Cellular Differentiation Flashcards

1
Q

What can these types of embryonic stem cells differentiate into?

Totipotent, Pluripotent, Multipotent

A

Totipotent- can turn into embryonic or extra embryonic tissue, fertalized ovum and first few divisions

Pluripotent- can turn into any germ layer; mesoderm, ectoderm, endoderm. THIS one is “stem cells”

Multipotent- can only turn into a limited number of cell types arising from one germ layer. Adult and cord blood cells

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2
Q

Which Go cells can return to cell cycle?

What do they need to be able to do that?

A

fibroblasts, endothelial, and liver epithelial.

Need signal: mitogen or Growth Factor

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3
Q

In which state are adult stem cell?

A

Multipotent- can give rise to only a limited amount of cell types

There is a balance of proliferating and death. Don’t want too much of either

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4
Q

What is a subpopulation and where do you find it?

How do they divide?

A

A group of multipotent cells in adult to regenerate lost cells.

Found in basal layer of a tissue.

The cell replicates > one goes on to rapidly divide/differentiate > transient amplifying cell (intermediate) > cell

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5
Q

Niche

A

Microenvironment for subpopulations

Provides the signals needed to maintain stem cells.

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6
Q

What is Wnts signaling

A

secreted by fibroblasts under GI crypt.

part of maintenance for stem cell sub pop in GI

example of signal from a niche

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7
Q

How do transcription factors and epigenetics play a role in differentiation?

A

All cells have the same genome. Specific TF and chromatin remodeling allow the cells to express the genes that need to be expressed for that certain cell.

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8
Q

What are the two major transcription factors that ensure the self-renewal and pluripotency of embryonic stem cells?

How does epigenetics affect them?

A

OCT4, SOX 2

Methylation of genes for OCT4 and SOX2 lead to differentiation.

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9
Q

What do keratinocytes do and what layers do they go into?

A

Stem cells of epidermis

Basal cells- stem cells, attached to basal lamina

Prickle cells- stratum spinosum, lots of desmosomes

Granular Cells- granular layer, waterproof barrier, fill with keratin

Squames- dying terminally differentiate cells fill with keratin

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10
Q

what are the Keratinocyte signals and what do they tell the cell to do?

A

Integrin- stay a basal keratinocyte (stem cell)

Notch- produce transit amplifying cells

Hedgehog- Produce sebaccous gland cells

Wnt- Produce hair follicle cells

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11
Q

What type of cells do adipocytes derive from?

Which transcription factor initiates triglyceride storage?

A

Mesodermal- mesenchymal

PPARy- acts like steroid receptor, heterodimerizes with RXR

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12
Q

What is the difference between a lipoblast and a lipocyte?

A

Both part of adipose tissue.

lipoblasts- Increasing lipid inclusions see

Lipocyte- mature cell, one large lipid filled inclusion, eccentric nucleus (on edge of cell), spherical shape, chicken-wire in H&E)

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13
Q

White vs Brown Adidose tissue

A

White- found in adults, 10% or more of body weight, triglyceride storage and endocrine secretions

Brown- during fetal development, lost during childhood, some around organs, thermogenic

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14
Q

Transdifferentiation of adipose

A

Differentiation with no cell division

White to brown adipose- induced by cold temp, chronic exercise, ‘browning phenomenon’

Brown to white- caloric excess

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15
Q

What are Chondrocytes and describe chondrogenesis?

What is the transcription factor that regulates the synthesis?

A

cartilage producing cells

Chrondroblasts (stem cells), mesenchymal
– secrete collagen based ECM matrix which remains in adult cartilage

SOX-9 induces cells to secrete collagen based matrix

Mature chondrocytes when completely surrounded
AVASCULAR, limited ability to repair

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16
Q

Hayline cartilage

What helps hold it together?

A

basic form found throughout the body

Chondrocytes are in lacunae

Collagen, GAG, proteoglycans, and adhesive glycoproteins help hold it together

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17
Q

Isogenous groups

A

groups of cells that appear in clusters because they recently divided

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18
Q

Elastic cartilage is found where and made out of what?

A

Hyaline matrix with elastin

Flexible support for soft tissue

Ear, nose

19
Q

Fibrocartilage

A

Hyaline matrix plus dense regular connective tissue

Resists deformation

Intervertebral discs.

20
Q

What makes up the bone matrix?

what types of cells are involve? what do they do?

What is a lucanae?

A

Osteocytes make up bones

collagen, calcium phosphate crystals and ground substance

osteoprogenitor> mesenchymal, stem cells

Osteoblasts- secrete ECM

Osteoclasts- bone reabsorbing, from phagocytes

Lacunae- space where cells exist in bone.

21
Q

What are the two ways to synthesize bone?

A

Endochondral ossification- from cartilage, long bone
specifically in hyaline cartilage during fetal and adolescence

Intramembranous ossification- condensation of mesenchymal cells that act as precursor to chondroblasts? Make up skull bones.

22
Q

What kind of cells make up skeletal muscles?

Where do the cells originate from? what is the TF?

What differentiates after muscle injury?

A

multinucleated, with sarcolemma (plasma membrane),
eccentric nucleus, striated

Myofibrils- made of myofilaments- actin myosin filaments

Myoblasts(progenitor cells that give rise to muscle cells)- mesodermal origin

TF- MyoD regulates myoblasts

23
Q

Cardiac Myocytes characteristics?

How do they repair?

A

Striated, round central nucleus,

Intercalating disks- between cardiac myocytes

No adult stem cell. some capacity to divide but damage usually repaired by fibrous tissue (connective tissue)

24
Q

Smooth muscle characteristics?

How do they repair?

What are myoepithelium cells?

A

Muscle fibers fusifom (elongated with tapered ends)

Nonstriated (multiple directions)

Central elongated nucleus

Repair: undergo hyperplasia and hypertrophy
– progenitors give rise to new myocytes, may be vascular parasites

Myoepithelium– associated with glands. epithelium that acquire smooth muscle characteristics

25
Q

Neuron terminology?
Perikaryon-
Nissl Bodies
Axon hillcock

A

Perikaryon- cell body

Nissl Bodies- correspond to rER

Axon hilcock- where axon meets cell body

26
Q

What doe the neuronal axon have inside its cytoplasm?

A

cytoskeleton
mitochondria
vessicles- cargo transported

Does not contain organelles

Protein synthesis may occur in axon in specialized cells

27
Q

Kinesins and dyneins which way do they go?

What do they carry?

A

Kinesin- antegrade transport- from cell body to periphery

    • microtubule associated protein (towards + of microtub)
    • vesicles from Golgi,

Dyneins- retrograde transport, periphery to cell body

    • microtubule associated protein
    • towards (-) end
28
Q

What do dendrites NOT have in it’s cytoplasm?

A

Do have organelles, dendrites don’t have golgi

Transport of dendrites is same as axon

29
Q

How are neurotransmitters released into the synapse?

A

Ca channels activated via Action potential > ca enters cell > binds to synamptotagmin > alters snare proteins > cause fusion of vesicle with presynaptic membrane > release of neurotransmitter molecules > bind to postsynaptic receptors

30
Q

Which two proteins bind to keep pre and post synaptic cells close together?

A

Neurexin (presynaptic)

Neuroligin (post synaptic)

31
Q

Astrocytes

What are the two types?

A

specialized glial cells, out number neurons 5 to 1

Provide physical support, maintain tight junctions at the blood brain barrier, associated with nodes of ranvier, regulate K+ concentrations.

two types: fibrous (white matter) and protoplasmic (gray matter)

Found in CNS

32
Q

Oligodendrocytes

A

CNS,

produce and maintain myelin sheath, extend to myelinated multiple axons in the area.

33
Q

Microglia

A

Phagocytic cells of CNS, mesenchymal origin

migrate into parts of the nervous system

Proliferate in response to disease or injury

34
Q

Ependymal cells

A

Line fluid filled cavities, single columnar

apical portion responsible for production, movement and absorption of cerebrospinal fluid

Found in infoldings that associate with astrocytes, tight junctions, and choroid plexus (modified ependymal cells that secrete CSF)

35
Q

Schwann cells

A

PNS neuroganglia

produce myelin sheath that surrounds axons, 1 cell per axon.

Node of ranvier- junction where two adjacent Schwann cells meet.

36
Q

Satellite cells

A

PNS neuroganglia

Line exterior surface of neurons in PNS. Insulate and support but do not produce myelin.

37
Q

Enteric Neuroglia

A

analagous to astrocytes

Barrier maintenance, support, regulation of neurotransmission and glial transmission

38
Q

How to make embryonic stem cell clones?

A

Embronic stem cells are pluripotent

Dolly the sheep- unfertilized egg, remove the nucleus. Add somatic cell nucleus. All the epigenetics were reverted back to pluripotent state

39
Q

What is the likely reason that clones don’t work?

A

errors could have been introduced to the DNA after so many divisions of a somatic cell.

40
Q

What is Therapeutic cloning?

A

Only in theory, use somatic cell nucleus and unfertilized egg.

Be able to clone one cell type that matches the patient

41
Q

Induced pluripotent stem cells

What are the retroviral vectors?

A

Able to revert fibroblast to pluripotent state but still not able to do in humans. The TF used can also act as oncogenes. Highly proliferative and organs often develop cancerous tumors.

Retroviral vectors are transcription factors inserted and turned on:
–OCT4, SOX2, and c-Myc

42
Q

Which tissues are easily seen to be targeted by chemotherapies?

A

Tissues that need to regenerate often, skin, hair, blood.

chemotherapies kill rapidly dividing cells by inhibiting replication or damaging DNA

43
Q

What type of cell is transplanted in a bone marrow transplant?

A

Hematopoeitic stem cell transplant

Give rise to erythrocytes and leukocytes