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Exam 1: lecture 1 | BIOL 4004 - Cell Biology, Quizzes of Cell Biology

Class: BIOL 4004 - Cell Biology; Subject: Biology; University: University of Minnesota - Twin Cities; Term: Spring 2013;

Typology: Quizzes

2012/2013

Uploaded on 02/10/2013

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TERM 1 DEFINITION 1
Leadingstrand: allows the new ly synthesized strand
complementary to the original strand to be synthesized 5' to 3'
in the same direction as the movem ent of the replication fork.
Lagging strand: opposite t o the working orientation of DNA
polymerase III, which moves on a tem plate in a 3' to 5'
manner, replication of the lagging stra nd is more complicated
than that of the leading strand.
TERM 2
exonucleolytic proofreading
DEFINITION 2
clips off any unpaired residues at the primer terminus,
continuing until enough nucleotides have been removed
to regenerate a correctly base-paired 3'-oH terminus that
can prime DNA snthesis
TERM 3 DEFINITION 3
This schematic diagram shows a current view of the
arrangement of replication protein sat a replication fork when
DNA is being synthesized
TERM 4
RNA polymerase
DEFINITION 4
catalyze the formation of the phosphodiester bonds that
link the nucleotides together to form linear
unwind the DNA helix
RNA polymerases can start an RNA chain without a
primer.
TERM 5 DEFINITION 5
(B) An electron micrograph showing t he replication machine
from the bacteriophageT4 sit moves along template
synthesizing DNA behind it.
(C) An interpretation of the micrograp h is given in the sketch:
note especially the DNA loop on the lagging strand Apparently
the replication proteins became part ly detached from the very
front of the replication fork
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Leadingstrand: allows the newly synthesized strand complementary to the original strand to be synthesized 5' to 3' in the same direction as the movement of the replication fork. Lagging strand : opposite to the working orientation of DNA polymerase III, which moves on a template in a 3' to 5' manner, replication of the lagging strand is more complicated than that of the leading strand. TERM 2

exonucleolytic proofreading

DEFINITION 2

clips off any unpaired residues at the primer terminus,

continuing until enough nucleotides have been removed

to regenerate a correctly base-paired 3'-oH terminus that

can prime DNA snthesis

TERM 3 DEFINITION 3

This schematic diagram shows a current view of the

arrangement of replication protein sat a replication fork when

DNA is being synthesized

TERM 4

RNA polymerase

DEFINITION 4

catalyze the formation of the phosphodiester bonds that

link the nucleotides together to form linear

unwind the DNA helix

RNA polymerases can start an RNA chain without a

primer.

TERM 5 DEFINITION 5 (B) An electron micrograph showing the replication machine from the bacteriophageT4 sit moves along template synthesizing DNA behind it. (C) An interpretation of the micrograph is given in the sketch: note especially the DNA loop on the lagging strand Apparently the replication proteins became partly detached from the very front of the replication fork

( A )The normal assembly of chromatin on the two daughter DNA helices produced at a replication fork requires the deposition of H2A-H2B dimers on to directly inherited H3-H tetramers swell as the assembly of new histone octamers At a centromere, the inheritance of H3 variant-H4 tetramer seeds the formation of new histone octamers that likewise contain the variant H3 histone. A similar seeding process could cause the adjacent locks of centric heterochromatin to be inherit TERM 7 DEFINITION 7 RNA polymerase simultaneously transcribing each of two adjacent genes. Molecules of RNA polymerase are visible as a series of dots along the DNA with the newly synthesized transcripts attached to them. The RNA molecules here not translated into protein but are instead used directly as components of ribosomes From the lengths of the newly synthesized transcripts, it can be deduced that the RNA polymerase molecules are transcribing from left to right. TERM 8

DNA is transcribed by the enzyme RNA

polymerase.

DEFINITION 8 The RNA polymerase (pale blue) moves stepwise along the DNA, unwinding the DNA helix at its active site. As it progresses, the polymerase adds nucleotides one by one to the RNA chain at the polymerization site, using an exposed DNA strand as a template The RNA transcript is thus a complementary copy of one of the two DNA strands. TERM 9 DEFINITION 9 Initiation of transcription of a eucaryotic gene by RNA polymerase II. The promoter contains a DNA sequence called the TATA box, which is located 25 nucleotides away from the site at which transcription is initiated. Through its subunit TBP, TFIID recognizes and binds the TATA box, which then enables the adjacent binding of TFIIB TERM 10 DEFINITION 10

The binding of TFIID causes a large distortion in the DNA

of the TATA box

This distortion is thought to serve as a physical landmark

for the location of an active promoter

It brings DNA sequences on both sides of the distortion

together to allow for subsequent protein assembly steps

initiation factors dissociate, allowing the large ribosomal

subunit to assemble with the complex and complete the

ribosome.

initiator tRNA is still bound to the P-site, leaving the A- site

vacant

Protein synthesis is therefore ready to begin

TERM 17 DEFINITION 17

If this recognition site differs substantially from the

consensus recognition sequence (5'-ACCAUGG-3')

scanning ribosomal subunits will sometimes ignore the

first AUG codon in the mRNA and skip to the second or

third AUG codon instead

TERM 18 DEFINITION 18

Cells frequently use this phenomenon, known as leaky

scanning, to produce two or more proteins, differing in their

N-termini, from the same mRNA molecule

TERM 19 DEFINITION 19

Schematic drawing showing how a series of ribosomes can

simultaneously translate the same eucaryotic mRNA

molecule.