Cell Differentiation Flashcards
How single zygote develops (3 stages)
Cell division
Cell specialisation
Cell death apoptosis
Differentiation has three steps:
- Maintenance: stem cells self renew
- Expansion: receive signals. Then commit and form progenitors
- Differentiation: becomes terminally different
What are progenitors?
Only differentiate into a limited number of cells
Cells potency and how it decreases?
A cells ability to produce different terminally differentiated cells
Potency decreases as cells commit down differentiation pathways
Importance of cell differentiation
- Repair damage
- Cells become specialised and form tissues and organs
What makes cells different to another?
Different cells have different patterns of gene expression so have distinct functional roles due to diff proteins they express
House keeping genes?
constitutive genes required for the maintenance of basic cellular function, they are expressed in all cells under normal conditions
TF are modular because contain two parts:
- Activation domain - interacts with RNA polymerase
- DNA binding domain - recognises and binds to promoter/ enhancer regions
Problems with progenitors:
- mutation occurs in stem cell/ progenitors
- stem cells over proliferate
- causes accumulation of progenitors (tumour)
- mutation stops progenitor from differentiating
What are multipotent cells
Become different number of cells but not every
What are pluripotent
Become any cell in the body
What are unipotent cells
Can only differentiate into specialised cells
The order of stem cells
Pluripotent
Multipotent
Unipotent
Example of multipotent cell
Hematopoietic stem cell
What is an Oligopotent cell
able to self-renew and form 2 or more lineages within a specific tissue
What is oligopotency
the ability of progenitor cells to differentiate into a few cell types.
It is a degree of potency
What makes cells different from one another
• Distinct functional roles
• Different proteins (associated with functions)
- Proteins defining cell type features Unique - Metabolic proteins
- Structural proteins
- Regulatory proteins
Molecular control of red blood cell
a/b globins
Carbonic anhydrase
Spectrin
Anion transporter
Molecular control of platelet production
Thrombin receptor
Collagen receptors
Fibrinogen receptor
Granule proteins
Examples of proteins that regulate red cells/ erythrocytes
- Cell feature-defining proteins (e.g. haemoglobin)
- Metabolic proteins (e.g. carbonic anhydrase)
- Structural proteins (e.g. spectrins)
- Regulatory proteins (e.g. GATA-1, a transcription factor)
How is a cells phenotype dictated
By its constituent proteins
Are transcriptional factors modular
Yes
What is critical in cell specialisation
Transcription
How do TF control differentiation
Different TF control different steps of differentiation
Different essential TF for each specialised cell
Key concepts of cell differentiation
Cell needs extracellular signals to expand and differentiate
Different transcription factors control different steps of differentiation
What is erythropoietin
Stimulated by Extracellular signal
Secreted by kidneys
That increases the rate of production of red blood cells
In response to falling levels of oxygen
Erythropoietin cycle
Low O2 in proximal tubule
Epo
Bone - stimulates stem cells
RBC progenitors
Increased O2 negatively feeds back on Epo
How Epo regulates red cell specific genes
Epo receptor in cell membrane
Gene regulatory protein is activated
Binds to regulatory DNA
Provoking activation of a gene to produce another protein
That binds to other regulatory regions and protein coding regions
Signalling cascade
RBC gene turned on
