Cell-cell Interations

Question 1

What is the importance of cell-cell interactions?

Answer 1

• important for unicellular organisms to communicate and cooperate with one another within a population
• important for cells within multicellular organisms must be able to communicate and cooperate with one another
  -important for cells to obtain information, respond to it, and pass on info

Question 3

Functions of the extracellular layers

Answer 3

• helps define cell shape
  -attaches the cell to other cells
• acts as a first defense

Question 4

Which forces does extracellular layers resist

Answer 4

-cross linked network resist tensile forces
- ground substances resist compressive forces

Question 5

What the ECM fibrous component is mostly made of

Answer 5

Collagen

Question 6

What is collagen

Answer 6

Cable-like protein bind together to form fibres
Forms a strong flexible extracellular layers

Question 7

What is ground substances made of

Answer 7

Proteoglycans

Question 8

What are proteoglycans

Answer 8

Proteins attached to polysaccharides
Hydrophilic, attracts water to form a gel that resist compression

Question 9

What does ECM allow the formation of

Answer 9

Tissues in animals

Question 10

What kind of proteins interact with elements of ECM and elements of cytoskeleton

Answer 10

Integrins

Question 11

What is areolar connective tissue

Answer 11

They are in lungs, skin and blood vessels. They contain ECM with high amount of elastin. They allow organs to stretch out and snap back to original size and shape

Question 12

What is cartilage tissue

Answer 12

In nose, ears, trachea, intervertebral discs, and ends of bones contains ECM with abundant collagen fibres embedded in a rubbery ground substances. Cushions and absorbs shock.

Question 13

What gives plant cells wall high tensile strength

Answer 13

Cellulose that are bundled into microfibrils.

Question 14

What does pectin do in gelatinous polysaccharides

Answer 14

Retain moisture and resist compression

Question 15

When new plant cells lay down a primary cell wall, what happens?

Answer 15

It defines the shape of the cell and counteracts turgor pressure

Question 16

What does turgor pressure allow?

Answer 16

Allow plants to remain upright and causes developing cells to grow

Question 17

What does growing cells secrete. Explain

Answer 17

Expansins, they loosen connections between microfibrils and allow the cell wall to expand

Question 18

What holds together cells

Answer 18

Middle lamella

Question 19

What do mature plant cells lay down and when.

Answer 19

Secondary cell wall after cell expansion has stopped.

Question 20

In leaves and wood what kind of secondary cell wall helps protect them

Answer 20

Leaves its waxes, protects tissues against dehydration
Wood its lignin, a high still and strong material

Question 21

How are animals glued together

Answer 21

Tight junctions and desmosomes

Question 22

How do animal cells communication with adjacent cells?

Answer 22

Gap junctions

Question 23

How do plant cells communication with each other

Answer 23

plasmodesmata

Question 24

What does animal cells and plants have in common regarding communication

Answer 24

Form channels of cytoplasm which allows material to move back and forth

Question 25

Define tight junctions

Answer 25

Water tight seal between two cells. It prevents the movement of substances between cells so the transport can only occur in a controlled away across the plasma membrane of tissue Found in epithelial tissues (epidermis of skin and lining of the stomach)

Question 26

What are tight junctions made of

Answer 26

Membrane proteins that chains of proteins line up in adjacent cells which are “stitch” them together

Question 27

What are desmosomes?

Answer 27

Made of proteins that link to cytoskeletons of adjacent cells They resist pulling and shearing forces - common in both epithelial and muscles tissues: allow tissues to stretch without tearin

Question 28

What are cadherins

Answer 28

Integral membrane proteins that form bridges between anchoring proteins located inside each cells

Question 29

What’s special about cadherins?

Answer 29

Only bind to other cadherins of the same type, so only cells of the same type will be linked together.

Question 30

What are gap junctions

Answer 30

Connect adjacent cells and form channels

Question 31

When channels proteins in adjacent cells line up: what do they do?

Answer 31

-ions and small molecules are passed back and forth -regulation of gene expression in a coordinated manner - inactive or activation of proteins

Question 32

Which organelles extend through the plasmodesmata

Answer 32

Plasma membrane, cytoplasm, smooth ER

Question 33

What is the difference between plasmodesmata and gap junctions

Answer 33

Plasmodesmata are much larger than gap junctions so they allow for similar functions as well as movement of RNA molecules and proteins

Question 34

How do cells communicate over distances

Answer 34

Hormones