N-251 EXAM 1 LECTURE 4: MICROBIAL GROWTH単語カード | Quizlet

MICROBIAL GROWTH

- bacterial cells build up protoplasm and double in size

- the cells then divide into two daughter cells

BINARY FISSION

asexual reproduction where a single mother cell divides into two daughter cells (exact replica)

HOW IS BACTERIAL GROWTH MEASURED IF ITS DOUBLE IN SIZE IS HARDLY NOTICEABLE?

growth is measured by an increase in the number of bacterial cells (quantity)

WHAT IS A CALIBRATED LOOP USED FOR?

it is used for planting a measured quantity of a specimen to a streak plate

picks up small amounts - .0001 ml of liquid

POUR PLATE METHOD

innoculate an empty petri dish with 1.0 or 0.1 ml of bacterial dilution

add melted nutrient agar (cooled to 37 degrees C)

swirl to mix

colonies will grow in and on solidified medium

SPREAD PLATE METHOD

0.1 ml

innoculate plate containing solid medium

spread inoculum over surface evenly

colonies grow only on surface of medium

POUR/SPREAD PLATE METHOD OFTEN REQUIRES WHAT?

serial dilution of the biological samples

SERIAL DILUTION

Dilution of a substance several times by the same amount each time

IF 32 COLONIES ARE ON A PLATE OF 1/10,000 DILUTION, THEN WHAT IS THE COUNT?

32 X 10,000 = 320,000/ml in sample

WHY ARE COLONIES ISOLATED?

so that we can identify them

HOW MANY QUADRANTS ARE THERE IN AN AGAR PLATE STREAKED WITH BACTERIAL CULTURE?

4

MIN. TEMP AFFECT ON BACTERIAL GROWTH

lowest temp that permits growth

MAX. TEMP AFFECT ON BACTERIAL GROWTH

highest temp that permits growth

OPTIMUM TEMP

range of temp that promotes highest growth rate (37)

PSYCHROPHILES

optimum: 5 to 20 C

snow fields, polar ice, ocean depths

MESOPHILES

optimum: 20 to 50 C

majority of bacteria, human pathogens

THERMOPHILES

optimum: 50 to 80 C

habitats exposed to sun, hot springs

EXTREME THERMOPHILES

optimum: 80 C and above

soil and water associated with volcanic activity

OBLIGATE (STRICT) AEROBES

must have oxygen

use respiration to get energy

OBLIGATE (STRICT) ANAEROBES

cannot grow in the presence of oxygen

use fermentation to get energy

FACULTATIVE ANAEROBES

can live/grow with or without oxygen

grows better in oxygen tho

MICROAEROPHILIC ORGANISMS

needs oxygen but in small amounts

large amount will kill organism

AEROTOLERANT ORGANISMS

grows with or without oxygen

oxygen has no effect

growth occurs evenly throughout the culture tube

WHAT'S THE DIFFERENCE BETWEEN AEROBIC BACTERIA AND ANAEROBIC BACTERIA IN GETTING RID OF TOXIC BYPRODUCTS?

Aerobic bacteria have mechanisms to get rid of toxic byproducts of aerobic metabolism whereas anaerobes don't

WHAT ARE SOME OTHER REQUIREMENTS NEEDED FOR MICROBIAL GROWTH BESIDES NEEDING THE RIGHT TEMPERATURE AND LEVELS OF OXYGEN?

Nutrients

Energy

Inorganic sources

WHAT'S THE ORDER OF THE BACTERIAL GROWTH CURVE?

lag phase

exponential phase

stationary phase

death phase

CLOSED SYSTEM - BACTERIAL GROWTH CURVE

nutrients and space are finite

no mechanism to remove waste products (stuck in petri dish)

LAG PHASE

bacteria cells are adapting to environment before reproducing

EXPONENTIAL PHASE

bacteria cells are growing rapidly because of their abundant resources

reproducing at max. rate

STATIONARY PHASE

decline in growth rate

increase in death rate

too crowded

running out of resources

DEATH PHASE

no more resources or space

cells die rapidly