino acids Triplet Code In the genetic code, all “words” are made up of three letters (nucleotides). A codon is a three-nucleotide sequence that codes for an amino acid. Amino Acids Amino acids are bonded by peptide bonds to create polypeptides and then proteins. Many amino acids are coded for by more than one codon. For example: Leucine is represented by six codons: CUU, CUC, CUA, CUG, UUA, and UUG In most cases, codons that represent the same amino acid share the same first two nucleotides. Having many codons represent a single amino acid makes DNA more tolerant of point mutations. Start and Stop Codons Start Codon Signals the start of translation Is the amino acid methionine (AUG) Translation always begins with AUG… Stop Codon Signals the end of the amino acid chain Coded for by UAA, UAG, or UGA The Reading Frame For the mRNA code to be translated correctly, codons must be read in the right order. This order is called the reading frame Changing the reading frame completely changes the resulting protein. Therefore, it is very important for the mRNA to have a clear START and STOP codon. Common Language The genetic code is shared by almost all organisms (even viruses) It is considered to be a universal code That means that the codon UUU codes for phenylalanine in an armadillo, a cactus, a yeast, or a human. This suggests that all organisms arose from a common ancestor. This also means that scientists can insert a gene from one organism into another organism to make a functional protein Ribosomes To translate codons into a physical amino acid, a ribosome and tRNA are used. Ribosomes are a combination of rRNA and proteins. They catalyze the reaction that forms bonds between amino acids. They are the site of protein synthesis. Ribosomes Ribosomes have a large and small subunit that fit together and pull the mRNA strand through. The small subunit holds onto the mRNA strand. The large subunit holds onto the growing protein. Transfer RNA (tRNA) tRNA acts as a sort of adaptor between mRNA and amino acids. It carries free floating amino acids from the cytoplasm to the ribosome. The tRNA is shaped like a plus sign One end of the plus sign is attached to a specific amino acid. The bottom has an anticodon that recognizes a specific codon on the mRNA strand o Ex. The anticodon CCC pairs with the mRNA codon GGG. Amino Acids are linked to become a protein 1. The ribosome attaches to an mRNA molecule and exposes one codon. 2. The exposed codon attracts a complimentary tRNA molecule bearing an amino acid. The tRNA anticodon pairs with the mRNA codon. Amino Acids are linked to become a protein 3. The ribosome helps form a peptide bond between the two amino acids. The ribosome then breaks the bond between the tRNA molecule and its amino acid. 4. The ribosome pulls the mRNA strand the length of one codon. The tRNA disengages from the mRNA (leaving its amino acid bonded with the mRNA) to pick up a new amino acid. 5. The ribosome continues to move down the mRNA strand, attaching new amino acids to the growing protein, until it reaches a stop codon. How to make a protein… Ribosomes Large subunit P Site A Site mRNA Small subunit 20 A U G C U A C U U C G How to make a protein… aa1 aa2 2-tRNA 1-tRNA anticodon hydrogen bonds 21 U A C A U G codon G A U C U A C U U C G A mRNA How to make a protein… peptide bond aa1 aa3 aa2 3-tRNA 1-tRNA anticodon hydrogen bonds 22 U A C A U G codon 2-tRNA G A A G A U C U A C U U C G A mRNA aa1 peptide bond aa3 aa2 1-tRNA 3-tRNA U A C (leaves) 2-tRNA A U G G A A G A U C U A C U U C G A mRNA 23 Ribosomes move over one codon aa1 peptide bonds aa4 aa2 aa3 4-tRNA 2-tRNA A U G 3-tRNA G C U G A U G A A C U A C U U C G A A C U mRNA 24 aa1 peptide bonds aa4 aa2 aa3 2-tRNA 4-tRNA G A U (leaves) 3-tRNA A U G G C U G A A C U A C U U C G A A C U mRNA 25 Ribosomes move over one codon aa1 peptide bonds aa5 aa2 aa3 aa4 5-tRNA U G A 3-tRNA 4-tRNA G A A G C U G C U A C U U C G A A C U mRNA 26 peptide bonds aa1 aa5 aa2 aa3 aa4 5-tRNA U G A 3-tRNA G A A 4-tRNA G C U G C U A C U U C G A A C U mRNA 27 Ribosomes move over one codon aa4 aa5 Termination aa199 aa3 primary structure aa2 of a protein aa200 aa1 200-tRNA A C U mRNA 28 terminator or stop codon C A U G U U U A G Transcription to Translation End Product –The Protein! The end product of protein synthesis is a primary structure of a protein A sequence of amino acids bonded together by peptide bonds aa2 30 aa1 aa3 aa4 aa5 aa199 aa200 Transcription and Translation! How transcription and translation works Gene Expression and Regulation Depending on an organisms needs, a gene can make a lot of protein, a little protein, or none at all.