mcb2010 exam 1

who made the first microscope?

antoni van leewenhoek

who were the scientists that discovered spontaneous generation?

redi and pasteur

who developed postulates to demonstrate that microorganisms cause disease?

robert koch

koch’s postulate #1

suspective causative agent must be found in every case of the disease and must be absent from healthy hosts

koch’s postulate #2

agent must be isolated and grown outside the host

koch’s postulate #3

when agent is introduced into a healthy, susceptible host, the host must get the disease

koch’s postulate #4

same agent must be isolated(re-isolated) from now diseased experimental host. same agent must be found in the diseased experimental host

what did semmelweis do?

handwashing

what did lister do?

anti-septic technique

what did nightingale do?

nursing

what did snow do?

epidemiology

what did jenner do?

the first vaccine - cowpox provided immunity again smallpox

what did ehrilch do?

chemotherapy - “magic bullets”

what did pasteur do?

pasteurization; germ theory of disease

what was spallanzani significant for?

experimentally disproving the theory of spontaneous generation

what was linnaeus significant for?

the taxonomic system

what was woese and fox significant for?

proposing the three domains - bacteria, archaea, and eukarya

what was koch’s experiments?

etiology - studying causative agents of disease

what is gram known for?

gram’s stain test

which domain has the molecule peptidoglycan as part of its cell wall structure?

bacteria

what term was coined by leeuwenhoek that was used to identify microorganisms?

animalcules

what is gene therapy?

the insertion of working copies of a gene into the cells of a person with a genetic disorder in an attempt to correct the disorder

molecular biology discovered that

combines aspects of biochemistry, cell biology, and genetics to explain cell function at the molecular level

recombinant dna technology

DNA produced by combining DNA from different sources

gene therapy

inserting a missing gene/repairing a defective one in humans by inserting desired gene into host cells

how did biochemistry contribute to the field of microbiology?

design of herbicides and pesticides
drug design
diagnoses of illness/patient monitoring
treatment of metabolic diseases

what does bioremediation do?

uses living bacteria, algae, and fungi to detoxify polluted environments

characterisitcs of bacteria?

prokaryotic
unicellular + lacks a nucleus
found in moist environments
cell wall made of peptidoglycan
asexual reproduction
smaller than eukaryotes

characteristics of archaea?

prokaryotic
unicellular + lacks a nucleus
found in moist environments
cell wall
asexual reproduction
smaller than eukaryotes

characteristics of fungi?

eukaryotic
obtain food from other organisms
cell wall
multicellular
reproduce sexually and asexuallych

characteristics of yeasts?

fungi
unicellular
reproduce asexually by budding
some produce sexual spores

characteristics of molds?

fungi
multicellular
grow as long filaments
reproduce by asexual and sexual spores

characteristics of protoza?

single-celled eukaryotes
lack a cell wall
similar to animals in nutrition/structure
asexually reproduce

what forms of locomotion do protoza use?

psuedopods
cilia
flagella

characterisitcs of algae?

unicellular or multicellular
photosynthetic
simple reproductive structures
categorized based on pigmentation + cell wall composition

who proposed that living things could arise from nonliving matter?

aristotle

significance of redi’s experiments?

doubted aristotle’s theory when decaying meat kept from flies no maggots developed

what is serology?

the study of reactions between antibodies and antigens

what is immunology?

study of the immune system

what is chemotherapy?

use of drugs to target disease causing cells

who discovered penicillin?

fleming

who discovered sulfa drugs?

domagk

what are the 4 processes of life?

growth
reproduction
responsiveness
metabolism

characteristics of prokaryotic cells

lack nucleus
lack various structures bound with phospholipid membranes
composed of bacteria and archaea

characteristics of eukaryotic cells

have nucleus
internal membrane-bound organelles
complex structure
composed of algae, protoza, fungi, animals and plants

what are glycocalyces?

gelatinous, sticky substance surrounding the outside of the cell

what are glycocalyces composed of?

polysaccharides, polypeptides, or both

what are the two types of glycocalyces?

capsule
slime layer

characteristics of capsules?

organized repeating units of organic chemicals

firmly attached to cell surface
may prevent bacteria from being recognized by host

characteristics of slime layer?

loosely attached to cell surface
water-soluble
sticky layer allows prokaryotes to attach to surfaces

characteristic of bacterial flagella?

filament
hook
basal body
function: movement; runs + tumbles

what are the different arrangements of bacterial flagella?

peritrichous flagella
single polar flagellum
tufts

what are taxis?

movement towards or away from a stimulus

positive taxis

movements towards the stimulus, tumbles become less frequent

negative taxis

movement away from an unfavorable stimulus

fimbriae

sticky, bristle-like projections
used by bacteria to adhere to one another and to substances in environment
shorter than flagella
serve an important function in biofilms

pili

special type of fimbriae
longer than fimbriae, shorter than flagella
bacteria typically only have 1 or 2 per cell
transfer DNA from one cell to another

functions of bacterial cell wall?

provides structure and shape and protect cell from osmotic forces
assist cells in attaching to other cells/resisting antimicrobial drugs
can target cell wall of bacteria with antibiotics
cell wall made of peptidoglycan

what are the two types of bacterial cell walls?

gram positive and gram negative

gram positive cell walls

thick layer of peptidoglycan
contains unique chemicals called teichoic acids and lipoteichoic acids
appear purple with gram’s staining procedure
60% mycolic acid

gram negative cell walls

thin layer of peptidoglycan
bilayer membrane outside the peptidoglycan contains phospholipids, proteins, and lipopolysaccharide (LPS)

appear pink with gram’s staining procedure

bacterial cytoplasmic membrane

referred to as phospholipid bilayer, composed of integral proteins and peripheral proteins,

function: energy storage, harvest light energy in photosynthetic bacteria, selectively permeable, naturally impermeable to most substances, proteins allow substances to cross membrane and maintain concentration and electrical gradient

passive processes that move substances across membranes:

diffusion, facilitated diffusion, and osmosis

active processes that move substances across membranes

active transport and group translocation

cytoplasm of bacterial cell

cytosol, inclusions, endospores, ribosomes, and cytoskeleton

cytosol

liquid portion of cytoplasm, mostly water, contains cells DNA in region called nucleoid

inclusions

may include reserve deposits of chemicals

endospores

defensive strategy against unfavorable conditions produced by some bacteria
provides resistance against extreme conditions

ribosomes

sites of protein synthesis, composed of polypeptides and ribosomal RNA

cytoskeleton

composed of 3-4 types of protein fibers, can play different roles in cell

external structures in archaea

glycocalyces, flagella, fimbriae and hami

hami in archaea

present in some, used for attachment

archaea cell wall

no peptidoglycan, contain specialized polysaccharides and proteins (some dont have cell walls)

archaea cell membrane

all have cell membrane, maintain electrical and chemical gradients, control import and export of substances from the cell

carolus linnaeus grouped similar organisms that can successfully interbreed into categories called

species

oil immersion lenses increase both ________ and ________.

magnification
resolution

with regard to microscopy, contrast is best described as

the differences in intensity between an object and its background.

what do you call a microscope’s ability to distinguish two objects that are close together?

resolution

the various forms of radiation differ in their

wavelength

what is the basis for assigning organisms into domains?

ribosomal nucleotide sequences

which unit is most appropriate to measure the size of cells?

micrometer

what is one way in which microbiologists can distinguish different bacteria that are similar in morphology and staining characteristics?

biochemical testing

why are some bacteria, such as those of the genera mycobacterium and nocardia, NOT effectively stained with the gram stain?

they have large amounts of waxy lipid in their cell walls.

why is a negative stain called such?

the background is stained, leaving the cell colorless.

simple microscopes

single magnifying lens
leeuwenhoek used this to examine microorganisms
bright field microscope

compound light microscopes

contains objectives (10x, 40x, 100x)
oil immersion increases resolution
total lens magnification = ocular lens x objective lens
bright field microscope

dark-field microscopes

light specimen against dark background
special filter

phase contrast microscope

used to examine specimens that may be damaged or altered by staining and attaching them to slides
contrast created since light waves are out of phase
used for viewing internal structures

fluorescence microscopes

direct uv source at specimen
specimen radiates energy back as longer wavelengths
used in immunofluorescence to identify pathogens and to make visible a variety of proteins

electron microscopy

have greater resolving power and magnification
detailed views of bacteria, viruses, internal cellular structures, molecules, and large atoms

what are the two types of electron microscopes?

transmission electron microscopes
scanning electron microscopes

what is the purpose of staining?

increasing contrast and resolution

what do acidic dyes stain?

alkaline structures

what do basic dyes stain?

acidic structures

what are simple stains?

single dye stains

what are types of simple stains?

crystal violet
sefranin (grams stain)
methylene blue

what are differential stains?

stains that use more than one dye
used to differentiate between cells, chemicals and structures

what are types of differential stains?

gram stain
acid fast stain
endospore stain
histological stain

what are special stains?

stains used to identify microbial structures

what are types of special stains?

negative stain
flagellar stain
fluorescent stain