Moss - Tissues and Stem Cells

Question 1

what happened to cells due to the evolution of multicellularity?

Answer 1

cells in the human body have lost the capacity for independent survival, rather they are members of a cohesive and integrated organism

Question 2

how many cells are there in the human body?

Answer 2

more than 10¹⁴

Question 3

how many distinct varieties of cells are there in the adult human body?

Answer 3

~210, not including subtle differences

Question 4

what do all cell varieties have?

Answer 4

the same genome

Question 5

how can similar-looking undifferentiated cells give rise to very different adult organisms?

Answer 5

through development

Question 6

what cells divide and differentiate into mature cells found in tissues and organs?

Answer 6

stem cells and progenitor cells

Question 7

what are the three main factors that contribute to the stability of tissue organization?

Answer 7

cell-to-cell communication

selective cell adhesion

molecular cell memory

Question 8

what contribution does cell-to-cell communication give to the stability of tissue organization?

Answer 8

direct contact and diffusible signals will influence the survival, proliferation, and behavior of cells

Question 9

what is an example of cell-to-cell communication in tissue stability/organization

Answer 9

tissue growth can induce the formation of blood vessels; nerves die if they don’t find a cell to innervate

Question 10

what contribution does selective cell adhesion give to the stability of tissue organization?

Answer 10

cells form selective attachment to other cells or to the basement membrane or ECM

loss of attachments can change their cell behavior

Question 11

what kind of binding do cadherins and other cell adhesion molecules use?

Answer 11

cadherins and other cell adhesion molecules follow certain molecular rules, such as homophilic binding

Question 12

what contribution does molecular cell memory give to the stability of tissue organization?

Answer 12

gene expression patterns established during development are stabilized, thus maintaining cell identity throughout life

even as cells proliferate and generate new cells, they pass on the inherited pattern to their cellular progeny

Question 13

in what way would skin be classified?

Answer 13

as a stratified squamous epithelium

Question 14

what happens to cells in the epithelium?

Answer 14

the basal cell layer is attached to the basal lamina

as cells begin to die they detach from the basal lamina, move up through the different layers until it reaches the surface and flakes off

Question 15

what are the different layers found in the epithelium (from top to bottom)?

Answer 15

Squame about to flake off

keratinized squames

granular cell layer

prickle cell layer

basal cell layer

basal lamina

connective tissue of dermis

Question 16

what skin layers are keratinocytes?

Answer 16

basal cell layer

prickle cell layers

granular cell layer

keratinized squames

Question 17

how would the cell layers in the intestine be classified?

Answer 17

simple columnar epithelium

Question 18

TRUE or FALSE: Progenitor cells have limited capacity to divide

Answer 18

TRUE

Question 19

TRUE or FALSE: Stem cells have a lifetime capacity to divide as long as they are in the stem cell niche

Answer 19

TRUE

Question 20

In the lumen of the gut, how do cells develop?

Answer 20

cells move up from the bottom as they develop from dividing stem cells

once stem cells divide, they become dividing precursor cells

once they reach the top of the crypt, they become nondividing terminally differentiated cells

in the case of the gut lumen, absorptive cells and secretory cells

Question 21

what do all self-renewing tissues have?

Answer 21

stem cells

Question 22

what are stem cells?

Answer 22

multi- or pluripotent (maybe totipotent)

practically unlimited division potential

daughters either remain stem cells or become committed to differentiation

Question 23

what is multipotent?

Answer 23

many cell types

Question 24

what is pluripotent?

Answer 24

all cell types of the body

Question 25

what is totipotent?

Answer 25

all cell types, plus extraembryonic tissues

Question 26

what are the three ways stem cells may divide?

Answer 26

symmetrically asymmetrically symmetrically with commitment

Question 27

why are stem cell divisions slow?

Answer 27

to preserve the genome

Question 28

what is symmetric division of stem cells without commitment?

Answer 28

stem cells divide and their daughters remain stem cells

Question 29

what is asymmetric stem cell division?

Answer 29

stem cells divide one daughter remains a stem cell the other daughter cell differentiates and divides until it is terminally differentiated

Question 30

what is symmetrical stem cell division with commitment?

Answer 30

stem cells divide and their daughter cells both commit to differentiation

Question 31

what creates the stem cell niche?

Answer 31

paneth cells

Question 32

what surrounds the outside of the crypt?

Answer 32

the basement membrane

Question 33

what maintains stem cell identity?

Answer 33

Wnt signaling from Paneth cells, and other signals from nearby tissues

Question 34

what does the Wnt pathway do in the crypt?

Answer 34

it maintains the proliferation zone

Question 35

What does Wnt signaling do in the crypt?

Answer 35

it helps define the stem cells of the intestinal crypt

Question 36

what happens without the Wnt signal?

Answer 36

Wnt-responsive genes are off

Question 37

what happens when the Wnt signal is on?

Answer 37

transcription of Wnt-responsive genes, leading to proliferation of gut stem cells

Question 38

what kind of pathway is the Wnt pathway?

Answer 38

a signal transduction pathway

Question 39

what are the two types of non-dividing, differentiated intestinal cells?

Answer 39

absorptive cell secretory sell (goblet cell)

Question 40

what does the adsorptive cell in the intestines do?

Answer 40

uses cilia to take in nutrients from the gut

Question 41

what does the secretory (goblet) cell do in the intestine?

Answer 41

secretes mucous

Question 42

where are specialized cells derived from?

Answer 42

multipotent stem cells different numbers of each are produced

Question 43

how do stem cells divide? what do they produce?

Answer 43

they divide slowly and give rise to rapidly-dividing cells (committed precursor cells or transit-amplifying cells) that are fated to differentiate

Question 44

what are the rapidly dividing cells that stem cells give rise to?

Answer 44

committed precursor cells or transit-amplifying cells

Question 45

TRUE or False: Differentiated cells do not divide

Answer 45

TRUE

Question 46

what do the differentiated cells do?

Answer 46

they move away from the stem cells

Question 47

in the intestine, where do the cells of the villus move?

Answer 47

up

Question 48

in the intestine, where do the differentiated cells of the crypt (Paneth cells) move?

Answer 48

down

Question 49

what eventually happens to all differentiated cells?

Answer 49

they die via apoptosis and are phagocytosed

Question 50

how are stem cells and tissues maintained?

Answer 50

* specialized cell types derive from multipotent stem cells * Different numbers of each type are produced * stem cells divide slowly and give rise to rapidly-dividing cells (committed precursor cells or transit-amplifying cells) that are fated to differentiate. * Differentiated cells don't divide * The differentiating cells move away from the stem cells. * cells of the villus move up * Paneth cells of the crypt move down * All differentiated cells eventually die via apoptosis and are phagocytosed

Question 51

what type of stem cell are blood cells derived from?

Answer 51

hematopoietic stem cells

Question 52

what are the types of blood cells?

Answer 52

* erythrocytes (RBCs) * leukocytes (WBCs) * granulocytes * neutrophils * eosinophils * basophils * lymphocytes * monocytes * platelets (fragments of megakaryocytes) * osteoclasts

Question 53

what do granulocytes contain?

Answer 53

many lysosomes and secretory vesicles

Question 54

what can happen to monocytes?

Answer 54

they can become macrophages

Question 55

how much blood do people have?

Answer 55

about 5 liters

Question 56

what is different about the development of blood cells from stem cells vs. other cells?

Answer 56

lineage commitment occurs in steps in blood cells precursors continue to divide they are essentially transit amplifying cells

Question 57

how are embryonic stem (ES) cells made?

Answer 57

cells of the inner cell mass of the blastocyst ae used to make ES cells

Question 58

what are embryonic stem (ES) cells?

Answer 58

pluripotent or totipotent cells that can be cultured indefinitely created from inner cell mass of blastocyst or derived from unused human IVF embryos

Question 59

what do invitro differentiation protocols require?

Answer 59

knowing and administering the specific factors and culture conditions to produce different cell types

Question 60

what can aggregates of pluripotent cells form?

Answer 60

organoids

Question 61

what are organoids?

Answer 61

small organ-like structures, like and eye-like structure formed from aggregates of pluripotent cells may not be functional but have parts of functional cells

Question 62

how is a cell reprogrammed/cloned?

Answer 62

somatic cell nuclear transfer (SCNT) highly variable technique and many attempts are needed for one success

Question 63

what is required for cloning?

Answer 63

extensive epigenetic reprogramming of differentiated cells a process that is inefficient and inexact

Question 64

what is a potential use for SCNT?

Answer 64

to make personalized “ES” cells

Question 65

where do human ESCs come from?

Answer 65

from embryos from IVF

Question 66

in what ways besides IVF can ES-like cells be obtained?

Answer 66

Somatic Cell Nuclear Transfer (SCNT) Co-transfection of a a cocktail of three or four master regulatory factors into a differentiated cell to create an iPS cell

Question 67

how can SCNT create ES-like stem cells?

Answer 67

the nucleus of a patient's cell is transferred to the cytoplasm of an ES or ES-like cell

Question 68

what is an iPS cell?

Answer 68

created when a cocktail of three or four factors are placed into a differentiated cell the factors becomes expressed in fibroblasts and the cells revert to an ES-like state

Question 69

what are the most commonly used regulatory factors to create iPS cells?

Answer 69

Oct¾, Sox2, Myc, Klf4 Oct¾, Sox 2, Nanog, Lin28

Question 70

why are iPS cells so useful?

Answer 70

they can be derived from an individual's own fibroblasts with minimal invasiveness they offer a solution to the immune rejection problem, and provide material for studying patient-specific disease mechanisms

Question 71

what diseases are within reach of cures when stem cell engineering is achieved?

Answer 71

muscular dystrophy Parkinson's disease Type I diabetes Heart Attack Neurodegenerative diseases Spinal cord Injury, etc.