FTM_02 Flashcards
What is the purpose of the cytoskeleton
- Structural support and stability
- Organization
- Cell division
- Cell movement
- Tracks for motor proteins to move organelles and vesicles
3 types of protein filaments are
1) Actin (thin-filaments or microfilaments)
2) Intermediate filaments
3) Microtubules (thick filaments)
Functions of microtubules
- Intracellular transport
- Cell motility (cilia, flagella)
- Mitotic spindle formation
Structure of microtubules
- hollow -α and β tubulin protein subunits
- polar (+ and - ends)
Structure of centrioles
9 triplets of microtubules arranged around a central axis
Function of centrioles
- Organize the centrosome
- Basal body of cilia and flagella
- Mitotic spindle formation
What is the nickname for the centrosome
-Microtubule organizing center (MTOC)
Function of the centrosome
- Organize microtubules • Initiate microtubule formation
- Microtubules are nucleated at the centrosome at their negative (-) ends
- Positive (+) ends point out and grow toward the cell periphery
Structure of the centrosome
- pair of centriole perpendicular in the center
- contain a gamme tubulin ring complex
Polymerization of microtubules are directed and organized at
MTOC’s
Polymerization of microtubules is a _____ dependent process
GTP
Tau proteins are
Proteins that stabalize axonal microtubules
What happens if hyperphosphorylation of tau proteins occur
-Alzheimers disease
Colchicine (Vinblastine Vincristine)
- Anticancer compound
- Prevents polymerization and breaks down mitotic spindle
Paclitaxel
- Anticancer drug
- Stabilizes and prevents microtubule disassembly
- Unable to achieve metaphase spindle conformation
Name all the microtubule motor proteins
- Dynein Family
- Kinesin Family
What direction do Dynein motor proteins move
Move in the (-) direction along microtubules
What direction do Kinesin motor proteins move
Move in the (+) direction along microtubules
What are two examples of structure that are highly motile and are comprised of microtubules.
-Cilia and flagella.
Axonemal motor proteins are associated with
Cilia and flagella.
***that makes sense bc they are both made of microtubules.
The 9+2 arrangment is characteristic of
Cilia
Motor protein associated with cilia
Dynein arms
9+0 arrangment is characteristic of
Primary Cilia
Primary cilia is basically
Sensory cilia.
Makes up chemorecptors, photoreceptors and mechanocreceptors
Describe Polycystic Kidney Disease
Disease in which cysts develop in the kidney.
Affects the functioning of mechanoreceptors
Involved w/primary cilia
What is the function of intermediate filaments
Have a rope like structure
Stabilize cell structure
Resist shearing forces
List the 6 classes of intermediate filaments
1 & 2: Keratin
3: Vimentin
4: Neurofilaments
5: Lamins
6: Beaded Filaments
What are the two types of actin
- F-actin
- G- actin
Describe G-actin
-unpolymerized actin
Describe F-actin
- F (filament) actin
- Polymerized actin
- Polymerization requires ATP
Function of F-actin
- makes up microvilli and stereocillia
- important in cell motility and locomotion
- aids in absorption
Explain the polarity of F-actin
- Fast growing (+) positive end
- Slow growing (-) negative end
What is Phalloidin
- A fungal toxin which lead to excessive F-actin polymerization.
- Inhibits cell movement
- Causes liver and kidney failure
What are Cytochalasins
- A fungal toxin in which actin cannot be polymerized
- inhibits cell movement and can lead to apoptosis
Describe stereocilia
- longer than microvilli
- comprised of actin
- Limited distribution
- Epididymis
- Proximal ductus deferens
- Sensory hair cells of inner ear
Name the motor protein associated with actin
-myosin
Myosin II is very important in generating:
-Movement/contraction of muscular and skeletal tissue
Release of inorganic phosphate from myosin ll causes
-power stroke
The power stroke is
The force generated that causes a conformational change b/w the actin and myosin heads
Explanation of cell movement
1) Protrusion:
Actin polymerization (+) protrudes (goes beyond) lamellipodium
2) Attachment:
Cytoskeleton gets anchored to the extracellular matrix
3) Contraction
Cell drawn forward via myosin-ll
Protrusions of the cell membrane are ALWAYS driven by what filament
ACTIN
What are the three types of protrusions
• Filopodia
- Finger-like projections
- Core of long, bundled actin filaments
• Lamellipodia
- Sheet-like structures
• Pseudopodia
- 3 dimensional projections
What are inclusions
Structures produced by metabollic products of the cell
Give 3 examples of inclusions
1) pigement
2) glycogen
3) lipids
What is Lipofuscin
- type of pigment
- brownish-gold
- found in non-dividing cells
- builds over time
What is Hemosiderin
- a type of pigment
- brown color
- found in macrophages that engulf RBC’s
- iron storage
What is Melanin
- type of pigment
- produced by melanocytes
- oxidation of tyrosine causes pigment to be dark brown, brown, reddish color
- responsible for skin and hair color
What is this histological image representing
Neutrophil Migration
What is this histological image
Glycogen
What are these histological images of
Lipids
What is this histological image of
Lipofuscin
What is this histological image of
Melanin
What is this histological image of
Myosin - ll and actin interaction.
What is this histological image of
Stereocilia
What is this histological image of
Microvilli
What is this histological image of
Cilia
What is this histological image of
- Centriole
- Note there are 9 microtubules and they are REALLY fused together
