click below
click below
Normal Size Small Size show me how
Microbiology
Microbiology -Chapter 4
Question | Answer |
---|---|
legionella and neisseria are examples of: | gram-negative aerobic rods and cocci |
treponema pallidum and borrelia burgdorferi belong to the group of: | spirochetes |
bacteria that use organic compounds for the source of both carbon and energy are referred to as: | chemoheterotrophs |
microorganisms that show optimal growth at modreate temperatures (between 25*C and 40*C) are called: | mesophiles |
bacteria that use oxygen, but only at low concentration, are classified as: | microaerophiles |
beadlike chains of cocci formed after cell division along a single axis are called: | streptococci |
straight, rod shaped bacteria, some of which are endospore forming, are referred to as: | bacilli |
staphylococci and streptococci are best classified in the group of: | gram-positive cocci |
host dependent bacterium: | rickettsia |
bacteria whose overall shape is spherical or nearly spherical are referred to as: | cocci |
microorganisms that acquire energy from light are called: | phototrophs |
microorganisms that grow only in the presence of oxygen are called: | aerobes or obligate aerobes |
Describe the different stages of the bacterial population growth curve. | Lag phase—bacteria are not increasing greatly in number as they become accustomed to the growth environment Log phase—bacterial number increases exponentially Stationary phase—due to depletion of nutrients and accumulation of metabolic waste, the number |
Discuss four methods to measure bacterial growth. | Measurement of dry weight of cell mass—involves washing, drying, and weighing the cell mass Turbidimetric (spectrophotometric)—cell mass is measured by determining the amount of turbidity (cloudiness) in a sample, which equates to the number of cells; a |
Discuss the nutritional requirement for bacterial growth with regard to carbon. | Carbon requirement classification for bacterial growth: • Autotrophs—can obtain carbon from atmospheric carbon dioxide • Heterotrophs—obtain carbon from organic compounds |
Discuss the influence of pH on bacterial growth. | Most bacteria prefer a neutral pH (7) and are called neutrophils. Acidophiles prefer an acidic growth environment, and alkalophiles prefer an alkaline environment. |
shapes of bacteria | according to their morphologic characteristics most bacteria are classified into different basic shapes: coccus, bacillus, spirochetes (spiral or helical), and pleomorphic |
Cocci | bacteria whose overall shape is spherical or nearly spherical. Several cocci are human pathogens causing, for example, UTI, food poisoning, toxic shock syndrome, gonorrhea ,some forms of meningitis, throat infections, pneumonias ,and sinusitis |
Bacilli | rod shaped bacteria, som eof whic are endospore forming. Diseases caused by baccili include anthrax ,botulism, and tetanus and GI infections such as E.coli and salmonella |
Pleomorphic | bacterial species that are morphologically indistinct, or variable depending on environmental conditions |
E. Coli | gram-negative bacillus |
Staphylococcus aureus | gram-positive coccus |
Spirals | occurs as vibrios, spirilla ,or spirochetes |
Vibrios | curved or comma shaped rods and severla species are human pathogens associated with gastroenteritis, cholera, food poisoning, and septicemia |
Spirillum | thick, rigid, spiral organism that can cause rat bite fever, an uncommon but worldwide condition caused by rodent bites. |
Spirochetes | thin, flexible spirals and can cause leptospirosis , Lyme disease, and syphillis |
Classification | domain ,kingdom, phylum, class, order, family ,genus, species (Do Keep Ponds Clean Or Frogs Get Sick) |
Lyme disease | Organism: Borella burgdorferi Tranmission: Deer tick bite |
Syphilis | Organism: Treponema pallidum Transmission: sexual contact |
Leptospirosis | Organism: Leptospira interrogans Transmission: contact with water, food, or soil contaminated by urine of an infected animal |
Streptococcus (gram-positive cocci) | microaeropilic or facultatively anaerobic organisms that produce lactic acid. the classification of Streptococcus species is based on the hemolytic patterns of their colonies on blood agar. Although a number of hte species are pathogenic, many of the spe |
Staphylococcus (gram-positive cocci) | cause a wide variety of diseases in humans and other animals through their production of toxins or tissue invasion. Staphylococcus toxins are a common cause of the enterotoxin and the ability of staphylococci to grow in foods with relatively low water ac |
mycobacteria | the genus Mycobacterium includes gram positive, aerobic, acid-fast rods that have the tendency to form filaments. They are widespread organisms in water, soil, and food sources, although some are obligate intracellular parasites in animals and humans, |