Biology: DNA Replication

replication fork

A _________ is the partial opening of a DNA helix to form two single strands.

a single replicon

A bacterial chromosome is typically replicated as ________.

endonuclease; exonuclease

An ________ cuts DNA internally and an _______ cuts at the ends of DNA

DNA ligase

As the lagging strand is being synthesized, adjacent Okazaki fragments are joined by the enzyme _________.

eukaryotes

Based on replication proteins, DNA replication in archaea is most similar to that of _________.

telomeres

Short, repeated sequences of DNA are a characteristic of:

a short internal RNA

Telomerase uses which of the following as a template?

replicon

The DNA controlled by an origin is called a ________.

DNA primase

The enzyme DNA _________ synthesizes RNA primers required by DNA polymerase during replication.

helicase

The enzyme ______ uses ATP to unwind the DNA template.

protect the ends of chromosomes

The function of telomeres is to ________.

the replication fork

The partial opening of a DNA helix to form two single strands is called _________.

eukaryotes have multiple, linear, large chromosomes

What are some basic differences in prokaryotic and eukaryotic replication?

telomeres

What is the name of the regions at the ends of eukaryotic chromosomes?

PCNA

What is the name of the subunit that acts as the sliding clamp which keeps the replicating enzyme complex attached to the template in eukaryotic cells?

leading strand

strand that is synthesized continuously and requires a single primer

lagging strand

strand that is synthesized in small fragments that are later connected and requires multiple primers

both the leading and the lagging strand

The enzymes in the replisome are active on ________.

polymerase

attaches a nucleotide to the 3' end of the DNA strand

makes a primer about 10-20 nucleotides in length and makes a primer of RNA complementary to the DNA

DNA primase _________.

linear chromosomes

DNA replication in eukaryotic cells is complicated by the fact that eukaryotic cells have _______.

leading 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.

primase; helicase; DNA ligase

During DNA replication, the enzyme _______ synthesizes RNA primers, the enzyme _________ unwinds the double helix, and the enzyme _________ joins two strands of DNA together.

exonuclease

E. coli polymerases I, II, and III have 3' to 5' ___________ activity, which provides them with a proofreading function, i.e. they can remove a mispaired base.

helicase

Enzyme that unwinds the double helix

cellular aging

Experiments have shown that telomerase is involved in ________.

low

In an aging cell, the activity of telomerase would be _______.

primosome

In the replisome, the _______ is composed of primase, helicase, and accessory proteins that prime the lagging strand.

primase

Makes a 10-12 bp complementary primer to the DNA

lagging

On this strand, the removal of the last primer leaves a gap that cannot be primed at the ends of the chromosome.

single-strand binding proteins

When the double stranded DNA helix is unwound, two single strands of DNA are formed. These strands have to be stabilized because their hydrophobic bases are exposed to water. The proteins that stabilize the two single strands are called ________.

DNA polymerase I

Which DNA polymerase removes and replaces RNA primer segments in the synthesis of the lagging strand because it has 5' to 3' exonuclease activity?

topoisomerase (gyrase)

enzyme that relieves coiling in DNA strands ahead of the replication fork

eukaryotes

Which type (or types) of cells has more than one origin of replication per chromosome?

lymphocytes

Because they must be able to continue to divide, the level of telomerase stays high in ________, despite their age.

telomerase

The enzyme _______ contains a small internal piece of RNA, which is used as a template to extend the end of a linear DNA molecule.

processivity

The DNA polymerase III enzyme of E. coli contains a subunit called the B subunit, which dramatically increases the enzyme's ________.

processivity

The ability of a DNA polymerase to remain attached to its template is called the polymerase's ________.

telomerase

The amount of the enzyme _________ declines within cells as they age resulting in a gradual shortening of the ends of chromosomes.

the need for a primer and the directionality of polymerases

The problems in replicating the ends of linear chromosomes are caused by ________.

telomerase

Which enzyme prevents chromosomal shortening by attaching a repeat sequence to the ends of chromosomes?

telomeres

Which of the following are short repeats of DNA on the ends of eukaryotic chromosomes?

polymerases, primase, helicase, sliding clamp, and clamp loader

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)?

eukaryotic

Which type (or types) of cells uses (or use) a primase that is a combination of RNA polymerase and DNA polymerase and makes short RNA primers which are then extended with DNA to produce the final primer?

to ensure timely replication of multiple, relatively large chromosomes

Why do eukaryotic cells have multiple origins of replication?

telomeres; telomerase

________ are short protective repeats of DNA at the ends of eukaryotic chromosomes which are generated by the enzyme _______.