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Virology > Molecular Biology Review (Lecture 5) > Flashcards

Molecular Biology Review (Lecture 5) Flashcards

1
Q

What are the goals of viruses and how do they achieve that?

A

replicate its genome and assemble new progeny by taking over host cell’s cellular processes and have it focus on the virus’s goals

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2
Q

What does it mean that cellular processes are localized?

A

there is a specific place where only these processes (DNA replication, transcription, translation) can occur

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3
Q

In which direction is DNA read and then synthesized?

A

read 3’-5’ and synthesized 5’-3’ (bottom strand = leading)

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4
Q

What type of bond are between nucleotides?

A

phosphodiester bond

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5
Q

What are non-coding RNAs?

A

tRNAs and rRNA types of RNA

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6
Q

What are enhancer proteins?

A

help the transcription of the genes

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7
Q

Which type of polymerase binds to promoter sequences on the DNA?

A

DNA-dependent RNA polymerase

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8
Q

How much of our genes are actually made into proteins?

A

1.5%

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9
Q

What is the enzyme that replicates DNA?

A

DNA-dependent DNA polymerase

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10
Q

Where does the DdDp bind to on the DNA?

A

origin of replication (ORI)

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11
Q

What enzyme puts down the RNA primer needed for DNA replication?

A

DNA-dependent RNA polymerase

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12
Q

Which enzyme binds to DNA right after the DdDp sits on the DNA? And why?

A

helicase to unwind the DNA

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13
Q

What are the 3 important properties of DNA-dependent DNA polymerase?

A

requires RNA primer, high fidelity of copying (resistant to error), proofreading ability

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14
Q

What is the proofreading ability of DdDp attributed to?

A

exonuclease activity 3’-5’

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15
Q

Why does DdDp need an RNA primer?

A

cannot initiate de novo synthesis because DNA nucleotides don’t have a free 3’OH group

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16
Q

What does “de novo” mean?

A

synthesize on its own, “from new”

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17
Q

What is the enzyme needed for transcription?

A

DNA-dependent RNA polymerase

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18
Q

What are the 4 important properties of DNA-dependent RNA polymerase?

A

binds to the promoter region of DNA, built-in helicase activity, de novo synthesis of RNA, NO proofreading ability

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19
Q

What is the difference between preliminary mRNA and mature mRNA?

A

depending if it had gone through the 3 necessary modifications

20
Q

What are the necessary 3 modifications of preliminary mRNA in order for it to leave the nucleus?

A

5’ cap, poly (A) tail, and RNA splicing

21
Q

What are the 3 important reasons why mRNA needs a 5’ cap?

A

help mRNA get out of nucleus, prevent it from degradation of RNases, translation initiation complex recognizes 5’ cap to start translation

22
Q

What is the “Initiation” step of translation?

A

initiation complex forms when it recognizes the 5’ cap

23
Q

What makes up the initiation complex?

A

small subunit and tRNA molecule that recognizes the start codon –> large subunit goes on top of it

24
Q

What step in translation is the key step for viruses?

A

initiation since the viruses need to get their transcripts recognized by the host cell translation machinery

25
Q

What is the difference between monocistronic and polycistronic?

A

monocistronic transcripts can code for ONLY ONE protein /polypeptide | polycistronic transcripts can code for MORE THAN ONE different protein off of the same transcript

26
Q

Which organisms have monocistronic transcripts?

A

eukaryotes

27
Q

Which organisms have polycistronic transcripts?

A

prokaryotes and viruses

28
Q

Which type of transcripts do eukaryotic translation machinery only recognize?

A

monocistronic

29
Q

What is the role of the ER?

A

protein folding, packaging, and some modification

30
Q

What is the role of the Golgi?

A

modification of proteins and transport them out

31
Q

What is the exocytic pathway?

A

proteins that get secreted by the cell

32
Q

Where does the Golgi direct proteins when they need to be degraded?

A

lysosome

33
Q

What are the 3 endocytic pathways?

A

phagocytosis, pinocytosis, and receptor-mediated endocytosis

34
Q

What is phagocytosis?

A

“cell eating”; constantly taking in molecules from the environment; ex of phagocytic cell = immunological cells

35
Q

What is pinocytosis?

A

cell-drinking, taking up fluids

36
Q

What cytoskeleton element mediates phagocytosis and pinocytosis and why?

A

actin because these cells are constantly stretching

37
Q

What is receptor-mediated endocytosis?

A

use of receptors to get inside the cell (mode of entry with viruses)

38
Q

What specific type of protein mediates the receptor-mediated endocytosis and how?

A

clathrin-coated proteins that assemble under the receptor-endocytic area of the membrane to take substance in

39
Q

What are the 4 roles the cytoskeleton?

A

cell movement, chromosome separation, transport of organelles/things inside cell, provides shape and mechanical strength

40
Q

What are microtubules and what does it establish in the cell?

A

cytoskeleton element made up of tubulin; establishes polarity in the cell (gives direction of transport)

41
Q

Where is actin usually located within the cell and what is it’s role?

A

usually around the plasma membrane and is involved with the movement of the plasma membrane and other vesicles

42
Q

What is the role of intermediate filaments?

A

provide cell structure and help cells adhere to neighboring cells

43
Q

What are the 4 hurdles that viruses face after attachment?

A

receptors and polymerases, actin remodeling, ribosomes and viral mRNA compatibility, and viral-host cell mRNA competition

44
Q

How are receptors and polymerases a hurdle for the virus to enter the host cell?

A

receptors = virus needs to have a receptor to be readily available and exposed to bind with to get into cell ||| polymerase = (depending on nature of nucleic acid) DdDp needs to be active/available for DNA viruses or same with RdRp for RNA viruses

45
Q

How is actin a hurdle for the virus and what will it do to overcome this in order to enter the host cell?

A

actin (present on cell membrane) serves as a blockage for viral entry so virus needs to remodel actin via receptor-mediated endocytosis or cause it to remodel to bring virus in

46
Q

How are ribosomes and viral mRNA compatibility hurdles for the virus?

A

viral mRNA do not have 5’cap = need to get it or find a way for ribosomes to recognize viral mRNA

47
Q

How does the competition against host cell mRNA affect the virus?

A

virus only want their genome and transcripts to be translated and replicated = need to use up all of host-cell’s resources and can’t share with host cell mRNA

Virology (23 decks)

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