BCMB 311 Exam 1 Questions with Verified Correct
Answer
what are the basic features of a cell?
-contain a membrane
-enclose genetic material and biomolecules
-consume fuels to release energy and build biomolecules
-can replicate
What are some advantages and disadvantages of light microscopy as compared to electron
microscopy?
light microscopy allows us to see some cellular structures and allows us to view live cells and
their dynamic behaviors. however, due to light resolution, anything smaller than 0.2 micrometers
is undistinguishable. fluorescent light microscopy allows to determine localization of of proteins
and allow us to generate 3D models.
electron microscopy allows us to see fine structures of the cell, however this cannot be done with
live cells. specimen must also be super thin
What are some ways features within a cell be labeled in light microscopy? (Stains/dyes,
specific antibodies coupled to a fluorophore, genetic fusions between a gene encoding a
protein-of-interest and a fluorescent protein)
-staining reveals the different components of a cell, making each component easier to see.
-fluorescent dyes bind to certain structures
,-fluorescently labeled antibodies can bind to specific targets within a cell making them visible;
fluorescent dye also allows us to see colocalization
How does fluorescence work? Be able to explain the following: fluorophore, excitation
wavelength, emission wavelength
a post-translationally fluorescent modified active site called a fluorophore. fluorescent molecules
absorb light at one wavelength (excitation wavelength) and emit it at another, longer wavelength
(emission wavelength); higher energy photon is absorbed then emitted at a lower energy with
some lost as heat
What is "resolution" in the context of microscopy? What is the numerical resolution limit
of light microscopy? In basic terms, what aspect of the nature of light causes this
limitation?
resolution is the smallest distance between two objects that allows them to be identified as
different objects. light microscopy is limited at 0.2 micrometers. this is limited by the diffraction
of light
How can a fusion protein be used to study the localization of a protein in a living cell by
fluorescence microscopy?
What does "confocal" fluorescence microscopy do differently than non-confocal
fluorescence microscopy? What is an optical section?
confocal scans the specimen with a laser beam, focused on a single point at a specific depth in
the specimen. a pinhole aperture allows only fluorescence emitted from this point to be included
in the image. scanning the beam across the specimen generates a sharp image of the plane of
, focus (optical section). a series of optical sections at different depths allows a 3D structure to be
made.
What would be different about the images of a cell when taken by TEM vs SEM?
SEM includes the coating of the specimen in a heavy metal, allowing the microscope to build 3D
objects with great depth and resolution between 3nm and 30nm. TEM acts similar to light
microscopy but can resolve up to 1nm.
Know the basics about the structures and roles of the: nucleus, nuclear envelope, ER, Golgi
apparatus, mitochondria, lysosome, peroxisome, chloroplast, and transport vesicles?
nucleus: information store of the cell
mitochondria: generates usable energy from food molecules; uses molecular fuels and oxidizes
them to produce ATP and CO2
lysosomes: contain enzymes for degradation and recycling of biomolecules
peroxisomes: contain hydrogen peroxide and are sites of certain chemical reactions such as
inactivation of toxins. also the sites where yeas and plants break down fats
transport vesicles: carry internal protein cargo and membrane from the ER to the golgi network
as part of the secretory pathway
golgi apparatus: composed of a stack of flattened membrane-composed discs; each stack
Answer
what are the basic features of a cell?
-contain a membrane
-enclose genetic material and biomolecules
-consume fuels to release energy and build biomolecules
-can replicate
What are some advantages and disadvantages of light microscopy as compared to electron
microscopy?
light microscopy allows us to see some cellular structures and allows us to view live cells and
their dynamic behaviors. however, due to light resolution, anything smaller than 0.2 micrometers
is undistinguishable. fluorescent light microscopy allows to determine localization of of proteins
and allow us to generate 3D models.
electron microscopy allows us to see fine structures of the cell, however this cannot be done with
live cells. specimen must also be super thin
What are some ways features within a cell be labeled in light microscopy? (Stains/dyes,
specific antibodies coupled to a fluorophore, genetic fusions between a gene encoding a
protein-of-interest and a fluorescent protein)
-staining reveals the different components of a cell, making each component easier to see.
-fluorescent dyes bind to certain structures
,-fluorescently labeled antibodies can bind to specific targets within a cell making them visible;
fluorescent dye also allows us to see colocalization
How does fluorescence work? Be able to explain the following: fluorophore, excitation
wavelength, emission wavelength
a post-translationally fluorescent modified active site called a fluorophore. fluorescent molecules
absorb light at one wavelength (excitation wavelength) and emit it at another, longer wavelength
(emission wavelength); higher energy photon is absorbed then emitted at a lower energy with
some lost as heat
What is "resolution" in the context of microscopy? What is the numerical resolution limit
of light microscopy? In basic terms, what aspect of the nature of light causes this
limitation?
resolution is the smallest distance between two objects that allows them to be identified as
different objects. light microscopy is limited at 0.2 micrometers. this is limited by the diffraction
of light
How can a fusion protein be used to study the localization of a protein in a living cell by
fluorescence microscopy?
What does "confocal" fluorescence microscopy do differently than non-confocal
fluorescence microscopy? What is an optical section?
confocal scans the specimen with a laser beam, focused on a single point at a specific depth in
the specimen. a pinhole aperture allows only fluorescence emitted from this point to be included
in the image. scanning the beam across the specimen generates a sharp image of the plane of
, focus (optical section). a series of optical sections at different depths allows a 3D structure to be
made.
What would be different about the images of a cell when taken by TEM vs SEM?
SEM includes the coating of the specimen in a heavy metal, allowing the microscope to build 3D
objects with great depth and resolution between 3nm and 30nm. TEM acts similar to light
microscopy but can resolve up to 1nm.
Know the basics about the structures and roles of the: nucleus, nuclear envelope, ER, Golgi
apparatus, mitochondria, lysosome, peroxisome, chloroplast, and transport vesicles?
nucleus: information store of the cell
mitochondria: generates usable energy from food molecules; uses molecular fuels and oxidizes
them to produce ATP and CO2
lysosomes: contain enzymes for degradation and recycling of biomolecules
peroxisomes: contain hydrogen peroxide and are sites of certain chemical reactions such as
inactivation of toxins. also the sites where yeas and plants break down fats
transport vesicles: carry internal protein cargo and membrane from the ER to the golgi network
as part of the secretory pathway
golgi apparatus: composed of a stack of flattened membrane-composed discs; each stack
