Lectures 23-24

Question 1

What is a cytoskeleton?

Answer 1

provides eukaryotic cells the abilities to
adopt a variety of cell shapes,
organize the components in the cytoplasm,
interact mechanically with the environment,
carry out coordinated movement.

Question 2

What are the three major types of filaments are their diamters?

Answer 2

1. ___intermediate filament____ (__10_ nm diameter)
2. ___microtubules____ (__25_ nm diameter)
3. ___actin filament___ (__7__ nm diameter)
   II.

Question 3

What is the structure of intermediate filaments?

Answer 3

1. subunits are fibrous proteins with N-terminal globular head, C-terminal globular tail,
   and a central elongated helical rod domain.
2. Coiled-coil dimmer  tetramer  8 tetramers twist into rope-like filament

Question 4

What is the function of intermediate filaments?

Answer 4

provide great mechanical strength
1. __muscle_ cells and __skin__ epithelial cells
2. along the length of nerve cell axons.

Question 5

What is a tissue?

Answer 5

is an ensemble of cells, not necessarily identical, but from the same origin, that
together carry out a specific function.

Question 6

What are the four major types of tissue in animals?

Answer 6

1. __connective tissue___ – such as bone, blood
2. __epithelial tissue___ – layers of cells that cover organ surfaces
3. __nervous tissue___ – central nervous system and peripheral nervous system
4. __muscular tissue___ provides contractility

Question 7

What is the function of a tight junction?

Answer 7

• connect plasma membrane of adjacent cells, typically epithelials, in a sheet
  partition plasma membranes – apical vs basal membranes
• form barrier to protect organs

Question 8

What is the function of the adherens junction?

Answer 8

linking actins of adjacent cells

Question 9

What is the function of the desmosome?

Answer 9

linking intermediate filaments
Key connecting proteins called ___cadherins___

Question 10

What is the function of gap junctions?

Answer 10

are protein channels – made of connexins

Question 11

What is the function of hemidesmosomes?

Answer 11

anchoring cells to ECM through integrin

Question 12

What is the structure of the Extracellular Matrix (ECM)?

Answer 12

1. __collagen__ is one of the major components.
2. other components such as laminin, fibronectin, gelatin, and more.

Question 13

What do mutations in the ECM create?

Answer 13

skin blisters

Question 14

What is a tumor?

Answer 14

solid lesion formed by an abnormal growth of cells –__neoplasm__
usually caused by multiple mutations in __somatic__ cells

Question 15

What are the functions of metastatic cancer cells?

Answer 15

1. change cell junctions
2. break loose
3. epithelial-mesenchyme transition (EMT)
4. degrade extracellular matrix (ECM)
5. metastasize

Question 16

What creates oncogene?

Answer 16

hyperactive_ proto-oncogene due to mutations or other DNA abnormalities

Question 17

What is the counteraction of oncogene?

Answer 17

1. oncogenes – promoting growth in normal situation
   a. cause cancer when hyperactive (or __gain-of-function__ mutation)

Question 18

What is the counteraction of tumor suppressor genes?

Answer 18

2. tumor suppressor genes – provide growth check in normal situation
   a. cause cancer when inactive (or __loss-of-function___ mutation)

Question 19

Describe the tumor size chart

Answer 19

visible on x-ray when __108__ cells, palpable when __109__ cells, causes
death when _1012__ cells

Question 20

What is Gleevec?

Answer 20

_ is a new type of anti-cancer drug that inhibits oncogenic kinase(s).

Question 21

What is the tissue renewal rate for most nerve cells?

Answer 21

zero

Question 22

What is the tissue renewal rate for intestinal cells?

Answer 22

3-6 days

Question 23

What is the tissue renewal rate for red blood cells?

Answer 23

120 days (replenished by stem cells in bone marrow)

Question 24

What is the tissue renewal rate for bone tissue?

Answer 24

10 years

Question 25

What is the tissue renewal rate for skin cells?

Answer 25

2 months

Question 26

What is a stem cell?

Answer 26

an undifferentiated cell that can continue dividing indefinitely, generating daughter cells that undergo terminal differentiation into particular cell types

Question 27

What are the characteristics of stem cells?

Answer 27

Undifferentiated, able to self renew, ___small______ number, ___slow__ dividing

Question 28

Embryonic Stem Cells

Answer 28

taken from the inner cell mass of early embryo at __blastocyst__ stage a. can be maintained in culture almost indefinitely b. can differentiate into many cell types depending on ___growth factors___ or ____hormones______.

Question 29

Adult Stem Cells

Answer 29

stored in particular niches, multipotent a. intestinal stem cells lie near the bottom of the ___crypt__ b. epidermal stem cells at the basal layer adherent to the basal lamina c. hemopoietic ( or hematopoietic ) stem cells (HSC) in the bone marrow d. hair follicle stem cells in the bulge

Question 30

Induced Pluripotent Stem cells

Answer 30

a. use ___differentiated_somatic____ cells from adult b. introduce three key genes: __c-Myc____, __Sox-2____, __Oct-4__ c. the differentiated cells return to undifferentiated and pluripotent status, iPS. d. iPS then can differentiate into many different cell types

Question 31

What is totipotent?

Answer 31

capable of giving rise to extra-embryonic tissues and the complete embryo

Question 32

What is Pluripotent?

Answer 32

capable of giving rise to many different cell types

Question 33

What is multipotent?

Answer 33

capable of giving rise to limited set of cell types