chpt 12 Flashcards
DNA replication
where does DNA replication happen in eukaryotes?
the nucleus
where does DNA replication happen in prokaryotes?
the cytoplasm
semiconservative means what?
each double helix had an old and new strand, each serves as a template for a new strand
what is the origin of replication?
starting point for replication
helicase is when…
the double helix begins to unwind
after helicase what is formed?
a replication fork
what is DNA polymerase?
new strands of complementary DNA nucleotides is created for 2 template strands
the new strand made in the direction for unwinding is called what?
the lagging strand
fragments on the lagging strand are stitched together by what?
DNA ligase
DNA polymerase has what type of ability?
proofreading ability
what is the central dogma?
DNA —— RNA ——- Protein
transcription begins where?
at the prometer
does the double helix unwind in translation or transcription?
transcription
mRNA processing only happens in what?
eukaryotes
how many steps are in the mRNA processing?
3 steps
what’s the 1st step in mRNA processing?
the addition of the 5’ cap
what’s the 2nd step in mRNA processing?
the addition of DOLY (A) tail
what’s the 3rd step in mRNA processing?
Splicing
mature mRNA transcript leaves the nucleus through what?
nuclear pores
3 mRNA nucleotides are equal to
1 codon
the genetic code has how many codons in total?
64 or 4^3
what is degeneracy?
redundancy
most amino acids are encoded by?
more than 1 codon
translation occurs where?
in the cytoplasm for both eukaryotes and prokaryotes
ribosomes equal?
2 subunits (proteins+mrRNAs)
prior to start translation, what happens?
amino acids are attached to 3’ end of appropriate tRNA
initiator tRNA binds to what?
mRNA at start codon
fully assembled ribosomes have 3 docking sites. what are they called?
- A (aminoacyl) site
- P (peptidyl) site
- E (exit) site
A site does what?
holds next tRNA to be delivered to ribosomes by codon and anticodon interactions
P site does what?
holds most recently delivered tRNA by codon and anticodon interactions
what also starts in the P site?
tRNA met starts
what does the E site do?
holds previously delivered tRNA and is now ready to leave the ribosome without the amnio acids
what is elongation?
the amino acid chain gets longer
what happens in translocation?
ribosomes shift from 5’ to 3’ and elongation repeats
new proteins assembled one amino acid at a time or seen as….
N to C
what occurs in translation termination?
when ribosome encounters a STOP codon a protein release factor binds to site A instead of a tRNA aa
