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BIOL 3542 > Final Exam - Cell Differentiation and Stem Cells > Flashcards

Final Exam - Cell Differentiation and Stem Cells Flashcards

1
Q

Differentiation

A

-Differentiation is a transient and step-wise changes in cell form
Changes include: Cell morphology, Gene expression (mRNA), Protein expression/activity (translation/post-translational modification)

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2
Q

Terminally differentiated

A
  • a stable state or fate
  • associated with reduced or no cell division
  • describes a cell that has become fully structurally and functionally differentiated and will not undergo any further differentiation
  • terminally differentiated cells often do not undergo further cell division
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3
Q

Cellular memory

A
  • Two ways that cell properties can be inherited during cell division
    1. Persistence of gene-regulatory proteins, Transcription factors can be inherited and reinforce their expression through a positive feedback loop
    2. Maintenance of chromatin modifications, Chromatin marks (methylation of DNA), These and histone modifications are inherited during semi-conservative DNA replication
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4
Q

Positive feedback loop

A
  • a type of regulation in which the end-product of a pathway or process can activate an earlier stage
  • Transcription factors can be inherited and reinforce their expression through a positive feedback loop
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5
Q

Chromatin

A

-cellular memory can be inherited during cell division due to maintenance of chromatin modification (through chromatin marks and histone modifications during semi-conservative DNA replication)
-the material of which chromosomes are made
-composed of DNA packaged into nucleosomes by histone proteins and is also associated with many other proteins that influence its structure
-chemical modifications to DNA and histone proteins affect the structure of chromatin
and determine whether a given gene is available for transcription or has been packed away so that it is inaccessible

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6
Q

Semi-conservative replication

A

-chromatin marks and histone modifications are inherited during semi-conservative DNA replication = maintenance of chromatin modifications (a way that cell properties can be inherited during cell division)

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7
Q

Skeletal muscle

A
  • Mature skeletal muscle cells do not divide

- Due to being highly specialized expressing genes necessary for muscle contraction

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8
Q

Myotome

A
  • Region of the somite that gives rise to the progenitors of skeletal muscle
  • myoblasts are specified in the somite from the myotome
  • Muscle cell fate is specified in the somite
  • Forms the myoblasts
  • part of the somite that gives rise to muscle
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9
Q

Myoblasts

A
  • specified in the somite from the myotome
  • Muscle cell precursors /progenitors that migrate from the somite to specific regions of the embryo (such as the limbs) and later form the mature skeletal muscles
  • These are an intermediate cell type which upon formation are committed to form muscle
  • Migratory
  • Removal of growth factors (Fgf) signals for the cells to differentiate into muscle
  • Transcription factors Pax-3 and Pax-7 are linked to the properties of myoblasts (undifferentiated, migratory, cell division)
  • a committed but still undifferentiated muscle cell
  • three features:
    1) Pax-3 (transcription factor) and Pax-7 (transcription factor) associated with the properties of the myoblasts (division and migration)
    2) Growth factors: Fgf pathway is one of several involved, Removal of growth factors is associated with maturation (cells stop dividing, migration is complete, express genes associated with final function)
    3) Family of transcription factors, myoD and myogenin, myf 5 and mrf 4: All are sufficient for muscle cell specification, Are dynamic when expressed
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10
Q

Satellite cells

A
  • Vertebrate skeletal muscle still cells
  • Primary source of growth and regeneration of skeletal muscles
  • Quiescent (rarely divide and generally inactive in mature muscle)
  • Sequestered (isolated) from the muscle fibre
  • Unlike mature muscle fibre cells, satellite cells express Pax-7
  • undifferentiated stem cell present in adult muscle that can be reactivated to produce more skeletal muscle cells if the muscle is damaged
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11
Q

Quiescent

A
  • rarely divide and generally inactive in mature muscle

- ex) satellite cells

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12
Q

myoD

A
  • Family of homologues and transcription factors myoD, myogenin, mrf4 and myf5 required for various steps of muscle cell differentiation
  • All are sufficient for muscle cell differentiation
  • are dynamic when expressed
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13
Q

mrf4

A
  • Family of homologues and transcription factors myoD, myogenin, mrf4 and myf5 required for various steps of muscle cell differentiation
  • All are sufficient for muscle cell differentiation
  • are dynamic when expressed
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14
Q

myf5

A
  • Family of homologues and transcription factors myoD, myogenin, mrf4 and myf5 required for various steps of muscle cell differentiation
  • All are sufficient for muscle cell differentiation
  • are dynamic when expressed
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15
Q

myogenin

A
  • Family of homologues and transcription factors myoD, myogenin, mrf4 and myf5 required for various steps of muscle cell differentiation
  • All are sufficient for muscle cell differentiation
  • are dynamic when expressed
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16
Q

PAX-3

A
  • a transcription factor associated with the properties of the myoblasts (division and migration)
  • required for myoblast differentiation and determination
  • re-expressed in satellite cells
  • caues reactivation of division and migration
  • Pax-3 and Pax-7 are closely related proteins with some overlapping function
  • Pax-3: expressed in and required for myoblast specification and determination
  • Pax-7: later expressed in satellite cells and required to maintain these stem cells
  • Pax-3 re-expressed in satellite cells and causing cells to proliferate and become myoblast-like in properties
17
Q

PAX-7

A
  • a transcription factor associated with the properties of the myoblasts (division and migration)
  • Pax-3 and Pax-7 are closely related proteins with some overlapping function
  • Pax-3: expressed in and required for myoblast specification and determination
  • Pax-7: later expressed in satellite cells and required to maintain these stem cells
  • Pax-3 re-expressed in satellite cells and causing cells to proliferate and become myoblast-like in properties
18
Q

Growth factors

A
  • one of the features of the myoblasts
  • Fgf pathway is one of several involved
  • Removal of growth factors is associated with maturation (cells stop dividing, migration is complete, express genes associated with final function)
19
Q

Organ identity factors

A
  • also called “master regulators”
  • a single gene (or small group of related genes) is sufficient and necessary for development of an organ
  • often conserved function in animal development
  • regulate tissue-specific genes/proteins required for cell and organ function (terminal differentiation)
  • Pax6 (mouse) /eyeless (Drosophila)=eye development … rhodopsin and melanin
  • Nkx2.5 (mouse) / tinman (Drosophila) = heart … heart myosin
  • Pdx1 (mouse) = pancreas development …. insulin
20
Q

Pax6/eyeless

A
  • an organ identity factor
  • Pax6 (mouse) /eyeless (Drosophila)=eye development … rhodopsin and melanin
  • One copy of the gene= defects, eye is smaller
  • Pax6 and eyeless are homologues
  • Family of transcription factors necessary and sufficient for eye development
  • Highly conserved, can probably be interchanged
  • Pax-6 loss of function (-/-) there is a complete loss of eye structure
  • Expression of this in the antenna region of the fly is sufficient to produce ectopic eyes in the fly
21
Q

Nkx2.5/tinman

A
  • an organ identity factor

- Nkx2.5 (mouse) / tinman (Drosophila) = heart …. heart myosin

22
Q

Pdx-1

A
  • an organ identity factor
  • Pdx1 (mouse) = pancreas development …. insulin
  • a transcription factor required for pancreas development
  • no Pdx-1=no pancreas
  • only expressed in cells of endoderm that will give rise to the pancreas
  • Is expressed in buds that will give rise to pancreas tissue
  • In mouse, there is a ventral bud and dorsal bud from the endoderm tube
  • Later fuse to form the pancreas

Pancreas development:

  • Pancreas cells undergo growth and branching to form pancreatic ducts (empty into the duodenum)
  • Main cell types differentiate
  • Acinar cells=Exocrine function (digestive enzymes)
  • Beta cells=Endocrine function (insulin producing), Associated with the blood stream (regulate glucose homeostasis)
  • Pancreas is NOT regenerative like our liver

BIOL 3542 (10 decks)

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