Microbiology Ch. 9 - Microbial Growth

binary fission

the most common mechanism of cell replication in bacteria is a process called ________

first

the cell grows and increases its number of cellular components in which step of binary fission

second

the replication of DNA starts at a location on the circular chromosome called the origin of replication, where the chromosome is attached to the inner cell membrane

third

replication continues in opposite directions along the chromosome until the terminus is reached

fourth

the center of the enlarged cell constricts until two daughter cells are formed, each offspring receiving a complete copy of the parental genome and a division of the cytoplasm (cytokinesis)

cytokinesis, FtsZ

the process of ________ and cell division is directed by a protein called ____

cell separation

the Z-ring produced by FtsZ proteins activates to produce a peptidoglycan cell wall and builds a septum that divides the two daughter cells

doubling time

the time it takes for the population to double through one round of binary fission

fragmentation

a type of cell division where parent cells break off fragments from themselves that are capable of independently forming into a new organism

budding

a type of alternative reproduction of bacteria in which a mother cell grows and attached baby cell (ex. yeast)

Nn = No x 2^n

formula for calculating number of bacterial cells created over time

1.6 × 10^6 or 1,600,000

With a doubling time of 30 minutes and a starting population size of 1 × 10⁵ cells, how many cells will be present after 2 hours, assuming no cell death?

replicate

bacterial counts _____ with each generation

lag phase, log phase, stationary phase, death or decline phase

bacterial growth curve includes what phases?

lag phase

no increase in number of living bacterial cells, but cells grow larger and are metabolically active, synthesizing proteins needed to grow within the medium is called __________

log phase

exponential increase in the number of living bacterial cells due to binary fission is called the __________ (in this phase, cells are more susceptible to antibiotics as the cells are growing and dividing in this phase)

stationary phase

plateau in number of living bacterial cells; rate of cell division and death roughly equal is called the ________. waste builds and nutrients are gradually used up; gradual depletion of oxygen begins to limit aerobic cell growth.

survival

during the stationary phase, cells switch to _____ mode of metabolism as growth slows, so too does synthesis of peptidoglycans, proteins, and nucleic acids. stationary cultures are less susceptible to antibiotics that disrupt these processes (many cells undergo sporulation)

death or decline phase

exponential decrease in number of living bacterial cells where many cells lyse and release nutrients into the medium, allowing surviving cells to form endospores. This phase is called ___________

persisters

cells that are characterized by a slow metabolic rate (do not respond to antibiotic treatment) these are left during the death phase

direct cell count

this refers to counting the cells in a liquid culture or colonies on a plate

direct cell count

Petroff-Hausser chamber, florescence staining, or coulter counter is an example of what type of cell counting?

petroff-hausser chamber

a special slide designed for counting the bacterial cells in a measured volume of a sample. A grid is etched on the slide to facilitate precision in counting. red cells on gird are counted

fluorescence staining

this direct method of bacteria count involves staining to differentiate between viable and dead bacterial cells in a sample for purposes of counting (viable=green, dead cells=red)

indirect methods

plate count (CFU) and optical density are what types of methods for counting bacteria?

plate count

(colony forming unit) this type of indirect bacteria counting method includes spreading the bacteria on a plate and counting the colonies on the plate (each colony counts as one bacteria) this is considered as inaccurate/low estimate

optical density

this bacteria counting method measures clearness/cloudiness (turbidity) of the sample

serratia

gram-negative rod-shaped bacteria (water, soil, plants, animals)

corynebacterium

gram-positive bacteria bacilli (rod-shaped) that are widely distributed in nature

staphylococcus

found on the skin and nose of healthy individuals (may cause staph infections) treatments involve antibiotics

serial dilution

the important first step before proceeding to the spread plate. The goal is to obtain plates with CFUs in the range of 30-300 (involves dilutions of multiples of 10 to simplify calculations)

p. aeruginsoa

common infectious bacteria that is a problem in healthcare settings for its antibiotic resistance

e. coli

normally live in the intestines of healthy people and animals. Some strains cause illness including diarrhea, vomiting

salmonella spp.

rod-shaped gram-negative that are commonly found in intestines of poultry, pigs, and cattle that cause infection through consumption of contaminated foods

listeria

causes problems in pregnant women, newborns, elderly, and weakened immune systems (headache, fever, vomiting, diarrhea

vibrio spp.

gram-negative bacteria found in coastal waters, known for causing vibriosis infections through raw or undercooked seafood

L. pneumophila

gram-negative bacteria responsible for severe form of pneumonia (through droplets

quorum sensing

this is the way that bacteria communicate with each other (results in the coordination of activities in response to environmental stimuli)

false

true or false: cells that are the same species can only communicate

autoinducers

detect the population density and activates specific genes

biofilm

a _______ is what microorganisms grow in nature that are complex and dynamic ecosystems that for on a variety of environmental surfaces (almost every surface in a liquid environment has this)

obligate aerobes

loves oxygen

obligate anaerobes

hates oxygen

facultative anaerobes

prefer oxygen, but have to have it

aerotolerant anaerobes

equal distribution of oxygen and non-oxygen environment

microaerophiles

oxygen = 20% not completely oxygenated but higher to the top

detox reactive oxygen species

in this reaction, an electron donor oxidizes hydrogen peroxide, or other peroxides, to water

catalase

enzyme that converts hydrogen peroxide to water and oxygen

acidophile

microorganisms that grow optimally at pH less than 5.55 (acid lovers) ex. Yellowstone hot springs bacteria (mud pets)

neutrophile

most bacteria are _______, meaning they grow optimally at a pH within one or two pH units of the neutral pH of 7 (human body pathogens)

alkaliphile

microorganisms that grow best at pH between 8.0 and 10.5 (basic, ocean)

DNA

high pH break hydrogen bonds of _____

lipids

pH effects _____ by alkaline pH hydrolyzing membranes

proteins

pH effects _____ through denaturing them

proton motive force

this collapses when H+ gradient is disrupted by pH alkaline

H+

acidophiles remove _____ from the cytoplasm

saturated

acidophiles consist of _________ fatty acids

rigid

acidophiles are structurally _____

fluid

alkaliphiles are structurally ______

unsaturated

alkaliphiles consist of ___________ fatty acids

psychrophiles

grow at 0 C and below and have an optimum growth temp. of 15 C are called _____

s. aureus, b. cereus, L. monocytogenes

thermophiles

organisms that grow at optimum temps of 50 C to 80 C are called _____

thermus aquaticus, geobacillus sp.

mesophiles

adapted to moderate temps. with optimal growth of ranging from 20 C to 45C (human microbiota at 37 C)

s. aureus, e. coli, salmonella sp., lactobacillus sp.

hyperthermophiles

characterized by growth ranges from 80 C to over 110 C

pyrobolus sp., pyrodictium sp.

low

membranes lose fluidity at _________ temperatures (proteins too rigid)

high

membranes are too fluid in _____ temperatures (proteins, nucleic acids denature)

psychrophiles

proteins of _______ are highly hydrophobic to increase flexibility

unsaturated

membrane lipids of psychrophiles are _______ (kinky) and packed loose/fluid

hyperthermophiles

____________ include a ratio of saturated and polyunsaturated lipids to limit membrane fluidity (packed more tightly)

halotolerant

do not require salt for growth but can grow in high salt is called a _________

photoautotrophs

use light for energy and CO2 is primary carbon source

ex. algae, cyanobacteria

photoheterotrophs

use light for energy but cannot use CO2 as sole carbon source