Cell Differentiation, Aging, Death and Regeneration. Flashcards
(50 cards)
What happens when a cell differentiates?
It undertakes major changes in shape, size, metabolic activity, and overall function.
What does the exact role of a tissue in an organism depend on?
what type of cells it contains.
What are stem cells?
Cells with the potential to develop into many different types of cells inn the body.
What are the two major types of stem cells?
1) embryonic stem cells
2) adult stem cells
What are the three key features of stem cells?
1) divide and renew (themselves over a long time)
2) unspecialized, (so cannot do specific functions in the body)
3) have the potential to become specialized cells (eg. muscle, blood and brain cells)
What do stemcells typically have?
The capacity to mature into many different cell types.
What are transcription factors?
Proteins one of a class of proteins that bind to specific genes on the DNA molecule and regulate which genes are transcribed in a cell (either promoted or inhibited).
Why are transcription factors vital for stem cells?
They regulate which genes are transcribed in a cell, therefore cause cells to differentiate.
How do transcription factors function?
they turn themselves on and off at different types during differentiation.
Explain the mechanism of differentiation.
Genes are turned on or off through transcription factors.
What do transcription factors regulate?
Gene expression.
What is “cell potency”?
The varying ability of stem cells to differentiate into specialized cell types.
Which cells differentiate more? the ones with high or low potency?
high potency
What are the three types of stem cells?
1) Totipotent: give rise to all cells found in an embryo and extraembryonic cells.
2) Pluripotent: give rise to all cells within the body, but not the placenta.
3) Multipotent: develop into a limited number of cell types in a specific lineage.
What cells have proliferative capacity?
- Labile cells
- Stabile cells
- Permanent non-dividing cells
Explain “labile cells”. State examples.
- continuously divide
- eg. surface epithelial cells of the skin and gastrointestinal tract
Explain “stabile cells”. State examples.
- nondividing under normal circumstances
- induced to reenter the cell cycle by exposure to growth factors
- eg. parenchyma cells of the liver, kidney, pancrease, mesenchymal cells.
Explain “permanent non-dividing cells”. State examples.
- lost all capacity for proliferation
- eg. nerve cells, cardiac muscle
What are the two main categories of cell aging?
- programmed
- damage or error theories
What are programmed theories? What does regulation depend on?
aging follows a biological timetable (a continuation of the one that regulates childhood growth and development).
- regulation depends on changes in gene expression that affect the systems responsible for maintenance, repair and defence responses.
What are damage or error theories?
Emphasize environmental assaults to living organisms that induce cumulative damage at various levels of aging.
What are the three subcategories of the programmed theories?
1) PROGRAMMED LONGEVITY (aging results of a sequential switching on and off of certain genes
2) ENDOCRINE THEORY (biological clocks through hormones control the pace of aging)
3) IMMUNOLOGICAL THEORY (immune system is programmed to decline over time, leading to an increase in vulnerability to infectious disease)
What are the five subcategories of the damage or error theories?
1) WEAR AND TEAR THEORY (vital parts of cells wear out)
2) RATE OF LIVING THEORY (the greater an organism’s oxygen basal metabolism, the shorter its lifespan)
3) CROSS-LINKING THEORY (accumulation of cross-linked proteins damages cells and tissues).
4) FREE RADICALS THEORY (free radicals cause damage to the macromolecular cmponents of the cells)
5) SOMATIC DNA DAMAGE THEORY (with an increase of age, genetic mutations occur, causing cells to deteriorate and malfunction).
What is the biological name for “cell death”?
apoptosis
