Tissue Architecture

Question 1

What are the cytoskeleton functions at a tissue level?

Answer 1

Muscle movement

Question 2

What are the cytoskeleton functions at a cellular level?

Answer 2

Cell morphology, motility, cell adhesion and division

Question 3

What are the cytoskeleton functions at a subcellular level?

Answer 3

Organization, tensile strength, chromosome segregation, cell polarity and vesicular movement

Question 4

How are cytoskeleton filaments adaptable?

Answer 4

They begin as small soluble subunits that, when signaled will form large filamentous polymers

Question 5

How do cytoskeleton elements stabilize?

Answer 5

They are generally thermally unstable but when they group together and stagger they gain strength and develop rope like properties

Question 6

What is the function of intermediate filaments and where are they found?

Answer 6

They provide tensile strength to the cell able to withstand mechanical forces. They are generally found in cytoplasm, anchored to plasma membrane.

Question 7

How are intermediate filaments formed?

Answer 7

alpha helical monomers coil to form a dimer. Two dimers will stagger eachother formed a tetramer. Tetramers will then form a lateral association to give rope like properties.

Question 8

What happens when intermediate filaments are mutated?

Answer 8

Can cause blistering and has been linked to progeria when nuclear lamina is disrupted

Question 9

What is the function of microtubules and where are they found?

Answer 9

They are used in cell organization and movement of vesicles/organelles. They are used in mitotic spindles, cilia/flagella.

Question 10

How are microtubules formed?

Answer 10

alpha and beta tubulin forms a heterodimer that line up and form a protofilament that have a plus and a minus end. These filaments form a tube that can rapidly assemble and disassemble

Question 11

What is the role of gamma tubulin?

Answer 11

They act as anchor units in the formation of microtubules that polymers can grow out from.

Question 12

What is taxol?

Answer 12

a drug that binds and stabilizes microtubules. This can result in a stoppage of cell cycle since spindles will not function

Question 13

What is the function of microfilaments and where are they found?

Answer 13

Present in all cell types and they are used for locomotion, phagocytosis, cell division and contraction

Question 14

How are microfilaments formed?

Answer 14

Actin filaments are twisted polymers of G-actin that have structural polarity like microtubules.

Question 15

What is phalloidin?

Answer 15

a drug that binds and stabilizes filaments which can result in a stoppage of cell function

Question 16

How do proteins modify actin function?

Answer 16

They provide stability to the structure since it is highly unstable. They can be used to stabilize, strengthen, cross-link or organize

Question 17

What is the extracellular matrix/basal lamina and where is it found?

Answer 17

It is interlocking fibrous proteins and proteoglycans that are secreted by the cell then secreted out to aggregate. They interact with cells via transmembrane proteins and composition is tissue dependent.

Question 18

What is collagen?

Answer 18

main structural protein in ECM. They are trimeric proteins with many different types. They associate in fibers, sheets or transmembrane interactions.

Question 19

How are collagen molecules formed?

Answer 19

Three alpha helical chains are produced, they are formed in the ER into a triple helix shape by hydroxylation/glycosylation then secreted out to the extracellular space as procollagen. There they are cleaved and form collagen

Question 20

What is scurvy?

Answer 20

when vit C is not present collagen will not be hydroxylized and will lose structural integrity. This results in tissues not forming properly so wounds reopen, body falls apart and you lose teeth

Question 21

What is Ehlers-Danlos Syndrome?

Answer 21

Mutations in the genes for collagen synthesis alter the structure, production or processing of collagen and weakens connective tissues, skin, bones etc.

Question 22

What are cell connections/junctions? (4)

Answer 22

Connections between neighboring cells that allow for mirgration, signaling, immunity etc- 4 types- anchoring, occluding, channel forming or signal relaying

Question 23

What is the cadherin superfamily and what kind of cell interaction is it involved in?

Answer 23

They are Ca2+ dependent adhesion molecules that form desosome and adheren junctions between cells. They use actin and intermediate filaments.

Question 24

What is the purpose of cadherin junctions?

Answer 24

To form “sheets” between cells. Help in shaping the tissues/ provide tension and durability.

Question 25

Examples of cadherin superfamily

Answer 25

e-cadherin- epithelial
N cadherin- neural
VE- cadherin- vascular endothelial

Question 26

What is EMT in caherins?

Answer 26

Epithelia to Mesenchymal Transition- used to determine if there are invasive metastatic tumors. There will be a decrease in E cadherin for N cadherin

Question 27

What is the IG superfamily and what is its function?

Answer 27

Calcium independent transmembrane glycoproteins that are heavily involved in immune cell interactions.

Question 28

What are selectins?

Answer 28

Calcium dependent glycoproteins that bind to extracellular carbs. They are important in host defense. They will increase during inflammatory response

Question 29

What are integrins?

Answer 29

They are heterodimeric molecules involved in cell junctions. They couple the cell matrix to cytoskeleton and activate cell signaling pathways