BIOC0007 QUESTIONS AND ANSWERS WITH COMPLETE
SOLUTIONS VERIFIED LATEST UPDATE
where is chromosome loop start replication
origin of replication
what enzyme replicates the DNA in bacterial chromosomes
DNA helicase (DnaB)
what enzymes replicate DNA in chromosomal of Eukaryotas
ORC
how long are RNA primes used in DNA replication
5 to 10 nucleotide base pairs
how does replication occur in leading strand
continuous replication from 3' to 5' direction
how does replication on lagging strand
• The beta clamp dissociated and temporarily releases the lagging stand
• The DNA helicase continues to unwind the parental DNA. The unwound DNA has
single stand binding proteins added to stop it incorrectly reannealing, as is unstable is
left exposed
• This activates the primase to produce a short RNA primer on the growing lagging
strand.
• The DNA polymerase binds to the DNA again and becomes locked in by the clamp
• The DNA polymerase uses the RNA primer to start a short copy of the lagging strand
• The DNA polymerase stalls when reaches the RNA primer of the previous Okazaki
, fragment
• The cycle then repeats
how are primers from the Okazai fragments removed
o Occurs in the lagging strand after elongation
o Required filling in small nick between Oskazaki fragments and RNA primer where the
clamp was holding, DNA polymerase I extends the Okazaki fragment while its 5'-3'
exonuclease activity removes the RNA primer. This process, called nick translation,
results in movement of the nick along the lagging strand.
o DNA polymerase I dissociates after extending the Okazaki fragment 10-12
nucleotides. DNA ligase binds to the nick and uses to seal the sugar backbone
what is the structure of DNA polymerase
multi-subunit complex - made of large proteins
how many subunits in E.coil DNA polymerase
at least 5
how many subunits in eukoyotic DNA polymerase
at least 15
how does DNA polymerase have an inbuilt proofcheack
• If when synthesising the DNA an incorrect base is inserted.
• Will cause distortion in the tight pair base
• Will cause complex to move to ε subunit. Which has the 3' to 5' exonuclease.
• This will remove one base pair, and then slide back into active site and synthesis will
resume.
• DNA polymerase still cause 1 in 10000 mistakes
SOLUTIONS VERIFIED LATEST UPDATE
where is chromosome loop start replication
origin of replication
what enzyme replicates the DNA in bacterial chromosomes
DNA helicase (DnaB)
what enzymes replicate DNA in chromosomal of Eukaryotas
ORC
how long are RNA primes used in DNA replication
5 to 10 nucleotide base pairs
how does replication occur in leading strand
continuous replication from 3' to 5' direction
how does replication on lagging strand
• The beta clamp dissociated and temporarily releases the lagging stand
• The DNA helicase continues to unwind the parental DNA. The unwound DNA has
single stand binding proteins added to stop it incorrectly reannealing, as is unstable is
left exposed
• This activates the primase to produce a short RNA primer on the growing lagging
strand.
• The DNA polymerase binds to the DNA again and becomes locked in by the clamp
• The DNA polymerase uses the RNA primer to start a short copy of the lagging strand
• The DNA polymerase stalls when reaches the RNA primer of the previous Okazaki
, fragment
• The cycle then repeats
how are primers from the Okazai fragments removed
o Occurs in the lagging strand after elongation
o Required filling in small nick between Oskazaki fragments and RNA primer where the
clamp was holding, DNA polymerase I extends the Okazaki fragment while its 5'-3'
exonuclease activity removes the RNA primer. This process, called nick translation,
results in movement of the nick along the lagging strand.
o DNA polymerase I dissociates after extending the Okazaki fragment 10-12
nucleotides. DNA ligase binds to the nick and uses to seal the sugar backbone
what is the structure of DNA polymerase
multi-subunit complex - made of large proteins
how many subunits in E.coil DNA polymerase
at least 5
how many subunits in eukoyotic DNA polymerase
at least 15
how does DNA polymerase have an inbuilt proofcheack
• If when synthesising the DNA an incorrect base is inserted.
• Will cause distortion in the tight pair base
• Will cause complex to move to ε subunit. Which has the 3' to 5' exonuclease.
• This will remove one base pair, and then slide back into active site and synthesis will
resume.
• DNA polymerase still cause 1 in 10000 mistakes
