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Lifesciences 11 > Ch 17 Viruses and Bacteria > Flashcards

Ch 17 Viruses and Bacteria Flashcards

1
Q

describe viruses

A
  • very, very small
  • smaller than cells
  • particles that cause diseases and sickness
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2
Q

who discovered and who named viruses

A
  • discovered by Dimitri Iwanoski
  • Named by Martinus Beijerinck
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3
Q

what are viruses

A

a noncellular particle made of genetic info and proteins that infects cells

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4
Q

who is responsible for helping to understand the nature of viruses

A

Wendell Stanley isolated a virus particle which lead to their nature being understood using an E- microscope

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5
Q

what is the structure of a virus

A
  • core of nucleic acid, surrounded by a protein coat (capsid)
  • Either RNA or DNA not both
  • few genes
  • bacteriophages are viruses that invade bacteria and have a tail and fibres
  • Some are rods, cubes, tad pole shaped, or a variety of others
  • 10-400 nanometers in size
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6
Q

why are viruses very specific

A

most viruses only infect certain organisms, certain target species specifically

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7
Q

what are the two types of virus lifestyle

A

Lytic and Lysogenic

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8
Q

describe lytic infection

A
  • lytic viruses cause the host cell to lyse (burst) and release the new viruses

Infection: A virus touches a host cell by chance, and uses fibres to hold on while it injects DNA or DNA copy of RNA

Growth: after DNA was inject it can’t be distinguished from the host’s DNA so it is copied and mRNA is formed which shuts down the other cell operations

Replication: The materials of the cell are used to make more viruses which lyse out of the cell

  • this process is called lytic infection
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9
Q

describe lysogenic infection

A
  • Once the virus has infected it lies in wait, inserting it’s self into the DNA of the host
  • Once there it is know as a prophage and may lie in wait for many generations

Prophage Activity

  • can actually be helpful, blocking other viruses and making useful molecules. But after a certain time it will turn to a lytic infection due to various factors
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10
Q

what are retroviruses

A
  • have RNA not DNA
  • must make a DNA version of their RNA for insertion
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11
Q

what do scientists think of the origin of viruses

A
  • developed after living cells as they need them to reproduce
  • might have evolved from early bacteria
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12
Q

how are prokaryotes catogorized

A
  • Eubacteria or Archaebacteria
  • the two groups of bacteria
  • range from 1-10 micrometers
  • don’t have a nuclear envelope or organelle membranes
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13
Q

describe eubacteria

A
  • larger group
  • have a cell wall made of complex carbohydrates
  • have flagella that they use for movement
  • very diverse, many phylums
  • some are simple, some are complex
  • Cyanobacteria can photosynthesize but don’t have chloroplasts, found worldwide
  • Prochlorobacteria can also photosynthesize, but are rare, green
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14
Q

describe archaebacteria

A
  • lack a carbohydrate in the cell wall
  • different lipids, ribosomes, and genes
  • many extremophiles
  • methanogens live in oxygen free environments and produce methane
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15
Q

describe the variation in bacterial form

A

cell shape: can be rods (bacilli), spheres (cocci), or spirals (Spirilla)

Can be found in pairs, chains, clusters, etc

Cell wall: can have 1 or 2 walls
bacterial movement: can have 1+ flagella, some lash, spiral, snake, some are inmobile

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16
Q

how can you identify how many cell walls a bacteria has

A

a method called gram (named after Christian Gram), staining can show how many legs of a cell wall an organism as

gram + = purple = 1 wall

gram - = red = 2 walls

17
Q

what are the different ways bacteria obtain energy

A

Autotrophs:

  • phototrophic autotrophs use the energy of the sun
  • Chemotrophic autotrophs obtain energy from inorganic molecules like hydrogen sulfide

Heterotrophs:

  • Take in organic molecules to breakdown, called chemotropic heterotrophs, they eat food
  • phototrophic heterotrophs need energy from food but also use the sun
18
Q

how do bacteria make the energy they need

A

the energy bacteria need is supplied by respiration and fermentation

19
Q

what are the three types of relationship bacteria can have to oxygen

A
  • Obligate Aerobes need oxygen
  • Obligate Anaerobes are poisoned by oxygen
  • Facultative Anaerobes don’t need oxygen but oxygen is not dangerous for them
20
Q

how do bacteria reproduce

A
  • bacteria can reproduce very quickly, some every 20 minutes

Binary Fission: Doubles in size, duplicated DNA, splits into two, asexual

Conjugation: a protein bridge is formed between two bacteria, one bacteria then gives the other some genes (sexual)

Spore formation: in unfavourable conditions bacteria can form spores, a self contain unit where the bacteria parts lay dormant until conditions are favourable (not technically reproduction)

21
Q

why are bacteria important for us

A
  • produce food
  • digest petrol
  • clean up waste and poison
  • mine materials
  • made drugs and chemicals
  • can be symbiotic with other organisms (gut bio)
22
Q

what roll do bacteria play in the environment

A
  • nutrient flow: decompose dead organisms into good compounds
  • sewage decomposition: break down sewage into simpler, useful compounds
  • nitrogen fixation: bacteria take N2 and turn it into something plants can use
23
Q

what can viruses do to people

A

viruses can attack human cells causing damage like small pox, polio etc

24
Q

how can we deal with viruses

A
  • preventing infection is important (vaccines Is good)
  • the symptoms can be treated
25
Q

what are interferons

A

Interferons:

proteins released by viruses that cause difficulty for other viruses to infect and reproduce

not fully understood

26
Q

how do viruses relate to cancer

A

Oncogenic viruses can cause cancer

27
Q

how do bacteria relate to disease

A
  • most bacteria don’t cause diseases
  • Louis Pastors showed that some can
  • they can damage cells or release toxins
28
Q

what are rickeltsins

A

Rickeltsins are bacteria that reside in other cells to grow

29
Q

what can be used to fight bacteria

A

Vaccines or antibodies can be used

30
Q

how can we control bacteria

A
  • sterilization: killing off bacteria on a surface using heat, uv, disinfectants, etc
  • Food processing:
    • refrigerate
    • boil, fry, steam
    • good canning prevents exposure
    • chemical treatment like salting or pickling helps

Lifesciences 11 (14 decks)

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