Module 7 Flashcards

(33 cards)

1
Q

Bacteria and viruses are model genetic organisms, why?

A

small
simple
genes can be manipulated

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2
Q

Viruses are aggregates of nucleic acids and proteins yet they are not considered living, why?

A

Viruses are not considered living because they cannot carry out essential life processes, such as metabolism and reproduction, without hijacking a host cell’s machinery.

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3
Q

protein shell of viral genome

A

Capsid

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4
Q

building block of capsids

A

Capsomere

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5
Q

Membrane covering capsids derived from host cells (phospholipid bilayer)

A

Viral Envelope

Like camouflage using your target’s skin

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6
Q

Virus that infects bacteria

A

Bacteriophage (phage)

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7
Q

Parts of Bacteriophage

A

Head
Tail Sheath
Tail Fiber

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8
Q

Process of Virus Replication

A
  1. Virus DNA injected into cell
  2. Viral DNA undergoes translation and transcription making Viral DNA and mRNA; mRNA translated into capsid proteins.
  3. Viral DNA plus capsid proteins reassemble into new virus particles that will eventually exit the cell.
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9
Q

Mechanisms of viral infection and differentiate

A
  1. Lytic cycle - ends in host cell lysis
  2. Lysogenic - no lysis of host cell
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10
Q

Steps of lytic cycle (TLDR at bottom of answer):

A
  1. T4 phage uses its tail fibers to stick to specific receptor sites on
    the outer surface of an E.coli cell
  2. Sheath of the tail contracts, thrusting a hollow core through the
    wall and membrane of the cell. The phage injects its DNA into the
    cell
  3. Empty capsid of the phage is left as a ghost outside the cell. The
    cell’s DNA is hydrolyzed
  4. The cell’s metabolic machinery, directed by phage DNA, produces
    phage proteins, and nucleotides from the cell’s degraded DNA are
    used to make copies of the phage genome. The phage parts come
    together. THree separate sets of proteins assemble to form phage
    heads, tails, and tail fibers
  5. Phage then directs production of lysozyme, an enzyme that
    digests the bacterial cell wall. With a damaged wall, osmosis
    causes the cell to swell and lyse, releasing 100 to 200 phage
    particles

TLDR: Phage injects DNA into cell, phage controls all production methods, makes copies of phage genome, phage directs production of lysozyme causing burst of virus copies

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11
Q

Lysogenic cycle steps:

A
  1. Phage attaches to host cell and injects DNA
  2. Phage DNA circulates
  3. Phage DNA integrates into bacterial chromosome, becoming a prophage
  4. Bacterium produces normally, copying the prophage and
    transmitting it to daughter cells
  5. Many cell divisions produce a colony of bacteria infected with
    prophage
  6. Occasionally, a prophage exits the bacterial chromosome,
    initiating a lytic cycle

TLDR: Phage injects dna into host, dna circulates and integrates into host chromosome becoming PROPHAGE, copies itself repeatedly, many cell divisions later produce infected colony, sometimes prophage exits, sometimes cell lyses.

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12
Q

Phages that use both cycles are called _______

A

Temperate phages

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13
Q

Viruses that contain reverse transcriptase enzyme

A

Retroviruses

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14
Q

Probable origins of viruses

A

Probably evolved after first cells; originated from fragments of cellular nucleic acids that could move from one cell to another

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15
Q

Small, circular DNA in bacteria and yeast

Replicate independently

A

Plasmid

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16
Q

DNA segments that move from one location to another
within a cell’s genome

17
Q

Naked circular RNAs that infect plants

Do not code for proteins

Disrupt plant growth and other metabolic processes

18
Q

Replicating infectious PROTEINS

May cause neurological disorders

19
Q

How prions infect

A

Zombie-like, prion attaches to a normal protein converting it into a new prion

20
Q

Incurable degenerative neurological disorder
leading to spongiform encephalopathy and caused
by a prion found in humans

Transmitted among members of the Fore Tribe of Papua New Guinea via cannibalism

21
Q

Characteristics of Bacteria

A

Short generation time
Adaptable

22
Q

Characteristic of Bacterial Genome

A

One double-stranded circular DNA molecule

23
Q

Dense region of the DNA bounded by a membrane

24
Q

Bacteria divide by _______; preceeded by replication of the bacterial chromosome from a _______ origin of replication

A

binary fission; single

25
Combining of DNA from two individuals into a single genome in bacteria equivalent to sexual reproduction
Genetic Recombination
26
Types of Genetic Recombination (3)
1. Transformation 2. Transduction 3. Conjugation
27
Summarize Griffith's experiment (Transformation)
Living infectious S cells: Kill mice Living mutant R cells (S Cells w/o envelope): Killed by immune system, no effect on mice Heat killed S cells: No effect on mice Killed S plus living R: S cells found in dead mice.
28
Transfer of Naked DNA from one bacterial cell to another
Transformation
29
Transfer of DNA through a bacteriophage
Transduction
30
DNA transfer between 2 temporarily joined bacterial cells Facilitated by a sexual PILUS The ability to form a sex pilus and donate DNA (‘maleness’), results from an F factor as a section of the bacterial chromosome or as a plasmid
Conjugation
31
This is used for chromosome mapping in bacteria through interrupted mating technique F factor incorporated into the bacterial chromosome
Hfr Bacteria High frequency recombination bacteria
32
Bacterium with an F factor that carries adjacent bacterial genes is in a ____ state
F' state
33
If an F-bacterium incorporates an F’ factor, then that bacterium becomes a partial diploid, or _________
merozygote