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Test 1 FTM > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

What are the three different types of protein filaments that form the cytoskeleton?

A

Actin filaments or microfilaments ( 7nm in diameter)
intermediate filaments ( 8- 12 nm)
microtubules (25 nm)

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2
Q

Functions of the cytoskeletal protein filaments?

A 
structural support and stability
organization 
cell division 
cell movement 
tracks for motor proteins
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3
Q

Functions of microtubules?

A
  1. Intracellular transport or movement of vesicles and organelles
  2. cell motility (movement of cilia and flagella)
  3. mitotic spindle (attachment of chromosomes and their movement during cell division
  4. rigid intracellular skeleton- shape and polarity
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4
Q

What is the structure of microtubules?

A

They are non-branching, rigid, and hollow

Made up of alpha and beta tubulin

Have positive end and a negative end

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5
Q

What are the structure of the centrioles?

A

They are made up of nine triplets of microtubules around a central axis

Each triplet is made up of one complete and two incomplete microtubules

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6
Q

What is the function of the centriole?

A

organize the centrosome

basal body formation (needed for the assembly of cilia and flagella)

mitotic spindle formation during cell division

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7
Q

What is the structure of the centrosome?

A

contains a pair of centrioles
arranged in a way that one is perpendicular to another

amorphous protein matrix (around 200)

gamma tubulin ring complexes
nucleation sites for the microtubules

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8
Q

What is the function of the centrosome?

A

organize microtubules

initiate microtubule formation
They are negative at the nucleated side and the positive end grows out to the periphery

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9
Q

Explain polymerization?

A

organized and directed by microtubule organizing centers (basal bodies and centrosome)

This mechanism is GTP dependent NOT ATP

This mechanism is highly dynamic
The positive side grows quickly while the negative end is slow growth

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10
Q

What is a microtubule associated protein?

A

Tau protein

normally found in the CNS and this protein stabilizes axonal microtubules

The hyperphosphorylation of the tau protein can result in the self-assembly of tangles found in AD

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11
Q

Explain the drug colchicine?

A

This drug is an anticancer compound that prevents the polymerization of tubulin molecules

Programmed cell death is the result

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12
Q

Explain vinca alkaloids?

A

There are two kinds vinblastine and vincristine

Both of these compounds prevent polymerization and thus lead to cell death

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13
Q

Explain Taxol (Paclitaxel)?

A

This an anticancer compound that stabilizes and prevents microtubule disassembly

arrests dividing cells during mitosis. they are unable to achieve metaphase and thus die.

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14
Q

The microtubule motor: dynein

A

This protein moves in the negative direction on the microtubule (retrograde) In other words, things are moved in the direction of the nucleus.

Binding sites for vesicles, organelles, and others

very fast movement!

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15
Q

What are the two families of dynein?

A

cytoplasmic dyneins and axonemal dyneins

axonemal (located in cilia and flagella)

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16
Q

Explain the kinesin family of microtubule motors?

A

This motor protein moves in the positive direction and thus away from the cell nucleus (anterograde)

Binding site for vesicles, organelles, and others

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17
Q

Cilia and flagella

A

very specialized motile structures

use microtubules and axonemal dynein motor proteins

The movement is produced by the bending of the axoneme

18
Q

Cilia (function and structure)

A

microtubule based, it is a hair like structure

motile

9+2 microtubule arrangement

move fluid and particles along epithelial surfaces
the cilia are anchored to the cell via the basal body

19
Q

What are the three primary cilia? what are their characteristics?

A

photoreceptors- sight

chemoreceptors - smell

mechanoreceptors- monitors the flow of fluid in the kidney

they have an 9+0 arrangement
connected to the cell via basal membrane
develops from one centriole following cell division

20
Q

What is the structure of intermediate filaments and what functions do they have?

A

They are rope like filaments that are made up of a non-polar and highly variable subunits

Functions:
stabilize cell structure- maintain the position of organelles

resist shearing forces- connect with desmosomes and hemidesmosomes

essential for the integrity of cell to cell and cell to ECM junctions

21
Q

What are the 6 classes of intermediate filaments?

A
  1. keratins (1 and 2)
  2. vimentin and vimentin like
  3. neurofilaments
  4. lamins
  5. beaded filaments
22
Q

explain keratins?

A

intermediate filament

found in all epithelial cells
acid and basic cytokeratins
50 isoforms

23
Q

Explain vimentin and vimentin-like?

A

intermediate filament

Diverse- found all over the body
vimentin is most found in mesoderm-derived cells
(muscles, blood vessels, bone etc)

vimentin-like are found in a variety of cells
desmin- muscle cells
glial fibrillary acid protein- glial cells and astrocytes

24
Q

explain neurofilaments?

A

intermediate filament

extend from the cell body onto the ends of axons and dendrites (support)
found primarily in neurons

25
Q

Explain lamins?

A

Found in the nucleus of all nucleated cells
found in the nuclear lamina
Lamin A and B proteins

26
Q

explain beaded filaments?

A

eye lens specific group

intermediate filament

27
Q

structure and function of actin filaments or microfilaments?

A

Made up of the protein actin
There is G actin (free actin molecules in the cyto) and there is F-actin (polymerized actin in filament and ATP DEPENDENT)

polarized: fast growing + end and slow - end

may be single, bundle, or networks

functions:
anchorage 
structural core of microvilli and stereocilia
cell motility 
extension of cell processes
28
Q

Explain Phalloidin?

A

This is a toxin that is found in the species amanita phalloides

this molecules disrupts the normal function of actin
It promotes excessive polymerization and inhibits depolymerization…. thus cell moement is no longer possible

liver and kidney failure after 4 to 8 days

29
Q

Explain cytochalasins?

A

another fungal product that blocks the polymerization of actin and thus inhibits cell movement, division, and leads to cell death

30
Q

structure of microvilli?

A

cylindrical, membrane bound cytoplasmic projection

core of 25 to 30 actin microfilaments
crosslinked by villin
anchored into the terminal web (bottom)

31
Q

explain stereocilia?

A

usually long microvilli ( 120 micrometers)

anchored to the terminal web

limited distribution:
epididymis
proximal ductus deferens
sensory hair cells in inner ear

32
Q

Actin motor?

A

Myosin family

Myosin II generates the force for skeletal muscle contraction

formed form two heavy chains and 4 light chains

each head binds and hydrolyzes ATP

33
Q

The steps to myosin structural change?

A
  1. attachment (rigor conformation)
  2. release (ATP binds and reduces myosin affinity for actin)
  3. Bending (ATP hydrolysis and conformational change)
  4. force generation (Weak binding of myosin to actin leads to the release of inorganic phosphate)

release triggers tight binding and power stroke

  1. reattachment (rigor conformation)
34
Q

What are the steps to cell movement?

A
  1. protrusion

actin polymerization at the plus end protrudes lamellipodium

  1. attachment

focal adhesions anchor the actin cytoskeleton to extracellular matrix via integrin proteins

  1. contraction

Cytoplasm is drawn forward

35
Q

What are the different types of protrusion structures?

A
  1. filopodia ( finger like projections)
  2. lamellipodia (sheet-like structures)
  3. pseudopodia ( 3-dimensional projections)
36
Q

Explain actin polymerization?

A

the actin filaments mostly orientate with the + end facing forward

  • end usually attached to the ARP complex
    actin-related protein

the front is assembling as the rear is disassembling

37
Q

Where is the ARP highly concentrated?

A

the front of the lamellipodia where the actin nucleation is most active

38
Q

Explain the steps of neutrophil migration?

A
  1. rolling
  2. activation
  3. adhesion
  4. transendothelial migration (diapedesis)
39
Q

explain chemotaxis and how it relates to the immune system?

A

movement within a tissue based on a chemotactic gradient.

towards the source of inflammation

40
Q

What are the inclusions? explain them?

A
  1. lipofusin (wear and tear pigment and generally found in non-dividing cells)
  2. hemosiderin- (seen in the spleen,liver, and lung. formed by indigestible residues of hemoglobin)
  3. melanin- (produced in melanocytes, gives rise to skin and hair color, sometimes seen in certain neurons)
  4. glycogen- storage form of glucose
  5. lipid- fat droplets and energy store

Test 1 FTM (35 decks)

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