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Biology > 2.2 > Flashcards

2.2 Flashcards

prokaryotic cells

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1
Q

what does a bacterial cell wall being hypertonic mean

A

water moves into the cell via osmosis as it has higher water potential than outside the cell

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2
Q

why do bacteria cells need a cell wall

A

prevents swelling & bursting
maintains shape
gives support
protection

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3
Q

what are bacteria walls mostly made of

A

peptidoglycan

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4
Q

what does a capsule do

A

protects bacterium from phagocytes
covers cell markers (makes bacteria harder to identify)
may help them survive dry conditions

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5
Q

what are pili and why do bacteria need them

A

thread - like projections needed to attach to host cell for sexual reproduction

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6
Q

why do pili make bacteria more vunerable to virus infections

A

can be used as an entry point

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7
Q

what is the structure of a flagellum and how does it move a cell

A

many stranded helix of protein flagellin
moves via rapid rotations

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8
Q

what are the known as mesosomes potentially used for

A

artefact from preparing cell for electron micrograph
associated with enzyme activity during separation of DNA & cross walls forming

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9
Q

what may other infoldings in a bacteria cell be used for

A

photosynthesis

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10
Q

explain plasmids in bacteria

A

small circles of DNA
reproduce without nucleoid
transferred from one bacterium to another (sexual reproduction)

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11
Q

what is a nucleoid in bacterium

A

single length of DNA not contained in a membrane
DNA is tangled

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12
Q

what ribosomes do bacteria have

A

70s (50s + 30s)
smaller

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13
Q

what is gran staining used for

A

distinguishing gram positive & gram negative bacteria

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13
Q

explain how gram staining effects gram positive bacterium

A

iodine gets trapped in thick peptidoglycan layer
doesn’t decolour when dehydrated with alcohol doesn’t pick up red safranin counter stain
left purple/blue colour

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14
Q

what are some differences between gram + & gram - bacterial cell walls

A

gram (+)
thicker peptidoglycan layer
teichonic acid
plasma membrane
gram (-)
thich middle peptidoglycan layer
outer & inner membrane lipopolysaccharides

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15
Q

explain how gram staining effects gram negative bacteria

A

dehydrated in ethanol dissolves lipopolysaccharide so peptidoglycan exposed iodine washed out therefore take up red safranin counter stain

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16
Q

overall how do antibiotics work

A

target bacterial cell walls & 70s ribosomes

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17
Q

how do beta - lactam antibiotics work

A

inhibit formation of peptidoglycan layer
<effect of gram (+)
>effect on gram (-)

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18
Q

how do glycopeptide antibiotics effect bacteria

A

large polar molecules
<effect on gram (+)
cannot penetrate outer membrane layer of gram (-) bacteria

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19
Q

how do polypeptide antibiotics effect bacteria

A

interact with phospholipids of the outer membrane
<effect on gram (-)
X effect on gram (+)

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20
Q

how do other antibiotics effect both bacteria equally

A

target processes such as protein synthesis carried out by 70s ribosomes

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21
Q

how can you classify bacteria

A
  • shape
    -respiratory requirements
  • gram +/-
22
Q

state the 4 shapes of bacteria

A

spherical (cocci)
rod-shaped (bacillic)
twisted (spirilla)
comma-shaped (vibrious)

23
Q

explain the 3 respiratory requirements of bacteria

A

obligate aerobes - need oxygen
facultative -anaerobes fine with/without oxygen
obligate anaerobes - cannot have oxygen

24
Q

roughly how big are viruses

A

0.02micrometers - 0.3 micrometers

25
Q

what parts do all viruses have

A

genetic material
capsid
receptors

26
Q

what is a capsid made of

A

repeating protein units known as capsomeres

27
Q

what is the role of VAPs (virus attachment particles)

A

attach viruses to their host cell

28
Q

give examples of DNA viruses

A

small pox
lambda phage

29
Q

what are bacteriophages

A

viruses which infect bacteria

30
Q

are DNA viruses or RNA viruses more likely to mutate

A

RNA
more steps in replication

31
Q

what type of virus is the immunodeficiency virus

A

RNA retrovirus

32
Q

name a positive ssRNA virus

A

tobacco mosaic virus

33
Q

name a negative ssRNA virus

A

ebola

34
Q

what viruses always have a protein capsid and lipid envelop

A

retroviruses

35
Q

why are viruses not classed as living

A

they cannot reproduce on their own

36
Q

what happens when a virus is taken in via endocytosis

A

host cell then digests capsid releasing genetic material

37
Q

what is the most common way that viruses infect cells

A

viral envelop fuses with host cell surface releasing viral genetic material into cell

38
Q

how do viruses often get into plant cells

A

vectors
insects pierce cell wall

39
Q

what does non-virulent & virulent mean

A

non virulent- not disease causing
virulent - disease causing

40
Q

what occurs in the lytic pathway

A

viral genetic material is replicated independently of the host DNA

40
Q

what is a provirus and when is it formed

A

the DNA thats inserted into the host cell during the lysogenic cycle

41
Q

When can viruses in the lysogenic state be activated

A
  • host is damaged
  • repressor/ protein decreases
42
Q

how do positive ssRNA viruses replicate

A

genetic material enters cell
single sense stand used directly as mRNA
translated by ribosomes into viral proteins

43
Q

how do negative ssRNA viruses reproduce

A

genetic material enters cell
circus imports RNA replicase
antisense strand transcribed to sense stand by RNA replicate
free bases act as mRNA
transcribed by ribosomes into viral proteins

44
Q

what enzymes are needed in reproduction of retro viruses

A

reverse transcriptase
integrase

45
Q

how do viral particles leave the host cell in the reproduction of retroviruses

A

exocytosis

46
Q

how do viruses cause symptoms of disease

A

lysis of host cell release their own lysosomes
digest themselves produce toxins

47
Q

why are virus infections often specific to particular tissues

A

due to the presence of absence of cell markers on host cells viruses can only bind to particular markers

48
Q

who does foot & mouth disease effect

A

coven-hoofed animals

49
Q

how is foot & mouth disease spread

A

body secretions (milk)
food & water
contact with diseased animals

50
Q

how is ebola spread

A

bodily fluids and blood
direct contact

51
Q

how do antiviral treatments work

A

target receptors
target enzyme for translation or replication of DNA/RNA
inhibit protease enzyme

52
Q

what do antiviral treatments do

A

reduce the time a persons sick
delay development of symptoms

Biology (33 decks)

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