KH2 Flashcards
What is the central dogma and information flow
DNA synthesis (replication), RNA synthesis (transcription), protein synthesis (translation)
Transcription has what kind of interaction of template with incoming monomer
Direct
What is the sequence of RNA transcribed from
A region of DNA that corresponds to the sequence of the non-template strand
What is the relationship between the non-template strand and the newly synthesized RNA strand and the template DNA strand
They are both complementary to and antiparallel to the template DNA strand
How is the template DNA strand exposed
By local unwinding of duplex DNA by helical associated with RNA polymerase
What happens after the original DNA duplex was unwound in the transcription bubble
It reforms behind RNA polymerase as it moves unidirectional along the DNA
How is the newly synthesized RNA strand kicked out
The reforming duplex behind the polymerase kicks it out
Where does the displaced single-stranded RNA exit through
A channel in the polymerase, 5’ end first
What facilitates the initial binding of RNA polymerase to DNA
DNA sequences called promoters
How does synthesis of RNA stop
Certain DNA sequences destabilize the attachment of RNA polymerase to the DNA as it moves. The RNS falls off the DNA and releases the RNA
What are the similarities between DNA replication and RNA transcription
- Template = DNA
- DNA duplex locally unwound by a helical at initial sites to expose template
- New strand synthesized 5’ to 3’ antiparallel to template, chain growth at 3’ end
- Monomers = nucleoside triphosphates
- Direct interaction between template DNA and incoming monomer
- Attack of 3’ OH- on alpha phosphate of incoming dNTP, beta and gamma phosphate dropped
Differences in DNA replication and transcription monomers
T: rNTPs
D: dNTPs
Differences in start sites and stop sites between transcription and DNA replication
T: start and stop sites on template
D: Start sites (origins) but no stop sites
Differences in strand separation between transcription and DNA replication
T: newly synthesized strand (RNA) separates from template strand
D: Newly synthesized strand (DNA) never separates from template strand
Differences in template strands between transcription and DNA replication
T: only one of the original DNA strands is a template strand (start with one molecule of double stranded DNA and we end with that DNA plus RNA)
D: Both of the original DNA strands independently serve as template strands (start with one molecule of double stranded DNA and end with 2)
What is translation
Protein synthesis
How many nucleotides are in codons
3
Which processes use direct interaction of template with next monomer molecule to be incorporated
Replication and transcription
Which process uses indirect interaction between template and next monomer to be incorporated
Translation (tRNA acts as an adaptor between template and growing chain)
What is the template for translation and what is the energized monomer
mRNA and aminoacyl tRNA (adaptor)
What is the function of aminoacyl tRNAs
Adaptors for transforming a nucleotide signal into an amino acid signal
What is the relationship of the 3-nucleotide anticodon to the codon on the mRNA
It is a sequence that is complementary to the codon
What is the structure of a ribosome
A ribonucleo-protein particle (RNA + protein) consisting of large and small subunits
What is the peptidyl transferase reaction catalyzed by
The large subunit RNA molecule
