Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

1. INFECTIONS > david (L1-3) > Flashcards

david (L1-3) Flashcards

1
Q

virulence

A

the degree of pathogenicity of the microbe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

determinants of virulence

A

determinants of virulence of a pathogen are any of its genetic or biochemical or structural features that enable it to produce disease in a host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

pathogens’ entry into human host

A

through:
Respiratory- inhaling spores
Gastro-intestinal- eating or drinking things
Urinary- or Genital-tracts-
insect bites or by accidental or surgical trauma to the skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

primary pathogens

A

obligate pathogens - survive very poorly in the env, they require a human host to survive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

spores

A

gram +ve bacteria produce spores (resting stages) that can last for many years until the env is good enough

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

psychrophile

A

grow best at low temperatures (min below 0, max 20)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

psychrotroph

A

able to grow at low temperatures but prefer moderate temperatures (min 0, max above 25)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

mesophile

A

most bacteria especially those living in association with warm blooded animals (min 10-15, max below 45)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

thermophile

A

among all thermophiles is wide variation in optimum and max temperatures (min 45, max above 100)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

acclimation phase

A

a downshift in T causes a transient (temporary) inhibition of most protein synthesis – causes a growth lag known as the acclimation phase

during the acclimation phase, a group of cold shock proteins (Csp) are dramatically induced (which are essential for the cell to resume growth at low temperature)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

listeria

A

non-spore forming Gram positive bacilli
Listeria is capable of growth over a wide range of temperatures (4 to 40°C)
widespread in the environment and is commonly found in vegetation, water, soil, wild/domestic animals, fish, birds as well as people.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

difference between gram positive and negative

A

gram +ve = inner membrane only

gram -ve = inner and outer membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

internalin A and B in listeria

A

Involved in the listeria cells’ invasion into mammalian cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

LLO and PO-PLC in listeria

A

Required for escape from a single membrane vacuole
LLO (listeriolysin) – a pore-forming cytotoxin
PI-PLC (PlcA) – an enzyme that removes charged head groups from phospholipids (esp. phophatidylinositol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

ActA in listeria

A

Required for movement through the cytoplasm, cell-to cell spread
ActA – interacts with host cell proteins to stimulate actin polymerization
Actin tail forms at one end of the cell, propels the bacterium through the cytoplasm
Projections from the host cell surface caused by bacteria enter adjacent cells; bacteria inside double-membrane vacuole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

PC-PLCB in listeria

A

Required for escape from double membrane vacuole:

PC-PLC (PlcB) – a phospholipase that cleaves the head group from many different kinds of lipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

PrfA in listeria

A

Regulation of virulence factors

PrfA – is a positive regulator of virulence genes, may respond to temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

listeria invasion and spread using its different proteins

A

ActA stimulates host cell proteins ARP and Profilin (which normally participate in nucleation of actin filaments to form host cell cytoskeleton) to polymerise actin at the surface of the bacterium (not the usual location)

Listeria polymerises actin at one end of the cell only

Ingestion leads to invasion of intestinal mucosa and subsequently systemic spread from macrophages to the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

acidophiles

A

Microorganisms which grow at an optimum pH well below neutrality (7.0)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

neutrophiles

A

microorganisms which grow best at neutral pH (7.0)

21
Q

alkaliphiles

A

microorganisms that grow best under alkaline conditions

22
Q

Obligate acidophiles

A

actually require a low pH for growth since their membranes dissolve and the cells lyse at neutrality (thus a high [H+] is required for membrane stability).

23
Q

obligate alkaliphiles

A

can grow around pH 10.
In an alkaliphilic Bacillus species a Na+ gradient (instead of the pmf) supplies the energy for transport & motility but a pmf can be established & drives respiratory ATP synthesis (even though the external surface of the membrane is so alkaline)

24
Q

BabA

A

adhesin recognising Lewis b antigen which binds sulphated mucin sugars on epithelial cells

25
Q

NAP

A

neutrophil activation protein – activates neutrophils

Leads to inflammation

26
Q

VacA

A

Vacuolating cytotoxin

Produces large vacuoles in mammalian cells

27
Q

UreI

A

an inner membrane protein that facilitates urea entry in a pH-controlled way i.e. only when the incubation pH is acid
it consists of six transmembrane regions

28
Q

Fur

A

it is the regulator of iron acquisition genes
it appears to regulate a subset of acid shock proteins. So, Fur senses pH as well as iron
(mutations have been identified in Fur that produce acid blind/iron-sensing & acid-sensing/iron blind phenotypes suggesting that iron and acid are sensed separately by this protein)

29
Q

proton pumps

A

A MECHANISM OF ACID RESISTANCE IN GRAM POSITIVE BACTERIA

F1F0-ATPases from tolerant bacteria are less sensitive to low pH
Glutamate decarboxylases (GAD) is a gram +ve enzyme that decarboxylases the glutamate amino acid and H+ protons to change the pH and produce γ-aminobutyrate (GABA) is exported from the cell
30
Q

regulators

A

A MECHANISM OF ACID RESISTANCE IN GRAM POSITIVE BACTERIA

several 2CSs in Listeria including LisRK
two component systems
it’s a way that all bacteria sense their env using 2 components
one component sits in the membrane and senses the env
if the ph changes, it is activated
and so the second component will change gene expression

31
Q

altered metabolism

A

A MECHANISM OF ACID RESISTANCE IN GRAM POSITIVE BACTERIA

e.g. often of glytolytic enzymes, to facilitate rapid growth recovery when pH stress removed

32
Q

cell density

A

A MECHANISM OF ACID RESISTANCE IN GRAM POSITIVE BACTERIA

a quorum sensing system & biofilm growth allow for increased acid tolerance in S. mutans

a way that cells communicate by secreting molecules at a certain density

33
Q

quorum sensing also known as…

A

quorum sensing = cell density dependent regulation

34
Q

envelope alterations

A

A MECHANISM OF ACID RESISTANCE IN GRAM POSITIVE BACTERIA

e.g. S. mutans has increased levels of mono-unsaturated and longer chain fatty acids at pH 5 than 7

35
Q

alkalisation

A

A MECHANISM OF ACID RESISTANCE IN GRAM POSITIVE BACTERIA

alkalisation of the periplasm
hydrolysing urea into ammonium
ammonium NH4+ increases the periplasm pH

36
Q

Obligate aerobes

A

require O2 for growth; they use O2 as a final electron acceptor in aerobic respiration

37
Q

Obligate anaerobes

A

(occasionally called aerophobes) do not need or use O2 as a nutrient. In fact, O2 is a toxic substance, which either kills or inhibits their growth. Obligately anaerobic prokaryotes may live by fermentation, anaerobic respiration, bacterial photosynthesis, or the novel process of methanogenesis.

38
Q

Facultative anaerobes (or facultative aerobes)

A

organisms that can switch between aerobic and anaerobic types of metabolism. Under anaerobic conditions (no O2) they grow by fermentation or anaerobic respiration, but in the presence of O2 they switch to aerobic respiration.

39
Q

Aerotolerant anaerobes

A

bacteria with an exclusively anaerobic (fermentative) type of metabolism but they are insensitive to the presence of O2. They live by fermentation alone whether or not O2 is present in their environment.

40
Q

Microaerophile

A

grows if the level of oxygen is below 0.2atm.

no growth in an anaerobic environment

41
Q

superoxide dismutase

A

In aerobes and aerotolerant anaerobes the potential for lethal accumulation of superoxide is prevented by the enzyme superoxide dismutase
NEEDS A METAL COFACTOR (ZINC IRON COPPER)

42
Q

catalase

A

decomposes H2O2 in nearly all organisms

43
Q

peroxidase

A

decomposes H2O2 in aerotolerant bacteria
this is because they lack catalase, so they decompose H2O2 (peroxide ) by means of peroxidase enzymes which derive electrons from NADH2 to reduce H2O2 to H2O.

44
Q

carotenoid pigments

A

All photosynthetic (and some non-photosynthetic) organisms are protected from lethal oxidations of singlet oxygen by their possession of carotenoid pigments which physically react with the singlet oxygen radical and lower it to its non-toxic “ground” (triplet) state. Carotenoids are said to “quench” singlet oxygen radicals.

45
Q

lethal oxidations

A

Obligate anaerobes lack superoxide dismutase and catalase and/or peroxidase, and therefore undergo lethal oxidations by various oxygen radicals when they are exposed to O2.

46
Q

detoxification of oxygen radicals equations

A

4[O2 -] + 2[H+] –> O2 + H2O2
O2 –(peroxidase + H+ from NADH)–> 2 H2O
H2O2 –(catalase)–> 2H2O + O2

47
Q

botulism

A

results from ingesting neurotoxins (produced by bacteria)

types A, B, E and F (exotoxins) are the most toxic for humans and are only activated by proteolytic cleavage

48
Q

type A exotoxin

A

the most potent type of endotoxin know

1. INFECTIONS (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions