Chapter 19: Cell Junctions and Extracellular Matrix

Question 1

What are 2 tissues essential to effective cell binding?

Answer 1

1. Epithelial tissue
2. Connective tisse

Question 2

What 2 things do
epithelial tissues do to structurally support cells?

Answer 2

1. Transmits cell stresses (via cytoskeletal membranes)
2. Anchors cells to eachother + the basal membrane

Question 3

How does connective tissue aid in the structural integrity of cells?

Answer 3

ECM directly bears mechanical stressors (tension/compression)

Question 4

What are 4 types of junctions typically found in vertebrate epithelium?

Answer 4

1. Tight junctions
2. Cell-to-cell anchors
3. Gap junctions
4. Cell-matrix anchoring junctions

Question 5

These connections gives space between cells with the same integrity of a plasma membrane; run along the entire width of each cell

Answer 5

Tight junctions

Question 6

What are the two types of cell-to-cell anchors?

Answer 6

1. Desmosomes
2. Adherens junctions

Question 7

These cellular connections allow for quick small molecule transport between two cells

Answer 7

Gap junctions

Question 8

What are two types of cell-matrix anchoring junctions?

Answer 8

1. Hemidesmosomes
2. Actin-linked junctions

Question 9

What proteins enforce the structure of tight junctions?

Answer 9

1. Claudin (critical)
2. Occludin

Question 10

These types of anchoring junctions connect cells to other cells; consist of adherins and desmosomes

Answer 10

Cell-to-cell cadherin

Question 11

This type of anchoring junction connects cells to the ECM; consists of actin-based anchors and hemidesmosomes

Answer 11

Cell-to-matrix (integrin)

Question 12

This type of cell junctions mediate the passage chemical and electrical signals

Answer 12

Communication junctions

Question 13

What are the 3 types of communication junctions?

Answer 13

1. Gap junctions
2. Chemical synapses
3. Plasmodesmata

Question 14

These are channels held together by connexons that connect two different cells by allowing the passage of small molecules between them

Answer 14

Gap junctions

Question 15

About how wide is the channel of a gap junction?

Answer 15

1.4 nm

Question 16

What problem of plant cells does the plasmodesmata aim to combat?

Answer 16

Cell communication between thick cell walls

Question 17

This is the thin tube that connects the smooth ERs of two different plant cells through their cell walls

Answer 17

Desmotube

Question 18

What ion plays an integral role in the synthesis and structure of cadherin proteins?

Answer 18

Ca2+

Question 19

What happens to cadherin proteins without adequate amounts of Ca2+

Answer 19

Floppy, not structurally sound, incapable of interacting with other cadherins

Question 20

How does trypsan solution allow for the easy lifting of cells in cell culture?

Answer 20

Cleaves proteins and chelates Ca2+ ions

Question 21

This is a triple stranded, super-coiled alpha helix that is intergral to cellular structure

Answer 21

Collagen

Question 22

Fibrilar collagen is synthesized by what cells?

Answer 22

Fibroblasts

Question 23

What are the 3 steps of fibrocollagen/collagen formation?

Answer 23

1. Procollagen triple helix formed (in ER & Golgi)
2. Procollagen cleaved and separated
3. Resulting collagen aggregates into fibers

Question 24

What is the normal repeat of collagen?

Answer 24

Glycine-proline-hydroxyproline

Question 25

What is the purpose of hydroxyproline in collagen fibers?

Answer 25

Stabilizes collagen fibers (allows for supercoiled helix to form)

Question 26

A severe lack of vitamin C (scurvy) does what to collagen?

Answer 26

Inhibits hydroxyproline formation (becomes Gly-proline-proline); looses stability and falls apart

Question 27

What are the symptoms of scurvy?

Answer 27

Tooth loss, slow wound healing, fragile blood vessels, bone pain, heart failure