Lecture 7: Multicellularity

Question 1

What do cells need in order to communicate

Answer 1

they need to be physically related to each other

Question 2

ECM

Answer 2

• Animal cells
• Cells secrete glycoproteins into extracellular fluid, weave together to form matric
• Cells express integrins on mb, attach to ECM
• Provides strength and rigidity to tissues
o Cartilage, bone, skin
• Organize cells, allow them to move or stay in place
• Provide signals to cells to guide function or development
• Contains adhering proteins
o Stick components of the ECM together and cells to ECM
• Fibers throughout offer structure for cell support, keep cells together, resiliency
o stitches
• Contains structural proteins
o Give the tissues strength and elasticity

Question 3

Fibronectin

Answer 3

protein of ECM

connectes cells to ECM, organizes components

Question 4

laminin

Answer 4

protein of ECM

connects cells to ECM, organizes components. Found in top layers of skin, especially

Question 5

collagen

Answer 5

protein of ECM

provides tensile strength in deep skin, organs, bones, cartilage, tendons

25% of total protein mass in body
75% of protein in skin

Question 6

elastin

Answer 6

forms elastic fibers for stretch and recoil

Question 7

how is collagen made

Answer 7

• Cells produce individual collagen fibers
• Immediately organize into a triple helix
• Outside the cell, collagen helices organize into larger collagen fibers

Question 8

loss of collagen

Answer 8

caused by rapid growth of any body site (genetic predisposition)

Question 9

importance of elastin

Answer 9

• Stretch and recoil

* Skin, some cartilage, blood vessels

Question 10

loss of elastin

Answer 10

• Sped up by toxins (like nicotine) and UV damage

* Wrinkles

Question 11

proteoglycans

Answer 11

• ECM also contains polysaccharides
• Repeated disaccharide units attached to a central protein
• Weave together and bind water, creating a gel that cushions cells and organs

Question 12

tight junctions

Answer 12

• Zip the membranes of two cells together so that nothing can slip in between them

Question 13

desmosomes

Answer 13

• Kind of linked but things can pass between

Question 14

gap junction

Answer 14

• Form a pore from the inside of cell to the inside another so things can diffuse across the membrane
• Hold hands but stick ur finger in an electric socket; electricity will pass between the two people

Question 15

adhering junctions

Answer 15

connect cells to ECM

• Membranes proteins called integrins connect cytoskeleton to ECM proteins

Question 16

tissues

Answer 16

a group of cells having similar function

Question 17

4 tissue types

Answer 17

o Epithelial (skin/top layer; forms a boundary)
o Connective: diverse: connect things to one another; cartilage
o Nervous: brain and spinal cord; deliver messages to other parts of your body
o Muscle: contract to form movement