Brainscape's Knowledge GenomeTM

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


See full index

MICR2208 > Lec 14: Bacterial nutrition, culture media & cultivation > Flashcards

Lec 14: Bacterial nutrition, culture media & cultivation Flashcards

1
Q

Nutrition in bacteria influenced by..

A

Sources of carbon, e- & external energy for growth

Diversity of chemicals needed to make bacterial cell components

The need for growth factors

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

Carbon

A

The backbone of organic molecules

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

Electrons

A

Electron flow in bio reactions -> energy

Needed to reduce molecules during biosynthesis

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

External energy source

A

Necessary to power cell

Make ATP

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

Autotroph

A

Carbon source: CO2

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

Heterotroph

A

Carbon source: organic molecules made by other molecules

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

Phototroph

A

Energy source: light

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

Chemotroph

A

Energy source: Exergonic (heat or energy is released) chemical reactions (oxidation of organic or inorganic compounds)

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

Lithotroph

A

Electron source: reduced inorganic molecules

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

Organotroph

A

Electron source: organic molecules

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

Carbon

A

Found in: most cell structure (e.g cell wall) & functional chemicals (e.g DNA)

External sources (come from): CO2 (inorganic), simple & complex sugars (organic)

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

Nitrogen

A

Found in: proteins, nucleic acids, some polysaccharides & lipids

External sources: NH4+, NO3, N2 (inorganic). Proteins, AA, urea (organic)

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

Hydrogen

A

Found in: organic compounds

Come from (external sources): organic compounds, H2O

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

Oxygen

A

Found in: organic compounds and electron transport chain (respiration)

Come from (external source): H2O, CO2, O2

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

Sulphur

A

Found in: S-AA (methionine, cysteine) & vitamins (biotin, thiamine)

Come from: SO4 (inorganic). Cysteine, methionine (organic)

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

Phosphorus

A

Found in: nucleic acids, phospholipids, ATP

Come from PO4

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

K, Ca, Mg, Fe

A

Found in enzymes & ribosomes

External sources: as ions in solutions (e.g K+)

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

Micronutrients or trace elements

A

Mn, Zn, Co, Ni, Cu

Found in: cofactors (helper molecules; bind to & assist enzymes to function properly)

Come from: as ions in solution

19
Q

Problems for cell in uptake of nutrients by bacteria

A

Microbes can only take in dissolved molecules (must take in nutrients from dilute solutions against conc gradient)

Cytoplasmic membrane prevents passage of most substances

Enormous variety of nutrients

Nutrient uptake mechanisms should be specific

20
Q

Bacteria mechanisms for nutrients uptake across membrane

A

Passive diffusion

Facilitated diffusion (ATP not required)

Active transport (ATP required)

Group translocation (ATP required). Transport of solute molecules to higher conc in which molecule is chemically modified during transport

21
Q

Facilitated diffusion

A

Diffusion across membrane involving carrier protein

Carrier protein in outward facing conformation binds to solute -> changes conformation to inward facing conformation -> releases solute into cell

22
Q

Active transport

A

Transport of solute molecules to higher conc (against conc) using transport proteins

ATP energy required

After binding solute -> solute binding protein approaches ATP binding cassette (ABC) transporter -> protein attaches to transporter and releases solute -> energy released by hydrolysis of ATP -> movement of solute across membrane

23
Q

Effect of environmental factors on microbial growth when culturing: oxygen

A

Some bacteria & most multicellular organisms are aerobic, some are anaerobes

24
Q

Aerotolerant anaerobes

A

grow equally well in presence or absence of oxygen

25
Q

Obligate anaerobes

A

grown only when oxygen is absent

26
Q

Facultative anaerobes

A

do not require oxygen. Can grow with or without oxygen. Most grow better aerobically (energy production better in oxygen)

27
Q

Microaerophiles

A

damaged by atmospheric O2 and require O2 for growth

28
Q

Effect of environmental factors on microbial growth when culturing: Temperature

A

Microbes cant regulate their internal temp -> affected by external temps

Enzymes vary in temp sensitivity

High temp -> membrane degrades

Low temp -> membrane becomes solid

29
Q

Psychrophile

A

Cold environments

Grow well at 0 degrees, optimum ~15 degrees

30
Q

Psychrotolerant

A

Cold environments

Grow at 0 degrees

Optimum ~25 degrees

31
Q

Mesophiles

A

Moderate temps

Optima ~20-45 degrees

32
Q

Thermophile

A

High temps

Optima ~55-65 degrees

33
Q

Hyperthermophile

A

Very high temps

Optima ~85-113 degrees

34
Q

Design of culture determined by..

A

Sources of carbon, electrons & external energy used for growth

Diversity of chemicals needed to make bacterial cell components

The need for growth factors

35
Q

Agar

A

A carbohydrate, extracted from
red algae

Usually added to liquid broth medium

Dissolves at 90 degrees

Sets at ~45 degrees, stable from 0-80 degrees when set

Easily sterilised

Not degraded by bacteria

Spread plate, streak plate, or pour plate yields single isolated colonies

36
Q

Culture media classified based on..

A

Chemical composition: defined (synthetic), complex

Physical nature: liquid, semisolid, solid

Function: supportive, enriched, selective, differential

37
Q

Defined or synthetic media

A

A medium in which all components are known

38
Q

Complex media

A

Medium containing some ingredients of unknown chemical composition

Formulated to support growth of wide range of bacteria

Used where nutritional requirements of particular organism are known

Examples: nutrient broth/agar, tryptic soy broth/agar (TSB/TSA), MacConkey agar

Typically made from protein digests & meat extracts

39
Q

Selective media

A

Have ingredients/conditions which inhibit growth of unwanted microbes & favour growth of specific organisms

Bacteria may also be selected by incubation with nutrients they specifically use

40
Q

Differential media

A

Distinguish between different genera or species based on biological/metabolic properties

Often contain acid-base indicators & selective agents -> limit range of bacteria growing

Example: mannitol salt agar. Staphylococcus aureus ferments mannitol -> produce acids-> pH indicator goes from red to yellow. Non-pathogenic staphylcocci remain red

41
Q

Supportive media

A

Support growth of many microorganisms

E.g TSB or TSA

42
Q

Enriched media

A

Blood & other nutrients are added to general purpose media -> encourage growth of fastidious microbes

Blood agar: horse/sheep blood. Enriched and differential (alpha, beta, gamma haemolysis)

Chocolate agar (contain lysed blood cells)

43
Q

MacConkey agar

A

Example of complex media

Use bile salts & dye crystal violet -> inhibit Gram +ve and not Gram -ve

Example of differential media

Have lactose & neutral red dye: lactose-fermenting (e.coli) colonies: red; non-fernenters (salmonella) are colourless

MICR2208 (13 decks)

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