Molec bio exam 2 MC

what is the role of SSB proteins?

"single strand binding proteins" kepp ssDNA from reforming duplexes

TATA binding protein is (TBP) is involved in transcription initiation of:

RNAP I, RNAP II and I

At the end of successful transcription initiation, __:

RNAP breaks free from promoter

Transcription begins when:

RNAP recog promoter seq, binds to DNA, and synth RNA from 5-->3' end of new piece

In eukaryotic cells, DNA replication occurs during:

S phase

Which transcription factor has a role in initiation of transcription from all three eukaryotic polymerases?

TBP

All of the following are correctly matched except _____.

TBP: only found in TFIID

the first protein to bind to core promoter in eukaryotes is:

TFIID

__________ is involved in both initiatnig transcription and repairing DNA damage.

TFIIH

What is the most important control point for regulation of genome expression?

Tc initiation

What is the role of parS in bacteria?

a DNA seq. that functions as a centromere

What is the role of the Rho protein in termination of transcription?

a helicase that actively breaks base pairs btwn template and transcript

The beta dimer of E coli DNA polymerase III forms __:

a ring which slides along the DNA

intrinsic terminators of bacterial Tc contain:

a specific stem loop structure (hairpin) in RNA

Aneuploidy, a hallmark of cancer cells refers to ___:

abnormal # of chromosomes in cell

The TATA box:

acts to position RNAPII for Tc initiation

What methods were used to identify replication origin binding proteins in the Bell and Stillman paper?

affinity chromatography, density gradient sedimentation, and DNA footprinting

Zinc finger containing transcription factors bind DNA via

alpha helix interacting w/ DNA in major groove

Some eukaryotic promoters contain an element positioned around +1 called:

an initiator (Inr) seq.

Which of the following statements about Okazaki fragments is TRUE?

both euk and bac. use DNA LIGASE I to seal nicks during maturation

This unique feature of Rpb1 of RNA pol II is necessary for viability and has several roles in transcription:

carboxyl terminal heptad repeats

What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only?

cells would get smaller & smaller

The principal microtubule organizing center in animal cells is the ____________.

centrosome

The sequence of mRNA will be the same as the ____________ strand of DNA

coding

At the end of DNA replication, the sister chromatids are held together by the ___________.

cohesins

Levels of Cdk activity change during the cell cycle, in part, because ________________.

cyclin levels change during the cycle

____________are regions in eukaryotic DNA that are thousands of base pairs away from a promoter, yet they regulated that promoter.

enhancers

How are telomeric repeats added to the ends of chromosomes without a template for DNA synthesis?

enzyme telomerase has RNA subunit containing the template for synth of repeats

An important difference between the initiation of prokaryotic and eukaryotic transcription of protein coding genes is that _____.

euk RNAP require Tc factors for promoter recog

Transcription in eukaryotes and prokaryotes differs in the followings ways EXCEPT:

euk mRNA has a cap added to the 3' end

The concentration of mitotic cyclin (M cyclin) ________________.

falls towards the end of M phase as a result of ubiquitylation and degradation

bacterial ftsZ is required for:

formation of contractile ring

Which of the following statements about heterochromatin is FALSE?

heterochromatin replicates early in S phase

In eukaryotes, condensin and cohesin are composed of a _______ of SMC proteins, each containing a(n) _________.

heterodimer, ATPase domain

What is the significance of the Autonomous Replication Sequence?

highly cons. DNA element in Saccharomyces which originally identified by ability to confer high frequency of transformation of plasmid DNA

How is the active conformation of the Cyclic-dependent Kinase (CdK) formed?

highly conserved alpha helices of the cyclin box bind to the PSTAIRE motif of CdK and the kinase adopts the active formation

during meiosis I:

homologous choromosomes interact thru homologous recombo.

During anaphase of meiosis I ___:

homologous chromosomes move toward opposite poles

You have isolated a strain of mutant yeast cells that divides normally at 30°C but cannot enter M phase at 37°C. You have isolated its mitotic cyclin and mitotic Cdk and find that both proteins are produced and can form a normal M-Cdk complex at both temperaturesWhich of the following temperature-sensitive mutations could NOT be responsible for the behavior of this strain of yeast

inactivation of an enzyme that ubiquitylates M cyclin

Topoisomerases remove supercoils to relieve torsional stress. In this context what is unusual about gyrase?

it adds negative supercoils

All of the following are TRUE regarding the origin recognition complex (ORC) EXCEPT:

it is bound to the origin of replication only during repl.

What is the role of the primer in DNA synthesis?

it provides a 3' hydroxyl group for the addition of the next nucleotide

Which of the following statements about the anaphase-promoting complex (APC) is FALSE?

its continuously active throughout the cell cycle

DNA Pol I uses 5' to 3' exonuclease activity to remove RNA primers but DNA Pol epsilon and DNA Pol delta do not.

its true

Which of the following statements about kinetochores is TRUE?

kinetochores require nuclear envelope disassembly in order to link chromosomes to the mitotic spindle

How does binding of the lac repressor to the lac operator block transcription initiation?

lac repressor binding blocks RNAP from interacting w/ DNA at the start site

Okazaki fragments need to be joined by a DNA ligase. How does this happen?

ligase uses ATP, forms an enzyme-ATP intermediate, then the 3'OH end joins the 5'P end

Catabolite activator protein (CAP) controls expression of:

many operons involved in metabolism of sugars

Which of the following statements about M phase is true?

mitotic spindle helps segregate the chromosomes to 2 daughter cells

Which of the following events does NOT usually occur during interphase?

nuclear envelope breaks down

Amphiletic attachment of spindle microtubules to the kinetochore occurs:

on the chance encounter of the plus end of the MT w/ the kinetochore

Which of the follow is true regarding initiation of bacterial DNA synthesis?

primase (dnaG) synthesizes an RNA on the template

How are Okazaki fragments formed?

primase synth. RNA primers to initiate 5-->3' DNA synth & DNA synth occurs overall in the 3-5' polarity on the lagging strand

Each time a ribonucleotide is added to the elongating RNA molecule during transcription, a _______ is released

pyrophosphate

During transcription, histone chaperones:

remove histones ahead of RNAP and replace them behind RNAP

Separase is inhibited until anaphase by the proteins:

securin and cyclin B

how do helicases work?

separate duplex DNA into single strands via ATP hydrolysis

How does a circular template stop replication?

short 23bp seq called TER sites recognized by TUS protein that stops replication

The primase is:

special RNA pol. coded for by dnaG gene

How do chromosomes become bi-oriented and aligned in the spindle mid-zone during mitosis?

spindle poles exert the same force on sister chromatids, but in oppo directions, creating a tug-of-war effect

Which of the following is an activity of the RecA protein?

stimulates protease activity in SOS response

Compared to mitosis, a unique feature of meiosis is the failure of the chromosome to replicate between __?

telophase of meiosis 1 & prophase of meiosis 2

During prokaryotic transcription, a hairpin stem-loop is formed followed by a stretch of U's at the 3′ end of nascent RNAs. What is the expected result?

termination of Tc as the result of reduced base pairing btwn template and RNA transcript

What is the final conclusion of the Bell and Stillman (1992) paper?

the ORC is a strong candidate for the initiator protein in yeast cells

Which of the following is the main reason that a typical eukaryotic gene is able to respond to a far greater variety of regulatory signals than a typical prokaryotic gene or operon?

the Tc of a euk. gene can be influenced by proteins that bind far from promoter

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2?

the cell would enter M phase under conditions when normal cells would not

Why is an RNA primer considered essential for DNA synthesis by DNA polymerase III?

the enzyme requires a free 3'-OH group

How do Eukaryotic regulatory co-activator and co-repressor complexes associate with DNA?

they are recruited by sequence-specific DNA binding proteins

The role of the sigma factor in bacterial RNA polymerase is __:

to position RNA pol correctly on template DNA

RNA Polymerase II:

transcribes genes encoding proteins

RNA polymerase I __:

transcribes the gene for large ribosomal RNAs

What distinguishes topoisomerase type I from topoisomerase type II in E. coli?

type I cleaves 1 strand of DNA duplex, and type II cleaves both strandsof duplex when altering supercoil

Single-strand nicks made by ________________________separate the two strands in a DNA molecule in the absence of rotation.

type I topoisomerases

If you have a strain of bacteria that produce nonfunctional sigma factor, which step would you expect to be affected?

unable to identify and tightly bind promoters

What is the function of TFIIH in the eukaryotic transcription initiation complex?

unwinds the DNA duplex, phosphorylates pol II carboxy terminal domain (CTD)

the RNA component of telomerase __:

varies in size and seq. but has conserved secondary structure

How does proofreading increase the accuracy of genome replication?

when the 3' terminal NT is not base paired to the template, it is removed by the EXOnuclease activity of DNA Pol

Which of the following is NOT good direct evidence that the cell-cycle control system is conserved through billions of years of divergent evolution?

yeast cells have only 1 CdK, humans have many

The general factor that is responsible for transcription of most E coli genes (under normal conditions) is __________.

Σ70

Some polymerases have proofreading activity in which erroneously added nucleotides are removed. What type of activity is represented by this proofreading?

3' to 5' exo

The proofreading activity of a DNA polymerase is associated with __:

3' to 5' exo nuclease activity

__________ are accessory proteins involved in assisting histones to associate with DNA.

CAF-1 & ASF-1

Which of these polymerases can replace DNA Pol alpha during eukaryotic replication?

DNA Pol Epsilon

which DNA Pol. is mainly responsible for genome replication in E. coli?

DNA Pol III

Which of the following would be used to determine the sequence of DNA binding protein sites?

DNA footprinting

What two proteins play a role in DNA replication by unwinding the duplex DNA and stabilizing the resulting single strands?

DNA helicase & SSBP

Which DNA polymerase is responsible for the removal of the RNA primers at the origin and at the 5' ends of the Okazaki fragments in E. coli?

DNA pol. I

__________ creates temporary breaks in the backbone of DNA enabling the two strands of DNA to be separated when replication is terminated

DNA topoisomerase

Initiation at oriC is regulated by __:

DnaA-ATP levels and SeqA

The conversion of a closed promoter complex to an open promoter complex in bacteria requires _____.

H bond breakage of base pairs around initiation site

What feature makes the origin recognition complex unique among DNA binding proteins?

ORC requires ATP for specific DNA binding

Interphase encompases all of the following stages of the cell cycle EXCEPT:

M

True or False: RNA polymerase may go through several cycles of abortive initiation before leaving the promoter to enter the elongation phase.

True