Questions and Answers
What are differentiated cells?
Specialized cells that carry out specific functions.
How are stem cells different from differentiated cells?
Stem cells can become any other cell type, whereas differentiated cells do not become other cells.
In human development, what happens to the initial embryonic stem cells to make them become other kinds of cells?
They receive chemical signals that inactivate genes that cause the cell to differentiate.
What does the ectoderm become?
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What does the mesoderm become?
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What does the endoderm become?
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How many different cell types are there?
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What are somatic stem cells?
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What role do somatic stem cells play in adults?
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How are somatic stem cells different from embryonic stem cells?
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Where are somatic stem cells found in the body?
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Is cell differentiation final and irreversible?
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How is the DNA arrangement different in a stem cell compared to a differentiated cell?
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How does DNA tightening affect gene expression?
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How many genes are needed to convert a somatic cell back to a stem cell?
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What is an iPS cell?
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What do niche cells do for stem cells?
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What activates the stem cell?
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What do these signal chemicals do to the DNA?
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Match the following cell niches with the differentiated cells produced:
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What is the function of red blood cells?
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What is the function of bone cells?
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What is the function of intestinal absorptive cells?
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What do hair follicle cells do?
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What is the function of neurons?
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Study Notes
Stem Cells Overview
- Differentiated cells are specialized cells that perform specific functions.
- Stem cells are unique in their ability to become any other cell type, while differentiated cells are limited to their specific roles.
Embryonic Development
- Initial embryonic stem cells differentiate into various cell types through chemical signals that deactivate certain genes.
- Three primary germ layers arise during development:
- Ectoderm: develops into skin and the nervous system.
- Mesoderm: forms blood vessels, bones, and muscles.
- Endoderm: becomes the digestive tract, respiratory system, and glands like the pancreas and liver.
Cell Types and Stem Cells
- The human body contains approximately 250 different cell types.
- Somatic stem cells, also known as adult stem cells, are responsible for repairing tissues and replacing damaged cells.
- Somatic stem cells have limited differentiation potential compared to embryonic stem cells, which can develop into a wider variety of cell types.
Location and Differentiation
- Somatic stem cells are found in niche environments throughout the body, including the brain, blood, heart, teeth, and liver.
- Cell differentiation is not necessarily irreversible, allowing potential reversion to a previous state.
DNA Structure and Gene Expression
- In stem cells, DNA is loosely arranged, enabling gene expression. In contrast, tightly wrapped DNA in differentiated cells restricts gene activation.
- DNA tightening during differentiation may silence genes, preventing the cell from reverting to a stem state.
Induced Pluripotent Stem Cells
- Induced Pluripotent Stem (iPS) cells are created by reprogramming differentiated cells back into a stem cell state using a minimum of four genes.
Role of Niche Cells
- Niche cells provide protection and ensure that stem cells remain undifferentiated, regulating their development through environmental signals.
Functional Cell Niches
- Blood niche: produces red blood cells, which carry oxygen using hemoglobin; no organelles are present.
- Bone niche: generates osteoblasts, crucial for building and repairing bones; secretes collagen.
- Intestinal niche: forms intestinal absorptive cells with microvilli that enhance nutrient absorption.
- Hair niche: gives rise to hair follicle cells that synthesize strong hair fibers via keratin.
- Brain niche: produces neurons (signal transmission) and glial cells (support neuron function), featuring long dendrites for communication.
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Description
Explore the fascinating world of stem cells with these study guide flashcards covering key concepts in Chapter 4 of your biology textbook. Learn about the differences between stem cells and differentiated cells, and how stem cells evolve during human development. Perfect for a quick revision or in-depth understanding of cellular biology.