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1 Microbiology Oral/Med > Bacterial Replication and Transcription 5.1 > Flashcards

Bacterial Replication and Transcription 5.1 Flashcards

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1
Q

Flow of genetic information in any cell depends on ?

A

central dogma

1) replication- copy DNA
2) transcription- convert DNA to RNA
3) translation- convert RNA into protein format

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2
Q

what do retroviruses do? exception for what?

A

encode an enzyme with the ability for reverse transcription via reverse transcriptase
*exception to central dogma

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3
Q

reverse transcriptase does what?

A

conversion of RNA information into DNA format

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4
Q

purpose of promotor?

A

regulates the flow of information from DNA to RNA (in both Pro and Euk)

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5
Q

Describe prokaryote genes

A

1) contiguous coding regions
2) upstream regulatory regions
3) transcription leads to a polycistronic RNA message- one RNA that contains several coding regions

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6
Q

describe eukaryote genes

A

1) exons= regions that code for genes
2) introns= extra DNA between exons
3) regulatory regions (regions that do NOT code for protein that regulate transcription)

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7
Q

exons vs introns

A 
exons= used
introns= not used..... not sure how to remember this, but stop flipping them
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8
Q

Regardles of species, DNA ALWAYS has these characteristics?

A

1) polydeoxyribose-phosphate backbone
2) purine and pyrimidines hydrogen bonded to complementary base pairs
3) antiparallel; coding 5’ to 3’
4) double stranded supercoil

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9
Q

What is unique characteristics to Pro DNA?

A

1) circular

2) nuclear regions celled “nucleoid”

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10
Q

double stranded DNA in its simplest form is alpha or beta and contains what grooves per tuern?

A

alpha

*contains major and minor groove per turn

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11
Q

hydrogen bonds in DNA can be broken with? reannealled with?

A

broken with heat

*renealled with cooling

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12
Q

DNA absobrs light best at what wavelength?

A

260 nm

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13
Q

does single or double standed DNA absorb more light?

A

single

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14
Q

as DNA melts, does its light absorbance increase or decrease?

A

increase

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15
Q

Each dsDNA has a melting temperature proportional to the amount of?

A

G:C bonds in the strand

*greater the amount of G:C; greater the MP will be

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16
Q

what is the nucleoid? contains?

A

nuclear region in Pro. (bc Pro has no membraned nucleus protecting its DNA)
*contains chromosomes, plasmids, and genetic exchange

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17
Q

chromosome? E. coli has how many?

A

single, haploid (one copy), supercoiled, structure in nucleoid area is composed of double stranded circular DNA-
*E. coli has ~4.7 million bases

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18
Q

what are plasmids?

A

extrachromosomal elements

*may contain information for virulence factors or antibiotic resistance factors

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19
Q

Genetic exchange occurs at the nucleoid through what 3 processes?

A

conjugation
transformation
transduction

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20
Q

What does Class 1 topoisomerases do?

A

introduce single stranded breaks for supercoiling

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21
Q

What does Class 2 topoisomerases do?

A

introduce double strand breaks to supercoil DNA

22
Q

what enzyme supercoils DNA?

A

gyrase (both topoisomerase 2 help)

23
Q

What are 3 antibiotics commonly used to inhibit gyrase?

A

Nalidixic acid, Ciprofloxacin, novobiocin

24
Q

Remember: DNA gyrase = _____ = creates supercoil

A

topoisomerase 2

25
Q

supercoiled DNA forms ___ held together by proteins? point of proteins?

A

domains
* proteins prevent the entire NA from uncoiling when one domain is nicked/uncoiled (which is necessary for replication and transcription)

26
Q

Cutting of DNA with restriction enzymes leads to?

A

“sticky ends” which are complementary but unbound ends

27
Q

purpose of modification and restriction enzymes?

A

used to analyze DNA, cuts foreign DNA

28
Q

modification and restriction enzymes will cut and WILL NOT cut what? why?

A

will cut unmethylated sequences

*will NOT cut methylated sequences bc that indicates the bacterias own DNA! Bacteria methylate their DNA for protection

29
Q

Where do modification and restriction enzymes cut DNA at? derived from?

A

will cut DNA at specific palindromic sequences

*derived from bacteria

30
Q

The CRISPR region is bascally a?

A

memory bank of nucleus acid sequences that have come into the bacterial cell

31
Q

Describe how CRISPR work? what protein additionally helps destroy invading DNA?

A

1) copy of nucleis acid info stored within genome of bacteria
2) the DNA is transcribed when the bacterial cell is under attack by virus
3) the cut CRISPR RNA seeks out invading viral DNA
4) CRISPR and Cas protein bind
5) together destroy invading DNA

32
Q

what does semiconservative mean?

A

Both strands of the DNA helix serve as templates for the synthesis of two new strands

33
Q

Semiconservative DNA replication requires what 6 enzymes?

A 
DNA polymerases
helicase
primase
ligase
Gyrase(topoisomerase II)
topoisomerase I
34
Q

DNA polymerases, in general, do what?

A

attaches nucleotides

35
Q

helicase

A

1) binds to DNA near replication fork

2) unwinds or splits open the double helix replication fork

36
Q

primase

A

makes short RNA starter chains

37
Q

ligase

A

1) links DNA molecules into single structure

2) completes replication

38
Q

Gyrase(topoisomerase II

A

promotes supercoiling

39
Q

topoisomerase I

A

relaxes supercoiled DNA

40
Q

DNA replication ALWAYS progresses what direction? (3 facts)

A

5’ to 3’
occurs on both strands simultaneously
occurs in both directions

41
Q

DNA polymerases require a primer to couple the? Primer composed of?

A

DNA oligonucleotides

*This primer is composed of RNA

42
Q

DNA replication starts at?

A

origin of replication

43
Q

New DNA synthesis occurs at?

A

growing forks and proceeds bidirectionally

44
Q

DNA synthesis progresses in the 5′ to 3′ direction continuously=____ strand or in pieces= _____ stand

A 
continous= leading strand
discontinuous= lagging strand
45
Q

How long does it take to complete one round of replication?

A

40 minutes

46
Q

How often do new replication initiation occur?

A

every 20 minutes

47
Q

Initiation of DNA synthesis precedes cell ___?

A

division

*Multiple growing forks may be initiated in a cell before complete septum formation and cell division

48
Q

Why is there a leading and lagging strand?

A

because replication is bidirectional

49
Q

leading vs lagging strand

A
  • -Leading strand synthesis moves towards replication fork (continuous)
  • -Lagging strand synthesis moves away from replication fork (discontinuous)
50
Q

Each newly opened single strand is

stabilized by?

A

single-strand binding proteins

51
Q

DNA polymerase I

A

1) removes RNA primers
2) fills gaps in DNA
3) involved in DNA repair-also has proofreading

52
Q

DNA polymerase III

A

proffreading** recognizes mismatches and redoes mistakes

**reduces mutations

1 Microbiology Oral/Med (26 decks)

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