post trancription and translation Flashcards
What are the main classes of RNA polymerase, and what do they synthesize?
RNA Polymerase I: Synthesizes rRNA.
RNA Polymerase II: Synthesizes mRNA.
RNA Polymerase III: Synthesizes tRNA and other small RNAs.
What is the difference between coding and non-coding RNA?
Coding RNA: mRNA, which encodes proteins.
Non-coding RNA (ncRNA): Includes rRNA, tRNA, and regulatory RNAs like miRNAs, which do not encode proteins.
What are microRNAs (miRNAs), and what is their role?
miRNAs are small non-coding RNAs involved in regulating gene expression, often by silencing target mRNAs.
What is Post-Transcriptional Gene Silencing (PTGS)?
A mechanism that uses small RNA fragments to suppress specific RNA, protecting against retroviruses and controlling gene expression.
How was PTGS applied in genetically modified tomatoes?
It was used to silence the polygalacturonase gene responsible for fruit softening, creating tomatoes for longer-lasting puree.
What is the role of tRNA in translation?
Carries specific amino acids to the ribosome.
Uses its anticodon to base-pair with the mRNA codon.
What are the major components required for translation?
mRNA: Provides the template.
Ribosomes: Catalyze protein synthesis.
tRNA: Brings amino acids to the ribosome.vDÁÉ
What is the function of ribosomes in translation?
Ribosomes, composed of rRNA and proteins, facilitate the joining of amino acids into a polypeptide chain.
What happens during the termination phase of translation?
Stop codons (UAA, UAG, UGA) signal the end of translation.
Release factors bind, causing the ribosome to release the mRNA and newly formed polypeptide.
How does translation differ between eukaryotes and prokaryotes?
Eukaryotes: Transcription occurs in the nucleus, translation in the cytosol.
Prokaryotes: Transcription and translation occur simultaneously in the cytosol.
What is the 5’ untranslated region (UTR), and why is it important?
The 5’ UTR forms complex secondary structures that must be unwound for translation initiation.
What is the role of the 5’ cap and 3’ polyA tail in translation?
They are essential for translation initiation and help protect mRNA from degradation.
What is translational control, and why is it important?
Translational control allows rapid changes in protein levels.
It involves mechanisms like mRNA storage or secondary structure regulation.
What are the components of a tRNA molecule?
Acceptor Arm: Binds to an amino acid.
Anticodon Arm: Matches codons on mRNA.
Additional arms may vary in size.
