2-cell anatomy: organelles Flashcards
how can you visualize internal cell structures?
fluorescent-based microscopy techniques
electron microscopy
what structures exist within the cell?
organelles
cytoskeleton (filaments/proteins)
what is light microscopy and what is the resolutioin
relies on glass lenses and light
resolution of 0.2 um
what is electron microscopy and what is the resolution?
relies on electron beams and electromagnets as the lenses
resolution of 0.1 nm
why is light microscopy favored to view cell structures?
-sample preparation is straightforward
-sample preparation is inexpensive
-overall, it is relatively non-destructive to cells
-can be used to visualize living cells of fixed (dead)
what can we use to stain and visualize contents within a cell?
fluorescent probes
what is the basic concept of fluorescent dyes?
-small fluorescent molecules that selectively bind to various cellular components can be added to cells
-dyes concentrate in different parts of the cell and can be used to highlight specific parts
-visualized using fluorescent microscope
what is an example of a fluorescent marker protein ?
GFP : green fluorescent protein
how does GFP work?
-gene sequence encoding GFP can be ligated to a gene sequence that encodes a protein of interest
cells _______ the GFP tagged fusion protein
translate
what is an advantage of GFP
GFP fusions can be visualized in live cells
examples of fluorescent proteins used in light microscopy?
GFP
Immunofluorescence
what is the basic concept of immunofluorescence?
-proteins visualized using antibodies and fluorescence
-antigen+primary antibody + secondary antibodies +marker
what is the main difference of GFP and immunofluorescence?
GFP tags can be used in live cells
Immuno- added to cells after they are dead
which antibody is fused to a fluorescent marker in immuno?
secondary
Hoechst dye marks what
nuclei
what is another use for fluorescent probes?
Genetic engineered animals
General Electron microscopy?
-EM has higher resolving power
-EM sample preparation is more complex
-EM is more destructive to cells
-EM can only be used on dead and dried specimens
Transmission Electron Microscopy general?
-samples stained with electron dense materials
-image collected based on electrons that move through sample
-samples are thinly sliced
-2D
Scanning EM
-simpler, small, cheaper than TEM
-lower resolution than TEM
-samples coated with electron dense heavy metals
-image collected based on electron scattering off sample surface
-image is 3D
what are organelles
specialized subunit within a cell that has a specific function, and usually separately enclosed within its own lipid bilayer
most organelles are bound by _________
lipid bilayers
what are some benefits of organelles
-allows for separation and specialization of cellular processes
-allows for efficient consolidation of functions within specific compartments
-allows for isolation of potentially deleterious reactive molecules/waste products
organelles can be grouped into 3 categories
- manufacture
- breakdown
- energy processing
which organelles are used in manufacture
nucleus, ER, golgi apparatus
what organelles are in breakdown
proteasome
lysosome
peroxisome
what organelles in energy processing
mitochondria
all _______ contain the same basic set of organelles
eukaryotes
what are features of the nucleus?
-round/elliptical shape
-double membrane
-membrane contains protein holes that facilitate entry and exit of proteins/nucleic acid
-contains one or more nucleoli
-contiguous with ER
what is the function of nucleus
-control center of cell
-principal site of DNA and RNA synthesis
-Nucleolus is the site of rRNA synthesis
what is structural features of ER
-membrane network that extends from the nucleus throughout the cell
-contains rough ER (ribosomes) and smooth ER
function of ER
-roles in lipid (SER) and protein (RER) biosynthesis
-storage site for Ca
-initial site of protein glycosylation
what is the system that ER is part of
part of exocytic (secretory) pathway
Golgi structural features
-stack of disc like compartments (cisternae)
-stack has polarity (cis is closest to ER) (trans further from ER)
function of Golgi
-major site of protein sorting and modification
-receives proteins and lipids from ER and dispatches them to various destinations
-site of extensive protein glycosylation
system that golgi is part of
part of exocytic (secretory) pathway
structural features of proteasome
-protein complex
-found in cytoplasm and nucleus
-not membrane bound
function of proteasome
-degrades foreign proteins in cytoplasm
-degrades cellular proteins that do not properly fold in the cytoplasm/ER
how are proteins tagged for proteasome degredation?
-tagged through a covalent linkage to a small protein (ubiquitin)
where does biogenesis and folding of polypeptides usually occur
cytoplasm/ER lumen
proteosome is in ______
cytoplasm
proteosome degrades proteins that misfold in __________
cytoplasm and ER
3 steps of Ub tagging
- ATP dependent conjugation of Ub to Ub activating enzyme (E1)
- Transfer of activated Ub to an Ub conjugating enzyme (E2)
- Transfer of Ub from the E2 to target proteins by an Ub proteins ligase (E3)
lysosomes structural features
-membrane bound spheres
-filled with enzymes (hydrolases)
function of lysosomes
-digestion of nucleic acids/proteins/lipids
-contents come to lysosome via endosomes
what systems is the lysosome part of
endocytic pathway
what are several pathways that contents come to the lysosome
- endocytosis
- autophagy
- phagocytosis
how does the Ub addition cause different outcomes
- based on the type of ubiquitin chain
- and/or whether a single or multiple Ub proteins are added
proteins can be _________ from the cell surface upon _______
internalized
ubiquitination
ubiquitin tag recognized by
clathrin coat
receptors can either _____ back to _____ or progress to lysosome for ______
recycle
plasma membrane
degradation
structural features of peroxisome
-membrane bound spheres
-contain enzymes involved in various oxidation reactions
function of peroxisome
-site of oxidative metabolism
-breakdown of fatty acids to produce acetyl CoA
-convert free radicals to peroxide
-convert peroxide to water
structure of mitochondria
-double membrane structure which forms folds called cristae
-contain own genome
function of mitochondria
-powerhouse of the cell
-provides energy ATP for the cell
organelle ___ and ____ can be used to classify types and used as diagnostic marker of disease
shape, size
many cancer cells have _____
enlarged nuclei, irregular nuclear contour
altered chromatin content
______ of cell organelle function is associated with a variety of disease pathologies
disruption
