Biol-K 324 Lec 21: Differentiation, Neurons, Immunology

Front 1

stem cells

Back 1

1. unspecialized cells

2. potentially reproduce themselves (self-renewal)

3. generate specialized progeny (differentation) indefinitely

4. divide and produce progenitor or precursor cells that can divide rapidly (TA cells)

5. multipotent and undifferentiated

Front 2

TA cells

Back 2

1. transit amplifying cells

2. progenitor or precursor cells that can divide rapidly

Front 3

post-mitotic cells

Back 3

stem cells that differentiate

Front 4

totipotent

Back 4

1. fertilized egg

2. cells in mammalian embryos up to 8 cell stage

3. initial cell divisions

Front 5

pluripotent

Back 5

1. inner cell mass cells

3. can become any of the 3 germ layers of the germ line

Front 6

unipotent stem cells

Back 6

1. produce only one cell type

2. ex; germ line stem cells

Front 7

multipotent stem cells

Back 7

1. can produce cells from one germ layer

2. usually from one tissue

3. formed in niches that provide signals to maintian a population of nondifferentiating stem cells

3. ex: adult stem cells

Front 8

gastrulation

Back 8

3 germ cell layers fromed

Front 9

germ layers

Back 9

1. formed during gastrulation

2. derivatives of each germ layer are restricted in fate

3. 3 types: ectoderm, mesoderm, endoderm

Front 10

ectoderm

Back 10

1. germ layer

2. formed at gastrulation

3. ex: nervous system, epidermis, mammary glands

Front 11

mesoderm

Back 11

1. germ layer

2. formed at gastrulation

3. ex: skeletal muscle, skeletal system, dermis, connective tissue, reproductive, cardiovascular, lymphatic, spleen

Front 12

endoerm

Back 12

1. germ layer

2. formed at gastrulation

3. ex: GI, liver, pancreatic, urinary, respiratory, thyroid

Front 13

terminal differentiation

Back 13

1. irreversible step

2. produces highly functionally specialized cells (ex: blood cells, keratinocytes, neurons)

Front 14

fertilization

Back 14

produces zygoe

Front 15

what does sperm do during fertilization?

Back 15

1. binds to zona pellucida

2. releases digestive enzymes

3. activates the cortical reaction to prevent polyspermy

Front 16

cleavage stage

Back 16

Front 17

compaction

Back 17

leads to the first differentiation of trophectoderm and inner cell mass

Front 18

trophoectoderm

Back 18

outer cells

Front 19

inner cell mass cells

Back 19

1. inner cells

2. isolated from blastocyst

3. placed in culture with feeder cells

Front 20

ES cell lines

Back 20

arise that can be cultured indefinitely as pluripotent stems cells

Front 21

pluripotency transcriptional circuit

Back 21

Front 22

what are required to maintain self-renewal and pluripotency and prevent differentiation

Back 22

Oct4

Sox2

Nanog

Front 23

Oct4

Sox2

Nanog

Back 23

1. required to:

a. maintain self-renewal

b. control pluripotency

c. prevent differentiation

2. activate their own genes, producing a self-perpetuating feedback circuit

Front 24

iPS cells

Back 24

1. induced pluripotent stem cells

2. produced by differentiation reversal

3. formed from somatic cells by expression of combinations of key transcription factors: KLF4, SOX2, OCT4, and c-MYC

Front 25

4 proteins expressed in differentiated cell

Back 25

1. Oct4

2. Sox2

3. Klf4

4. c-Myc

Front 26

Oct4, Sox2, Klf4, c-Myc

Back 26

1. expression of these proteins are in a differentiated cell

2. can reprogram the cell to become a pluripotent cell line

3. control iPS

4. ex: ES cells

Front 27

stem cell properties

Back 27

1. indefinite self-renewal

2. undifferentiated

3. maintained at relatively constant levels

Front 28

undifferentiation

Back 28

do not produced proteins characteristic of differentiated cells that they produce

Front 29

what maintains stem cell self renewal?

Back 29

local microenvironment/niche

Front 30

what maintains stem cell differentiation?

Back 30

local microenvironment/niche

Front 31

local niche

Back 31

1. composed of support cell types and factors produced by support and stem cells

2. extrinsic and intrinsic factors

3. local micro environments that provide cues to stem cells

4. when cells move away from the niche, they tend to differentiate

5. must maintain stem cells without allowing their excess proliferation and block differentiation

Front 32

self-renewing cell divisions are:

Back 32

1. symmetric (producing 2 stem cells)

2. asymmetric (producing 1 stem cell and 1 cell that differentiates)

Front 33

intestinal stem cells

Back 33

niche located blood vessels and mesenchymal cells

Front 34

neural stem cells

Back 34

1. located within neural tube

2. divide perpendicular, symmetric, and asymmetric planes

3. turnover is slow in the CNS

Front 35

hematopoietic stem cells

Back 35

1. blood cells are constantly replenished

2. give rise to all blood cell types

3. give rise to the myeloid and lymphoid stem cells

Front 36

resting potential

Back 36

1. -60 mV

2. maintained by ATP pump (3K+ out, 2 Na in)

Front 37

sensory neuron

Back 37

1. detects stimulus

stimulus --> sensory neuron --> interneuron --> motor neuron

Front 38

astrocytes

Back 38

1. glial cell type

2. regulate ionic composition of the fluids surrounding neurons, supporting their correct function

Front 39

glial cell

Back 39

1. support neural function

2. much more abundant than neurons

3. ex: astrocytes

Front 40

depolarization

Back 40

1. Voltage gated Na channels open

2. Propagate signal

3. peaks at +50 mV

Front 41

insulation

Back 41

1. produced by myelin sheath

2. increases conduction speed without increasing axon diameter

3. saltatory conduction

Front 42

myelinated neurons in CNS

Back 42

oligodendrocytes

Front 43

myelinated neurons in PNS

Back 43

Schwann cells

Front 44

primary lymphoid organs

Back 44

1. where lymphocytes are generated

2. thymus and bone marrow

Front 45

lymphocytes

Back 45

1. B/T cells

2. made in thymus and bone marrow

Front 46

secondary lymphoid organs

Back 46

1. where adaptive immune response begin

2. Lymph nodes and spleen

Front 47

physical barriers

Back 47

skin

Front 48

chemical barriers

Back 48

pH and enzymes

Front 49

types of immunity

Back 49

1. physical

2. chemical

3. innate immunity

4. adaptive immunity

Front 50

innate immunity

Back 50

1. phagocytes ingest and destroy pathogens

2. TLR activate macrophage and dendritic cells that engulf pathogens

3. presents antigens to adaptive immunity cells

4. complement system responds to bound antibodies or lectins to assemble a membrane attack complex (MAC)

5. natural killer cells (NK) protect against viral infraction

6. mediated by complement system and leukocytes

7. cells deployed rapidly

8. moderate specificity

9. pathogens are recognized by TLR

Front 51

TLRs

Back 51

1. toll like receptors

2. apart of innate immunity

3. identified as receptors for these toxins --> activate innate immunity

4. excessive TLR activation produces sepsis

Front 52

NK cells

Back 52

1. innate immunity

2. protect against viral infection

3. activated by virus infected cells

4. interferon-gamma

Front 53

interferon-gamma

Back 53

cytokine that boost anti-viral defense

Front 54

inflammation

Back 54

complex response to injury and infection

Front 55

innate and adaptive immunity interplay

Back 55

activate each other to protect the organism

Front 56

adaptive immunity

Back 56

1. lymphocyte bearing antigen-specific responses that adapt to the molecular nature of the infection

2. mediated by T and B lymphocytes

3. slow deployment of full activation (days)

4. high specificity

Front 57

immunoglobulins

Back 57

1. produced by B-cells

2. abundant in serum

3. composed of light and heavy chains

Front 58

what activates clonal expansion of B cells

Back 58

antigen presentation and B cell activation

Front 59

antigen presentation and B cell activation

Back 59

induces clonal expansion of specific B- cell clones

Front 60

antibody and antigen complimentarity

Back 60

highly specific

Front 61

asymmetric cell division

Back 61

two different types of daughter cells are formed from one mother

Front 62

symmetric division

Back 62

1. both daughter cells are identical

2. may have different fates if exposed to different external signals

Front 63

what is the source of the embryo proper?

Back 63

inner cell mass

Front 64

what is the source of the ES cells?

Back 64

inner cell mass

Front 65

ES cells

Back 65

1. formed from inner cell mass

2. pluripotent

3. capable of giving rise to all differentiated cell types of the organisms (except extra-embryonic tissues)

4. useful in the production of genetically altered miceand offer potential for therapeutic uses

Front 66

what controls pluripotency of ES cells

Back 66

controlled by multiple factors:

1. DNA methylation

2. chromatin regulators

3. certain micro-RNAs

4. transcription factors: Oct4, Sox2, and Nanog

Front 67

beta catenin

Back 67

1. component of Wnt signaling

2. implicated in preserving stem cells in the germ line and intestine

3. directing cells toward self-renewel rather than differentiation

Front 68

germ line cells

Back 68

give rise to eggs or sperm

Front 69

daughter cells that cant contact their niche cells

Back 69

undergo proliferation and differentiation

Front 70

Lgr5 receptor

Back 70

expressed in intestinal stem cells

Front 71

Paneth cells

Back 71

1. form part of the niche

2. located next to intestinal stem cells

Front 72

neural stem cells

Back 72

1. found in the subventricular zone of brain during development and adulthood

2. generate both nerve and glial cells

Front 73

blood-cell lineage

Back 73

different precursor types form and proliferate under the control of distinct cytokines

Front 74

action potential speed

Back 74

100 meters per second

Front 75

neuronal circuit

Back 75

sensory neuron ---> interneuron ---> motor neuron

Front 76

charged S1-S4 paddles

Back 76

1. induce opening of voltage gated channels

2. response to depolarization

Front 77

closing and inactivation of voltage-gated cation channesl

Back 77

result from movement of cytosolic "ball" segment into the open pore

Front 78

mechanical and chemical defenses

Back 78

1. provide protection against most pathogens

2. immediate and continuous

3. little specificity

Front 79

most important leukocytes for innate immunity

Back 79

1. neutrophils

2. phagocytic cells: macrophages and dendritic cells

Front 80

V and J segment rearrangements

Back 80

1. Ig light chains

2. controlled by RSSs

Front 81

V, D, and J segment rearrangements

Back 81

1. Ig heavy chains

2. controlled by RSSs

Front 82

RSSs

Back 82

1. control VJ/ VDJ rearrangement

2. separated by spacers

3. RAG 1 and RAG2

Front 83

RAG1 and RAG2

Back 83

1. recombinases

2. made only by lymphocytes

3. participate in nonhomologous end joining of DNA

Front 84

antibody diversity

Back 84

created by:

1. combinatorial joining

2. combinatorial association

3. after B cells encounter an antigen

Front 85

combinatorial joining

Back 85

1. random selection of Ig gene segments to be recombined

2. contribute to antibody diversity

Front 86

combinatorial association

Back 86

ability of heavy and light chains produced from rearranged Ig genes to associate with many different light chains and heavy chains

Front 87

junctional imprecision

Back 87

generates additional antibody diversity a the joints fo the gene segmetns joined during somatic recombination

Front 88

affinity maturation

Back 88

1. B cell encounters antigen

2. selection and proliferation of B cell

3. B cells produce high affinity antibodies

Front 89

B cell development

Back 89

1. heavy-chain genes are rearranged

2. expression of the pre-B-cell receptor

3. rearrangement of light-chain genes

4. assembly of IgM membrane bound B-cell receptor

Front 90

allelic exclusion

Back 90

1. only one of the allelic copies of the heavy chain locus and of the light-chain locus is rearranged

2. ensures that a B cell expresses Ig with a single antigen specificity

Front 91

polyadenylation

Back 91

1. different in Ig primary transcript

2. determines whether the membrane-bound or secreted form of an antibody is produced

Front 92

class switching

Back 92

allows B cells to adjust the effector functions of the Ig produced but retain their specificity for antigen