* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download The Central Dogma of Biology states that DNA codes for RNA, and
Gene regulatory network wikipedia , lookup
Holliday junction wikipedia , lookup
Gel electrophoresis of nucleic acids wikipedia , lookup
Community fingerprinting wikipedia , lookup
Molecular cloning wikipedia , lookup
Genetic code wikipedia , lookup
Molecular evolution wikipedia , lookup
RNA interference wikipedia , lookup
Transcription factor wikipedia , lookup
DNA supercoil wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Real-time polymerase chain reaction wikipedia , lookup
RNA silencing wikipedia , lookup
Non-coding DNA wikipedia , lookup
Biosynthesis wikipedia , lookup
Promoter (genetics) wikipedia , lookup
Polyadenylation wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Silencer (genetics) wikipedia , lookup
Non-coding RNA wikipedia , lookup
Messenger RNA wikipedia , lookup
RNA polymerase II holoenzyme wikipedia , lookup
Gene expression wikipedia , lookup
Deoxyribozyme wikipedia , lookup
Eukaryotic transcription wikipedia , lookup
THE CENTRAL DOGMA OF BIOLOGY STATES THAT DNA CODES FOR RNA, AND RNA CODES FOR PROTEINS When DNA codes for RNA, the process is called TRANSCRIPTION. When RNA codes for proteins, the process is called TRANSLATION. THERE ARE 3 TYPES OF RNA, HOWEVER ONLY MRNA IS INVOLVED IN TRANSCRIPTION Name mRNA rRNA tRNA Function Carries genetic information from DNA during TRANSCRIPTIO N in the nucleus to direct protein synthesis Associates with protein to form the ribosome Transports amino acids to ribosomes during TRANSLATION. Example What is the purpose of Transcription? Where does transcription take place? LET’S WATCH TRANSCRIPTION BEFORE WE EXAMINE THE STEPS! http://highered.mcgrawhill.com/sites/0072507470/student_view0/chapter 3/animation__mrna_synthesis__transcription___ quiz_1_.html TRANSCRIPTION STAGE 1: INITIATION Transcription begins when RNA Polymerase attaches to a PROMOTER on the DNA strand The promoter determines which of the two DNA strands will serve as the template strand. The promoter indicates where RNA Polymerase can attach to the DNA strand A common promoter on the DNA sequence is called the TATA Box. This is around 25 nucleotides from where transcription begins. Once RNA Polymerase attaches to the promoter, it unwinds the DNA template strand. RNA synthesis begins moving along the DNA template strand and RNA begins transcribing the DNA template strand. The new strand is created in the 5’ to 3’ direction. What would RNA Polymerase transcribe from the following promoter sequence? ACAGGCATATA TRANSCRIPTION STAGE 2: ELONGATION RNA Polymerase moves along the DNA strand and continues to unwind the helix. Polymerase reads the strand and transcribes a complementary mRNA strand. As polymerases passes over the strand the mRNA peels away and the DNA helix reforms. STAGE 3 TRANSCRIPTION : TERMINATION Transcription proceeds until after the RNA polymerase transcribes a terminator sequence in DNA. Shortly past the termination signal, the mRNA is cut from the Polymerase. How might transcription take place if your body required a large amount of mRNA to be made from a particular gene? THE MRNA SEQUENCE IS MODIFIED BEFORE IT LEAVES THE NUCLEUS TO ENTER THE CYTOPLASM A 5’ CAP is added A POLY A tail is added The The 5’ end is capped with a modified guanine nucleotide. Reduces degradation 3’ end received 50-250 adenine nucleotides . Reduces degradation Aids the mRNA in exiting the nucleus RNA IS SPLICED BEFORE IT LEAVES THE NUCLEUS. INTRONS Introns are non-coding regions in the mRNA sequence. They are removed before the mRNA exits the nucleus. EXONS Exons are the coding regions in the mRNA molecule. They are connected to form a complete mRNA strand. Think: Exons exit the nucleus