Lectures 23-24 Flashcards
What is a cytoskeleton?
provides eukaryotic cells the abilities to
adopt a variety of cell shapes,
organize the components in the cytoplasm,
interact mechanically with the environment,
carry out coordinated movement.
What are the three major types of filaments are their diamters?
- ___intermediate filament____ (__10_ nm diameter)
- ___microtubules____ (__25_ nm diameter)
- ___actin filament___ (__7__ nm diameter)
II.
What is the structure of intermediate filaments?
- subunits are fibrous proteins with N-terminal globular head, C-terminal globular tail,
and a central elongated helical rod domain. - Coiled-coil dimmer tetramer 8 tetramers twist into rope-like filament
What is the function of intermediate filaments?
provide great mechanical strength
1. __muscle_ cells and __skin__ epithelial cells
2. along the length of nerve cell axons.
What is a tissue?
is an ensemble of cells, not necessarily identical, but from the same origin, that
together carry out a specific function.
What are the four major types of tissue in animals?
- __connective tissue___ – such as bone, blood
- __epithelial tissue___ – layers of cells that cover organ surfaces
- __nervous tissue___ – central nervous system and peripheral nervous system
- __muscular tissue___ provides contractility
What is the function of a tight junction?
- connect plasma membrane of adjacent cells, typically epithelials, in a sheet
partition plasma membranes – apical vs basal membranes - form barrier to protect organs
What is the function of the adherens junction?
linking actins of adjacent cells
What is the function of the desmosome?
linking intermediate filaments
Key connecting proteins called ___cadherins___
What is the function of gap junctions?
are protein channels – made of connexins
What is the function of hemidesmosomes?
anchoring cells to ECM through integrin
What is the structure of the Extracellular Matrix (ECM)?
- __collagen__ is one of the major components.
- other components such as laminin, fibronectin, gelatin, and more.
What do mutations in the ECM create?
skin blisters
What is a tumor?
solid lesion formed by an abnormal growth of cells –__neoplasm__
usually caused by multiple mutations in __somatic__ cells
What are the functions of metastatic cancer cells?
- change cell junctions
- break loose
- epithelial-mesenchyme transition (EMT)
- degrade extracellular matrix (ECM)
- metastasize
What creates oncogene?
hyperactive_ proto-oncogene due to mutations or other DNA abnormalities
What is the counteraction of oncogene?
- oncogenes – promoting growth in normal situation
a. cause cancer when hyperactive (or __gain-of-function__ mutation)
What is the counteraction of tumor suppressor genes?
- tumor suppressor genes – provide growth check in normal situation
a. cause cancer when inactive (or __loss-of-function___ mutation)
Describe the tumor size chart
visible on x-ray when __108__ cells, palpable when __109__ cells, causes
death when _1012__ cells
What is Gleevec?
_ is a new type of anti-cancer drug that inhibits oncogenic kinase(s).
What is the tissue renewal rate for most nerve cells?
zero
What is the tissue renewal rate for intestinal cells?
3-6 days
What is the tissue renewal rate for red blood cells?
120 days (replenished by stem cells in bone marrow)
What is the tissue renewal rate for bone tissue?
10 years
What is the tissue renewal rate for skin cells?
2 months
What is a stem cell?
an undifferentiated cell that can continue dividing indefinitely, generating
daughter cells that undergo terminal differentiation into particular cell types
What are the characteristics of stem cells?
Undifferentiated, able to self renew, ___small______ number,
___slow__ dividing
Embryonic Stem Cells
taken from the inner cell mass of early embryo
at __blastocyst__ stage
a. can be maintained in culture almost indefinitely
b. can differentiate into many cell types depending on
___growth factors___ or ____hormones______.
Adult Stem Cells
stored in particular niches, multipotent
a. intestinal stem cells lie near the bottom of the ___crypt__
b. epidermal stem cells at the basal layer adherent to the basal lamina
c. hemopoietic ( or hematopoietic ) stem cells (HSC) in the bone marrow
d. hair follicle stem cells in the bulge
Induced Pluripotent Stem cells
a. use ___differentiated_somatic____ cells from adult
b. introduce three key genes: __c-Myc____, __Sox-2____, __Oct-4__
c. the differentiated cells return to undifferentiated and pluripotent status, iPS.
d. iPS then can differentiate into many different cell types
What is totipotent?
capable of giving rise to extra-embryonic tissues and the complete
embryo
What is Pluripotent?
capable of giving rise to many different cell types
What is multipotent?
capable of giving rise to limited set of cell types
