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Genes Evo & Dev Y1 > GED L20 > Flashcards

GED L20 Flashcards

1
Q

Describe the experiment which led to the conclusion of totipotency of cells & name the scientist responsible

A

• Separation of 1st 2 blastomeres -> Sea urchin eggs: (Hans Diresch)
- Each cell at the 2-cell stage or 4-cell stage of meiosis are totipotent.
&raquo_space; Cell has capacity to generate totality of cells present in an organism.

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2
Q

Describe what baby hair ligature experiments revealed & how this was done & name the scientist involved.

A

• Baby hair ligature experiments: (Hans Spemann)
 First nuclear transplantation experiments.
 Using baby hair to separate 1st 2 cells of frog embryo.
» Both cells develop into entire embryos rather than half an embryo.
 If Incomplete separation of cells using hair;
Continuous nuclear division -> one cell
&raquo_space; Develops sufficiently small nucleus to enter other cell via hole
&raquo_space; Other cell (previously not containing nucleus) -> develop into whole
Embryo.
> Illustrate 16 cell stage nuclei are totipotent
(Whole embryo can develop from stage 16 cell.)

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3
Q

Describe the experiment illustrating the natural loss of cell totipotency over time & nam ethe scientist involved

A

 Cloning of frog embryos: (Briggs & King)
 Nuclei up to blastula stage could produce entire embryo -> Totipotent.
 Nuclei further developed than blastula stage -> Not Totipotent.
&raquo_space; More differentiated cells lose their ability of totipotency over time.

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4
Q

What is the Waddington Landscape Hypothesis?

A

 Waddington Landscape Hypothesis:
 Totipotent cells become differentiated
> Once differentiation begins, it cannot be reversed.
> Potency decreases over time.

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5
Q

Describe the first successful cloning experiment of an entire organism & name the scientist involved

A

 Cloning Protocol: (John Gurdon)
 Extraction -> Terminally different pigmented cells -> Tadpole epithelia.
> Transplanted into denucleated wild type (pigmented) eggs
-> (Denucleated via UV radiation)
 Serial transplantations -> Produced blastula stage embryos
&raquo_space; Died.
 Transplant nuclei -> Dying blastula stage embryo -> Into Albino type Eggs
> Repeat several times.
 Eventually developed fully formed identical frogs

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6
Q

Define Pluripotency

A

• Pluripotency:

  • Cellular ability / potential -> Differentiate into any type of cell except embryonic / placental cells.
  • Cellular ability / potential -> Differentiate into any type of cell from a distinct set of cells.
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7
Q

Define Bipotency

A

• Bipotency:
- Cellular ability / potential -> Differentiate into any of two particular types of cell.
• Unipotency:
- Cellular ability / potential -> Differentiate into one particular type of cell only.

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8
Q

Define Totipotency

A

• Totipotency

  • Cellular ability / potential -> Differentiate into any type of cell
  • Ability / potential of a blastomere -> produce a fully-developed embryo.
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9
Q

Define Unipotency

A

• Unipotency:

- Cellular ability / potential -> Differentiate into one particular type of cell only.

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10
Q

Describe the first experiment to successfully clone a mammalian blastocyst & name the scientists involved

A

• Cloning of Mammals -> Dolly the Sheep: (Campbell & Wilmut)
 Nuclear Transfer -> Cultured cell line
- Donors:
 Eggs -> Scottish Blackface.
» Denucleated
 Udder cells -> Finn-Dorset
- Transfer udder cells -> denucleated egg.
- Fused with electric current & cultured
» Development -> Blastocyst
- Transferred to Scottish blackface surrogate
» Birth of Finn-Dorset lamb
> Genetically identical -> Nuclear donor (Udder cells)

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11
Q

Describe the trophectoderm of early mammalian blastocysts

A
  • Trophectoderm:
    » Outer layer of cells of a blastocyst.
    » Provide nutrients -> the developing embryo, facilitate attachment to the uterine
    lining and become part the placenta.
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12
Q

Describe the blastocoel of early mammalian blastocysts

A
  • Blastocoel:
    » Fluid-filled, inner cavity of a blastocyst resulting from cleavage of the oocyte after
    fertilization.
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13
Q

Describe the epiblast of early mammalian blastocysts

A
  • Epiblast: (Primitive mesoderm)
    » Forms embryo proper
    » Cell layer -> develops from inner cell mass (accumulation of cells attached to inner
    lining of trophoblast) of blastocyst.
    » Differentiates -> Ectoderm, mesoderm & endoderm
    » Develops -> Extraembryonic membranes.
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14
Q

Describe the hypoblast / primitive endoderm of early mammalian blastocysts

A
  • Hypoblast (Primitive endoderm)
    » Forms inner cell mass
    » Layer of cells which enclose epiblast / accumulation of cells attached -> trophoblast & separate from blastocoel.
    » Develops -> Extraembryonic membranes
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15
Q

Describe the development of development of stem cells using nuclear programming

A

 Treatment of Early Blastocysts / epiblasts -> certain conditions
» Produce permanently pluripotent cells
> Leads -> concept of embryonic stem cells.
 Permanently pluripotent blastocysts
&raquo_space; Genetically modified -> Generation of specific cell pathway / lineage
> Grow in culture
> Remove factors ensuring blastocysts remain pluripotent

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16
Q

Describe the basis of knowledge used to enable development of stem cells by nuclear programming

A
  • Extra-embryonic membrane -> Unique to mammals
    » Provides nutrients -> Embryo
  • Early stage blastocysts totipotent
    » Dev. -> Extra-embryonic mem & entire organism
  • Blastocysts -> Not totipotent
    » Dev. -> Everything but extra-embryonic mem.
17
Q

What is the source of pre-implantation embryos / embryonic stem cells?

A
  • Epiblast of pre-implantation embryos / Embryonic Stem Cells
     Source of pluripotent stem cells
    &raquo_space; Ability to produce all somatic & germ cells -> Except extraembryonic membranes.
    &raquo_space; Permanent maintenance -> Pluripotent abilities in culture.
18
Q

Describe the potency of an epiblast of an early mammalian embryonic stem cell

A

> > Ability to produce all somatic & germ cells -> Except extraembryonic membranes.
&raquo_space; Permanent maintenance -> Pluripotent abilities in culture.

19
Q

Describe the uses of stem cells

A

Uses:
 Study of in-vitro development
 Transplant -> Blastocysts
&raquo_space; Dev. of genetically modified organisms.
 Generation -> Teratomas.
&raquo_space; Benign Tumors
> Differentiate outside normal env.
–> Generate new tissues
-> (No metastasis but can use to predict potential dev. of embryonic stem cells)
 Study of disease & organ pathologies
 Used -> Drug screening
 Development of knockout genes
 Growth of organs/tissues
Eg. Eyeball, Parts of Brain, Neurons, Cortex Tissue, Spinal Chords.
- Led to significant replacement of animals in research.

20
Q

Who was responsible for the development of regenerative medicine methods & what did they do?

A

(Yoshiki Sasai)
 Growth of organs/tissues
Eg. Eyeball, Parts of Brain, Neurons, Cortex Tissue, Spinal Chords.

21
Q

Briefly describe the method of reprogramming differentiated cells & name the scientist responsible

A

• Reprogramming Differentiated cells: (Shinya Yamanaka)
 Differentiated cells reprogrammed -> return to Pluripotent Embryonic state
» Without use of nuclear transplantation.
&raquo_space; Production -> Induced Pluripotent Stem (iPS) cells

22
Q

Describe the process of differential cell reprogramming

A

 Process:
- Various solutions of gene mixtures added -> Fibroblasts
» Investigate which mixtures reprogramme cells
> Produce Pluripotent Embryonic cells

23
Q

What were the results of differential cell reprogramming?

A

 Result:
- Generation of clones -> Induced Pluripotent Stem (iPS) stem cells
» Act like Embryonic stem cells -> iPS
> Cocktail : Klf-4, Sox-2, Oct4, Myc

24
Q

What are cell reprogramming / iPS cells used for? List some of their benefits.

A

 Uses / Benefits:
- Can use any cell Eg. Skin -> Produce Pluripotent stem cells
» Embryonic stem cells not required -> Ethics
- Produce pluripotent stem cells
» Determine / manipulate development -> specific required cells.
- Produce genetically modified organism
- Used to generate human iPS cells
- Taken from those with disease
» Model diseases in vitro for investigation rather than patient
- Use in transplants
» Production of cells / organs / tissues which are not immunologically rejected.
- Produce iPS cells from patients
» Cell replacement therapies / regenerative medicine.

25
Q

Describe how successful cell transplant therapies can be performed using iPScells

A
  • Produce iPS cells from patients
    » Cell replacement therapies / regenerative medicine.
    Eg. Mouse -> Sickle Cell Anaemia
    > Isolate skin cells -> Develop iPs cells
    > correct mutation in cells / produce new functional cells
    > Induce dev. -> haematopoetic cells (used to generate RBCs / stem cells)
    > Transplantation back into organism can cure disease.
26
Q

Do cells lose genetic material as they develop?

A

• Cells do not lose genetic material during development

27
Q

What are the main points derived from the Waddington Landscape Hypothesis?

A

• Waddington Landscape Hypothesis:
 Totipotent cells become differentiated
> Once differentiation begins, it cannot be reversed.
> Potency decreases over time.

28
Q

Describe cell potency

A

• Cell Potency:

- Ability of a cell to differentiate into other types of cell.

29
Q

Describe induced pluripotency

A

• Induced Pluripotency:
- Pluripotency of a cell derived as a result of reprogramming any non-pluripotent cell into an Induced Pluripotent Stem Cell.

30
Q

What are embryonic stem cells derived from?

A

• Embryonic Stem cells -> Derived from Epiblast of pluripotent blastocysts / pre-implantation embryos.

31
Q

What are the uses of iPS cells?

A

• Uses -> iPS cells:
- Regenerative medicine
- In-vitro study of disease-causing cells
- Genetic modifications
- Transplantations
- Growth of tissues / organs
- Production of specific required cells -> Use in medicine
- Cloning
- Study of disease & organ pathologies
Etc.

32
Q

Who was the first scientist so illustrate totipotency of 2-stage cell embryos in sea urchins?

A
  • Hans Driesch

|&raquo_space; First to show each cell of a two-cell stage sea urchin is totipotent

33
Q

Who used baby hair ligature experiments & illustrated totipotency in blastomere cells up to the 16th stage?

A
  • Hans Spemann
    &raquo_space; Used baby hair to constrict embryos and show that blastomeres in salamander
    embryos up are totipotent up to 16 cell stage
34
Q

Who was the first to successfully transplant nuclei into eggs?

A
  • Briggs and Kings

|&raquo_space; First to successfully transplant nuclei into eggs

35
Q

Who was the first to clone an entire organism?

A
  • John Gurdon

|&raquo_space; First to clone an animal

36
Q

Who was the first to clone a mammal?

A
  • Campbell and Wilmut

|&raquo_space; First to clone a mammal

37
Q

Who was the first to induce pluripotency in adult cells without nuclear transplantation?

A
  • Shinya Yamanaka

|&raquo_space; First to induce pluripotency in adult cells without nuclear transplantation

Genes Evo & Dev Y1 (23 decks)

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