Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Undeleted > Lecture 3 > Flashcards

Lecture 3 Flashcards

0
Q

what must have low mutiation rate to maintain speciese?

A

germ cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Most errors are corrected by

A

proofreading and DNA repair
post-relication repair mechanism

only 1 mistake every 10^9 base pair, 3 nucleotides every cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What needs to have low mutation rates to avoid uncontrolled proliferation/ cancer?

A

somatic cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What synthesize DNA by catalyzing

A

DNA plymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

the following reaction is catalyzed

A

DNAn residues + dNTP —> (DNAn+1 residues + P2O7^4-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How is the new DNA strand made?

A

template directed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What must be seperated for replication?

A

two parental strands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does DNA replications require? 4 thins

A

dATP
dGTP
dCTP
dTTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What needds a primer with a 3’ -OH to begin?

A

DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

DNA feeds through the …. during replication

A

polemerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Both strands are …. replicated

A

simultaneously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

DNa plymerase can only synthesize DNA in the

A

5’ to 3’ direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

synthesized continualsly

A

leading strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

synthesized in segemnts

A

lagging strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The enzyme tightens its “fingers” around the active site…

A

which is easiest if the correct base pair is there

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

exonucleolytic proofreading

A

takes place immediatly after incorrect bases is added
DNA plymerease requries a perfectly paired 3; terminus
3’ to 5’ exonuclease clips off unpaired residues at 3’ primer terminus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

5 to 3 allows efficent error correction

A

when a high energy bond is cleaved, provides energy for plymerization of that bond.
if it went the other direction, there would not be sufficent energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Laggin Strand Synthesis

A

backstitching process
DNA PRIMASE synthesizes an 10nt long RNA primer to rpime DNA synthesis.
RNA primer is erased by RNAseH and replaced with DNA; DNA ligase joins the ends

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What joins the ends?

A

DNA ligase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what does DNA helicase do?

A

unwinds DNA
protein with 6 identical subunits uses AT hydrolyses
cuases confomational change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

helps stabalize DNA, prevents hairpins, base pairing, allows DNA polimerase to still read and put in new

A

single- stranded DNA binding protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

keep DNA polymerase on DNA when moving; releses when double stranded DNA is encountered

A

sliding clamp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what pust the sliding clamp onto a primer template junction??

A

clamp loader
with laggins strand clamp loader is always present since it is procuding DNA in segments and the sliding clamp needs to continually be put bakc on

23
Q

mismatch repair

A

MutS binds to mismatch;

Mut: scans for the nick and triggers degradation of nicked strand

24
Q

How does it know if it is fixing the new strand or the old strnad?

A

it fixes the non methalated strand, which is the new strand… this is E coli

25
Q

Type 1 Topoisomerases

A

makes a single cut on one strand in the phosphodiester bond
thermodynamically favorable process
allows to remove tention and spin around
resealing is rapid

26
Q

Type II topoisomerase

A

makes double stranded break in DNA
1. brekas on double stranded helix reversibly to create gate
2. causes second strand to pass through
3. reseals break and dissociates
can seperate “decatenate” 2 interlocked DNA circules
can prevent severe tangling problems

27
Q

Replication origins

A

rich in A-T based pairs
bacteria-inition is only pt, only when sufficent nutrients, refractory periord for new strands to be metholated, 2 replication forks do all of it
euarkyotes- need more than 1 origin,

28
Q

Initiation of DNA replication in bacteria

A

initiator protein binds to specific site in ORI froming complex
Complex attracts DNA helicase + helicase loader
helicase is placed around a SS DNA exposed by assembly of complex
helicase loader remains engaged until helicase properly loaded
Helicase unwinds DNA so primase can make RNA primer on leading strand; remaining proteins assemble to create 2 replication formks w complexes moving in opposite direction w respect to the ORI

29
Q

Eukaryotic DNA replication

A

only occurs during S phase, 8 hours
done in clusters 20-80
heterochromatin is late replicating

30
Q

Origin of replication Yeast eukaryote

min requirements 3

A

binding site for ORC
A-T rich stretch for easy unwinding
binding site for proteins that thelp attract ORC(origin of replication complex)

31
Q

ORC interaction w/ ORI persists

A

throughout cell cycle

32
Q

protein that beind to from a ….

A

prereplicative complex and regulates origin acitivity

done by helicase and helicase loading proteins, Cdc6 and Cdt1

33
Q

Regulation of OR in Eukaryotes

In S phase,

A

activated Cdks lead to

  • dissociation of helicase loading proteins
  • activation of helicase
  • unwinding of DNA
  • loading of DNA polymerase, etc.
34
Q

Regulation in eukaryotes of ORC

prevent assembly of new ORC until next M phase resets cycle

A

single chance to form in G1 when Cdk activity is low

second window for pre-replicative complexes to be activated and disassembles in S phase when Cdks activity is high

35
Q

ORI function depends critically on distanct sequences

A

also affects transcription

global effect of decondensing chromatin structure

36
Q

DNA requires not only DNA but

A

synthesis and assembly of new proteins

37
Q

histone proteins are synthesised in what phase

A

S phase

38
Q

What is needed to destabilize DNA histone interface?

A

chromatin remodeling proteins

39
Q

As replication fork passes through chromatin, histone octamer breaks into;

A
  • an H3-H4 tetramer, distributed randombly to daughter duplexes
  • 2 H2A-H2B dimers which are released from the DNA
40
Q

H2A/H2B dimers are 1/2 old and 1/2 new

A

they are added at random to complete complex

41
Q

What does the addition of hisones require?

A

Histone chaperones (chromatin assembly factors)

42
Q

What is the sliding clamp called that directs to DNA?

A

PCNA

43
Q

Patterns of Histone modification can be inherited

A

some contain only parental histones, some only new but most are hybrids of new and old.
parental patterns of histone modification are spread through reader-writer complexes
epigentic inheritance responsibility

44
Q

End replication problem on lagging strand:

A

no place for RNA primer

45
Q

bacteria have cirular genome

A

eukakaryores have telomeres

46
Q

What is the special sequence at the end of eache chromosome

A

GGGTTA

47
Q

What enzyme relenishes these sequences by elongating parental strand in 5’ to 3’ direction using an RNA template on the enzyme

A

telomerase it’s a protein and RNA combination

48
Q

What completes the telomerase replication of laggins strands?

A 
DNA plymerase, using extension as template 
This mechanism(plus a 5' nuclease) ensures 3' end is longer, leaving a protruding SS end that loops back and tucks into the repeat
49
Q

structures protect ends and distinguishes them from broken ones that need to be repaired

A

T-loops

50
Q

What cells have full complement of telomere repeats at birth?

A

somatic cells

51
Q

What retain full telomerase activity?

A

stem cells

52
Q

Each chromosome end in a given cell contains variable # of telomere repeats depending on age

A

repeats are lost each genreation due to insufficient telomerase acitivity

53
Q

after many generations, daughter cells will have defective chromosomes and stop dividing; in this way the cell’s lifetime is regulated to guard against cancer

A

replicative senescence

may cause againg

54
Q

How many times do human fibroblasts divide before undergoing replicative senescence

A

60 times

55
Q

dyskeratosis congenita

A

carry mutant telomerase RNA gene

Undeleted (56 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions