Bio 1A03 Test 3 Questions and Answers
Verified 100% Correct
how does cyclin-cdk regulate mitosis? - ANSWER -cyclin-cdk binds to kinases
(constant concentration) in order to activate them. these kinases then phosphorylate
and activate proteins needed to break down the nuclear envelope, regulate
assembly of microtubules, etc
S cyclin-CDK - ANSWER -helps initiate DNA synthesis (cyclin A + cdk 2)
G1/S cyclin-CDK complex - ANSWER -prepares cell for DNA replication
Mitosis checkpoints - ANSWER -G1/S checkpoint, if cell is ready for DNA
synthesis (DNA Damage checkpoint)
G2 Checkpoint: Is everything replicated/cell ready for mitosis?
Pre-Anaphase checkpoint: All chromosomes attached to spindle fibers?
How does the G1/S checkpoint work? - ANSWER -If damage to DNA is present,
kinases phosphorylate the gene for p53, increasing the production of its protein
which accumulates in the nucleus and acts a transcription factor for the inhibitory
proteins. These proteins bind to and block G1/S cyclin-CDK complex so that the
cell can repair DNA.
How does the spindle-assembly checkpoint work? - ANSWER -Unattached
kinetochores release a "wait" signal from the lack of tension that recruits
checkpoint proteins. These remain until all kinetochores are attached to
micotubules. Seperase breaks apart sister chromatids
semiconservative replication - ANSWER -each new DNA molecule consists of
one new strand and one old strand
,conservative replication - ANSWER -2 parental strands rejoin after replication
dispersive replication - ANSWER -all 4 strands mix together
How was the semiconservative model confirmed? - ANSWER -Meselsohn &
Stahl created DNA strand out of radioactive isotope of Nitrogen, replicated DNA,
used centrifuge to separate the strands and used the placements of the new bands
compared to the original strand to prove this model
prokaryotic vs eukaryotic DNA replication - ANSWER -Prokaryotes: only 1 ORI,
replication moves in both directions due to circular DNA, no gaps in DNA
Eukaryotes: multiple ORI, okazaki fragments/dna ligase, free phosphate on 3' end
of strands, telomeres (DNA shortening)
RNA primer - ANSWER -5-10 nucleotide sequence that binds to BP with template
DNA strands so DNA Pol can begin replication (can only add to an existing strand)
After fragment/strand is complete, another DNA pol replaces the primer with DNA
nucleotides
leading strand - ANSWER -3'-5', only req's 1 primer
lagging strand - ANSWER -5'-3', multiple primers (one per okazaki fragment),
replicates *away* from replication fork
Helicase - ANSWER -breaks Hydrogen bonds between base pairs
topoisomerase II - ANSWER -relieves the stress of unwinding the DNA for
helicase by uncoiling/straightening it
single stranded binding proteins (SSBs) - ANSWER -bind to each side of the
DNA ladder keeping it from bonding back together during DNA replication
RNA primase - ANSWER -synthesizes RNA primers for DNA replication
, Initiator proteins for DNA replixation - ANSWER -Helicase, SSBs, topoisomerase
II
DNA polymerase I & III - ANSWER -dna pol I : elongation/synthesis/adding
nucleotides
dna pol III : removes RNA primer & replaces with DNA
(prokaryotes only; eukaryotes different)
Reason for Telomeres and Telomere shortening - ANSWER -the last RNA primer
on the lagging strand (3' end) has no 3' hydroxyl for DNA pol to attach to and
replaxe these nucleotides once they are removed (unlike in prokaryotes) leading to
shorter and shorter ends of DNA
What are telomeres? - ANSWER -ends of chromosomes designed to protect from
DNA shortening. Made of of 100s-1000s of TTAGGG tandem repeats. get
increasingly short with each division especially in somatic cells
telomere shortening does not occur in which types of cell? - ANSWER -gametes
and stem cells. they contain telomerase, a reverse transcriptase that binds to the
ends of the tails and adds repeats. potentially useful for aging/cancer
karyotype - ANSWER -A display of the chromosome pairs of a cell arranged by
size and shape.
ploidy - ANSWER -number of sets of chromosomes in a cell
haploid vs diploid - ANSWER -one set of chromosomes vs two sets of
chromosomes
mitotic spindle - ANSWER -a structure made of microtubules that controls
chromosome movement during mitosis
unlike animals, during cell division, plant cells do not contain ____ - ANSWER -
centrosomes (though they do have mitotic spindle). final location defines the poles.
Verified 100% Correct
how does cyclin-cdk regulate mitosis? - ANSWER -cyclin-cdk binds to kinases
(constant concentration) in order to activate them. these kinases then phosphorylate
and activate proteins needed to break down the nuclear envelope, regulate
assembly of microtubules, etc
S cyclin-CDK - ANSWER -helps initiate DNA synthesis (cyclin A + cdk 2)
G1/S cyclin-CDK complex - ANSWER -prepares cell for DNA replication
Mitosis checkpoints - ANSWER -G1/S checkpoint, if cell is ready for DNA
synthesis (DNA Damage checkpoint)
G2 Checkpoint: Is everything replicated/cell ready for mitosis?
Pre-Anaphase checkpoint: All chromosomes attached to spindle fibers?
How does the G1/S checkpoint work? - ANSWER -If damage to DNA is present,
kinases phosphorylate the gene for p53, increasing the production of its protein
which accumulates in the nucleus and acts a transcription factor for the inhibitory
proteins. These proteins bind to and block G1/S cyclin-CDK complex so that the
cell can repair DNA.
How does the spindle-assembly checkpoint work? - ANSWER -Unattached
kinetochores release a "wait" signal from the lack of tension that recruits
checkpoint proteins. These remain until all kinetochores are attached to
micotubules. Seperase breaks apart sister chromatids
semiconservative replication - ANSWER -each new DNA molecule consists of
one new strand and one old strand
,conservative replication - ANSWER -2 parental strands rejoin after replication
dispersive replication - ANSWER -all 4 strands mix together
How was the semiconservative model confirmed? - ANSWER -Meselsohn &
Stahl created DNA strand out of radioactive isotope of Nitrogen, replicated DNA,
used centrifuge to separate the strands and used the placements of the new bands
compared to the original strand to prove this model
prokaryotic vs eukaryotic DNA replication - ANSWER -Prokaryotes: only 1 ORI,
replication moves in both directions due to circular DNA, no gaps in DNA
Eukaryotes: multiple ORI, okazaki fragments/dna ligase, free phosphate on 3' end
of strands, telomeres (DNA shortening)
RNA primer - ANSWER -5-10 nucleotide sequence that binds to BP with template
DNA strands so DNA Pol can begin replication (can only add to an existing strand)
After fragment/strand is complete, another DNA pol replaces the primer with DNA
nucleotides
leading strand - ANSWER -3'-5', only req's 1 primer
lagging strand - ANSWER -5'-3', multiple primers (one per okazaki fragment),
replicates *away* from replication fork
Helicase - ANSWER -breaks Hydrogen bonds between base pairs
topoisomerase II - ANSWER -relieves the stress of unwinding the DNA for
helicase by uncoiling/straightening it
single stranded binding proteins (SSBs) - ANSWER -bind to each side of the
DNA ladder keeping it from bonding back together during DNA replication
RNA primase - ANSWER -synthesizes RNA primers for DNA replication
, Initiator proteins for DNA replixation - ANSWER -Helicase, SSBs, topoisomerase
II
DNA polymerase I & III - ANSWER -dna pol I : elongation/synthesis/adding
nucleotides
dna pol III : removes RNA primer & replaces with DNA
(prokaryotes only; eukaryotes different)
Reason for Telomeres and Telomere shortening - ANSWER -the last RNA primer
on the lagging strand (3' end) has no 3' hydroxyl for DNA pol to attach to and
replaxe these nucleotides once they are removed (unlike in prokaryotes) leading to
shorter and shorter ends of DNA
What are telomeres? - ANSWER -ends of chromosomes designed to protect from
DNA shortening. Made of of 100s-1000s of TTAGGG tandem repeats. get
increasingly short with each division especially in somatic cells
telomere shortening does not occur in which types of cell? - ANSWER -gametes
and stem cells. they contain telomerase, a reverse transcriptase that binds to the
ends of the tails and adds repeats. potentially useful for aging/cancer
karyotype - ANSWER -A display of the chromosome pairs of a cell arranged by
size and shape.
ploidy - ANSWER -number of sets of chromosomes in a cell
haploid vs diploid - ANSWER -one set of chromosomes vs two sets of
chromosomes
mitotic spindle - ANSWER -a structure made of microtubules that controls
chromosome movement during mitosis
unlike animals, during cell division, plant cells do not contain ____ - ANSWER -
centrosomes (though they do have mitotic spindle). final location defines the poles.
