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cellular and molecular biology > Lectures 23-24 > Flashcards

Lectures 23-24 Flashcards

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1
Q

What is a cytoskeleton?

A

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.

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2
Q

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

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

What is the structure of intermediate filaments?

A
  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
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4
Q

What is the function of intermediate filaments?

A

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

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5
Q

What is a tissue?

A

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

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6
Q

What are the four major types of tissue in animals?

A
  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
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7
Q

What is the function of a tight junction?

A
  • connect plasma membrane of adjacent cells, typically epithelials, in a sheet
    partition plasma membranes – apical vs basal membranes
  • form barrier to protect organs
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8
Q

What is the function of the adherens junction?

A

linking actins of adjacent cells

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9
Q

What is the function of the desmosome?

A

linking intermediate filaments
Key connecting proteins called ___cadherins___

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10
Q

What is the function of gap junctions?

A

are protein channels – made of connexins

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11
Q

What is the function of hemidesmosomes?

A

anchoring cells to ECM through integrin

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12
Q

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

A
  1. __collagen__ is one of the major components.
  2. other components such as laminin, fibronectin, gelatin, and more.
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13
Q

What do mutations in the ECM create?

A

skin blisters

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14
Q

What is a tumor?

A

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

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15
Q

What are the functions of metastatic cancer cells?

A
  1. change cell junctions
  2. break loose
  3. epithelial-mesenchyme transition (EMT)
  4. degrade extracellular matrix (ECM)
  5. metastasize
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16
Q

What creates oncogene?

A

hyperactive_ proto-oncogene due to mutations or other DNA abnormalities

17
Q

What is the counteraction of oncogene?

A
  1. oncogenes – promoting growth in normal situation
    a. cause cancer when hyperactive (or __gain-of-function__ mutation)
18
Q

What is the counteraction of tumor suppressor genes?

A
  1. tumor suppressor genes – provide growth check in normal situation
    a. cause cancer when inactive (or __loss-of-function___ mutation)
19
Q

Describe the tumor size chart

A

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

20
Q

What is Gleevec?

A

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

21
Q

What is the tissue renewal rate for most nerve cells?

A

zero

22
Q

What is the tissue renewal rate for intestinal cells?

A

3-6 days

23
Q

What is the tissue renewal rate for red blood cells?

A

120 days (replenished by stem cells in bone marrow)

24
Q

What is the tissue renewal rate for bone tissue?

A

10 years

25
Q

What is the tissue renewal rate for skin cells?

A

2 months

26
Q

What is a stem cell?

A

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

27
Q

What are the characteristics of stem cells?

A

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

28
Q

Embryonic Stem Cells

A

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______.

29
Q

Adult Stem Cells

A

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

30
Q

Induced Pluripotent Stem cells

A

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

31
Q

What is totipotent?

A

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

32
Q

What is Pluripotent?

A

capable of giving rise to many different cell types

33
Q

What is multipotent?

A

capable of giving rise to limited set of cell types

cellular and molecular biology (4 decks)

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