chp. 17 Flashcards
Translation-activiting enzyme, upstream on 5’ side.
Translation
Translation-activiting enzyme, upstream on 5’ side.
Translation
ribonucleotide triphosphate (NTP) that matches the base on the DNA template is in place, RNA polymerase cleaves off two phosphates and catalyzes the formation of a phosphodiester linkage between the 3’ end of the growing mRNA chain and the new ribonucleoside monophosphate. As this 5’ → 3’ matching and catalysis process continues an RNA that is complementary to the gene is synthesized
Transcription
detachable protein subunit called sigma must bind to the polymerease before transcription can begin. Bacterial RNA polymerase and sigma form a holoenzyme which consists of a core enzyme which contains the active site for catalysis. Once RNA polymerase begins moving along the DNA template synthesizing RNA the elongation phase of transcription is under way. During elongation all of the channels are filled. Termination ends transcription, transcription stops when RNA polymerase transcribes a DNA sequence that functions as a transcription-termination signal. Eukaryotic transcription- SAME AS BACTERIAL EXCEPT FOR THESE DIFFERNECES.
Bacterial transcription
three polymerase RNA polymerase I, II, III. Each polymerase transcribes only certain types of RNA in eukaryotes. RNA II is the only polymerase that transcribes protein-coding genes. Promoters in eukaryotic DNA are diverse, most include a TATA box. Instead of a sigma protein eukaryotic cells use basal transcription factors. Termination- involves short sequence called the polyadenylation signal.
eukaryotic transcription differences
When _____ genes of any type are transcribed, the initial product is termed a primary transcript. This RNA must undergo multistep processing before it is functional
eukaryotic
structure, two functional ends: anticodon and amino acid attachment
tRNA sequences are relatively short, ranging from 75 to 85 nucleotides in length. A CCA sequence at the 3’ end offered a site for amino acid attachment, while a triplet on the loop at the other end could serve as an anticodon (set of three ribonucleotides that forms base pairs with the mRNA codon). Same general structure- shaped like an upside-down L, they vary at the anticodon and attached amino acid.
tRNA
_____ has three steps. Step two the initiator aminoacyl tRNA bearing f-met binds to the start codon and step three- the large ribosomal subunit binds, completing the complex.
Translation initiation
when tRNA’s, the amino acids on the tRNAs, occupies both P and A site are in the ribosome’s active site. This is where peptide-bond formation—the essences of protein synthesis—occurs.
ribosome initiation
when the translocating ribosome reaches one of the stop codons, a protein called a release factor recognizes the stop codon and fills the A site.
ribosomes role in termination
the source of energy for protein synthesis
ATP
Cluster of ribosomes bound to a mRNA molecule
polyribosome
ribonucleotide triphosphate (NTP) that matches the base on the DNA template is in place, RNA polymerase cleaves off two phosphates and catalyzes the formation of a phosphodiester linkage between the 3’ end of the growing mRNA chain and the new ribonucleoside monophosphate. As this 5’ → 3’ matching and catalysis process continues an RNA that is complementary to the gene is synthesized
Transcription
detachable protein subunit called sigma must bind to the polymerease before transcription can begin. Bacterial RNA polymerase and sigma form a holoenzyme which consists of a core enzyme which contains the active site for catalysis. Once RNA polymerase begins moving along the DNA template synthesizing RNA the elongation phase of transcription is under way. During elongation all of the channels are filled. Termination ends transcription, transcription stops when RNA polymerase transcribes a DNA sequence that functions as a transcription-termination signal. Eukaryotic transcription- SAME AS BACTERIAL EXCEPT FOR THESE DIFFERNECES.
Bacterial transcription
three polymerase RNA polymerase I, II, III. Each polymerase transcribes only certain types of RNA in eukaryotes. RNA II is the only polymerase that transcribes protein-coding genes. Promoters in eukaryotic DNA are diverse, most include a TATA box. Instead of a sigma protein eukaryotic cells use basal transcription factors. Termination- involves short sequence called the polyadenylation signal.
eukaryotic transcription differences
