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Fundamentals Of Living Cells > Cell Differentiation And Gene Expression > Flashcards

Cell Differentiation And Gene Expression Flashcards

1
Q

Define cell differentiation

A

The process through which a cell undergoes changes in gene expression and gene activity to specialise and take on different roles in an organism

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2
Q

Is cell differentiation reversible?

A

No

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3
Q

What happens to the proportions of dividing cells when humans approach maturity

A

It falls

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4
Q

Define stem cells

A

Undifferentiated and unspecialised cells of the human body

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5
Q

What is a totipotent cell (with an example)?

A

Able to differentiate into every cell type in the body - zygote

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6
Q

What is a pluripotent cell (with an example)?

A

Able to differentiate into most, but not all cells (ie not placenta) - embryonic cells/ blastocyst

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7
Q

What is a multipotent cell (with an example)?

A

Can differentiate into a limited number of cells - hematopoietic and mesenchymal cells

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8
Q

What is a unipotent cell (with an example)?

A

Can only form one type of cell - sperm cells and dermocytes

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9
Q

What is the asymmetric division theory of how a stem cell divides and what does it produce?

A

A fate regulator (polarity protein) distributes unequally in the daughter cells - produces one differentiated cell and one stem cell

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10
Q

What is the symmetric division theory of how a stem cell divides and what does it produce?

A

Some cells may divide to give identical daughter stem cells while other stem cells divide to generate two progenitor cells committed to differentiation- two differentiated cells or two stem cells

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11
Q

Where do embryonic stem cells come from?

A

A four or five day old human in the blastocyst phase of development.

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12
Q

Why aren’t embryonic stem cells sometimes considered stem cells?

A

They differentiate into specialised cells so quickly

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13
Q

What type of stem cells are embryonic stem cells?

A

Pluripotent

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14
Q

What type of stem cells are adult stem cells?

A

Multipotent

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15
Q

What is a tissue specific cell?

A

A cell that can give rise to types of differentiated cells within the tissue they reside in

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16
Q

What is the function of adult stem cells?

A

To replace dead cells

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17
Q

What are the levels of adult stem cells like?

A

In low rate of cell turnover tissues (like brain) it is low and in high turnover rate tissues (like blood) it is high

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18
Q

What is a stem cell niche?

A

A special supportive micro-environment where tissue specific stem cells are maintained

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19
Q

What are stem cell niches influenced by?

A

Neighbouring niche cells, secreted soluble signalling factors, physical parameters and environmental signals

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20
Q

What are the main factors in stem cell niches?

A
  • secreted factors
  • inflammation and scarring
  • extracellular matrix
  • physical factors
  • hypoxia and metabolism
  • cellular components
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21
Q

Where do blood cells come from (dependant on the maturity of the human)

A

Made in embryonic structures until week 20 when they originate from the bone marrow

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22
Q

What is a hematopoietic stem cell?

A

Multipotent stem cells anchored to fibroblast-like osteoblasts or the marrow of long bones

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23
Q

What do hematopoietic stem cells produce?

A

All blood cells and some immune system cells

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24
Q

What are mesenchymal stem cells?

A

Stromatolites cells found in bone marrow and other organs. They’re poorly defined and heterogenous.

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25
Q

Do mesenchymal stem cells self renew?

A

No

26
Q

What do mesenchymal stem cells produce?

A

Chondryocyctes, osteoblasts, myocytes and adipocytes

27
Q

What is a chondrocyte?

A

Cartilage cell

28
Q

What is an osteoblast?

A

Bone cell

29
Q

What is a myocyte?

A

Muscle cells

30
Q

What are progenitors?

A

Oligopotent cells only found in the myeloid or lymphoid lineage

31
Q

Can progenitors replicate indefinitely?

A

No, only a limited number of times

32
Q

What helps to determine how a cell differentiates?

A

The type and number of proteins

33
Q

What allows the analysation of the transcription profile of each cell?

A

RNA sequencing and microassays

34
Q

How do TFs affect gene expression?

A

They bind to regulatory regions of genes and affect its expression by switching it on or off

35
Q

Where are the two places TFs can be?

A

Differentiation of stem cells and some are tissue specific

36
Q

What is a basal transcriptions factor?

A

A TF necessary for the RNA polymerase to function at the site of transcription in eukaryotes

37
Q

What is considered the most basic set of proteins needed to activate a gene for expression?

A

Basal TFs

38
Q

Where do basal TFs bind to activate transcription?

A

The 5’ region of DNA

39
Q

How do specific TFs differentials regulate the expression of various genes?

A

By binding to the adhesive regions of DNA or the promoter regions

40
Q

What do specific TFs ensure?

A

The genes are expressed in the right cell at the right time in the right amount

41
Q

How do the different TFs know which genes to bind to?

A

The binding elements (motifs) in their promoters and enhancers

42
Q

What is a housekeeping gene?

A

Transcribed in all or nearly all cell types

43
Q

What is a luxury gene?

A

The specialised genes expressed in only some types of cells

44
Q

What is a pioneer factor?

A

TFs that can bind to condensed/ closed chromatin, remodel and initiate cell fate and differentiation

45
Q

What does a master regulator do?

A

Control the differentiation of the cell

46
Q

How common are pioneer factors in embryonic stem cells (and why)?

A

Very - needed to maintain their pluripotency

47
Q

Is DNA methylation heritable and reversible?

A

Yes

48
Q

What does DNA methylation result from?

A

External or environmental factors as part of the development programme

49
Q

Describe what DNA methylation does (and what it results in)

A

Covalent addition of the methyl group at the 5-Carbon of the cytosine ring resulting in 5-methyl-cytosine (5-mC)

50
Q

Where does 5-mc occur in somatic cells?

A

CpG sites

51
Q

Where does 5-mc occur in embryonic stem cells?

A

Can happen anywhere

52
Q

What is a CpG site?

A

A place where a cytosine is next to a guanine

53
Q

What does a de-novo methyltransferase do?

A

Methylate CpG pairs during differentiation

54
Q

What does a maintenance methyltransferase do?

A

Methylates the opposite strand

55
Q

What are the consequences of DNA methylation?

A

-methylation could increase folding and silencing

56
Q

In embryonic stem cells are the majority of CpG sites methylated?

A

Yes

57
Q

Where are globin genes expressed and what happens when they aren’t?

A

Red blood cell lineages- they’re methylated in all other cell types

58
Q

Give the steps of somatic cell nuclear transfer (SCNT)

A
  • remove nucleus from a differentiated somatic cell and place it in a denucleated egg cell
  • new nucleus is reprogrammed by factors in the egg cytoplasm
  • the new egg behaves like a zygote (totipotent)
59
Q

What is an induced pluripotent stem cell (iPSc)?

A

Pluripotent stem cells artificially produced from somatic cells

60
Q

What is yamanakas cocktail and when is it used?

A

The four transcription factors iPScs are exposed to

61
Q

What are iPScs used for?

A

Gene therapy
Model disease and drug screening
Regenerative medicine/ cell transplantation

Fundamentals Of Living Cells (41 decks)

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