Cytoskeleton

Question 1

The inside of a cells is basically an _________ ________ _________

Answer 1

organized super highway

Question 2

Give a brief history of cytoskeleton discovery (2 dates)

Answer 2

1903: Nikolai Kolstov first described cytoskeleton as a network of tubules that control shape
1931: Paul Wintrebert coined cytoskeleton

Question 3

What are the 3 main types of cytoskeletons?

Answer 3

Microfilaments (actin)
Intermediate filaments
Microtubules

Question 4

Describe the shape of the 3 types of cytoskeletons

Answer 4

Microfilaments: 2 strands intertwined
Intermediate filaments: Like a strong rope (many strands intertwined)
Microtubules: Hollow cylinder

Question 5

What are microfilaments made of?

Answer 5

Linear polymers of G-actin

Question 6

What are microfilaments used for?

Answer 6

• Generate force when the growing end bashes against the membrane
• Act as a scaffold for myosin motor proteins to walk along
• muscle contraction, cell movement, intracellular transport, maintenance of eukaryotic cell shape, cytokinesis (cell division), cytoplasmic streaming.

Question 7

What are intermediate filaments made of?

Answer 7

Tetramers of red-like proteins that are tightly bundled into long ropelike filaments

Question 8

What are intermediate filaments used for?

Answer 8

• Provide internal scaffold to help anchor organelles and the nucleus and organize 3D structure of cell
• Maintain overall cell shape and form part of the cell-cell connections that allow cells to communicate with each other

Question 9

What are mutations intermediate filaments linked to?

Answer 9

Premature again and muscular dystrophy

Question 10

What are microtubules made of?

Answer 10

Hollow cylinders composed of tubulin protein monomers

Question 11

How do microtubules grow?

Answer 11

They grow at the positive and and shrink at the negative end

Question 12

What are microtubules used for?

Answer 12

They form part of motile structures such as cilia and flagella
Crucial for cell division
Transport organelles along their length

Question 13

How did scientists discover the functions of the cytoskeleton?

Answer 13

Direct observations of the cytoskeleton
Effects of mutations in cytoskeleton structure or function
How the cytoskeleton responded to various conditions

Question 14

What are the 3 main function of the cytoskeleton?

Answer 14

1. Structural support
2. Motility
3. Regulate biochemical activities

Question 15

What makes the cytoskeleton good for maintaining cell shape?

Answer 15

Quick to dismantle and reassemble in another part of the cell

Question 16

How do nutrient absorbing epithelial cells in the small intestine use cytoskeletons?

Answer 16

They use microfilaments to form microvilli, which increases the surface area of the cells

Question 17

In the small intestine, what kind of diseases can effect the microvilli? why is this bad?

Answer 17

Celiac disease triggers an immune response that damages the intestines’ lining. This is bad because it prevents the absorption of some nutrients

Question 18

Another main use of the microfilaments is the cell division _________ ring

Answer 18

contractile

Question 19

Describe the Brownian ratchet

Answer 19

It’s a way for cells to expand
G-actin is only added to the end of a microfilament when there is space and energy (via ATP). Space is made via brown movements, which is tiny vibrations. Once space is made, the cytoskeleton can expand and change the direction or shape of the cell

Question 20

Cell motility comes from the interaction of the cytoskeleton and _____

Answer 20

motor proteins

Question 21

What can motor proteins do?

Answer 21

Walk along the cytoskeleton, form cross-links with transmembrane proteins, vesicles, or other cytoskeleton filaments

Question 22

How do animal cells change shape to move?

Answer 22

microfilaments reorganize to create cellular extensions. This extension combined with the interactions of the plasma membrane (or the proteins in it) and external substrate help to move the cell

Question 23

What is an example of animal cells moving?

Answer 23

Wound healing: fibroblast cells migrate to the site of injury to aid in tissue repair

Question 24

What is phagocytosis?

Answer 24

The process by which a cell extension surrounds and engulfs a foreign object.

Question 25

What are macrophages? How do they help?

Answer 25

They are immune cells. They help my engulfing and destroying dead and dying cells, as well as pathogens like bacteria, viruses and other foreign objects

Question 26

What is the difference between cilia and flagella?

Answer 26

Cells that have cilia have many short cilia | Flagellated cells possess 1-3 long flagella

Question 27

What is the use of cilia and flagella?

Answer 27

Propel single-celled organisms through fluid or move fluid over the surface of multicellular tissues

Question 28

What examples of cilia and flagella?

Answer 28

Cilia and windpipe to sweep mucus with debris out the lungs Cilia on a woman's oviduct's to move an egg toward the uterus Sperm of many animals, algae, and some plants have flagella

Question 29

What are the movements of cilia and flagella?

Answer 29

Cilia rows | Flagella uses and undulatory movement

Question 30

How do microtubules form cilia and flagella

Answer 30

microtubules run the length of these structures. 9 doublet microtubules around the circumference and 2 microtubules in the center. Dynein moto proteins walk along the outer microtubules doublets Nexin Proteins cross-link the microtubules doublets together

Question 31

What is the bending of cilia and flagella driven by?

Answer 31

Dynein motor proteins

Question 32

What is the rotation of flagella driven by?

Answer 32

Proton gradients

Question 33

What is Kartagener's syndrome caused by? What can it cause?

Answer 33

Caused by defects in the microtubule-based movement of cilia and flagella They are sterile due to immobile sperm Tend to suffer lung infections Frequently have organs on the wrong side of the body (due to incorrect cilia-based signaling during embryogenesis

Question 34

What type of cytoskeleton creates muscle cells? Do they have motor proteins on them.

Answer 34

actin filaments. Yes

Question 35

What is the purpose of the myosin motor proteins in the muscle cells?

Answer 35

The walking of the protein brings the filaments closer together, causing muscle contraction

Question 36

How do cytoskeletons help vesicles?

Answer 36

Vesicles and other organelles travel along the cytoskeleton scaffold. Some motor proteins can walk along the scaffold and carry their cargo that way

Question 37

Vesicles containing _______ travel along the microtubules. For example, a frog's ____ ______ depends on the distribution of the above

Answer 37

pigments, skin colour

Question 38

How do neurotransmitters travel from one side of the axon to the end?

Answer 38

Kinesin motor proteins move vesicles containing neurotransmitters Dynein motor proteins move the empty vesicles back towards the cell body

Question 39

In the neuron axon, ______ _______ travel in specific direction along the microtubules

Answer 39

motor proteins

Question 40

What is ALS caused by?

Answer 40

Defects in axonal transport associated with motor neuron diseases