Lecture 7 Flashcards by Olivia Mahaffey

What are the key properties of a stem cell?

Able to self-renew and differentiate into specialised cell types

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What are the different levels of stem cell potency?

Totipotent, pluripotent, multipotent

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Where do embryonic stem cells come from?

Inner cell mass of the blastocyst

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How do differentiated adult cells differ from adult stem cells?

Differentiated cells are specialised; adult stem cells can self-renew and generate multiple cell types

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What defines a stem cell?

A cell that can self-renew and produce specialised differentiated cells

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What are the two perspectives on stem cells?

Progressive restriction of cell fate during development; maintenance of adult tissue homeostasis

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What does the river analogy represent in stem cells?

Adult tissue homeostasis/ staying in a stable enviroment with limited potency / able to repair damage by differentiation of a certain type of cells.

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What pathways does the epigenetic landscape represent?

Developmental pathways where cells progressively choose fates

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How does potency differ in the river and landscape analogies?

River = restricted; landscape = progressive fate decisions

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What does developmental history influence in stem cells?

Influences specification and differentiation

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Can cells change fate after specification?

Yes, via transdifferentiation or induced pluripotency

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What are totipotent stem cells?

Can form all embryonic and extraembryonic tissues

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What is a classic example of a totipotent cell?

The egg (zygote)

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What are pluripotent stem cells?

Can form all germ layers but not extraembryonic tissues

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What are multipotent stem cells?

Restricted to a tissue or germ layer but produce multiple cell types

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Give an example of multipotent stem cells

Intestinal epithelium stem cells

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Until what stage are embryonic cells totipotent?

Until the morula stage

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What happens at the compacted morula stage?

Cells begin slight differentiation

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What does the inner cell mass become?

The embryo

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What is the source of embryonic stem cells?

Inner cell mass of the blastocyst

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What can embryonic stem cells do in chimeras?

Contribute to all embryonic tissues

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What are embryonic stem cells used for experimentally with mice?

Producing transgenic and knockout mice

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What does the trophoblast form?

Placenta and extraembryonic membranes

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What happens to cells during development?

They gradually specialise

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What phase are most adult cells in?

G0 (resting phase)

Can some G0 cells re-enter the cell cycle?

Yes, some are quiescent

What happens to permanently withdrawn cells?

They do not divide again

Are adult stem cells fast or slow cycling?

Slowly cycling

Are adult stem cells common or rare?

Rare

What is the potency of most adult stem cells?

Multipotent

Do adult stem cells self-renew?

Yes, for long periods

What is the function of an adult stem cell?

Replace cells lost due to injury, turnover, or disease

Examples of adult stem cells

Epidermal, haematopoietic, intestinal crypt, myogenic (satellite cells)

How can stem cell potency be tested?

Experimental assays (e.g., teratoma formation)

How do telomeres relate to stem cells?

Maintain long-term self-renewal

What is a stem cell niche?

Microenvironment maintaining stemness

What are OSKM factors?

Transcription factors maintaining/reprogramming pluripotency

What happens in the teratoma assay?

Injection of cells into SCID mice to test pluripotency

What indicates pluripotency in this assay?

Tumours containing all three germ layers

How do progenitor cells differ from stem cells?

Limited lifespan and no permanent self-renewal

How can stemness be tested?

Transplantation and serial transplantation

What do axial stem cells demonstrate in transplantation?

Contribution to mesoderm but with restricted potential

What are telomeres?

Chromosome end caps maintaining integrity

What happens to telomeres each cycle?

They shorten

What is the Hayflick limit?

Cells stop dividing when telomeres are depleted

Why can stem cells divide longer?

High telomerase expression

What are key pluripotency transcription factors?

Oct4, Sox2, Nanog, Klf4, Myc

Where are these factors highly expressed?

Inner cell mass

What type of proteins are they?

Transcription factors

What do Oct4, Sox2, Nanog, Klf4 activate?

Activate pluripotency genes

What is Myc’s role?

Opens chromatin for gene access

What is autoregulation in this network?

Factors regulate each other

What genes are suppressed?

Differentiation genes

What do OSKM factors reprogram?

Reprogramming differentiated cells

What do reprogrammed cells become?

Pluripotent stem cells

What do iPS cells forms?

Form all germ layers and teratomas

Why is asymmetry important in stem cells?

Produces one differentiated and one stem cell

How can asymmetry occur?

Unequal division or post-division signalling

What is a stem cell niche?

Environment maintaining stemness

What can niches involve?

Signals, cell contact, or self-signalling

How can stem cells lose potency?

Through intrinsic differences or external signals

How can different cell types arise from one stem cell?

Sequential signalling + cell memory

What determines cell fate?

Signal combinations and concentrations

What do cells pass through during differentiation progression?

Cells pass through intermediate stages

What patterns show the different stages?

Gene expression patterns

What are master regulators?

Genes that drive full differentiation programs

How are differentiation principles used experimentally?

Sequential signalling in ES/iPS protocols

What triggers muscle differentiation?

Signalling molecules and MRF genes

What are MRFs?

Myogenic regulatory factors

Which MRFs expand cells?

Myf5, MRF4

Which MRF drives differentiation?

MyoD

What makes MyoD special?

Master regulator of muscle differentiation

What does MyoD activate?

Its own expression and muscle genes

What is a feed-forward circuit?

A gene activates itself and downstream targets simultaneously

Why is intestinal epithelium a good model?

Clear spatial separation of differentiation stages

What is the “conveyor belt” model?

Cells move and differentiate along the crypt-villus axis

What signalling molecules regulate intestinal stem cells?

Wnt and BMP

What does high Wnt do?

Promotes stemness and division

What does high BMP do?

Promotes differentiation and stops division

Where is Wnt highest?

Bottom of the crypt

Where is BMP highest?

Toward the top

Lecture 7 Flashcards

(81 cards)