chapter 3 microscopy Flashcards
define light microscope that uses light to observe a specimen
light microscope
define light microscope
uses light to observe a specimen
uses two lenses to magnify the image
compound microscope
define the compound microscope in your words
uses two lenses to magnify the image
what is a objective lens? and how much does it magnifies?
lens closest to the specimen, magnifies between 10x-100x
what is ocular lens?
it is the eyepiece, magnifies by 10x
calculating magnification:
how do you calculate compound microscope
total magnification= objective lens x ocular lens
what is a resolution, define it.
two points can be distinguished if they are how much of a distance apart.
ability to distinguish fine detail and structure, and distinguish 2 points a certain distance apart.
- two points can be distinguished if they are at least 4 nm apart.
resolution :
True or false.
Light must pass between 2 objects for them to be seen as 2 separate things.
true
resolution:
true or false.
does not need light of a short-enough wavelength to fit between them, as it will automatically appear as 1 objct
false
what is the resolution general principle
the shorter the wavelength, the better the resolution.
3 (characteristics ) of electron microscope
uses electron instead of light
electrons travel in much shorter waves than light
resolving great power
this microscope allows us to view viruses and internal cell structures, and allows greater magnification
electron microscope
what are the two types of electron microscope?
scanning and transmission
transmission
to see internal structures
- very thin slices, can be cut from sample- thin sections
-samples generally stained with a metal to make structure opaque to electrons.
scanning
to see surfaces less powerful
what is atomic force and is it a part of electron microscope?
atomic force is to see molecules, uses thin metal probe to scan a specimen that has bumps and depressions
and not electron microscope.
human eye can see an object about ??
0.2 mm
compound light microscope can view an object about
0.2 ûm
electron microscope can view an object about
2 nm
chromophore
stains are composed of positively and negatively charged ions, one of which is coloured
what is a simple stain
only one dye used to highlight the entire microorganism
what are the four simple steps (simple stain)
1) smear sample on slide
2)fix with heat (heat is added, so the specimen can stick into the glass)
3) add stain
4) wash, dry, and view
how do stains work?what is the charge on the outer surface?
bacteria have a net negative charge on their outer surface
charge attracts stains with positively charged chromophores, and repels stains with negatively charged chromophores.
positive stains, define the characteristics
stain will bind to the bacterium
bacterium appears coloured
background appears clear
ex: crystal violet
negative stains, define the characteristics
will not bind to the bacterium
bacterium appears clear
background is colored
ex:nigrosin
differential stains, define it
react differently with different bacteria, thus can be distinguish between them
ex: gram stain
- differentiates bacteria based on the structure of the cell wall
bacteria with a thick cell wall retain the primary stain crystal violet an appear purple which is what?
gram positive example : streptococcus pyogenes
bacteria with a thin cell wall lose crystal violet during destaining, take on the color of the counterstain safranin and appear pink
gram negative example: e.coli
define what the definition of spore stain is
stains an internal structure of some bacteria
primary stain colors endospores green
spore stain
what is the primary stain color of spore stain
endospores green
what does counterstain (safranin) colors the rest of the cell? and name an example
it colors it pink, an example would be bacillus anthracis
what is a flagella stain?
flagella stain, stains the external structure
what does mordant do to flagella?
it thicken the flagella so they can be observed under a light microscope.
acid-fast stain
: define what it does
it detects the presence of waxy compound in cell wall and used to identify the genus mycobacterium
such as mycobacterium tuberculosis
mycobacterium leprae
acid-fast-stain:
mycobacterium cell wall retains the dye _____
carbol fuschin
counterstain with methylene blue stains non- acid bacteria and tissues green
false, tissues blue
capsule stain:
define what it is
detects a thick layer of polysaccharide outside the cell and this is a capsule
capsule stain a negative stain colours the what?
background
capsule stain:
the positive stain colors the what?
cell
the capsules does not take up most dyes and remains ______
colorless
define the characteristics of prokaryotes
dna is not enclosed within a nucleus
one circular chromosome
they lack membrane-enclosed organelles
single celled organisms such as bacteria and archae
define the characteristics of eukaryortes
dna is found in the nucleus :surrounded by a nuclear membrane
Dna is arranged as multiple chromosomes
they have membrane-enclosed organelles
examples are protozoa,fungi,animals,plants,algae
the bacteria morphology (shape)
coccus
bacillus
vibrio
spirillum
spirochete
coccus- cocci- spherical
bacillus- rod shaped
vibrio- curved
spirillum- spiral shaped
spirochete- corkscrew shaped
external structures
capsules and slime layers
sticky, gelatinous layer is what to the cell?
it is external to the cell
capsules and slime layers are composed of what?
polysaccharide, protein or both
what is the definition of capsule
if the layer is organized and firmly attached to the cell wall it is known as a capsule
if the layer is organized and firmly attached to the cell wall it is a
capsule
if the layer is unorganized and loosely attached to the cell wall it is known as a
slime layer
define what a slime layer is
if the layer is unorganized and loosely attached to the cell wall
in some bacteria capsules a play a role in virulence which is a protection against
phagocytosis
protection against phagocytosis example is streptococcus pneumoniae, with a capsule and without capsule causes what
with a capsule,it causes a disease, without a capsule causes no disease
True or false.
slime layers often allow bacteria to attach to surfaces, such as medical implants, water pipes and teeth
true
how are polysaccharide slime made?and what happens when it attaches to teeth ?
from sucrose , attaches to teeth which can lead to cavities
what are the four bacterial cells typical arrangements of flagella
monotrichous
Lophotrichous
amphitrichous
peritrichous
define what these terms mean
1)monotrichous
2)Lophotrichous
3)amphitrichous
4)peritrichous
1) a single polar flagellum
2) two or more flagellum originating from one pole
3) tufts of flagella originating from opposite poles
4) flagella distributed all over the cell
Flagellar motility:
flagella turn causing cell to move in one direction, which is also referred to as
run
periodically flagella reverse direction causing a random change in direction which is also referred to as
tumble
when a cell senses it is moving toward an attractant, it ___ less frequently, so the ___ in the direction of the attractant are longer.
tumble and run
flagella allow chemotaxis:
movement toward or away from a stimulant
toward a nutrient is called what
away from a toxin
is called an attractant
repellent
define what fimbriae and pili are
short, hair like appendages and hollow
what is a fimbriae, name an example
allow the cell to adhere to surfaces
contribute to pathogenecity (the possibility to cause a disease)
some strains of E.coli have fimbriae that allow them to attach to the intestinal wall
define what pili means
allows attatchment of two bacteria to each other
involved in transfer of genetic material between bacteria
example would be e.coli sex pilus
true or false:
bacterial cell wall:
-semi-rigid structure giving shape to the cell
major function is rupture the cell-protecting it against environmental changes
useful in the identification of bacteria, for example: the gram stain
point number 2 is wrong, the major function is to prevent the rupture of the cell.
what is the bacterial cell wall composed of?
it is composed of the complex macromolecule which is called peptidoglycan
- it is a mesh like structure composed of polysaccharide and amino acids
-polysaccharide portion is composed of two alternating monosaccharides
N-acetyl glucosamine (NAG )
N-acetyl muramic acid (NAM)
peptide portion composed of short chains of amino acids
a generalized view of peptidoglycan
polysaccharide chains run parallel
peptide chains link polysaccharides together
forms a mesh-like net surrounding the cell
the gram positive cell wall is made of what?
made of peptidoglycan outside the plasma membrane and they also contain teichoic acids
wall teichoic acids in gram positive cell wall is attached to what
peptidoglycan
lipoteichoic acids in gram positive cell wall is attached
attached to plasma membrane and extend through the peptidoglycan
Can gram positive bacteria have only one or two membrane
one membrane which is the cytoplasmic membrane
describe what the gram negative cell wall is
thin peptidoglycan layer that is sandwiched between two membranes
outer membrane made of lipids (phospholipids),proteins, and lipopolysaccharides(LPS)
Polysaccharide portion of LPS is composed of O-sugars in gram negative cell wall? which is useful for establishing gram negative bacteria
true
Lipid portion of LPS is toxic, true or false
true
the gram negative cell wall is also reffered to as
endotoxin
what does exotoxin mean and endotoxin?
exo is meant to do harm while endo is not meant to do harm
how does gram stain work?
gram positive cells explain…
gram negative cells explain…
thick peptidoglycan traps the crystal violet and appears purple
thin peptidoglycan does not trap Crystal violet and the other membrane gets disrupted by alcohol and the crystal violet is washed away, safranin counterstain stains the cell pink.
what are the components of peptidoglycan that makes them special?
completely different from anything found in animal cells
many antibiotics have been discovered that act against peptidoglycan
example is penicillin which inhibits products of peptidoglycan
also degraded by one of our natural diseases:lysozyme
-found in tears , saliva, mucous
plasma membrane is composed of what
phospholipid bilayer
what does the cell membrane do(name one )
seperate the interior (cytoplasm) from the outside environment
- serves as a semi-permeable barrier
-selectively allows inflows and outflows of the materials
exists in a semi fluid state
antimicrobial agents define them
alcohols disrupt the membrane
can be used as a disinfectant
internal components:
Cytoplasm define the characteristics of it
the substance inside the plasma membrane
about 80% water
contains most of the stuff needed for life such as suhar,amino acids, nucelotides,enzyms, and some structional structures
this contains the bacterial chromosome
the nucleotid
all genetic information required for cell’s structures and functions
the nucleoid
this internal component is not surrounded by a nuclear membrane
the nucleoid
Define the characteristics
- this may also contain plasmids, which smaller double stranded dna molecules, also contain non-essential-genes like antibiotic resistance
the nucleoid
define the definition of ribosomes
the site of protein synthesis (translation)
is ribosome only made of protein?
no, it is also made of ribosomal RNA (rRNA)
what are the two parts of ribosomes ? and how much does it complete together ?
the two parts of ribosomes are 30S subunit and 50S subunit, together they make 70S ribosome
Ribosomes of bacteria differ from Eukaryotic ribosomes
yes they do differ as, eukaryotes have 80 ribosomes, several antibiotics target bacterial ribosomes
several antibiotics target bacterial ribosomes
prevent the bacteria from making new proteins
define storage granules (inclusion bodies)
usually deposits or granules of nutrients, stored for later use
examples :
-sulfur granules
-polysaccharides
-lipid inclusions
-enzymes
-magnetite
variety of inclusion bodies occur in different bacterial species- can serve as a basis for identification
storage granules (inclusion bodies)
define what endospores
formed only by some Gram positive bacteria
special resting structure-allows bacteria to enter dormant state
endospores
endospores
extremely durable (resists heat, desiccation, chemicals, radiation, etc)
- some endospores can survive in boiling water for hours
remains dormant until good growth conditions occur- can form a new population
what does bacillus anthracis cause?
causes anthrax
what does clostridium botulinum cause?
causes the food borne illness botulism
name the steps of sporulation
- cell replicates its DNA
- septum forms, dividing the cell into unequal compartments
3.larger compartments engulfs the smaller
4.peptidoglycan and other protective material forms around the forespore (spore coat)
5.finished spore is freed from the mother cell as the mother cell dies.
what are the internal components?
cytoplasm
the nucleoid
ribosomes
storage granules
endospores
sporulation
define the characteristics of eukaryotic cell structure
includes microorganisms
higher organisms
includes microorganisms : Algae, fungi, protozoa
Higher organisms : Plants and animals, larger and more complex than prokaryotes , genetic material is housed in a nucleus
-membrane bound organelles
is the cytoplasmic membrane the same basic structure as in prokaryotic cells?
yes they do have the same cytoplasmic membrane
what does cytoplasmic membrane contain?
contains phospholipids, proteins, and sterols, sterols make membrane relatively rigid compared to bacteria
true or false.
Not all eukaryotes have a cell wall?
true
define the characteristics of cell wall
not all eukaryotes have a cell wall
- allows endocytosis
it is simple structure compared to bacteria made of cellulose (algae,plants)
and chitin (fungi)
define the characteristics of cytoplasm.
substance inside the plasma membrane, but outside the nuclear membrane
cytoplasm has complex internal structure, what is it called?
cytoskeleton
protein filaments on the inside of the plasma membrane, provides support and shape & transports substances through the cell
cytoskeleton
Ribosomes:
- larger and heavier than bacterial ribosomes (eukaryotes)
80s
made of strands of the protein actin, often interact with strands of other proteins
microfilaments
long, hollow cylinders made up of many molecules of the protein tubulin. Tubulin consists of two subunits, x tubuin , and b tubulin.
microtubules
intermediate filaments
made up of fibrous proteins organized into tough, ropelike assemblies that stabilize a cells’ strcuture and help maintain its shape
membrane bound organelles
structures with specialized functions and not present in bacteria
what are some-examples of membrane bound organelles
nucleus, mitochondria, chloroplasts
what is a nucelus?
compartment holding genetic material
what is mitochondria?
site of energy producion
what is chloroplasts?
site of photosynthesis in algae and plant cells
appendages external to the cell are
flagellum and cilia
what is a flagellum and cilia?
long flexible projections that contain protein and cytoplasm
-move in whipped likefashion which can be used in motility and sweeping material past stationary cells
define the characteristics of prokaryotic vs eukaryotic flagella , distinguish between the two
prokaryotic flagella:
- made of protein subunits
-protrude through the cell wall and cell membrane
-stiff, twirl like propeller
eukaryotic flagella:
covered by cell membrane
whipping action
a bundle (9+2) of microtubules (made of protein)
