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MIMM 324 > Lecture 8 > Flashcards

Lecture 8 Flashcards

1
Q

Properties of archea

A
  • Unicellular microorganisms
  • Circular chromosomes
  • No nucleus and no nuclear enveloppe
  • Cell walls made of impermeable S layer of proteins
  • Special phospholipids on mmebrane
  • Complex translation initiation mimicking eukaryotes
  • Methionine, not N-formyl methionine, to start translation
  • Histone-like proteins
  • Complex RNA polymerase machinery
  • DNA replication machinery alike eukaryotic counterparts
  • Distinct ribosomal RNA sequences
  • Live in extreme environments (volcanic hot springs,
    salt lakes, etc.)
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2
Q

Viruses of archea

A

-different than phages and eukaryotic viruses
* Unusual morphology (lemon, droplet, bottle shapes, etc)
* All have dsDNA as genome (one has ssDNA)
* Most have internal or external lipid envelopes
* Many are temperate viruses that integrate their genome into host cell DNA
* Many do not have an identifiable DNA polymerase gene: they use the hosts polymerase

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3
Q

When were bacteriophages discovered and by who?

A

-Frederick Twort
Glassy transformation
1915
-Felix d’Herelle
Bacteriophage
1917

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4
Q

When did we see bacteriophages

A

1940 EM

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5
Q

Who got the nobel prize of physiology in 1978 and why

A

Werner Arber, Daniell Nathans and Hamilton for the discovery of restriction enzymes and their application to problems of molecular genetics

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6
Q

when was the first ms2 rna genome sequenced

A

1976

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7
Q

when was the first lambda dsrna genome sequences

A

1982

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8
Q

true or false: phage and bacteria don’t co evolve

A

false they do through gene transfer

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9
Q

true ro false; crispr is thanks to the co-evolution of phage and bacteria

A

true

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10
Q

what does the word phage come from

A

phagein which means to devour

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11
Q

true or false: phages don’t use the hosts biosynthetic machinery

A

false: they do most of the time either all or some

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12
Q

Names of the different phage morphology

A

caudovirales: tailed phages
-myoviridae aka contractile tail: T4 phages
-siphoviridae: non contractile flexible tail ex: lambda phage
-podoviridae: non-contractile short tail: t7

microviridae: spherical phage ex: φX174

Inoviridae: fibrous phage exL M13

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13
Q

MS2

A
  • Single-stranded RNA bacteriophages
  • Belong to levivirus genus
  • Naked icosahedral capsid
  • Linear single-stranded positive sense RNA, 4kb
    -1 copy of the maturation protein
    -180 copies of coat protein
    -26nm long
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14
Q

why is the secondary structure of the phage rna important

A

because it regulates how the proteins are synthesized

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15
Q

replication of Ms2: go see your notes

A

explain the process

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16
Q

how are some of the stem loops opened

A

they are opened when a certain part of the genome has been translated by the ribosome

17
Q

RNA folding kinetics regulate translation of
maturation protein

A

there is a short window when the rna is in this weird unstable conformation
-it’ll be open just long enough for the fmet maturation protein to be translated

18
Q

MS2 genome replication

A
  • Replicase binds to the start of coat gene to shut down
    coat protein translation.
  • Replicase is associated with three host proteins,
    S1 protein of the small ribosomal subunit,
    translational elongation factors EF-Tu and EF-Ts.
  • S1 directs replicase to the start of coat gene.
  • EF-Tu/GTP may help replicase to initiate RNA synthesis.
  • EF-Ts recycles EF-Tu/GDP to EF-Tu/GTP
19
Q

MS2 assembly

A

as more and more proteins are synthesized, these dimerize and that complex will be able to recognize and bind to the replicase operator hairpin -> shuts down the synthesis of replicase-> start formation of the capsid structure
-strong affinity for the operator and the proteins
each capsid has one copy of the rna

20
Q

Application of MS2/RNA binding in monitoring
RNA under microscope

A

can look at the location and thanks to the mrna in other cells
-aka you can see when rna is transported

21
Q

jX174

A
  • Belong to Microviridae
  • Microvirus
  • Naked icosahedral capsid
  • Circular single-stranded DNA
22
Q

entry of jX174

A

*Capsid interacts with sugar residues (likely glucose)
in the lipopolysaccharide.
*DNA is delivered through the spikes
(containing G and H proteins).
*H protein mediates the penetration step thanks to its N-terminal transmembrane helix

23
Q

viral genome replication of jX174 go see notes

A

explain

MIMM 324 (26 decks)

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