20 Questions
What is the function of progenitor cells?
Progenitor cells are in transit from the stem cell state to a differentiated state, contributing to the renewal and differentiation of tissues.
Where are stem cells best found in the body?
In tissues with rapidly renewing cell populations such as blood cells, skin cells, and cells lining the digestive tract.
How are stem cell divisions often asymmetric?
In asymmetric divisions, one daughter cell remains as a stem cell, while the other becomes committed to a path that leads to differentiation.
Why are stem cells often rare and difficult to identify?
Stem cells are often rare and need special histologic methods to be identified due to their low frequency and specific locations within tissues.
In what types of tissues are stem cells not readily apparent?
Stem cells are not readily apparent in tissues with stable cell populations, such as connective tissues, smooth muscle, and the cells lining blood vessels.
What are the two key features that characterize meiosis?
- Synapsis and DNA breaks and repairs resulting in crossovers between homologous chromosomes. 2. Production of haploid cells.
Where does meiosis occur in the body?
Meiosis occurs in specific cells called germ cells in the gonads (ovaries & testes).
What is the result of the union of haploid eggs and sperm at fertilization?
The union forms a new diploid cell (the zygote) that can develop into a new individual.
What are the two types of germ cells involved in meiosis?
Oogonia in the ovaries and spermatogonia in the testes.
What are the two key structures of a chromosome during the first meiotic division?
Each chromosome contains two identical sister chromatids bound to each other by cohesin proteins at the centromere region.
What is the role of telomerase in cancer cells?
To rebuild telomere sequences and prevent the cell from losing its potential to divide.
How do cancer cells differ from normal cells in terms of contact inhibition?
Cancer cells do not exhibit contact inhibition and continue to divide even when in contact with other cells or structures.
Explain the behavior of cancer cells in response to growth factors.
Cancer cells continue to divide even in the absence of stimulatory growth factors and do not respond to inhibitory growth factors.
What is angiogenesis and how does it relate to cancer?
Angiogenesis is the formation of new blood vessels, and cancer cells undergo this process to create their own blood supply for growth and development.
How do telomeres contribute to the immortality of cancer cells?
Telomeres prevent DNA repair enzymes from binding the chromosome ends together, allowing cancer cells to continuously divide.
What is differentiation and how does it relate to cancer cells?
Differentiation is the process of cellular development by which a cell acquires a specific structure and function. Cancer cells lack differentiation, meaning they are non-specialized and do not contribute to the functioning of a body part.
Describe the abnormal nuclei found in cancer cells.
The nuclei of cancer cells are enlarged and may contain an abnormal number of chromosomes. Some cancer types have nuclei that are so enlarged they take up most of the cell.
What is the main characteristic that allows cancer cells to have unlimited potential to replicate?
Cancer cells have the ability to replicate indefinitely, unlike normal cells which divide about 60 to 70 times and then stop dividing.
How do the characteristics of cancer cells differ from normal cells?
Cancer cells lack differentiation, have abnormal nuclei, and have unlimited potential to replicate, unlike normal cells.
Explain how mutations contribute to the loss of control over the cell cycle in cancer cells.
Mutations in cancer cells ultimately cause a loss of control over the cell cycle, leading to uncontrolled cell growth.
Study Notes
Stem Cells
- Progenitor cells function as precursors to differentiated cells, giving rise to specific cell types
- Stem cells are best found in the body's developing tissues, such as embryonic tissues, and in certain adult tissues, like bone marrow and skin
- Stem cell divisions are often asymmetric, meaning one daughter cell remains a stem cell, while the other differentiates into a specific cell type
- Stem cells are often rare and difficult to identify due to their low numbers and lack of specific markers
- Stem cells may not be readily apparent in fully differentiated tissues, like muscles and nerves
Meiosis
- Two key features of meiosis are crossing over, which increases genetic variation, and the halving of the chromosome number, resulting in haploid cells
- Meiosis occurs in the reproductive organs, specifically in the ovaries and testes
- The union of haploid eggs and sperm at fertilization results in a diploid zygote, with a complete set of chromosomes
- The two types of germ cells involved in meiosis are oocytes (egg cells) and spermatocytes (sperm cells)
- During the first meiotic division, chromosomes are characterized by their synapsed homologous pairs and the presence of a centromere
Cancer Cells
- Telomerase is key in cancer cells, as it allows them to maintain telomere length, contributing to their immortality
- Cancer cells differ from normal cells in that they lack contact inhibition, allowing them to continue growing and dividing despite physical contact
- Cancer cells behave abnormally in response to growth factors, often exhibiting uncontrolled growth and division
- Angiogenesis, the formation of new blood vessels, supports cancer cell growth and proliferation
- Telomeres contribute to the immortality of cancer cells by allowing them to maintain their telomere length, bypassing the normal process of telomere shortening
- Differentiation, the process of becoming a specific cell type, is often lost in cancer cells, allowing them to maintain their proliferative state
- Abnormal nuclei found in cancer cells include changes in size, shape, and number
- The main characteristic that allows cancer cells to have unlimited potential to replicate is their ability to bypass normal cell cycle regulation
- Cancer cells differ from normal cells in their ability to ignore normal growth and division signals, and in their ability to self-replicate and self-sustain
- Mutations contribute to the loss of control over the cell cycle in cancer cells by disrupting normal regulation, allowing for uncontrolled growth and division
Test your knowledge of tissue renewal and the characteristics of stem cells with this quiz. Explore the concepts of stem cell division, differentiation, and their unique microenvironment.
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