exam 1 Flashcards
what is the three domain system?
archae, eukarya, and bacteria
what is biogensis?
developement of life from pre-exsiting forms of life forms
who observed the first microorganisms
Anton van Leeuwenhoek
mycology study of?
molds,yeasts, and mushrooms
who composed a microscope and observed thin slices of cork. Then he coined the term “cells”.
robert hooke
why is mycobacterium difficult to stain?
it’s difficult to stain because of the large amounts of waxlike lipids present in the cell wall.
why is gram staining in microbiology important?
it’s important because it differntiates bacterial cells with diff types of cell walls
You are performing a gram stain on gram negative bacteria and stop after adding mordant. How well the bacteria appear?
purple
which microscope is best for viewing details of internal structures within live cells?
phase contrast microscopy
what is incorrect about capsules?
involvement in DNA transfer
what is incorrect about prokaryotic cells?
prokaryotes lack a ribosome
what is expected to find in acid fast cell walls?
mycolic acid and peptidoglycan
what is the function of fimbriae?
numerous and hairlike structures that attach to surfaces
what is the function of glycocalyx?
protection from phagocytes
what is the function of a cell wall?
protects from osmotic pressure
what is the function of pili?
transfers genetic material
gram positive bacterium characteristics
gram positive bacterium characteristics
gram negative characteristics
lipopolysaccharide, phospholipid, lipoprotein, peptidoglycan, plasma membrane, and O-antigens
which of the following is correct regarding prokaryotic cells?
dna not associated with histones
what is the difference between eukaryotic and prokaryotic flagella?
eukaryotic flagella have a 9 + 2 arrangment of microtubules
what are structures NOT found in prokaryotic cells?
cilia
which structures allow a cell to survive adverse environmental conditions?
endospores
What is quorum sensing?
the ability of bacteria in biofilm to communicate with each other and coordinate their activities
a medium containing chemicals to inhibit growth of gram positive bacteria would be called?
selective
what technique is used to seperate bacteria and get individual colonies?
streak plate
bacteria is reproduced by ?
binary fission
culture mediums consisting of agar, peptone, and beef heart extract is?
a complex medium
when bacterial cell reproduce by splitting into two daughter cells, the process is called?
binary fission
in what phase of the growth curve is the population-doubling time fastest?
log phase
blood agar is used to observe hemolysis or clearing around streptococcus pyogenes colonies is an example of?
differential media
T/F: the endosymbiotic theory states that eukaryotic organelles evolved from symbiotic prokaryotes living within other prokaryotes?
true
Bacteria characteristics
prokaryotes, double bilayer, petidoglycan,, single cell, divide by binary fission, use flagella for motility
archaea characteristics
prokaryotes, lack peptidoglycan cell walls, live in extreme environments, don’t cause disease in humans( generally)
fungi characteristics
eukaryotes, chitin cell walls,yeast: unicellular, molds/mushrooms: multicellular
protozoa
motile via pseudopods, cilia or flagella, reproduce sexually/asexually, free living or require parastic host, eukaryotes
algae
eukaryotes, cellulose in cell wall, photosynthesis for energy,unicellular/multicellular, reproduce sexually/ asexually
viruses
dna/rna core surrounded by protein coat, required for a living host to replicate, inert outside a living host.
who is carl woese?
he created the domain classifcations
who is louis pasteur?
demonstrated that microorganisms are present in the air
who is rudolf virchow?
said that cells arise from preexisting cells(biogenesis)
who is paul ehrilch?
magic bullet. could destroy a pathogen without harming the host
who is alexander fleming?
discovered first antibiotic
brightfield microscope
bright background, low contrast, both stained/unstained
darkfield microscope
dark background, increase contrast between sample & field, some internal structures can be viewed
phase contrast
high contrast, can view life and cell internal structures, used to view microbial movement & detecting bacterial structures
confocal
cells stained with fluoroscent dyes, laser beam used to illuminate the fluroscent, sharp 3d images, used to study biofilms
acidic dye
chromophore is negatively charged, stain binds to molecules that are positively charged on surface of bacterium
why is gram staining important for prescription of antibiotic treatment?
distinguishes between gram +/- bacteria. many antibiotics specifically target cell wall synthesis, so it’s important to know what type of bacteria it is.
basic dye
chromophere is positively charged, stain binds to to molecules that are negatively charged on surface of bacterium
acid fast staining
only binds to bacteria that have waxy cell walls which can’t be decolorized by alcohol.
negative staining for capsules
capsules provide an exterior covering for the bacterium. They are stained with india ink or nigrosin. They appear to be halo around the cell which indicates a capsule is present.
What are endospores?
Dormant cellular structures that are resistant to harsh external conditions. The primary stain is malachite green. Cells appear red or pink with green dots when stained.
Which microscope forms an image from two sets of light rays, one from the light source and the other diffracted from a structure in the specimen?
phase contrast microscope
Bacteria that divide in multiple planes and form grapelike clusters are called
staphylococci.
Some bacteria stain Gram-positive and others stain Gram-negative because of differences in the structure of their
cell wall
what shape is bacillus?
rod shaped
what shape is coccus?
spherical shaped
what is the shape of vibrio, spirillum, and spirochete?
spiral
what is the bacteria whose arrangment is in pairs?
dipolocci or diplobacilli
what bacteria is in clusters?
staphylocci
what bacteria is in chains?
streptococci and streptobacilli
What are the sizes of two subunits used to compose prokaryotic ribosomes?
30s+50s
Which of the following contain 70S ribosomes?
Prokaryotes, mitochondria, and chloroplasts
Which of the following is NOT a feature of Mannitol Salt Agar?
ability to differentiate between different types of Gram negative bacteria
The following steps occur during binary fission. What is the third step?
inward growth of membrane
Which of the following best describes the rate of microbial death when treated with antimicrobial chemicals?
Cells in a population die at a constant rate.
Commercial sterilization is a limited heat treatment to destroy
Clostridium botulinum endospores.
More than half of our antibiotics are produced by species of
Streptomyces.
Which one of the following groups of pathogens are the easiest to treat with antimicrobial agents?
Bacteria
One disadvantage to using broad-spectrum antibiotics is that they
destroy normal microbiota.
