Cell 6 Flashcards
Enzymes from what organelles are required for steroid hormone synthesis?
mitochondrial and sER enzymes
What stain is used to see the ragged red fiber of the mitochondria in MERRF?
Gomori trichrome stain (MERRF- myoclonic epilepsy with ragged red fibers)
What is myoclonus?
involuntary twitching (can be both normal and pathologic depending)
What are the functions of peroxisomes?
1) beta oxidation of FFAs
2) plasmalogen synthesis
3) regulate H2O2
4) kill pathogens
5) oxidize EtOH (detoxification in cooperation with sER)
What is Zellweger syndrome?
impaired import of enzymes into peroxisomes
What are the types of cytoskeletal elements?
microtubules
microfilaments
thick filaments
intermediate filaments
What are the types of filaments?
actin (thin)
intermediate
myosin (thick)
Are cytoskeletal elements considered organelles?
yes
What is dynein?
ATPase that allow specialized structures such as cilia and flagella to have movement (ATP-dependent)
What functions are microtubules involved in?
mitosis and directing flow of traffic by serving as “tracks” like railways (ATP-dependent)
What is kinesin?
microtubule motor that transports cargo from negative end of the microtubule to the positive end of the microtubule along its tracks
What microtubule motor moves material from the positive end to the negative end of a microtubule?
dynein
What is the normal function of a tau protein?
they form crosslink with 2 microtubules to help organize and stabilize the array of microtubules in a given cell type
What happens to tau proteins in Alzheimer’s?
they become hyperphosphorylated and destabilize the microtubules. the tau proteins will accumulate in the cytoplasm of the nerve cell, leading to formation of neurofibrillary tangles
What happens to the neurofibrillary tangles after death of a cell?
the tangles remain because they are resistant to proteolysis
What staining technique can be used to identify actin microfilaments?
immunocytochemistry
At which end do actin microfilaments grow?
from the positive end, like microtubules
At which end do actin microfilaments disassemble?
negative end, just like microtubules
What inhibits actin polymerization?
cytochalasins
What structures are actin microfilaments found in?
microvilli, cell cortex, adherens belt, filopodia, lamellipodium, stress fibers, and contractile ring (mitosis)
Where will you find cytokeratins?
epithelial cell
Where will you find desmin?
muscle (smooth and striated)
Where will you find glial fibrillary acidic protein (GFAP)?
astrocytic glial cells
Where will you find neurofilament protein?
neurons
Where will you find nuclear lamin?
nucleus of all cells
Where will you find vimentin?
many mesodermal tissues
Why is it important to know where intermediate filaments are localized?
important in identifying the source of a tumor. if 2 diff. filaments are found in the same cell, it means it is a more aggressive tumor
What is the difference between neurofilaments and glial intermediate filaments?
neurofilaments add great tensile strength to axons by extensive cross bridges. Glial intermediate filaments do not have much cross bridges
What kind of inclusions will you find in hepatocytes of a patient who is alcoholic?
inclusions composed of keratin intermediate filaments
What is epidermolysis bullosa simplex?
mutations in keratin gene prevent keratin from assembling into strong networks. result in blistering of the skin due to the synthesis of defective keratins
What are Rosentha’s fibers?
aggregates of GFAP and other proteins. characteristic of pilocytic astrocytoma (tumor of glial cell)
How are centrioles positioned inside a centrosome?
perpendicular to each other
How are centrioles organized?
9 triplet sets of microtubules (9x3)
What is the function of centrosomes, especially centrioles?
they serve as mitotic microtubule organizing center (MTOC)
What cells have two nucleus?
multi-nucleated cells such as muscle cells and liver cells as well
Describe the nuclear envelope
2 lipid bilayers forming a perinuclear space between them
Which layer of the nuclear envelope is usually continuous with rER?
outer membrane
Can nucleus have more than one nucleolus?
yes
What’s in Cajal bodies?
contain the molecular machinery involved in splicing a pre-mRNA
What are PML (promeloctic leukemia bodies) bodies?
involved in DNA repair and initiating apoptosis
