Microbio Lab Quiz (4.1 and 4.2)

Generation time

the time it takes for the bacteria population to double

“one cell into two”

genetically determined

influenced by nutritional and environmental factors

Lag phase

bacterial cells are metabolically active

lag phase (image)

What is A?

Log phase

cells are producing at en exponential rate

• number of cells doubles every generation time

log phase (image)

What is B?

Stationary Phase

rate of cell reproduction is equal to the rate of cells dying

Stationary phase (image)

What is C?

Death Phase

cells dying off at exponential rate

Death Phase (image)

What is D?

Bacterial growth

increase in the number of cells

Qualitative

what organism is growing

Quantitative

how many bacterial cells are present

Spectrophotometer

used to determine the amount of bacterial cells present in a liquid sample

measure turbidity

absorption

how much light is absorbed by the specimen

greater absorption = higher cell count

lower absorption = lower cell count

transmittance

how much light passes through the sample

greater transmittance = lower cell count

lower absorption = higher cell count

aerobic cellular respiration

metabolism that utilizes oxygen to create energy in the form of ATP

anaerobic respiration/ fermentation

metabolism that does not utilize oxygen to create ATP

aerobe

organisms that require oxygen for cellular respiration

• contain enzymes that process toxic oxygen metabolites

obligate aerobes

an organism that cannot grow without oxygen and needs oxygen at atmospheric levels

microaerophiles

an organism that uses oxygen for cellular respiration, but at a concentration lower than in the atmosphere

• require oxygen in small amounts

anaerobe

organisms that do not use oxygen for cellular respiration

obligate anaerobes

do not use oxygen for cellular respiration and cannot grow in the presence of oxygen

aerotolerant anaerobes

do not use oxygen for respiration, but can grow if oxygen is present

facultative anaerobes

can grow with or without oxygen

• can switch between aerobic and anaerobic respiration to grow

obligate aerobe

obligate anaerobe

microaerophile

facultative anaerobe

Oxygen Requirements for anaerobes/ aerobes

Capnophiles

bacteria that require an increased carbon dioxide environment

species of bacterial capnophiles:

• haemophilus influenzae

different methods that allow for anaerobic or capnophile growth

• gasPak jars

• specialized media

diplococcus

two round shaped bacteria

streptococcus

chain of round shaped bacteria

tetrad

a group of four round shaped bacteria

staphylococcus

grape like clusters of round shaped bacteria

sarcina

cubical packets of eight round shaped bacteria

random

singles or no specific arrangement of round shaped bacteria

diplobacillus

pair of rod shaped bacteria

streptobacillus

chain of rod shaped bacteria

random

singles or no specific arrangement of rod shaped bacteria

coccobacillus

bacteria that are partially circular shaped and partially rod shaped

vibro

one-half spiral turn (C-shaped)

spirillum or spirochete

loosely or tightly wound spiral

no specific arrangement

test used to detect the presence of the enzyme Catalase

useful in distinguishing gram positive cocci

• differentiate between staphylococci (positive = bubble) and streptococci (negative = no bubbles)

hydrogen peroxide (H2O2) forms as a by-product of aerobic metabolism

H2O2 is toxic to cells

the enzyme catalase breaks down H2O2 in water and oxygen

2 H2O2 ——catalase——→ 2 H2O + O2

Catalase Test

calase positive

• staphylococcus

• micrococcus

test used to detect the presence of the enzyme Cytochrome C Oxidase for cellular respiration

differentiating gram negative bacilli

Cytochrome c oxidase is the final enzyme used in the electron transport chain

Oxidase reagent:

• reacts with cytochrome c oxidase turns purple

• chromogenic reducing agent: chemical that develops color as it is oxidized

Oxidase Test

Oxidase Positive

• Pseudomononadaceae

• Neisseria

Spectrophotometer

catalase negative

• enterococcus

• streptococcus

Oxidase Negative

• Enterobacteriaceae

• Escherichia coli

• Serratia marcescens