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Psych/Soc > Biology Class 4 > Flashcards

Biology Class 4 Flashcards

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1
Q

Virus

A

Obligate intracellular parasite

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2
Q

Components of a virus

A

Head, Tail fibers, genome (nucleic acid)

Capsid (protein shell containing genetic information)

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3
Q

Basic steps of Virus

A
  1. Attachment (adsorption)
    - specific
    - host not yet infected
  2. Injection (Penetration)
    - host is infected

Following this, one of 3 life cycles take place

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4
Q

3 different life cycles

A

Lytic, lysogenic & productive life cycle

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5
Q

Lytic Cycle

A
  1. Transcribe & translate the viral genome
    Early genes: hydrolase, capsid proteins
  2. Replicate the viral genome
  3. Lysis of host & release of new viral particles
    Late genes: lysozyme
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6
Q

Lysogenic Cycle

A
  1. Integrate viral genome with hos genome
  2. Normal host activity, including reproduction
  3. Excision & lytic cycle
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7
Q

Advantages to productive cycle

A
  1. Protection from immune system
  2. Easy infection (envelope can fuse with another membrane)
  3. Get more virus (long life)
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8
Q

Why does virus want to kill the hose genome in lytic cycle?

A
  1. All cellular energy used to work with the viral genome

2. Create a pool of free dNTPs to use in viral genome replication

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9
Q

Why does virus want to kill the hose genome in lytic cycle?

A
  1. All cellular energy used to work with the viral genome

2. Create a pool of free dNTPs to use in viral genome replication

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10
Q

While transcribing & translating host genome, how does the virus make sure its genome is not expressed in the lysogenic cycle?

A

Viral genome codes for repressors to make sure it’s not expressed

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11
Q

Lysogen

A

When virus incorporated in the host genome, host is referred to as lysogen

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12
Q

Provirus/Prophage

A

Host genome and viral genome are incorporated together

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13
Q

Animal virus

A

Virus with an envelope (productive cycle)

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14
Q

Subviral particles: Prions

A 
Proteins (both good ones and mutant ones)
Characteristics:
- no DNA or RNA
- non membranes
- no organelles
- very small
- extremely stable
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15
Q

How do mutant (bad) prions come?

A
  1. Spontaneous mutation
    - mutation in gene coding for mutant prion and then prions accumulate & lead to cell death
  2. Be genetically transmitted
    - can have bad prion & pass off to offspring
  3. Ingested through diseased tissue
    - Healthy cell transcribing & translating normal “good” prion
    - Consumption of mutant “bad” prion from diseased tissue
    - Mutant “bad” prion changed normal “good” prions to bad ones
    - Cell death
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16
Q

Subviral particles: Viroids

A 
- virus-like
Characteristics:
- circular RNA
- no capsid
- must be coinfected
- don't code for proteins
- act as miRNAs or siRNAs to block translation
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17
Q

Mechanism of viroid

A

Mechanism 1

  1. +RNA circular form as template to make -RNA
  2. -RNA linear form
  3. Ligase to make a circular -RNA
  4. Use -RNA as template to make +RNA
    • RNA makes more circular +RNA viroids

Mechanism 2

  1. +RNA circular form as template to make -RNA
  2. -RNA is template to make +RNA linear form
  3. Multiple +RNA linear form
  4. Circularized to form more viroids

Both mechanisms equally preferred

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18
Q

How viral genome (+RNA or -RNA) is made

A

Mechanism 1

  1. +RNA (same as mRNA) can either be translated using host ribosomes to form viral proteins OR complementary form using RNA dependent RNA polymerase to make -RNA
  2. Use RNA dependent RNA polymerase to make more +RNA
    * In this situation, the virus will code for the enzyme on its +RNA genome

Mechanism 2

  1. -RNA available and you use RNA dependent RNA polymerase to make +RNA
  2. +RNA is now available to translate using host ribosomes to make viral proteins OR to make complementary -RNA using RNA dependent RNA polymerase
    * In this situation, the virus will have to carry then code for the enzyme

Mechanism 3 (+RNA lysogenic)

  1. +RNA that will create ssDNA using RNA dependent DNA polymerase
  2. ssDNA will replicate using host DNA polymerase to make dsDNA
  3. dsDNA can be inserted into host cell genome which can then be transcribed and translated using host enzymes to make viral proteins OR transcribed using only hosr RNA polyermases to make +RNA
19
Q

Problems with +RNA lysogenic

A
  1. Very rapid mutation
  2. Will permanently be in host genome

Ex. HIV

20
Q

Bacteria: Structure

Shape

A
  1. Round - coccus
  2. Elongated - bacillus
  3. Spiral - spirochetes
21
Q

Bacterial: Structure

Flagella

A

____“trichous”

  • mono (1 flagella)
  • amphi (2 flagella)
  • peri (multiple flagella)

Have basal unit connected to cell membrane
- hook is connected to basal unit
- flagella is connected to hook
As hook rotates, the cell moves

22
Q

Chemotaxis

A

Moving towards favourable chemicals & away from unfavourable chemicals

23
Q

Bacteria: Structure

Cell wall/ cell membrane

A

Gram positive - stains purple
- has cell membrane surrounded by thick cell wall
Gram negative - stains pink
- has thin inner cell membrane, then cell wall, then outer cell membrane

24
Q

Is gram + or gram - harder to kill with antibiotics?

A

Gram - because it has antibody degrading enzymes in periplasmic space (inbetween OM and IM)

25
Q

Mesophiles

A

Bacteria that live in medium temperature

26
Q

Psychrophiles

A

Bacteria that live in cold temperature

27
Q

Thermophiles

A

Bacteria that live in hot temperatures

28
Q

Faculative Anaerobe

A

Oxygen Present - use it to survive

Oxygen Absent - ferment & survive

29
Q

Obligate Aerobe

A

Oxygen Present - use it to survive

Oxygen Absent - Die

30
Q

Obligate Anaerobe

A

Oxygen Present - Die

Oxygen Absent - ferment & survive

31
Q

Tolerant Anaerobe

A

Oxygen Present: doesn’t use it, but tolerates it to survive

Oxygen Absent: Ferment & survive

32
Q

Energy Sources

Photo vs Chemo

A

Photo - energy from Sun

Chemo - energy from ATP

33
Q

Where Carbon chains come from

Auto vs Hetero

A

Auto - CO2 (will build own sugar but needs carbon source)

Hetero - eats other critics

34
Q

Example of photoautotroph

A

Plants

35
Q

Example of chemoautotroph

A

Deep sea vent bacteria

36
Q

Example of photoheterotroph

A

Carnivorous plants

37
Q

Example of chemoheterotroph

A

Humans

38
Q

Carrying capacity

A

Maximum amount of bacteria an environment can sustain

39
Q

Phases of Reproduction

A
  1. Lag Phase - little population growth, nothing happening except bacteria getting ready to split
  2. Exponential/log phase - bacteria are happily dividing and growing
  3. Stationary phase - reach carrying capacity, bacteria is unable to divide because nutrients are depleted and will be over crowded
  4. Death - Cells die
40
Q

Binary Fission vs Conjugation

A

Will grow in population size, but no genetic diversity (phases of reproduction)

Produce sexually
- will have genetic diversity but no growth in population size

41
Q

Conjugation Process

A

F+ bacterium (male) that has genome & F plasm

  • F plasmid is for fertility
  • F plasmid has everything needed to create conjugation bridge /sex pilus to copy F plasmid into F- (female)
  • F- now becomes F+
42
Q

Transduction

A

Transfer genomic DNA from one cell to another by viral infection

43
Q

HFr Cell

A
  • When F plasmid is incorporated into host genome
  • now called High Frequency of recombinant cell
  • will be copied over throughout genome and cross over resulting in recombination (increase in genetic diversity)

Psych/Soc (24 decks)

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