* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Nervous System
Endogenous retrovirus wikipedia , lookup
Bisulfite sequencing wikipedia , lookup
DNA repair protein XRCC4 wikipedia , lookup
Metalloprotein wikipedia , lookup
Molecular cloning wikipedia , lookup
Gene regulatory network wikipedia , lookup
RNA silencing wikipedia , lookup
DNA supercoil wikipedia , lookup
Community fingerprinting wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Proteolysis wikipedia , lookup
Non-coding DNA wikipedia , lookup
Promoter (genetics) wikipedia , lookup
Two-hybrid screening wikipedia , lookup
Eukaryotic transcription wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Protein structure prediction wikipedia , lookup
Real-time polymerase chain reaction wikipedia , lookup
Polyadenylation wikipedia , lookup
RNA polymerase II holoenzyme wikipedia , lookup
Biochemistry wikipedia , lookup
Transcriptional regulation wikipedia , lookup
Point mutation wikipedia , lookup
Silencer (genetics) wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Gene expression wikipedia , lookup
Messenger RNA wikipedia , lookup
Genetic code wikipedia , lookup
Protein Synthesis From Gene to Polypeptide What is a gene? Recall that a gene is a specific section of DNA along the length of a chromosome. It has a beginning (the “promoter”) and an end (the “termination signal”). A gene holds the information (“recipe”) for making a specific polypeptide (protein). Gene 1 and Gene 2 have different N-base sequences. Insulin and the receptor protein differ in the #, types, and sequence of amino acids. Gene Nucleotide DNA Structure An overview of the path from DNA to protein DNA vs. RNA Similarities Nucleic acids Made of nucleotides with a sugar, nitrogen base, and phosphate groups Differences RNA has ribose sugar (instead of deoxyribose) RNA has uracil instead of thymine RNA is single-stranded Base-pairing between DNA & RNA during transcription Videos: http://www.teachersdomain.org/reso urce/tdc02.sci.life.gen.proteinsynth/ http://www.californiastreaming.org/pl ayer.asp?mediaID=12495&segmentID =20846 mRNA Location: nucleus and cytoplasm Structure: single, unfolded chain of nucleotides. Contains a series of codons. 3 bases = codon = code for an a.a. Function: to carry the “recipe” for the protein from the nucleus to the ribosomes. tRNA Location: cytoplasm Structure: single chain folded into “cloverleaf” shape. Has an anticodon on one end and binds an amino acid on the opposite end. Function: to transfer (deliver) the correct amino acids to the ribosome. There are many different tRNAs; each carries a different a.a. rRNA/Ribosome Location: cytoplasm (“free” or on the rough ER) Structure: rRNA, combined with proteins. Has two subunits. Function: coordinates the building of a protein. Binds mRNA and tRNA; catalyzes peptide bond formation. Transcription: What is it? Creating the “messenger” Making a strand of mRNA using DNA as a template. mRNA = copy of gene Allows for transfer of info from DNA to site of protein synthesis (cytoplasm) Translation: What it is Making a polypeptide (chain of amino acids) using an mRNA template. mRNA = copy of gene Every 3 letters on mRNA = codon = codes for a specific amino acid (a.a.). e.g.: the codon AUG codes for methionine (“met”) Amino acids will be bonded together in a specific sequence. Correct a.a. sequence is critical to the protein being functional (having the right shape). Steps of Transcription: 1. RNA polymerase binds to a promoter on specific gene in DNA Promoter marks beginning of info to be transcribed 2. DNA molecule in that region “unzips” Hydrogen bonds are broken and strands move apart. Only one of the DNA strands is used as template for transcription Transcription, cont’d… 3. RNA nucleotides are paired to complementary bases on the DNA template strand Complementary base-pairing: C-G, G-C, TA, A-U 4. Covalent bonds (S-P) connect the RNA nucleotides into a single strand. RNA Polymerase helps position the nucleotides and catalyzes the formation of the covalent bonds. Transcription, cont’d… 5. mRNA strand lengthens until RNA polymerase reaches a “termination signal” 6. mRNA strand separates from the DNA template. DNA re-twists into double-helix. mRNA Carries Message from Nucleus to Cytoplasm http://nobelprize.org /educational/medicin e/dna/b/transcriptio n/transcription_ani.h tml http://www.teachersd omain.org/resource/ls ps07.sci.life.stru.celltr ans/ Problem Solving If you know the DNA sequence, you can determine the mRNA sequence More Practice Use the DNA sequence below to determine the mRNA sequence: DNA: T-A-C-G-A-T-A-T-C mRNA: A-U-G-C-U-A-U-A-G mRNA-tRNA connection mRNA contains the “codes” for the amino acids. tRNA delivers the amino acids. tRNA brings the right a.a. to the right place in the protein by binding to the mRNA. Codon and anticodon are complementary. The “Genetic Code” The amino acid brought by tRNA is specified by the mRNA codon, NOT the anticodon. http://www.dnalc.org/view/155 13-How-many-bases-code-foran-amino-acid-3D-animationwith-basic-narration-.html http://www.dnalc.org/view/164 94-Animation-22-DNA-wordsare-three-letters-long-.html mRNA, tRNA, and a ribosome work together in constructing a protein mRNA = “messenger”; it contains the message that is being translated. tRNA = “transfer”; it transfers (delivers) the right a.a. to the right codon. It is the “interpreter”. When you translate an mRNA sequence, you are the “interpreter”. You determine the correct a.a. for each codon by looking at the Genetic Code table. rRNA = “ribosomal”; as part of the structure of the ribosome, it helps bond amino acids together. At the ribosome: Steps of Translation 1. mRNA attaches to a ribosome in the cytoplasm. 2. A tRNA, carrying the amino acid “met”, binds to the start codon (AUG) on mRNA. A second tRNA w/an a.a. binds to the ribosome. H-bonds between complementary base pairs allows the tRNA to bind with mRNA (anticodon to codon). 3. A peptide bond is formed between the a.a. Translation, cont’d 4. The first tRNA leaves and the ribosome moves over to a new codon. 5. The process of a.a. delivery and peptide bond formation continues until the chain is 100+ amino acids long. 6. When a stop codon is reached, translation ends and the polypeptide is released. 7. The polypeptide’s a.a. sequence will determine how the protein folds into a 3-D functional shape. http://nobelprize.org/educational/medicine/dna/b/translation/translation_ani.html http://www.teachersdomain.org/resource/lsps07.sci.life.stru.celltrans/ Mutations Changes in the N-base sequence of DNA. Typically 1 letter: substitution, deletion, or insertion The change in DNA results in one or more different mRNA codons. The different codon(s) may result in a different amino acid(s). A change in the amino acid sequence of a protein will likely change the protein’s shape. (Remember-shape determines function!) Substitution Mutation “Sickle” shape of the red blood cell is due to the hemoglobin proteins having an abnormal shape. Due to the difference of one amino acid (val vs glu), the protein doesn’t fold correctly. Beginning of Gene is located. DNA unwinds & transcription begins. As RNA polymerase moves down the DNA template, more RNA nucleotides are added, growing the RNA strand. Transcription stops at the end of the gene. The amino acid “Tyr” is carried by a tRNA, but it is coded for by the mRNA codon (UAC)