bio421 (examII)

lec 17

What are the functions of microtubules

Provide structure for the cell

Provide structure to Enable movement

Vital for chromosome segregation

Used for intracellular transport

What are the general use for motor proteins

move across microtubules for intracellular transport

What are the families for microtubules motor proteins

Kinesin

Dynein

What are the major need to have two different microtubule directions

to have the motor proteins have different directionality

What stabilizes microtubules

MAP

How do motor proteins provide movement

Both use ATP to walk along microtubules in there specific direction

dynein walk

towards the microtubule minus end

kinesins walk

in both the positive and minus direction

just not and the same time

and direction is specific to the molecule

Which axon has the greater speed

a. axon with shorter synapses and wider distance

b. axon with wider synapses and shorter distance

c. axon with skinny synapses and longer distance

d. axon with wider synapses and longer distances

axon with wider synapses and shorter distance

speed of action potential conduction is primarily determined by the axon's diameter and myelination. A wider axon has less internal resistance, allowing for faster ion flow and thus, faster conduction velocity.

What direction is towards the synapses for the axon?

anterograde

What direction is towards the cell body for the axon?

retrograde

Which motor type is responsible for retrograde in neurons?

a. dynein

b. kinesin

-dynein bc dynein can move in the minus direction (only)

-kinesin bc kinesin can move in both the minus and positive end (although minus is preferred)

Spindle fibers are ___ and spindle poles are ____

a. microtubules; centrosomes

b. centrosomes; microtubules

microtubules centrosomes

List 3 different role for MT during chromosome division (no definition)

Astral

Polar Microtubules

Kinetochore Microtubules

Astral Microtubules

radiate outward from the centrosome and connect with the cell cortex

Polar Microtubules

Antiparallel Microtubules connecting opposite centrosomes

Kinetochore Microtubules

Connect to each side of chromosome

label this diagram

 1. Polar microtubule

2. Kinetochore microtubule

3. kinetochore

4. Astral microtubule

5. Microtubule organizing center

Considering the walking direction what mt motor protein is located at #3?

kinesin

Considering the walking direction what mt motor protein is located at #2?

kinesin

Considering the walking direction what mt motor protein is located at #5?

dynein

Considering the walking direction what mt motor protein is located at #4?

kinesin

How do cells function as communities?

They interact with other cells via cell junctions and through the extracellular matrix

The space between cells is filled with the _____

extracellular matrix

Extracellular matrix composition

Proteins

• collagen

• intergrins )

Gel fomring polyssachrides

(proteins, polysaccharides (secreted locally and assembled into a meshwork with the surface of the cell that produced them))

What is collagen’s responsibility in the extracellular matrix (ECM)?

provides tensile strength

What is collagen’s gel forming polysaccharides in the extracellular matrix (ECM)?

delete (make up soft tissue ig eye also called GAGs—> glycosaminoacids)

Integrins

adaptors connect outside the ECM to the actin inside the cytoskeleton

What are the five factors that contribute to the ECM?

1. Functions as adhesive substrate

2. Provides structure

3. Presents growth factors as their receptors

4. Sequesters and stores growth factors

5. senses and transduces mechanical signals (transport force throughout the cell)

Collagen fiber are assembled outside the cell

(((FIX CARD))

steps for collagen production

Procollagen —>

What is Procollagen?

Precursor collagen molecules that have unstructured terminal ends.

Triple-helix form

slide 31