Chapter 5 Flashcards by Mikayla Cleary

Which enzyme synthesizes RNA primers

DNA primase

How well did you know this?

Not at all

Perfectly

Relaxes DNA by nicking and then closing one strand of duplex DNA

Type I topoisomerase

How well did you know this?

Not at all

Perfectly

If E. coli genome requires 20 mins to replicate itself, how can the genome of drosophila be replicated in only 3 mins

Drosophila contains more origins of replication than E. coli

How well did you know this?

Not at all

Perfectly

What kind of nucleotide has a two-ring structure with an amine functional group

Purine

How well did you know this?

Not at all

Perfectly

The duplication of genetic information carried in chemical form as DNA

DNA replication

How well did you know this?

Not at all

Perfectly

Permanent change in the DNA

Mutation

How well did you know this?

Not at all

Perfectly

The rate at which observable change occurs in DNA sequences

Mutation rate

How well did you know this?

Not at all

Perfectly

The mechanism the cell uses to copy the nucleotide sequence

DNA templating

How well did you know this?

Not at all

Perfectly

First nudeotide-polymerizing enzyme

DNA polymerase

How well did you know this?

Not at all

Perfectly

Each nucleotide added to a growing DNA strand comes from

Nucleoside (a sugar and a base) triphosphate (3 phosphate groups)

How well did you know this?

Not at all

Perfectly

What happen when nucleosides pair and the 2 phosphate groups are released

Provides energy for phosphodiester bond

How well did you know this?

Not at all

Perfectly

Semiconservative replication

How well did you know this?

Not at all

Perfectly

Conservative replication

How well did you know this?

Not at all

Perfectly

Dispersive replication

How well did you know this?

Not at all

Perfectly

A localized region of replication that moves progressively along the parental DNA double helix

Replication fork

How well did you know this?

Not at all

Perfectly

Origin of replication takes place where which base pairs are predominant

A and T

How well did you know this?

Not at all

Perfectly

Binds to double helix and breaks hydrogen bonds

DNA helicase

How well did you know this?

Not at all

Perfectly

Changes DNA topology by breaking and rejoining double - stranded DNA

Type II topoisomerase

How well did you know this?

Not at all

Perfectly

Polymerized only in the 3’ to 5’ chain direction

Okazaki fragments

How well did you know this?

Not at all

Perfectly

Daughter strand that is synthesized continuously

Leading strand

How well did you know this?

Not at all

Perfectly

Daughter strand that is synthesized discontinuously

Lagging strand

How well did you know this?

Not at all

Perfectly

The synthesis of each Okazaki fragment ends when

DNA polymerase runs into the RNA primer attached the 5’ end of previous daughter fragment

How well did you know this?

Not at all

Perfectly

Bind tightly and cooperatively to exposed single-stranded DNA stabilizing the unwound, single-stranded conformation

Single strand dna-binding proteins (ssb)

After the polymerase “double-checks” its base pairing the next error-correcting reaction is

Exonucleolytic proofreading

Clips off any unpaired residues at the primer terminus

Proofreading exonuclease

Why do RNA polymerase enzymes not need an efficient exonucleolytic proofreading mechanism

- Errors in RNA are not passed on | - Defective RNA molecule has no long term significance

The Initiation of DNA replication is highly regulated. Once DNA helicase is loaded, it

Begins to unwind DNA exposing DNA for primase to synthesize the RNA primer

An origin of replication experiences what caused by a delay in the methylation of "A' nucleotides

Refractory period

Initiation is blocked until

"As" are methylated

Human cells growing in culture are labeled for a short time with

^3H-thymidine (radioisotope of hydrogen)

Development of the emulsion reveals the pattern of labeled DNA through

Autoradiography

The rate and the direction of replication-fork movement can be determined by

Autoradiography

Replication origins tend to be activated in clusters called

Replication units

DNA replication in most eucaryotic cells occur during

The S phase

Are replication origins activated simultaneously?

How can replication fork initiation and fork movement accurately monitored?

DNA microarrays

Particularly condensed state of chromatin

Heterochromatin

Less condensed chromatin

Euchromatin

Tends to be replicated very late in phase

Heterochromatin

Regions of the genome whose chromatin is least condensed are replicated

First

Each DNA sequence that can serve as an origin of replication contain:

- A binding size for ORC (origin recognition complex) - A stretch of DNA rich in As and Ts - At least one binding site for proteins that help attract ORC

How is replication regulated to ensure all the DNA is copied only once

ORC complex

2 DNA helicase loadings proteins

cdc6 and cdt1

Passage of a cell from G1 to S phase is triggered by the activation of

Protein kinases

Contain tandem repeats of a short sequence (GGGGTT)

Telomeres

Replaces tandem repeats each time a cell divides and recognizes the tip of an existing repeat sequence

Telomerase

Processes that correct spontaneous DNA changes

DNA repair

DNA changes are caused by

- Heat - metabolic accidents - radiation - exposure to environmental substances

Extreme sensitivity to UV radiation

Xeroderma pigmentosum

Can release guanine and adenine from DNA

Depurination

Converts DNA base to an altered base

Deamination

Covalent linkage between two adjacent pyrimidine bases

Thymine dimers

Recognizes wrong base, removes, and inserts correct nucleotide

Base excision repair

Large mutation/abnormal helix shape, remove multiple nucleotides, synthesizes nucleotides with DNA polymerase

Nucleotide excision repair

Both strands of double helix are broken, broken ends are brought together and rejoined

Nonhomologous end joining

Both strands are broken, uses sister chromatids to repair

Homologous recombination