Microbio Lecture 3

Front 1

describe binary fission

Back 1

the cell elongates as new material is synthesized,
replicates its chromosome, and moves the newly formed
chromosomal DNA into each future daughter cell
 then, a cross wall (septum) is formed at midcell, dividing
the parent cell into two identical daughter cells, each
having its own chromosome and a complement of other
cellular constituents

Front 2

is microbial growth exponential or linear?

Back 2

exponential.

Front 3

what is a generation time?

Back 3

the time it takes for a population to double in number

Front 4

Nt = N0 x 2n

Back 4

know equation.

Front 5

what is a closed system or batch culture? what are the phases of microbial growth in these conditions?

Back 5

nutrients are not renewed and waste products are not removed.

lag phase

log(exponential) phase

stationary phase

death phase

Front 6

what are the major environmental factors?

Back 6

temperature

pH

water

o2

nutrients ( carbon, energy sources, GF)

Front 7

which type of microorganism has the lowest and highest optimal temperature?

Back 7

psychrophiles low

hyperthermophiles high

psychrotrophs

mesophiles

thermophiles

Front 8

what kind of microorganism has optimum growht between pH 0 and 5.5? between 5.5 and 8? and between 8 and 11.5?

Back 8

acidophiles 0-5.5

neutrophiles - 5.5-8

alkaliphiles - 8-11.5

Front 9

the internal pH is usually the same as the external pH for a microorganism. t/f

Back 9

f.

the internal pH of cells must stay relatively close to neutral enen though the external pH is highly acidic or basic

Front 10

water availability depends on ____ and ____

Back 10

how moist and dry an environment is

and the concentration of solutes dissolved in waster that is present

Front 11

describe hypertonic hypotonic and isotonic

Back 11

plasmolysis

lyse

no net movement.

Front 12

what survives at high concentration of NaCl?

what survives at high levels of dissolved solutes?

what are osmophiles/ xerophiles

Back 12

Extreme halophiles

halotolerants

can grow in environments high in sugar,

able to grow in dry conditions.

Front 13

what are compatible solutes?

Back 13

halophiles synthesize or uptake them.

increase the osmotic concentration of the cytoplasm above that of the habitat so that the plasma membrane is always pressed firmly against the cell wall

Front 14

examples of compatible solutes?

Back 14

KCl, sucrose, glycerol, glycine betaine

Front 15

what are obligate aerobes?

Back 15

depndent on the presence of atmospheric oxygen (20%) for growth

o2 is the final electron acceptor of the ETC

Front 16

what are microaerophiles?

Back 16

need oxygen, but at lower than atmospheric level (1-10%)

Front 17

what grows can grow in the absence of oxygen, but grow better in the presence of it.

Back 17

facultative anaerobes.

they use ooxygen during aerobic respiration, but they can
also exhibit anaerobic respiration, using alternative
terminal electron acceptor(s), such as nitrate, for their
electron transport chain(s), or they are fermentative

Front 18

aerotolerant anaerobes grow better inthe presence of O2. t/f

Back 18

f. grows equally well in its presence or absence

can tolerate o2, but do not use it in their energy - conserving processes.

Front 19

what are obligate anaerobes?

Back 19

no like o2

does not contain enztmes that neutralize toxic o2 derivatives(reactive oxygen specites)

Front 20

what do reactive oxygen species do? and what forms dot hey take?

Back 20

they can damage proteins, lipids and nucleic acids.

singlet oxygen

superoxide free radicals O2-

peroxide anion O22-

hydroxyl radical OH

Front 21

what are some enzymatic neutralizations of ROS?

Back 21

catalase

peroxidase

superoxide dismutase

superoxide dismutase/catalase in combination

superoxide reductase

Front 22

what are the major elements of nutritional chemicals?

Back 22

C, O, N, H, P, S

Front 23

what are phototrophs/ chemo/ auto/ hetero/litho/organo

Back 23

photo: use sunlight as their energy source

chemo: use organic molecules (glucose)

auto: use CO2 and some inorganic molecules as carbon source

heterotrophs: organic chemicals

litho: acquire electrons or H atoms for redox reactions from inorganic molecules

organo: acquire them from organic molecules

Front 24

growth factors are?

Back 24

organic chemicals that they cannot make themselves

amino acids, vitaminms, purines, and pyrimydines.

Front 25

when nutrients are low ...the environment is said to be _____

Back 25

oligotrophic

Front 26

______ are assemblages of microbial cells adhered to a surface and enclosed in an adhesive matrix excreted by the cells.

Back 26

Biofilms

Front 27

what are extracellular polymeric substances? (EPS)

Back 27

encloses biofilms.

they are typically a mesh-like accumulation of poly saccharides

Front 28

how is biofilm formation initiated?

Back 28

cell attachment to a surface followed by expression of biofilm-specific genes often as a result of quorum sensing

Front 29

what is quorum sensing?

Back 29

coordinated expression of certain genes

Front 30

steps in biofilm formation

Back 30

attachment

colonization

development

active dispersal

Front 31

functions of biofilms?

Back 31

self-defnese mechanism: biofilms resist physical forces that sweep away unattached cells, phaogcytosis by immune system cells, and penetration of toxins (eg antibiotics)

Allows cell to remain in a favorable niche

Allows cells to live in close association with one another ---- more cell cell communication.

Front 32

at what temperatures does agar solidify and liquefy?

Back 32

solid 40

liq 100c

Front 33

Defined (synthetic) media are prepared by:

Back 33

adding the precise amounts of pure inorganic and organic chemicals to pure water

exact composition is known

Front 34

complex media are made from:

Back 34

digests of microbial, plant, or animal products

exact composition is not known

supports a wide variety of microbes

Front 35

enriched media are:

Back 35

complex media containing specific growth factors.

Front 36

how does selective media work?

Back 36

it supresses the growth of unwanted microbes while they encourage that of desired ones due to environmental condition or the presence of inhibitory ingredients

Front 37

defferential media includes at least one indicator that:

Back 37

detects particular chemical reactions occurring during growth on a colony level

Front 38

MacConkey agar is a selective medium. t/f

Back 38

it is selective AND differential for differentiation of G- lactose-fermenting enteric bacteria

Front 39

crystal violet and bile salts are added to MacConkey agar to

Back 39

inhibit the growth of Gram positive, but not gram negative.

selective for G-

Front 40

________ is the only sugar source in MacConkey, and its fermentation is indicated by growth-dependent blue to red colorization on plate due to _______

Back 40

D-Lactose

acid production

Front 41

what is the difference between anaerobic media and aerobic?

Back 41

anaerobic media:

richer in organic constituents

contain reducing agents (thioglycolate) to remove O2

contain redox indicator that displats anoxic conditions

Front 42

pure culture are composed of cells arising from a _____ ______

Back 42

single progenitor

this progenitor is termed a colony-forming unit (CFU)

Front 43

what temperatures range is for deep-freezing? lyphilization?

Back 43

deep: -50 to -95C

lyophilization: dehydration of a frozen culture -54 to -72 using an intense vacuum

Front 44

explain Direct microscopic count

plate counts

membrane filtration

most probable number

turbidity

Back 44

asdfasdfasdf

Front 45

what is wet weight and dry weight

Back 45

cells in liquid culture are centrifuged and the liquid supernate is removed
 the weight of the resulting packed cell mass is proportional to the number of cells in the culture

The dry weight can be determined by heating the centrifuged cells in an oven before weighing them