Stem Cell Culture and Organ Culture - Class 12 Biotechnology - Chapter 9 - Notes, NCERT Solutions & Extra Questions
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Extra Questions - Stem Cell Culture and Organ Culture | NCERT | Biotechnology | Class 12
The undifferentiated mass of cells in tissue culture is called:
A. Tissue
B. Embryo
C. Callus
D. Spore.
The undifferentiated mass of cells in tissue culture is known as a callus. This grouping of cells is found in an undifferentiated state, where they can further divide to form tissues. Unlike tissue, callus does not perform a particular function as tissues do. Tissues are groups of cells that already perform specific functions. On the other hand, an embryo, which develops from a zygote, is a structured mass of cells that forms during the growth process after fertilization. Spores, in contrast, usually refer to a reproductive unit rather than a mere undifferentiated mass of cells.
Therefore, the correct answer to the question is: C. Callus
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Briefly describe the stem cells and their properties.
Stem cells are non-specialized cells with the inherent property of self-renewal and potency, allowing them to divide via mitotic cell division and differentiate into a wide range of specialized cell types. Found in many multicellular organisms, including humans, they are sourced from places like the umbilical cord, placenta, and adult organs. Stem cells have the potential to regenerate tissues or organs, making them vital for therapeutic applications such as regenerative medicine and disease treatment research.
Differentiate totipotent, pluripotent and multipotent stem cells.
Totipotent stem cells can differentiate into all cell types, including extra-embryonic tissues, making them capable of forming an entire organism. An example is the zygote formed post-fertilization.
Pluripotent stem cells can develop into nearly any cell type in the body except for extra-embryonic cells such as the placenta. These are primarily derived from the inner cell mass of the blastocyst.
Multipotent stem cells are limited to differentiating into cell types related to their tissue of origin, such as hematopoietic stem cells forming blood cells.
What are embryonic stem cells and how do they differ from adult stem cells?
Embryonic stem cells (ESCs) are pluripotent cells derived from the inner cell mass of a blastocyst and are capable of differentiating into almost any type of cell in the body. They possess the potential for indefinite self-renewal and are primarily used in research and therapy due to their broad differentiation potential.
Adult stem cells, also known as somatic stem cells, are multipotent and found in mature tissues like bone marrow or the brain. They generally differentiate into cell types specific to the tissues in which they reside, their role mostly limited to repair and maintenance. Unlike ESCs, adult stem cells have a limited capacity for self-renewal and differentiation.
Describe some applications of stem cells.
Stem cells are pivotal in regenerative medicine for repairing damaged tissues, such as in muscle damage and cardiac failure. They are also used in treating neurological conditions like ALS and spinal cord injuries through nerve regeneration. Additionally, they are effective in skin replacement for burn victims and chronic wounds. In autoimmune disorders, like Type 1 Diabetes and Multiple Sclerosis, stem cells are being researched to replace damaged cells and reduce immune system attacks. In pharmaceuticals, they assist in drug screening and disease modeling.
What parameters should be monitored during stem cell culture?
During stem cell culture, it is essential to monitor several key parameters to ensure optimal growth and maintenance of the stem cells' defining characteristics. These include:
Cell line sterility: Regular testing for microbial contaminations such as bacteria, fungi, and mycoplasma is crucial.
Cell line authenticity: Preventing cross-contamination through proper authentication of cell lines before use.
Cell line stability: Monitoring for genetic and phenotypic changes using techniques like RT-PCR, immuno-cytochemical staining, and flow cytometry.
pH and pO2 levels: Continuously measured in culture medium.
Overarching environmental conditions: Including temperature and humidity in incubators.
What is organ culture?
Organ culture involves the in vitro development of a part or the entire organ using tissue culture techniques. Tissues are explanted and grown such that they maintain their anatomical relationships and physiological functions similar to their parent tissue. The technique aims to preserve the structural integrity and functionality of the organ or its segments in a controlled environment. This method facilitates the study of biochemical, functional, and interaction characteristics of tissues under near-natural conditions within an artificial setting.
Describe the main characteristics of organ culture.
Organ culture involves the in vitro growth of organ parts to preserve anatomical and physiological functions similar to the parent tissue. Key characteristics include structural integrity, maintaining essential cell-to-cell interactions and enabling signal exchange. However, the absence of a vascular system limits nutrient and gas diffusion, possibly causing central necrosis. Organ cultures predominantly manage nutrient and gas exchanges at gas-liquid interfaces and are typically constrained by physical dimensions and diffusion rates. They support directed normal development and maintain functional characteristics.
Discuss the various types of organ culture.
Organ culture involves growing parts of an organ or the whole organ in vitro, maintaining its anatomical and physiological functions. Types include:
Histotypic culture: High-density cultures of a defined cell type, often using scaffolds or matrices to mimic tissue structure.
Organotypic culture: Co-culture of different cell types to create tissue-like structures, facilitating heterologous cell interactions and functional differentiation.
Whole embryo culture: Culturing whole embryos in vitro to study development, often using specific apparatus and conditions to mimic in utero environment.
What are the advantages of organ culture over cell culture?
Organ culture offers several advantages over traditional cell culture. First, it maintains the structural integrity and cell-to-cell interactions of the original tissue, allowing for more accurate simulation of natural organ functions. This helps in better studying the biochemical and functional characteristics of tissues under controlled conditions. Additionally, organ culture supports the study of complex cell interactions and responses within their native microenvironments, which is often lost in simpler cell cultures. Furthermore, organ culture facilitates the study of hormonal effects and other biological influences in a tissue-specific context.
Describe the applications of organ culture.
Organ culture is utilized to study the behavior and characteristics of tissues in vitro, providing insights into biochemical and functional attributes. It is pivotal for understanding the effects of hormones on organs. Organ cultures are also used in transplantation, where organs generated from a patient's own stem cells potentially eliminate the need for immunosuppressive drugs. This technique fosters advancements in regenerative medicine by allowing researchers to explore and potentially remedy diseases more effectively. Moreover, organ cultures facilitate the assessment of tissue-specific responses and organ functionality under laboratory conditions.
Describe the various support systems used in organ culture.
In organ culture, support systems are crucial for maintaining the physiological and anatomical integrity of tissues. Nutrient and gas exchange is facilitated by maintaining tissues at a gas-liquid interface, which allows optimal oxygen and nutrient diffusion, crucial for cell viability. Structural supports, such as hydrophobic surfaces or scaffolds, help in retaining tissue geometry and minimizing alterations during growth. Additionally, the use of hyperbaric oxygen enhances oxygen permeation, supporting cellular functions and growth in the organ culture system. These supports ensure the preservation and functionality of cultured organs.
Stem cells are present in:
(a) unicellular organisms
(b) multicellular organisms
(c) non-living things
(d) viruses
Stem cells are present in (b) multicellular organisms.
Differentiation potential of stem cells specifies:
(a) Stochastic differentiation
(b) Asymmetric replication
(c) Potency
(d) Self-renewal
The differentiation potential of stem cells refers to:
(c) Potency
This term highlights the variety of cell types into which a stem cell can differentiate. It categorizes stem cells as totipotent, pluripotent, multipotent, or unipotent depending on their ability to differentiate into different cell types.
Which of the following cells is a multipotent cell?
(a) T-cell
(b) B-cell
(c) HSC
(d) Monocytes
The correct answer is (c) HSC (Hematopoietic stem cell).
Hematopoietic stem cells (HSCs) are multipotent, meaning they have the ability to differentiate into a closely related family of cells, including various types of blood cells such as red blood cells, white blood cells, and platelets. These cells are specifically capable of developing into all cells of the hematopoietic system.
A stem cell is:
(a) a cell out of which the stem of the tree is made up of
(b) a part of the tissue that forms the outer layer of the skin in human beings.
(c) it is a cell that can divide and give rise to specialised cells.
(d) a type of specialised cell
Stem cells are characterized by their ability to self-renew through mitotic cell division and their capacity to differentiate into a specialized adult cell type. Hence, the correct answer is:
(c) it is a cell that can divide and give rise to specialised cells.
__________ can be cured with stem cells.
(a) Spinal cord injuries
(b) Type 1 diabetes
(c) Both (a) and (b)
(d) None of these
(c) Both (a) and (b)
Spinal cord injuries: Research is being carried out using adult stem cells to regenerate new nerve cells and potentially repair damaged spinal cord tissues.
Type 1 diabetes: Stem cells, especially those derived from hematopoietic stem cells, are being explored for their potential to treat Type 1 diabetes by regenerating insulin-producing pancreatic beta cells.
The stem cells may be obtained from sources such as:
(a) Bone marrow
(b) Umbilical cord blood
(c) Adipose tissue
(d) All of these
(d) All of these
Stem cells can be derived from various sources including bone marrow, umbilical cord blood, and adipose tissue. Each of these sources contains adult stem cells that can differentiate into various cell types.
Assertion: Embryonic stem cells can give rise to different cell types.
Reason: Embryonic stem cells are pluripotent.
(a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true but the reason is not the correct explanation of the assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.
(a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
Explanation: The assertion states that embryonic stem cells can give rise to different cell types, which is true because embryonic stem cells are known for their ability to differentiate into any cell type in the adult body. The reason provided is that embryonic stem cells are pluripotent, which is also true. Pluripotency is a characteristic of embryonic stem cells that enables them to differentiate into any of the three germ layers: ectoderm, mesoderm, or endoderm. Therefore, the reason correctly explains why embryonic stem cells can give rise to different cell types.
Assertion: Stem cells are undifferentiated and found in multicellular organisms, and undergo numerous mitotic cycles.
Reason: Stem cells have ‘self-renewal’ feature and do not exhibit ‘cellular potency’.
(a) Both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true but the reason is not the correct explanation of the assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.
(c) Assertion is true but reason is false.
Explanation:
Assertion: Stem cells are indeed undifferentipated cells that are found in multicellular organisms and are capable of undergoing numerous mitotic cycles to facilitate growth and repair.
Reason: The reason is incorrect because stem cells do exhibit 'cellular potency', which is the capacity to differentiate into different cell types. Moreover, 'self-renewal' is a feature of stem cells allowing them to divide and replicate themselves while maintaining their undifferentiated state. This is directly linked to cellular potency, not in opposition to it.
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Notes - Stem Cell Culture and Organ Culture | Class 12 NCERT | Biotechnology
Comprehensive Class 12 Notes on Stem Cell Culture and Organ Culture
Introduction to Stem Cell Culture and Organ Culture
The study of stem cells and organ culture is a vital area in contemporary biomedical research, with immense potential for both basic and translational applications. Stem cells offer promises for treating numerous diseases currently lacking effective therapy, while organ culture allows researchers to investigate the development and function of tissues in an in vitro environment. This article will delve into the details of stem cell culture, organ culture, their various types, characteristics, and applications.
Stem Cell Culture
Definition and Importance
Stem cells are undifferentiated cells with the ability to self-renew and differentiate into various specialized cell types. They play a crucial role in biomedical research, particularly in studying disease mechanisms and developing regenerative therapies.
Types of Stem Cells
Embryonic Stem Cells
Embryonic stem cells (ESCs) are derived from the inner cell mass of the blastocyst around five days after fertilization. They are pluripotent, capable of differentiating into any cell type of the body, making them highly promising for clinical applications.
Adult Stem Cells
Also known as somatic stem cells, adult stem cells can be found in various adult tissues such as bone marrow, liver, and brain. They are multipotent or totipotent and play a critical role in tissue repair and regeneration.
Hematopoietic Stem Cells
Hematopoietic stem cells are responsible for producing all blood cell types and are primarily found in the bone marrow. They are pivotal in generating the complete hematopoietic system required for various bodily functions.
Mesenchymal Stem Cells
Mesenchymal stem cells (MSCs) are multipotent cells derived from the mesoderm, found in bone marrow. They can differentiate into cells like myocytes, osteoblasts, chondrocytes, and adipocytes, contributing to tissue repair and regeneration.
Classification Based on Potency
Stem cells can be classified based on their differentiation potential:
Totipotent Stem Cells
Totipotent stem cells can form all cell types in the body, including the extra-embryonic tissues (e.g., zygote).
Pluripotent Stem Cells
Pluripotent stem cells can differentiate into almost any cell type but cannot form extra-embryonic tissues.
Multipotent Stem Cells
Multipotent stem cells can develop into multiple cell types within a specific lineage, such as hematopoietic stem cells producing various blood cells.
Unipotent Stem Cells
Unipotent stem cells can only produce one cell type but retain the ability to self-renew.
Classification based on differentiation potency
Characteristics of Stem Cells
Stem cells possess unique abilities:
- Self-Renewal: They can proliferate indefinitely.
- Differentiation: They can transform into specialized cell types.
- Plasticity: The ability to change fate in response to environmental cues.
Maintenance of Stem Cell Culture
Maintaining stem cell cultures requires stringent conditions to retain their self-renewal and differentiation capabilities. Key factors include controlled pH, oxygen levels, and nutrient-rich media.
Process of stem cell culture
Applications of Stem Cells
Medical Treatments
Stem cells are being explored for treating:
- Neurological Diseases: Such as Amyotrophic Lateral Sclerosis (ALS) and spinal cord injuries.
- Wound Healing: Using keratinocyte stem cells for skin regeneration.
- Cardiovascular Diseases: Restoring heart tissue function.
- Auto-immune Disorders: Including Type 1 Diabetes and Multiple Sclerosis.
Challenges in Stem Cell Research
Research faces challenges like immunological rejection and safety concerns, particularly regarding tumour growth and microbial infections.
Organ Culture
Definition and Comparison with Cell Culture
Organ culture involves growing parts of an organ or the entire organ in vitro, preserving their physiological and anatomical integrity. Unlike cell culture, organ culture retains the complex structural environment of the tissue.
Characteristics of Organ Culture
Structural Integrity
Organ cultures maintain the structural integrity of tissues, allowing cell-to-cell communication and functional interactions similar to the in vivo environment.
Nutrient and Gas Exchange
Since organ cultures lack a vascular system, nutrient and gas exchange are critical issues. Maintaining tissues at the gas-liquid interface helps alleviate some of these challenges.
Growth and Differentiation in Organ Culture
Organ cultures focus more on maintaining existing tissue structures rather than proliferation. Growth factors are crucial for promoting differentiation within these cultures.
Types of Organ Culture
Histotypic Culture
Involves high-density cultures of characterised cell lines, forming structures like vascular tubules in collagen matrices.
Organotypic Culture
Co-cultures of different cell lineages create tissue-like structures. Example: Co-culturing fibroblasts and epithelial cells to produce milk proteins in mammary gland models.
Applications of Organ Culture
Organ culture allows the study of tissue behaviour, hormonal impacts, and the effects of various treatments, offering valuable insights for medical research.
Differences between cell culture and organ culture
Limitations and Future Prospects
Organ cultures face challenges like high variability, reproducibility issues, and high preparation costs. Advancements in 3D cell culture techniques, such as organoids and organs-on-chips, present promising future research avenues.
Conclusion
The study of stem cell culture and organ culture is paramount for advancing biomedical research and developing new treatments. Despite challenges, the potential applications in regenerative medicine and understanding disease mechanisms highlight the significance of these research areas.
This comprehensive guide provides essential Class 12 notes on stem cell culture and organ culture, offering a detailed overview for students and educators alike.
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