FORM & FUNCTION (Cytoskeleton)

Question 1

cell shape/morphology

Answer 1

-determines cellular fucntions
*macromolecules synthesis also determines that

Question 2

cell surface specialization definition

Answer 2

-unique adaptation of PM and adjacent structures that enable specific funtions within the body
-includes different membrane structures, junctions and associated proteins

Question 3

importance of cell surface specialization

Answer 3

-allows cells to carry our specific roles in different tissues and organs
-facilitates communication and connection between cells
-enhances the efficency of various cellular processes

Question 4

cell surface specialization connection to cytoskeleton

Answer 4

-cytoskeleton plays a critical role in defining shape and facilitating movement
-integral to the formation and function of specialized surface structures

Question 5

cytoskeleton components

Answer 5

1. Microtubules
2. Microfilaments (actin-filaments)
3. Intermediate filaments

Question 6

microtubules

Answer 6

-tubulin-based filaments
-involved in cell division, intracellular transport and cell shape maintenance
-throughout cytoplasm
-road for motor proteins

Question 7

microfilaments

Answer 7

-actin-based filaments
-responsible for cell movement, muscle contraction and cell shape changes
-smallest
-concentrated at cell periphery
-essential component of microvilli
-facilitate cell motility (immune cell migration)

Question 8

intermediate filaments

Answer 8

-protein composition is cell-type specific
-provide mechanical strength
-help maintain cell integrity
-essential component in cell junctions
-facilitates adhesion and anchoring between cells within tissues
*cruicial in resisiting mechanical stress

Question 9

microtubule roads

Answer 9

-orginated from centrosome and grow outwards
-each centrosome has 2 centrioles oriented at a right angle
-motor proteins carry intracellular cargos and ‘walk’ along the MT roads
-organize the cell interior

Question 10

formation of MT

Answer 10

-tublin dimer polymerizes into protofilament
-multiple protofilaments form a MT
-contains a space “lumen” in the middle

Question 11

MT remodelling

Answer 11

-highly regulated and targeted by drugs
-can grow and shrink by many factors
-remodelling reorganizes cellular content
-dynamics can be targeted by drugs to treat certain inflammatory conditions and cancer

Question 12

cilia and flagella

Answer 12

-hair like structures extending from cell surface
-involved in cellular movement and the transport of extracellular molecules

Question 13

MT (cilia and flagella)

Answer 13

-form the core structural component
-gives them shape and flexibility

Question 14

cilia

Answer 14

-beats by performing a repetiive cycle of movements (power stroke followed by recovery stroke)
-typically found in epithelial cells
-beat in coordinated fashion to move extracellular materials (ex. mucus)

Question 15

flagella

Answer 15

-longer than cilia
-provide motility for sperm

Question 16

vet relevance (cilia)

Answer 16

-cruicial for respiratory and reproductive health in animals
-dysfunction can lead to respiratory infections or infertility

Question 17

MT and cell division

Answer 17

-form the mitotic spindle (responsible for aligning and seperating chromosomes during mitosis)
-dysfunction can lead to genetic abnormalities

Question 18

actin vs. MT composition

Answer 18

actin: actin monomers
MT: alpha and beta tubulin

Question 19

actin vs. MT structure

Answer 19

actin: helical polymers with 2 intertwined strands of actin-monomers
MT: cylindrical

Question 20

actin vs. MT polymerization dynamics

Answer 20

Actin: treadmilling (monomers added to plus end and removed from minus)
MT: exhibit dynamic instability

Question 21

Immune cell migration (actin filaments)

Answer 21

1. Actin polymerization at the leading edge form a protrusion
2. Cell adhesion: glycoprotein on immune cells binds to ECM proteins, anchoring cell to its surroundings
3. Actomyosin contraction: myosin motors generate forces by sliding along actin filaments, leading to contraction at cell’s rear end
4. Rear end retraction: actin filaments dissemble and the cell’s rear end retracts, allow the cell to move forward

Question 22

epitheleial cells

Answer 22

-must be attached to each other and anchored to connective tissue
-polarity in them defines their function
1. apical: facing free space (lumen)
2. basal: facing connective tissue
3. lateral: between cells
*cytoskeleton helps maintain these structures

Question 23

cell jucntions

Answer 23

1. Tight: forms barrier
2. Adherens: mechanical strength
3. Demosomes: mechanical strength
4. Gap junction: communication
5. Hemidesomes: mechanical strength

Question 24

cell junctions on basal and lateral surface

Answer 24

-key to epithelial integrity and function