MMG 301 Exam Questions And
Verified Answers
Describe the following bacterial morphologies: coccus,
diplococcus, streptococcus, staphylococcus,bacillus, spirochete, filamentous, vibrio -
Answer coccus: a ball
diplodocus: two balls
streptococcus: a chain of balls
staphylococcus: a triangle of balls
spirochete: a loose spiral, zig zag
filamentous: a straight but wavy string
vibrio: a squised pillow sac, or a bean
Understand the differences between light and electron microscopes; be able to label
the parts of a brightfield microscope, and transmissiterm-2on and scanning electron
microscopes - Answer light: glass lense
different designs:
bright field: light is transmitted through the specimen, objects viewed against bright
background, contrast limits viewing of cells since they are transparent, most bacterial
cells are NOT easily seen with this microscope but some can still be seen, used for
simple stains
phase contrast: converts changes in refractive index into contrast
dark field: specimen viewed on a dark background
fluorescence: relies on artifical or natural fluorescence
electron: magnets
provide high resolution and high magnification, used to study cell internal structure an
dsurfaces, uses a beam of electrons, disadvantage: must preseve and dehydrate the
specimen, view it in a vacuum
types:
TEM: choice to resolve internal cell structures and very thin appendages on bacteria,
can visaulize details down to molecular level
,theoretical limit of resolution: .2 nm, limitations: cells dried and dead, preparation: cells
to plastic to slice, staining: metal salts, in a vacuum
SEM: images created from secondary elecron emitted off object surface, smaple prep:
dry, coated with metal ions
advantages: high depth of field, ideal for viewing surfaces colonized by bacteria
create a crude diagram (microscope slide and objective lens) of how immersion oil is
beneficial to light microscopy - Answer oil immersion gives an increased amount of light
passing through the specimen, image on pg 4 of module 2 slides
for a given change in numerical aperture or wavelength be able to explain its effect on
resolving power - Answer the smallest object resolvable: 0.5 x wavlength/ NA
short wavlength, better resolution
Arrange the steps in the Gram stain in the correct order; know
colors, stains, washes, and results of each step - Answer 1. flood the heat-fixed smear
with crystal violet for 1 min
result: all cells purple
2. add iodine solution for 1 min (mordant or iodine forms complexes in cell wall)
results: all cells remain purple
3. decolorize with alcohol breily, 20 seconds
results: gram positive cells are purple and gram negative cells are colorless
4. counterstain with safranin for 1-2 minutes
result: gram positive cells are purple, gram negative cells are pink to red
discriminate between how transmission and scanning electron microscopes operate:
how do they each visualize the specimen and explain which is best for surfaces and for
visualizing internal or external cell structures - Answer SEM: if you want to look at the
surface of the specimen, specimen scanned through
SEM: images created from secondary elecron emitted off object surface, smaple prep:
dry, coated with metal ions
advantages: high depth of field, ideal for viewing surfaces colonized by bacteria
TEM: choice to resolve internal cell structures and very thin appendages on bacteria,
can visaulize details down to molecular level
theoretical limit of resolution: .2 nm, limitations: cells dried and dead, preparation: cells
to plastic to slice, staining: metal salts, in a vacuum
, TEM: if you want to look at the internal structure of the specimen, specimen passed
through
label the parts of a phospholipid molecule; be able to diagram a lipid bilayer (like the
bottom left of slide 4) - Answer module 3 page 4
phospholipids are made of fatty acids linked to glycerol phosphate linked by an ester
bond, some phospholipids also contain charged groups on the phosphate
phosphlipids form a lipid bilayer, phospholipids are AMIPHIPATHIC molecules:
hydrophobic and hydrophillic, phosphlipids can move within the bilayer
know the chemical structural differences between ester lipids and ether lipids - Answer
bacteria and eukaryotes: have ester lipids
ester: double bond onto a carbon
archaea have severl types of ether lipids: ether has. a C-O-C bond
explain what the fluid mosaic model of membrane structure is - Answer proteins can be
located on one side of the bilayer, and some proteins span both layers
since most substances cannot difuse through the membrane, they must be transported
across the membrane by speical proteins
the fluid charactersitic of the membrane allows proteins to move relative to eachother
review the three main functions of the cytoplasmic membrane - Answer permeable
barrier:
surrounds teh contents of the cell, its what makes a cell a cell
prevents leakage and functions as a gateway for transport of nutrients into and wastes
out of the cell
protein anchor:
site of many proteins that particpate in transport, bioenergetics and chemotaxis
proteins that perform energy generation, nutrient transport, chemical sensing and
motility are anchored int the cyptoplasmic membrane
energy conservation:
site of generation and dissipation of the proton motive force, since ions cannot diffuse
through the membrane, an eletrically charged membrane is created, this charge is used
for energy production
understand why most nutrients need to be transported into the cell through the
cytoplasmic membrane - Answer - the cytoplasmic membrane is a barrier for required
cell nutrients, transport proteins are needed to facilitate entry of these chemicals into
Verified Answers
Describe the following bacterial morphologies: coccus,
diplococcus, streptococcus, staphylococcus,bacillus, spirochete, filamentous, vibrio -
Answer coccus: a ball
diplodocus: two balls
streptococcus: a chain of balls
staphylococcus: a triangle of balls
spirochete: a loose spiral, zig zag
filamentous: a straight but wavy string
vibrio: a squised pillow sac, or a bean
Understand the differences between light and electron microscopes; be able to label
the parts of a brightfield microscope, and transmissiterm-2on and scanning electron
microscopes - Answer light: glass lense
different designs:
bright field: light is transmitted through the specimen, objects viewed against bright
background, contrast limits viewing of cells since they are transparent, most bacterial
cells are NOT easily seen with this microscope but some can still be seen, used for
simple stains
phase contrast: converts changes in refractive index into contrast
dark field: specimen viewed on a dark background
fluorescence: relies on artifical or natural fluorescence
electron: magnets
provide high resolution and high magnification, used to study cell internal structure an
dsurfaces, uses a beam of electrons, disadvantage: must preseve and dehydrate the
specimen, view it in a vacuum
types:
TEM: choice to resolve internal cell structures and very thin appendages on bacteria,
can visaulize details down to molecular level
,theoretical limit of resolution: .2 nm, limitations: cells dried and dead, preparation: cells
to plastic to slice, staining: metal salts, in a vacuum
SEM: images created from secondary elecron emitted off object surface, smaple prep:
dry, coated with metal ions
advantages: high depth of field, ideal for viewing surfaces colonized by bacteria
create a crude diagram (microscope slide and objective lens) of how immersion oil is
beneficial to light microscopy - Answer oil immersion gives an increased amount of light
passing through the specimen, image on pg 4 of module 2 slides
for a given change in numerical aperture or wavelength be able to explain its effect on
resolving power - Answer the smallest object resolvable: 0.5 x wavlength/ NA
short wavlength, better resolution
Arrange the steps in the Gram stain in the correct order; know
colors, stains, washes, and results of each step - Answer 1. flood the heat-fixed smear
with crystal violet for 1 min
result: all cells purple
2. add iodine solution for 1 min (mordant or iodine forms complexes in cell wall)
results: all cells remain purple
3. decolorize with alcohol breily, 20 seconds
results: gram positive cells are purple and gram negative cells are colorless
4. counterstain with safranin for 1-2 minutes
result: gram positive cells are purple, gram negative cells are pink to red
discriminate between how transmission and scanning electron microscopes operate:
how do they each visualize the specimen and explain which is best for surfaces and for
visualizing internal or external cell structures - Answer SEM: if you want to look at the
surface of the specimen, specimen scanned through
SEM: images created from secondary elecron emitted off object surface, smaple prep:
dry, coated with metal ions
advantages: high depth of field, ideal for viewing surfaces colonized by bacteria
TEM: choice to resolve internal cell structures and very thin appendages on bacteria,
can visaulize details down to molecular level
theoretical limit of resolution: .2 nm, limitations: cells dried and dead, preparation: cells
to plastic to slice, staining: metal salts, in a vacuum
, TEM: if you want to look at the internal structure of the specimen, specimen passed
through
label the parts of a phospholipid molecule; be able to diagram a lipid bilayer (like the
bottom left of slide 4) - Answer module 3 page 4
phospholipids are made of fatty acids linked to glycerol phosphate linked by an ester
bond, some phospholipids also contain charged groups on the phosphate
phosphlipids form a lipid bilayer, phospholipids are AMIPHIPATHIC molecules:
hydrophobic and hydrophillic, phosphlipids can move within the bilayer
know the chemical structural differences between ester lipids and ether lipids - Answer
bacteria and eukaryotes: have ester lipids
ester: double bond onto a carbon
archaea have severl types of ether lipids: ether has. a C-O-C bond
explain what the fluid mosaic model of membrane structure is - Answer proteins can be
located on one side of the bilayer, and some proteins span both layers
since most substances cannot difuse through the membrane, they must be transported
across the membrane by speical proteins
the fluid charactersitic of the membrane allows proteins to move relative to eachother
review the three main functions of the cytoplasmic membrane - Answer permeable
barrier:
surrounds teh contents of the cell, its what makes a cell a cell
prevents leakage and functions as a gateway for transport of nutrients into and wastes
out of the cell
protein anchor:
site of many proteins that particpate in transport, bioenergetics and chemotaxis
proteins that perform energy generation, nutrient transport, chemical sensing and
motility are anchored int the cyptoplasmic membrane
energy conservation:
site of generation and dissipation of the proton motive force, since ions cannot diffuse
through the membrane, an eletrically charged membrane is created, this charge is used
for energy production
understand why most nutrients need to be transported into the cell through the
cytoplasmic membrane - Answer - the cytoplasmic membrane is a barrier for required
cell nutrients, transport proteins are needed to facilitate entry of these chemicals into
