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Microbiology > Lectures 7-9 > Flashcards

Lectures 7-9 Flashcards

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Biology 101 flashcards
1
Q

bacterial growth

A

binary fission

cell elongation
septum formation
completion of septum
formation of walls
cell separation

facilitated by proteins MinC, D and E

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2
Q

MreB

A

protein essential for bacterial cell morphology

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3
Q

stages of bacterial growth

A

lag
log/exponential
stationary
death

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4
Q

effect of temperature on bacterial growth

A

low temp. - membrane gelling, transport processes too slow for growth
optimum - enzymatic reactions occur at max. rate
high temp. - protein denaturation, collapse of cytoplasmic membrane, thermal lysis

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5
Q

psychrophile

A

bacteria with optimum temp between 0 and 10 degrees

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6
Q

chemotroph

A

energy sourced from oxidation of organic and inorganic compounds

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7
Q

lithotrophs and organotroph

A

use reduced inorganic compounds (litho) and organic compounds (organo) to source electrons

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8
Q

organisms that source carbon from organic molecules from other orgnanisms

A

heterotrophs

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9
Q

chemoorganoautotroph

A

chemo - energy from organic/inorganic compounds
organo - electrons sourced from organic compounds
auto - sources its own carbon

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10
Q

reduction of pyruvate

A

by NADH (electron donor)

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11
Q

homofermentative

A

if lactate is produced following glycolysis

if other mixed products are produced, the process is heterofermentative

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12
Q

the nitrogen cycle

A
  1. obtain nitrogen
    - uptake of NH4 or NO2
    - release of NH4 by decomposition
  2. microbial oxidation of NH4
  3. dentrification (NO3-NO-N2O) in anaerobic conditions (NO3 is terminal electron acceptor)
  4. nitrogen fixation
  5. nitrogen leaching from soil
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13
Q

2 examples of nitrifying bacteria

A

nitrosomonas

nitrobacter

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14
Q

DNA structure

A

H bonds between base pairs
double helix
anti-parallel strands - 3’ and 5’

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15
Q

bacterial genomes

A 
small compared to eukaryotes
genes densely packed
no introns
operons grouped together (genes with related functions)
coupled transcription and translation

plasmids may be present (replicate independently)
1 or 2 chromosomes

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16
Q

episome

A

when plasmid becomes integrated into bacterial chromosomal DNA

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17
Q

bacterial DNA replication

A

2 types:

bi-directional replication
- occurs during cell division

rolling circle replication
- occurs during conjugation

both occur during replication of some plasmids

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18
Q

enzymes at the replication fork

A

helicase
DNA polymerase III
primase

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19
Q

3 mechanisms of horizontal gene transfer

A

transformation - uptake of short DNA fragments

transduction - transfer of DNA via bacteriophages

conjugation - requires cell to cell contact

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20
Q

natural transformation - gene transfer

A

3 stages:

  1. competence - extracellular binding
  2. uptake - conversion to single stranded DNA, stabilisation
  3. integration - homologous recombination
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21
Q

transduction

A

generalised - donor DNA from any part of donor can be transferred - lytic cycle

specialised - specific DNA region of donor transferred - lysogenic cycle

22
Q

presence of F plasmid (an episome containing its own origin of replication)

A

ability to synthesis F pilus
mobilisation of DNA for transfer to another cell
alteration of cell surface receptors

cells with an integrated F plasmid are called Hfr

23
Q

pathogenicity

A

the way in which a microorganism causes disease

24
Q

factors influencing severity of a disease

A 
host 
immunological status
physiological status
genetic make up
route of infection
25
Q

in order to cause disease a pathogen has to…

A

colonise host tissues
grow within host tissues
avoid host defence mechanisms
cause damage to the host

26
Q

toxins as effectors

A

neurotoxins - cause paralysis

enterotoxins - cause sickness and diarrhoea

cytotoxins - cause cell death

27
Q

AB toxinsmechanism

A

B portion binds to cell and facilitates translocation of A which posesses catalytic properties

28
Q

cytolytic toxins

A

damage cytoplasmic membrane

29
Q

pathogen

A

microorganism that causes disease

30
Q

LPS

A

endotoxin

causes production of cytokines from immune cells upon binding to cell surface receptors

31
Q

innate immunity

A

non-specific, general
immediate response
no immunological memory

32
Q

innate immune cells

A

humoral:

  • complement
  • enzymes
  • cytokines

cellular:

  • phagocytes
  • natural killer cells
33
Q

features of adaptive immunity

A

specific to antigen
lag time between exposure and response
immunological memory after exposure

34
Q

adaptive immune cells

A

humoral:

  • cytokines
  • antibodies

cellular:

  • T cells
  • B cells
35
Q

2 precursor molecules after bone marrow for immune cells

A

lymphoid precursor

  • thymus maturation to t cell
  • bone marrow maturation to B cell

myeloid precursor

  • monocytes - go to dendritic cells and macrophages
  • granulocytes - go to mast cells and neutrophils
36
Q

antibody structure

A

4 polypeptide chains

  • 2 heavy
  • 2 light

antigen binding sites at the ends of both variable light chains

37
Q

IgM structure

A

circulating as a pentamer (5 attached antibodies) or on surface of a B cell

38
Q

which antibody is involved in primary response

A

IgM

39
Q

which antibody is involved in secondary response

A

IgG

40
Q

IgA

A

found in mucous, saliva, breast milk

different shape to others

41
Q

IgD

A

part of B cell receptor

activates basophils and mast cells

42
Q

IgE

A

protects against parasitic worms

responsible for allergic reactions

43
Q

IgG

A

secreted by plasma cells into the blood

crosses placenta into foetus

44
Q

IgM

A

attached to surface of B cell OR secreted into blood

responsible for first stages of immunity

45
Q

process of adaptive immunity - extracellular

A

antibodies recognise foreign pathogens and opsonise them

the phagocytes bind to the pathogens via their Fc receptors and eventually destroy them

46
Q

process of adaptive immunity - intracellular

A

cytotoxic T cell binds to infected cell
perforins from T cell make holes in membrane of infected cell
infected cell lyses

47
Q

describe the antibody production graph with respect to primary and secondary immune responses

A

initial antigen exposure: slow antibody production, steady increase until a low peak then steady decline but doesnt quite reach 0

second antigen exposure: rapid antibody production, peaks very high

48
Q

types of vaccination

A 
toxoid
attenuated (live)
conjugate vaccines
DNA vaccines
recombinant vector vaccines
subunit
49
Q

subunit vaccine

A

pathogen grown then chemicals used to split it apart
only inject useful part e.g. epitope (binding site of antigen)
chances of adverse reactions are lower
used against Hep B

50
Q

live attenuated vaccine

A

weakened version of live microbe
elicit strong cellular/antibody responses and often cause lifelong immunity

cannot be given to a weakened immune system
microbes may mutate and become virulent
easy to create
need to stay refrigerated

51
Q

how can we knock out genes

A

homologous recombination

Microbiology (6 decks)

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