Med Micro Exam 2 Flashcards
What are some growth requirements for microbes?
-electrons sources(organic and inorganic compounds)
-carbon sources(autotrophs and heterotrophs)
-energy sources [light(phototrophs) and chemical (chemotrophs)]
What is microbial growth?
-increase in population of microbes
-due to reproduction of individual microbes
What are results of microbial growth?
-colonies
-biofilms
What elements do most nutrients need to reproduce?
-carbon
-oxygen
-nitrogen
-hydrogen
Oxygen and obligate anaerobes relationship:
-oxygen is deadly for obligate anaerobes
-toxic forms of oxygen are highly reactive and excellent oxidizing agents
-resulting oxidation causes irrepairable damage to cells
What are the 4 toxic forms of oxygen?
-Singlet O2
-superoxide radicals
-peroxide anion
-hydroxyl radical
Obligate aerobes
only live in oxygen
Obligate anaerobes
can’t live in oxygen
Facultative anaerobes
prefer to live in oxygen but can live without it
Aerotolerant anaerobes
they don’t give a shit they live all over in both
Nitrogen requirements:
-insufficent nitrogen ends anabolism to make amino acids and nucleotides
-nitrogen fixation by certain bacteria is essential to life
Chemical requirements
-phosphorus
-sulfur
trace elements:
only required in small amounts
Growth factors:
necessary organic chemicals that can’t be synthesized by certain organisms.
Temperature:
-organisms have an optimal temperature due to protein structure and lipid membranes of cells and organelles
pH ranges:
-organisms sensitive to changes in acidity
-H ions interfere with H bonding
Neutrophiles:
grows best in narrow range around neutral pH
Acidophiles:
grows best in acidic habitats
Obligate acidophiles:
-won’t grow if pH is over 7
Acid-tolerant organisms:
can tolerate low pH
Alkalinophiles:
live in alkaline soils and waters
What do microbes require?
they require water to dissolve enzymes and nutrients
crenation:
disappearance of cytoplasm and death of cell
osmotic pressure
pressure exerted by a cell membrane by a solution containing solutes that can’t freely cross the membrane
hydrostatic pressure
water exerts pressure in proportion to its depth
barophiles
live under extreme pressure
antagonist relationship
bacteriophage and bacteria
synergistic relationship
when organisms team up to create a disease that one couldn’t do on its own
-biofilm
biofilms
-complex relationships among numerous microorganisms
-many microorganisms are more harmful as part of biofilm
quorum sensing:
-microbes excrete a compound
-when the compound is high in density, the other cells know other similar microbes are nearby
biofilm formation
- free living bacteria in environment
- settlement and attachment
- formation of EPS
- cell communication and division of labor
- new cells arrive , water channels form in biofilm
defined media
concentrations of chemicals are known
complex media
chemical composition are unknown
-nutrients are derived from yeast, soy, beef
-supports growth of wide variety
-good when nutritional needs of microbe is unknown
what does an enzyme bind to?
substrate, very specific
genotype:
set of genes in the genome (y, Y)
phenotype:
physical features of the organism (yellow)
What is the result of transcription?
mRNA
Central Dogma
theory stating that genetic information flows only in one direction
3 stages of transcription
- initiation
- elongation
- termination
Operon
promotor, operator and a series of genes
Operator
regulatory element
mutation:
change in nucleotide sequence of genome
it is rare and hereditable
point mutation:
one base pair is affected
gross mutations
includes inversions, duplications, transpositions
ionizing radiation
energize electrons to leave atoms
nonionizing radiation
does not energize electrons
