Genes located in euchromatin are less likely to be expressed than genes in heterochromatin.
False, heterochromatin is the most condensed form of chromatin and is inaccessible to proteins needed for gene expression.
100
RNA primers are synthesized by _________.
primase
100
Leading strand DNA synthesis does NOT require a RNA primer to start replication.
False, DNA polymerases cannot start synthesis of a new strand without a 3' hydroxyl, which is provided by a RNA primer.
100
____________ recognize and repair mismatches.
Mismatch repair proteins
(specifically MutS dimers; MutSalpha in eukaryotes)
100
The error rate of DNA replication without proofreading or mismatch repair is ______________
10^-3 to 10^-4
200
Nucleosomes in a 30-nm chromatin fiber have histone H3's lysine 9 covalently modified with an acetyl group.
False, acetyl modification of lysine 9 favors the 'beads-on-a-string" chromatin state. Methyl modification of lysine 9 favors packing of nucleosomes into a 30-nm fiber.
200
DNA polymerase is held on the DNA template by binding to ____________.
the sliding-clamp called PCNA
200
DNA synthesis of the leading strand is discontinuous.
False, lagging strand synthesis is discontinuous; synthesized in pieces called Okazaki fragments.
200
If mismatch repair proteins removed the template strand during repair, instead of the new strand, then the result will be ___ mutations, instead of no mutations.
2 mutations
200
The error of DNA replication with proofreading, but no mismatch repair is ________
10^-5 to 10^-7
300
Histone H4 bends the linker DNA so that nucleosomes can be packed closer together into a 30-nm fiber.
False, Histone H1 is needed for packing nucleosomes into a 30-nm fiber.
300
Single-stranded DNA that forms during replication is protected by ________________.
single-strand DNA binding protein
300
Origin of replications are typically stretches of DNA that have more A:T base pairs than G:C base pairs.
True
300
The error rate during DNA replication is reduced by both _________ and mismatch repair.
proofreading
300
The error of DNA replication with proofreading and mismatch repair is __________.
10^-9
400
Each nucleosome consists of about 1000 base pairs of DNA wrapped around a core of 8 histones.
False, there is about 147 base pairs of DNA wrapped around a core of 8 histones for each nucleosome.
400
__________ removes RNA primers from newly synthesized strands of DNA.
Nuclease
400
Proofreading by the DNA polymerase is 5' to 3'.
False, DNA synthesis is 5' to 3', and proofreading is 3' to 5'.
400
Double strand breaks can be repaired by homologous recombination or _________________.
non-homologous end joining.
400
The more DNA lesions there are during DNA replication, the higher the __________ will be.
mutation rate
500
Chromatin is made more accessible when enzymes cut the histone tails off nucleosomes.
False, histone tails are covalently modified by NOT cut off.
500
_____________ catalyzes forming of a phosphodiester bond between two adjacent Okazaki fragments.
DNA ligase
500
DNA replication happens at symmetrical replication forks.
False, replication forks are asymmetrical because one strand is synthesized in the same direction as the fork moves, while the other strand is synthesized in the opposite direction.
500
Excision repair of DNA lesions requires proteins that recognize the lesion, __________ the backbone, remove the DNA with the lesion, synthesize new DNA and _________ the backbone.
cut
seal
500
How does an increase in mutation rate often predispose an individual to having a tumor or cancer?
An increase in mutation rate increases the probability that mutation will activate (gain of function) a proto-oncogene or inhibit (loss of function) a tumor supressor protein, which give a cell a proliferation advantage.