Lecture 2: Cellular Organization 2

Question 1

Protein filaments

Answer 1

1) actin filaments (microfilaments)
Functions:
-important for whole cell movement (neutrophils)
-cell anchorage, structural core of microvilli and stereocilia

-assembled w actin: G-actin= free actin in cytoplasm, F-actin= polymerized actin (ATP dependent)

2) intermediate filaments
- stabilizes cell
- not involved in cell movement

3) microtubules (tubulin)
- positive and negative end
- cell motility, uses motor proteins to move things in cell
- mitotic spindle

Question 2

Microtubule polymerization

Answer 2

GTP dependent
Positive end= fast growing

MAPS (microtubles associated proteins):

• Tau proteins= Abundant in neurons of the CNS, stabilize axonal microtubules
• hyperphosphorylation of Tau proteins can create tangles= Alzheimer’s

Question 3

Colchicine

Answer 3

Chemotherapy

Prevents microtubule polymerization by binding unpolymerized tubulin molecules

Given to dividing cells then the mitotic spindle breaks down and cell death occurs

Question 4

Taxol (paclitaxel)

Answer 4

Chemotherapy

Stabilizes and prevents microtubule disassembly by preferentially bonding tubuli within assembles microtubules

Arrests dividing cells (unable to achieve metaphase spindle conformation)

Question 5

Dynenin

Answer 5

Motor protein
Moves along microtubules toward negative end
Found in cilia and flagella
Binding site for organelles, vesicles, other microtubules
Largest and fastest of motors

Question 6

Cilia

Flagella

Primary cilia

Answer 6

All important for movement
Movement produced by bending of core (axoneme)

Cilia- 9+2 arrangement

Primary cilia- 9+0 arrangement
Defects: poly cystic kidney disease

Question 7

Kinesin

Answer 7

Move along microtubules toward positive end (anterograde)

Binding site for vesicles, organelles, and other microtubules

Question 8

Cell movement

Answer 8

(PAC)

Protrusion- actin polymerization at the positive end protrudes lamellipodium (leading edge of cell)

Attachments- focal adhesion anchor actin cytoskeleton to ECM vis integrity proteins

Contraction- bulk of trailing cell and cytoplasm is drawn forward (via myosin 2)

Types of protrusion:

1) filopodia- finger like projections
2) lamellipodia- sheet like projections
3) pseudopodia- 3D projections

Question 9

Phalloidin

Answer 9

Found in Amanita phalloides

Disrupts normal function of actin

Binds F actin more tightly than G actin
Promotes excessive polymerization and inhibits depolymerization

Inhibits cell movement

Question 10

Cytochalosin

Answer 10

Blocks polymerization of actin

Question 11

Neutrophil migration: Extravasation

Answer 11

1) rolling
2) activation
3) adhesion
4) transendothelial migration (process of diapedesis)

Chemotaxis:
-movement within the tissue along a chemotactic gradient towards the source of inflammation

Question 12

Inclusions:

Lipofuscin

Answer 12

Wear and tear pigment

Brownish gold pigment

Seen in nondividing cells

Question 13

Inclusions:

Hemosiderin

Answer 13

Brown pigment

Iron storage complex found in cytoplasm

In indigestible residues and hemoglobin

Question 14

Inclusions:

Melanin

Answer 14

Brown

Question 15

Inclusions:

Glycogen

Answer 15

Nonmembrsne bound, TEM dense bodies, storage form of glucose

Question 16

Inclusion:

Lipid

Answer 16

Non-membrane bound, TEM dense, energy store and source of short carbon chains for membrane synthesis

Lipid storage disease:
-lipidoses: lipid droplets accumulated in abnormal amounts or locations