Session 5 Flashcards
What is translation?
Formation of a protein based on an mRNA sequence.
Where does transcription occur?
In the nucleus.
Why does translation occur?
In the cytoplasm.
What are the different types of RNA?
mRNA (messenger), rRNA (ribosomal), tRNA (transfer), miRNA (micro) and non-coding RNA.
What is required for DNA replication to occur?
DNA polymerase, activated substrates (dNTPs), template DNA.
What is required for transcription of DNA?
RNA polymerase, activated substrates (NTPs), template DNA.
What is required for DNA translation?
A ribosome, activated substrates (amino acids), template mRNA
What occurs in DNA transcription?
Promoter sequence (TATA box) on DNA is recognise and transcription initiation factors bind. RNA polymerase binds downstream from the initiation factors and begins transcribing DNA. Section of DNA undergoing replication is elongated. Pre-mRNA synthesis ceases when a termination sequence is reached. RNA is then processed.
How is RNA processed?
Forms mRNA from pre-mRNA.
Capping: 5’cap to protect against degradation.
Tailing/polyadenylation: polyA tail at 3’ end to protect against degradation.
Splicing: removes introns from the mRNA sequence.
How are nucleus acids degraded?
Using nucleases.
Endonuclease: creates breaks within the polynucleotide (can be specific or non-specific).
Exonuclease: degrades polynucleotide from end (5’ specific or 3’ specific).
Which ribosomes exist in prokaryotes? What are they composed of?
70S ribosomes.
Made up of 30S and 50S subunits.
What ribosomes exist in eukaryotes? What are they comprised of?
80S ribosomes.
40S and 60S subunits.
How does translation occur?
40 S subunit and met-tRNA starts at the 5’cap and moves along mRNA until it finds a start codon (AUG). met-tRNA binds to start codon to become T site. More tRNA binds to he A site (next codon) and a peptide bonds forms between the amino acids attached to the tRNA (using peptidyl transferase). Met then moves from the P site to the A site and the P site is translocated along to replace the a site. Transcription continues until a stop codon is reached and the ribosome detaches.
What enzyme catalysed elongation in DNA translation?
Peptidyl transferase.
Order the following in terms of relative length (longest first): protein, pre-mRNA, gene on DNA, mRNA.
Gene on DNA, pre-mRNA, mRNA, protein.
