ch.14
Short fragments of DNA created on the lagging strand of DNA during replication are called
Okazaki fragments.
The problems in replicating the ends of linear chromosomes are caused by (choose all that apply) ____.
- the need for a primer - the directionality of polymerases
In a DNA double helix, two hydrogen bonds form between
A-T
The partial opening of a DNA helix to form two single strands is called
the replication fork.
Which of the following enzymes involved in DNA replication are found at the replication fork in all three types of cells (bacterial, archaeal, and eukaryotic)? Choose all that apply.
- helicase - primase - clamp loader - polymerases - sliding clamp
Select all of the following that are components of a nucleotide.
- phosphate group - sugar - nitrogenous base
The DNA backbone is composed of (choose all that apply)
- sugars - phosphate groups
Of the following list, which 3 items are required for DNA replication?
- template - nucleotides -polymerase
How many hydrogen bonds are formed between adenine and thymine in the double DNA helix?
2
X-ray diffraction was used to determine that the diameter of a DNA molecule is ___
2nm
Which of the following occurs during mismatch repair?
An incorrectly incorporated base is replaced with the correct one.
Which of the following serves as the sliding clamp subunit that allows the replicating enzyme complex to stay attached to the template in eukaryotic cells?
PCNA proliferating cell nuclear antigen
Why do eukaryotic cells have multiple origins of replication?
To ensure timely replication of multiple, relatively large chromosomes
Franklin used a technique called x-ray _______ to suggest that DNA has a helical structure.
diffraction
While one strand is synthesized continuously, replication is _______ on the other strand, because polymerases can only synthesize DNA in one direction and the two DNA strands run in opposite directions.
discontinuous
On which strand does the removal of the last primer leave a gap that cannot be primed at the ends of the chromosome.
lagging
During DNA replication, the ______ strand is synthesized continuously while the _____ strand is synthesized as small fragments that are connected to each other to form a continuous strand.
leading lagging
DNA ______ is an enzyme that joins to adjacent Okazaki fragments during the synthesis of the lagging DNA strand.
ligase
The experiments used to distinguish between the three potential DNA replication mechanisms were performed by
meselson and stahl
The discovery of a substance called nuclein, later to be named nucleic acid, was accomplished by
miescher
during _______ repair, cells remove bases that have been incorrectly incorporated by DNA polymers and replace them with the correct base.
mismatch
Radiation, UV light, x-rays, and chemicals in the environment can cause mutations in DNA and are therefore referred to as
mutagens
Which origins are more sequence-specific?
oriC
Repeating sugar and phosphate units in a single DNA strand make up the
phosphodiester backbone
The enzyme DNA _______ synthesizes the RNA primers required by DNA polymerases during replication.
primase
The function of telomeres is to
protect the ends of chromosomes
When trying to discover the substance responsible for transformation, Avery, MacLeod and McCarty removed _______ from their preparation and found that the transforming activity persisted.
protein
The two main eukaryotic DNA polymerases that extend DNA are
epsilon delta
The enzyme DNA _____ is the topoisomerase involved in DNA replication.
gyrase
In an aging cell, the activity of telomerase would be
low
The DNA controlled by an origin is called a
replicon
DNA replication that leads to the production of double helices with one parental strand and one newly synthesized strand is consistent with
semiconservative replication
The stability of DNA molecules is due to
the sum of the hydrogen bonds between base pairs
The enzyme DNA _____ relives coiling in DNA strands ahead of the replication form
topisomerases
What class of enzymes relieve torsional strain in DNA strands ahead of the replication fork?
topisomerases
Bacterial replication (for example in E. coli) begins at
a single origin
DNA'S phosphodiester _____ is composed of sugars and phosphates
backbone
Telomeres are related to
cellular aging
Genes, which contain trait specifying information, are located on
chromosomes
Which model for DNA replication suggests that both strands of the double helix remain intact and the new DNA double helix consists of two new DNA strands?
conservative
The enzyme _______ uses ATP to unwind the DNA template
helicase
Which of the following statements accurately compare the helicases in bacteria, archaea, and eukaryotes?
- Bacterial and archaeal/eukaryotic replicative helicases are not homologous. - Bacterial and archaeal/eukaryotic replicative helicases move in opposite directions along DNA.
Which enzymes did Avery, MacLeod, and McCarty use in order to identify the genetic material?
- DNA digesting enzymes - RNA digesting enzymes - Protein digesting enzymes
Which of these are part of the Watson-Crick model?
- Each DNA molecule is composed of two strands that run antiparallel. - Each DNA molecule is composed of 2 phosphodiester strands.
Discontinuous replication occurs on one strand during DNA replication. Which of these are reasons for discontinuous replication?
- The antiparallel nature of the DNA strands - The 5' to 3' synthesis activity of polymerase
Which of these are involved in the unwinding of DNA?
- Topoisomerase - Single-strand binding proteins - Helicase
Features of the Watson and Crick model include ____.
- a helical structure - a sugar phosphate backbone - a double stranded structure
The DNA structure proposed by Watson and Crick involve
- a helical structure - two grooves (major and minor) - a sugar phosphate backbone
Miescher's nuclein was later termed nucleic acid because it was ____.
- found in the nucleus - slightly acidic
DNA primase (choose all that apply)
- makes a primer about 10 -20 nucleotides in length. - makes a primer of RNA complementary to the DNA
How are the origins of replication adjusted in eukaryotic cells, so that early in the embryonic development of eukaryotic organisms DNA can be replicated faster?
Cells can increase the number of origins used in early development.
Even with the proofreading abilities of ____, mutations still occur.
DNA polymerase
Which enzyme covalently links nucleotides together during DNA replication?
DNA polymerase
In eukaryotes, priming is accomplished by a complex of primase and
DNA polymerase a
Which of the following facilitates the reversal of damage to our hereditary material before a permanent mutation can occur?
DNA repair systems
Based on replication proteins, DNA replication in archaea is most similar to that of
eukaryotes
Which types of cells have more than one origin of replication?
eukaryotes
When the interaction of genes alters genetic ratios, this is called?
genes