Cells to Tissues

Question 1

adhesive structures

Answer 1

tight junction, adherens junction, spot desmosome, hemidesmosome, gap junction

Question 2

tight junction (adhesive proteins, substrate, & function)

Answer 2

adhesive proteins: occludin, claudin, JAMs
bind to: actin filaments
function: prevents materials from moving in between cells (can also serve as receptor and entryway for viruses - especially in the intestine)

Question 3

adherens junction (adhesive proteins, substrate, & function)

Answer 3

adhesive proteins: cadherens
bind to: actin filament
function: form part of the circumferential belt to give structure/stability to the cell

Question 4

spot desmosome (adhesive proteins, substrate, & function)

Answer 4

adhesive proteins: desmosomal cadherens
bind to: intermediate filaments
function: attach to intermediate filaments
* made of cytoplasmic plaque associated with desmoglein and desmocollin

Question 5

hemidesmosome (adhesive proteins, substrate, & function)

Answer 5

adhesive proteins: integrin α6ß4
bind to: intermediate filaments
function: attaches cell to basal lamina (keeps cells in position & associated with ECM in order to survive)

Question 6

gap junction (adhesive proteins, substrate, & function)

Answer 6

adhesive proteins: connexins, innexins, & pannexins
bind to: indirect connection to cytoskeleton
function: communication - allows diffusion of small molecules between cells

Question 7

two types of cadherens

Answer 7

E-Cadherins & desmosomal cadherin

Question 8

E-Cadherins

Answer 8

found in adherens junctions
homophillic interaction: associate with another cadherin on extracellular side / interact with catenins that attach to circumferential belt

Question 9

desmosomal cadherin

Answer 9

made up of desmoglein and desmocollin;

Question 10

different regions of a polarized cell in a tissue

Answer 10

apical
lateral
basal

Question 11

apical domain

Answer 11

interacts with surface

Question 12

lateral domain

Answer 12

nteracts with/ is connected to adjacent cells

Question 13

basal domain

Answer 13

interacts with the basal lamina

Question 14

integrin

Answer 14

multi adhesive protein; transmembrane heterodimers (α & ß chains) that interact with ECM; can have outside-in & inside-out signaling

Question 15

outside-in signaling

Answer 15

integrin responds to outer ligand binding, conformation change passes through the molecule, across the plasma membrane, and induces change on the cytoplasmic side

Question 16

inside-out signaling

Answer 16

growth factor receptors (GFRs) can activate the integrin tail and induce conformation change on the outside of cell that alters ligand affinity

Question 17

basal lamina

Answer 17

region directly under the cell (generally in polarized epithelial cells); specialized form of ECM

Question 18

components common to all basal lamina

Answer 18

Type IV Collagens
Perlecan
Entactin
Laminin

Question 19

How is basal lamina formed?

Answer 19

Generated / secreted by the cells

Question 20

What are collagens?

Answer 20

Trimeric helix structures that form a network in the basal lamina & can interact with other proteins. Have unique synthesis process that begins in the rough ER and is completed outside the cell.

Question 21

How do the collagen isoforms differ?

Answer 21

size & structure, associations, function, & tissue

Question 22

notable collagen isoforms

Answer 22

Types IV, I, & II

Question 23

Type IV collagen

Answer 23

found in the basal lamina - makes up the framework

Question 24

Type I collagen

Answer 24

found in tendons - gives strength

Question 25

Type II collagen

Answer 25

found in cartilage - absorbs shock and gives strength

Question 26

general structure of collagen

Answer 26

C-terminal globular head
Trimeric helix
Small N-terminal globular domain

Question 27

What makes collagen unique?

Answer 27

it’s synthesis

Question 28

How is collagen synthesized and secreted?

Answer 28

Formation begins in the Rough ER; Propeptide (has additional peptides to prevent premature folding); Procollagen forms triple helices; Moves through the Golgi Apparatus; Lateral association begins; Excreted out of the cell by golgi dependent vesicles; Propeptides are cleaved; Assembly & crosslinking of fibrils

Question 29

proteoglycans

Answer 29

Molecule with a protein backbone and very large sugar dimers

Question 30

GAGs

Answer 30

glycosaminoglycans - large sugar dimers found in proteoglycans

Question 31

proteoglycan function

Answer 31

crosslinking & cushioning/buffer between molecules

Question 32

What are laminin and fibronectin?

Answer 32

Multiadhesive proteins: They have domains that act as binding sites for many different molecules. They are important in development because they form a cell substrate or highways for cells to migrate along.