micro lab quiz

how can bacteria be classified by oxygen need for growth?

aerobes or anaerobes

obligate anaerobe

need oxygen to grow, metabolism requires oxygen.

what is the terminal electron acceptor for obligate anaerobes?

oxygen

microaerophiles

prefer to grow in low oxygen concentrations (2-10%)

facultative anaerobes

grow well aerobically, but have capacity to grow anaerobically when oxygen is not present

aerotolerant anaerobes

can tolerate oxygen but do not use it for energy production. produce. energy strictly by fermentation

obligate anaerobes

cannot tolerate oxygen, must be cultured in environment with no oxygen

use nitrates or sulfate in place of oxygen as the terminal electron acceptor

catalase

removes toxic forms of oxygen by degrading hydrogen peroxide into oxygen and water

superoxide dismustase

removes toxic forms of oxygen by acting on superoxide anion and converting it to oxygen and hydrogen peroxide

what is the role of oxygen in aerobic respiration?

oxygen acts as the final electron acceptor in the ETC

what type of metabolism occurs in absence of oxygen

anaerobic metabolism

name two enzymes that are present in obligate aerobes but lacking in obligate anaerobes

catalase and superoxide dismutase

what are the four groups of microorganisms defined by optimal growth for temperature?

psycrophiles, mesophiles, thermophiles, hyperthermophiles

psychrophiles

love cold temperatures, optimal growth between -5 and 15 C. often found in waters of arctic and antarctic

mesophiles

microorganisms that grows best in temperatures 25-45 degrees C. most bacteria are in this category.

at what temperature do most human pathogens grow?

35-45 degrees C

thermophiles

microorganisms that grow best between 45-70 degrees C. Occur in soils or compost piles where midday temp can reach greater than 50 C

hyperthermophiles

microorganisms that grow best above 75 degrees C. many members of domain archaea occupy environments heated by volcanic activity where water is above 100 degrees C.

neutrophiles

microbes that grow at or near neutral pH

acidophiles

bacteria that grow at acidic pH values

alkaliphiles

baceria that grow at alkaline pH values

osmosis

process where water diffuses from areas of low solute concentration to areas of higher solute concentration

hypotonic

environment where solute concentrations on the OUTSIDE of the cell are LOWER than the cytoplasm

isotonic

environments where solute concentration is the same inside and outside the cell

hypertonic

environment where solute concentration is higher OUTSIDE of the cell than the cytoplasm. causes water to flow out of cell and cell to shrink

plasmolysis

dehydration of cytoplasm and cell shrinkage

obligate halophiles

require high concentrations of NaCl to grow

halotolerant

do not require salt but are capable of growth in it in moderate concentrations

osmophiles

organisms that can grow in environments where sugar concentrations are excessive