Genome Organization/Function/Replication
Bio119
I. The prokaryotic chromosomes
A. Kinds of genetic elements in prok and euks
1. Prok and Euk have chromosomes and plasmids
B. Prok. chromosome is usually _________________ (Fig. 16.10)
C. Usually only have 1 but number can be more if prok. is growing
D. Bacteria chromosome can be replicated throughout the cell cycle.
E. All prokaryotes are:____________________.
F. Majority of prokaryotic chromosome:_______________________.
G. Prok. genes usually do not have:______________________
H. An average gene length is about ________________
I. How many genes are there if genome is 6 Mb (6 x 109 bp)?
1.
J. Because chromosome is 1 mm long it needs to be:
K. This is accomplished by ______________________(Fig 4.31):
1. This is need to make chromosome fit into a small space.
2. DNA gyrase (topoisomerase II) introduces negative
supercoiling
3. DNA gyrases are also targets for quinolone type antibiotics
4. Topoisomerase I removes negative supercoiling, which is
needed during replication.
L. Because supercoiling brings negatively charged phosphates close,
M. Further compacting of the chromosome occurs with:
II. How does a bacterial cell replicate its chromosome?
A. In a ______________________ mode similar to Euks. (Fig. 13.2)
1. Strands separate and each are copied
2. Daughter genome gets:
a) _____________________ strand and a
Genome Organization/Function/Replication
Bio119
b) ____________________________________copy
B. Lots of proteins involved in replicating chromosome
1. Table 13.1
C. Initiation of replication (Fig. 13.3):
1. DNA replication starts at an origin of replication, called:
2. DNA binding proteins (______) bind the ________, which
causes:
3. __________ binds replication fork with _________and
promotes DNA ________________with help of
_____________.
4.
D. The formation of a replisome (Fig. 13.4):
1. Each replication fork has a leading strand and lagging strand
2. The leading strand is synthesized by: _________________
as a single contiguous molecule starting from an:
3. The lagging strand is synthesized in a discontinuous fashion.
E. DNA polymerization:
1. DNA polymerases polymerize:
2. Bacteria have:
3. ______________________ carries out the elongation stage
as the replication fork moves forward (Fig. 13.6).
4. Polyermases need:
5. Template must be primed with a nucleotide.
Genome Organization/Function/Replication
Bio119
F. Polymerization takes place from 5’ to 3’
1. leading strand is continuous
2. Lagging strand is built in fragments:
G. The RNA primer on lagging strand is removed by:
1. Gaps are filled by:
H. Termination occurs at the:
1.
I. __________________________________ occurs during
replication because DNA is helical and must rotate to accommodate
the replication fork.
1. Relief of tension and tangling is accomplished:
2. This makes temporary nicks in the DNA allowing it to:
J. Separation of daughter chromosomes is accomplished:
1. Causes:
2. DNA can untangle.
K. Mistakes also need to be repaired
1. Wrong base pairing can occur:
2. Polymerase error rate is:
3. Errors are corrected by:
4. Mismatch repair system:
5. How does this work (Fig. 13.7):
a)
b) MutS:
Genome Organization/Function/Replication
Bio119
c) MutH:
d) MutL:
e) MutH:
f) Exonucleases:
g) DNA Pol I:
h) DNA ligase:
L. If chromosome replication is complete in 40 min how can E. coli
grow with a generation time of 20 min?
M. Video 1: http://www.youtube.com/watch?v=teV62zrm2P0
N. Video 2: http://www.youtube.com/watch?v=4jtmOZaIvS0