Exam 2 ( 2) - Cytoskeleton

Question 1

What does the cytoskeleton do in general?

Answer 1

• maintain cell shape
• assist in the movement of cells + organelles

Question 2

what are the parts of the cytoskeleton?

Answer 2

Has three types of macromolecule fibers

-actin filaments
- intermediate filament
-microtubules
( assemble and disassemble as needed )

Question 3

Structure of Actin filaments?

Answer 3

SMALL
- extremely thin filaments
- made of G actin and F actin
- dense web under cell membrane
- Treadmilling

Question 4

Function of Actin Filaments?

Answer 4

• support microvilli in intestinal cells
  -intracellular traffic control
  - moves things
  - cytoplasmic streaming
• pseudopods of amoeboid cells
  -pinch mother cell in two after animal mitosis
• an important component in muscle contraction

Question 5

What is cytoplasmic streaming?

Answer 5

• A function in pseudopods or amoeboid cells

: movement of cytoplasm in a particular direction inside the cell moving the cell `

Question 6

what is treadmilling?

Answer 6

You can add and subtract to filament simultaneously –> extension and movement of fibers.

Question 7

Intermediate Filaments structure?

Answer 7

MEDIUM
- rope-like assembly of fibrous polypeptides
- vary in nature/ produced to meet the demands of cell

Question 8

What are some examples of intermediate filaments?

Answer 8

Vimentins, Keratin, Lamin, Neurofilaments

Question 9

What are the functions of the intermediate filaments?

Answer 9

• support nuclear envelope
• cell-cell junctions, like holding skin cells tightly together
• support cell

Question 10

What is the structure of Microtubules?

Answer 10

LARGE
- hollow made of 2 globular proteins
- a and B tubulin)
-a/B form diners

Question 11

what is a Dimer?

Answer 11

• made from a/B tubulin
• arrange themselves into tubular spirals of 13 dimers around

Question 12

what is the assembly of the microtubules?

Answer 12

• under the control of MTOC
• ## The most important MTOC is the centrosome

Question 13

What is the centrosome?

Answer 13

it’s the most important MTOC

makes a pair of centrioles

Question 14

what do centrioles do

Answer 14

the pair of centrioles organize microtubules that move chromosomes during division ( mitosis)

Question 15

What is the function of microtubules?

Answer 15

they interact with proteins kinesin and dynein to cause the movement of organelles

with help organelles can walk along microtubules

Question 16

how does treadmilling relate to microtubules?

Answer 16

microtubules have polarity therefore they treadmill making them dynamic

• add to the positive side, subtract from the negative side

Question 17

Microtubular array: Centriole structure

Answer 17

-short hollow cylinders
- made of 27 microtubules
- microtubules are arranged into 9 overlapping triplets

Question 18

Where are the centrioles made?

Answer 18

• one pair per animal cell
  -they are located in the centrosome
  -oriented at right angles next to each other

Question 19

centriole function

Answer 19

• determine the plane of division during mitosis
• many give rise to basal bodies of cilia and flagella

Question 20

Pattern 9 +2?

Answer 20

Seen in basal bodies
- related to each other ( all and flagella for Eukaryotes )

• inside is a cylinder of 18 microtubules arranged in 9 pairs ( insides are 2 microtubules)

Question 21

What are the basal bodies of cilia and flagella?

Answer 21

hair-like projections from the cell surface that aid in cell movement

Question 22

What does Cilia do?

Answer 22

• move in coordinated waves
• more abundant
• mucus + runny nose + cough

Question 23

What do flagella do?

Answer 23

• sperm
• move like a propeller or a cork screw
• less abundant