What are differences and similarities between prokaryotes and eukaryotes?
Prokaryotes are primitive organisms lacking a nucleus and membrane-bound organelles. The term ‘prokaryote’ is derived from the Greek words ‘pro’, meaning ‘before’ and ‘karyon’, meaning ‘kernel’ – ‘before nuclei’.
Eukaryotes are advanced organisms with a well-defined nucleus and membrane-bound organelles. The term ‘eukaryotes’ is derived from the Greek words ‘eu’, meaning ‘good’ and ‘karyon’, meaning ‘kernel’ – ‘true nuclei’.
The main differences and similarities between prokaryotic and eukaryotic cells are given above ⬆️.
ℹ️ According to scientists, cells, which were very simple prokaryotes, started forming on Earth at least 3.5 billion years ago. Eukaryotes are supposed to arose from symbiosis between prokaryotic cells. Eventually, an ancestral prokaryote endosymbiosed other cells, which became mitochondria and chloroplasts. The origin of other organelles is less clear.
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Prokaryotes are primitive organisms lacking a nucleus and membrane-bound organelles. The term ‘prokaryote’ is derived from the Greek words ‘pro’, meaning ‘before’ and ‘karyon’, meaning ‘kernel’ – ‘before nuclei’.
Eukaryotes are advanced organisms with a well-defined nucleus and membrane-bound organelles. The term ‘eukaryotes’ is derived from the Greek words ‘eu’, meaning ‘good’ and ‘karyon’, meaning ‘kernel’ – ‘true nuclei’.
The main differences and similarities between prokaryotic and eukaryotic cells are given above ⬆️.
ℹ️ According to scientists, cells, which were very simple prokaryotes, started forming on Earth at least 3.5 billion years ago. Eukaryotes are supposed to arose from symbiosis between prokaryotic cells. Eventually, an ancestral prokaryote endosymbiosed other cells, which became mitochondria and chloroplasts. The origin of other organelles is less clear.
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How scientists were discovering the cell?
While the invention of the telescope made the Cosmos accessible to human observation, the light microscope opened up smaller worlds, showing what living forms were composed of.
🔬 The cell was first discovered and named by an English “natural philosopher” Robert Hooke (1635-1703) in 1665. Using three lenses and a stage light, he improved the design of his compound microscope ⬆️, which allowed to see tiny pores in a piece of cork. Hooke came to call his discovery “cells”, “small rooms” in Latina, because they reminded him of the cells in a monastery. However, Hooke didn't realize at that time that “cells” could be alive.
🔬🦠 The first man to witness a live cell was a Dutch scientist, often called the “father of microscopy”, Anton van Leeuwenhoek (1632-1723), who, in 1674, described the algae Spirogyra and also protozoa and bacteria that he called “animalcules”. He was also the first to observe and describe spermatozoa in 1677.
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While the invention of the telescope made the Cosmos accessible to human observation, the light microscope opened up smaller worlds, showing what living forms were composed of.
🔬 The cell was first discovered and named by an English “natural philosopher” Robert Hooke (1635-1703) in 1665. Using three lenses and a stage light, he improved the design of his compound microscope ⬆️, which allowed to see tiny pores in a piece of cork. Hooke came to call his discovery “cells”, “small rooms” in Latina, because they reminded him of the cells in a monastery. However, Hooke didn't realize at that time that “cells” could be alive.
🔬🦠 The first man to witness a live cell was a Dutch scientist, often called the “father of microscopy”, Anton van Leeuwenhoek (1632-1723), who, in 1674, described the algae Spirogyra and also protozoa and bacteria that he called “animalcules”. He was also the first to observe and describe spermatozoa in 1677.
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How the scientific study of cells was founded and developed?
ℹ️ Cytology or Cell biology is the scientific study of cells.
📍 German scientists Theodore Schwann (1810–1882) and Mattias Schleiden (1804–1881) studied cells of animals and plants respectively. They identified key differences and similarities between the two cell types and in 1838-39 put forth the idea that cells were the fundamental units of both plants and animals. Thus, Schwann and Schleiden are generally regarded as the first scientists to establish cell theory.
☑️ However, both Schwann and Schleiden misunderstood how cells grow.
▪️ Schleiden believed that cells were “seeded” by the nucleus and grew from there.
▪️ Similarly, Schwann claimed that animal cells “crystalized” from the material between other cells. He summarized his observations into three conclusions about cells:
✅ The cell is the fundamental unit of structure, physiology, and organization in living things.
✅ The cell retains a dual existence as a distinct entity and a building block in the construction of organisms.
❌Cells form by free-cell formation, similar to the formation of crystals (spontaneous generation).
Today it is known that the first two tenets are correct, but the third is clearly wrong.
📍 Another piece of the cell theory puzzle was identified by another German researcher Rudolf Virchow (1821-1902) in 1855, who stated that all cells are generated by existing cells – Omnis cellula e cellula: “All cells only arise from pre-existing cells”.
📍 The key tenets of the modern cell theory are:
✅ All known living things are made up of cells.
✅ The cell is the structural & functional unit of all living things.
✅ All cells come from pre-existing cells by division. (Spontaneous Generation does not occur).
✅ Cells contain hereditary information, which is passed from cell to cell during cell division.
✅ All cells are basically the same in chemical composition.
✅ All energy flow (metabolism & biochemistry) of life occurs within cells.
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ℹ️ Cytology or Cell biology is the scientific study of cells.
📍 German scientists Theodore Schwann (1810–1882) and Mattias Schleiden (1804–1881) studied cells of animals and plants respectively. They identified key differences and similarities between the two cell types and in 1838-39 put forth the idea that cells were the fundamental units of both plants and animals. Thus, Schwann and Schleiden are generally regarded as the first scientists to establish cell theory.
☑️ However, both Schwann and Schleiden misunderstood how cells grow.
▪️ Schleiden believed that cells were “seeded” by the nucleus and grew from there.
▪️ Similarly, Schwann claimed that animal cells “crystalized” from the material between other cells. He summarized his observations into three conclusions about cells:
✅ The cell is the fundamental unit of structure, physiology, and organization in living things.
✅ The cell retains a dual existence as a distinct entity and a building block in the construction of organisms.
❌Cells form by free-cell formation, similar to the formation of crystals (spontaneous generation).
Today it is known that the first two tenets are correct, but the third is clearly wrong.
📍 Another piece of the cell theory puzzle was identified by another German researcher Rudolf Virchow (1821-1902) in 1855, who stated that all cells are generated by existing cells – Omnis cellula e cellula: “All cells only arise from pre-existing cells”.
📍 The key tenets of the modern cell theory are:
✅ All known living things are made up of cells.
✅ The cell is the structural & functional unit of all living things.
✅ All cells come from pre-existing cells by division. (Spontaneous Generation does not occur).
✅ Cells contain hereditary information, which is passed from cell to cell during cell division.
✅ All cells are basically the same in chemical composition.
✅ All energy flow (metabolism & biochemistry) of life occurs within cells.
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What are differences and similarities between prokaryotes and eukaryotes?
Prokaryotes are primitive organisms lacking a nucleus and membrane-bound organelles. The term ‘prokaryote’ is derived from the Greek words ‘pro’, meaning ‘before’ and ‘karyon’, meaning…
Prokaryotes are primitive organisms lacking a nucleus and membrane-bound organelles. The term ‘prokaryote’ is derived from the Greek words ‘pro’, meaning ‘before’ and ‘karyon’, meaning…
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How is the proper growth and replication of cells ensured?
The process which is vital for the growth, development, repair, and maintenance of living organisms is called the cell cycle. It is a series of events that cells go through to grow, replicate their DNA, and divide.
The two broad phases of the cell cycle are:
1️⃣ Interphase, during which cells grow, replicate their DNA and organelles, and prepare for division.
2️⃣ Mitosis, a process of cell division that results in two genetically identical daughter cells from a single parent cell.
ℹ️ The term “mitosis” was coined by Walther Flemming (1843-1905) in 1882 while documenting the process of chromosomal division in salamander larvae. The term comes from the Greek word ‘mitos’ meaning ‘thread,’ referring to the thread-like appearance of chromosomes during mitosis. Other names for the process are ‘karyokinesis’ (Schleicher, 1878) and ‘equatorial division’ (August Weismann, 1887).
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The process which is vital for the growth, development, repair, and maintenance of living organisms is called the cell cycle. It is a series of events that cells go through to grow, replicate their DNA, and divide.
The two broad phases of the cell cycle are:
1️⃣ Interphase, during which cells grow, replicate their DNA and organelles, and prepare for division.
2️⃣ Mitosis, a process of cell division that results in two genetically identical daughter cells from a single parent cell.
ℹ️ The term “mitosis” was coined by Walther Flemming (1843-1905) in 1882 while documenting the process of chromosomal division in salamander larvae. The term comes from the Greek word ‘mitos’ meaning ‘thread,’ referring to the thread-like appearance of chromosomes during mitosis. Other names for the process are ‘karyokinesis’ (Schleicher, 1878) and ‘equatorial division’ (August Weismann, 1887).
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How is the proper growth and replication of cells ensured? The process which is vital for the growth, development, repair, and maintenance of living organisms is called the cell cycle. It is a series of events that cells go through to grow, replicate their…
What are cell cycle phases in detail?
1️⃣ Interphase, the period preceding mitosis, is the longest phase of the cell cycle and has three distinct sub-stages.
🔻G1 Phase (Gap 1): right after cell division cells increase in size, produce RNA and synthesize proteins. Importantly, this phase ensures that everything is in place for DNA synthesis to occur in the next phase.
🔻S Phase (Synthesis): the cell’s DNA replicates, and at the end of this phase, each chromosome consists of two chromatids attached at the centromere.
🔻G2 Phase (Gap 2): the cell continues growing and prepares for mitosis, ensuring that all the DNA has been replicated without any errors.
2️⃣ Mitosis or the M phase, has multiple steps:
🔻Prophase: Chromosomes condense and become visible, the nuclear envelope starts to disintegrate, and the mitotic spindle begins to form.
🔻Metaphase: Chromosomes line up along the cell’s equatorial plate, and spindle fibers attach to the centromeres.
🔻Anaphase: Sister chromatids are pulled apart towards opposite poles of the cell.
🔻Telophase: The chromatids or chromosomes move to opposite ends of the cell and two nuclei form.
🔻Following mitosis (or as its final step), the cell undergoes cytokinesis where the cytoplasm divides, creating two daughter cells.
⚪️ The G0 phase is a “resting” phase where the cell exits the cell cycle and stops dividing. Some cells, like neurons and muscle cells, enter this phase semi-permanently and may never undergo division again. It is crucial for:
✔️Conserving energy and resources in non-dividing cells.
✔️Specializing cells for specific functions.
✔️Regulation of the Cell Cycle:
🟩 Checkpoints tightly regulate the cell cycle to prevent errors:
✅ G1 Checkpoint ensures that the cell has adequate energy resources and that the surrounding environment is favorable for DNA replication. If conditions aren’t right, the cell can exit to G0 phase.
✅ G2 Checkpoint confirms that DNA has replicated properly.
✅ M Checkpoint (Spindle Assembly Checkpoint) occurs during metaphase in mitosis and ensures that all chromosomes properly align and attach to the spindle fibers.
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1️⃣ Interphase, the period preceding mitosis, is the longest phase of the cell cycle and has three distinct sub-stages.
🔻G1 Phase (Gap 1): right after cell division cells increase in size, produce RNA and synthesize proteins. Importantly, this phase ensures that everything is in place for DNA synthesis to occur in the next phase.
🔻S Phase (Synthesis): the cell’s DNA replicates, and at the end of this phase, each chromosome consists of two chromatids attached at the centromere.
🔻G2 Phase (Gap 2): the cell continues growing and prepares for mitosis, ensuring that all the DNA has been replicated without any errors.
2️⃣ Mitosis or the M phase, has multiple steps:
🔻Prophase: Chromosomes condense and become visible, the nuclear envelope starts to disintegrate, and the mitotic spindle begins to form.
🔻Metaphase: Chromosomes line up along the cell’s equatorial plate, and spindle fibers attach to the centromeres.
🔻Anaphase: Sister chromatids are pulled apart towards opposite poles of the cell.
🔻Telophase: The chromatids or chromosomes move to opposite ends of the cell and two nuclei form.
🔻Following mitosis (or as its final step), the cell undergoes cytokinesis where the cytoplasm divides, creating two daughter cells.
⚪️ The G0 phase is a “resting” phase where the cell exits the cell cycle and stops dividing. Some cells, like neurons and muscle cells, enter this phase semi-permanently and may never undergo division again. It is crucial for:
✔️Conserving energy and resources in non-dividing cells.
✔️Specializing cells for specific functions.
✔️Regulation of the Cell Cycle:
🟩 Checkpoints tightly regulate the cell cycle to prevent errors:
✅ G1 Checkpoint ensures that the cell has adequate energy resources and that the surrounding environment is favorable for DNA replication. If conditions aren’t right, the cell can exit to G0 phase.
✅ G2 Checkpoint confirms that DNA has replicated properly.
✅ M Checkpoint (Spindle Assembly Checkpoint) occurs during metaphase in mitosis and ensures that all chromosomes properly align and attach to the spindle fibers.
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What happens if cells do not go through all checkpoints?
Not all cells go through all checkpoints of the cell cycle. Some fast-track through certain phases. Also, the time it takes for cells to complete the cycle varies. In humans, it ranges from two to five days for epithelial cells to an entire lifetime for certain neurons and cardiac cells.
Disruption in these regulatory checkpoints can lead to cells with damaged or missing genetic material.
Deregulation of the cell cycle can have grave consequences. When the checkpoints fail, it can result in:
🆘 Cells with incomplete or damaged DNA.
🆘 Uncontrolled cell division.
This uncontrolled division and growth of cells leads to the formation of tumors. Not all tumors are malignant, but those that are can invade nearby tissues and spread to other parts of the body (metastasis), leading to cancer ⬆️.
ℹ️ Cancer is a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body.
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Not all cells go through all checkpoints of the cell cycle. Some fast-track through certain phases. Also, the time it takes for cells to complete the cycle varies. In humans, it ranges from two to five days for epithelial cells to an entire lifetime for certain neurons and cardiac cells.
Disruption in these regulatory checkpoints can lead to cells with damaged or missing genetic material.
Deregulation of the cell cycle can have grave consequences. When the checkpoints fail, it can result in:
🆘 Cells with incomplete or damaged DNA.
🆘 Uncontrolled cell division.
This uncontrolled division and growth of cells leads to the formation of tumors. Not all tumors are malignant, but those that are can invade nearby tissues and spread to other parts of the body (metastasis), leading to cancer ⬆️.
ℹ️ Cancer is a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body.
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Which type of cell division is crucial for sexual reproduction and genetic diversity?
🟢↔️🟢 A type of cell divison that ensures genetic diversity and the continuity of species through sexual reproduction is called meiosis.
It is the process that is not part of the cell cycle and where a cell replicates DNA once but divides twice, producing four cells that have half the genetic information of the original cell. It is how organisms produce gametes or sex cells, which are eggs in females and sperm in males.
Meiosis involves 2️⃣ divisions, so it’s typically broken down into meiosis I and meiosis II ⬆️.
✔️ Cells enter meiosis I from interphase, which is much like interphase in the cell cycle. When cells commit to meiosis, DNA replicates. It consists of:
Prophase I
Metaphase I
Anaphase I
Telophase I
✔️ Meiosis II is similar to mitosis but involves the division of haploid cells. It consists of:
Prophase II
Metaphase II
Anaphase II
Telophase II
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🟢↔️🟢 A type of cell divison that ensures genetic diversity and the continuity of species through sexual reproduction is called meiosis.
It is the process that is not part of the cell cycle and where a cell replicates DNA once but divides twice, producing four cells that have half the genetic information of the original cell. It is how organisms produce gametes or sex cells, which are eggs in females and sperm in males.
Meiosis involves 2️⃣ divisions, so it’s typically broken down into meiosis I and meiosis II ⬆️.
✔️ Cells enter meiosis I from interphase, which is much like interphase in the cell cycle. When cells commit to meiosis, DNA replicates. It consists of:
Prophase I
Metaphase I
Anaphase I
Telophase I
✔️ Meiosis II is similar to mitosis but involves the division of haploid cells. It consists of:
Prophase II
Metaphase II
Anaphase II
Telophase II
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Which type of cell division is crucial for sexual reproduction and genetic diversity? 🟢↔️🟢 A type of cell divison that ensures genetic diversity and the continuity of species through sexual reproduction is called meiosis. It is the process that is not…
What are critical functions of meiosis?
Meiosis has several critical functions in organisms:
1️⃣ Production of Gametes is one of the primary functions. In animals, these gametes are the sperm and egg cells. In plants, meiosis leads to the formation of spores, which then develop into gametophytes that produce gametes.
2️⃣ Halving the Chromosome Number:
The chromosome number of a species remains constant from one generation to the next. By reducing the chromosome number by half, gametes form with a haploid (n) set of chromosomes. When two gametes fuse during fertilization, this restores the diploid (2n) number of chromosomes in the zygote, ensuring genetic stability across generations.
3️⃣ Promotion of Genetic Variation in multiple ways:
▪️Crossing-over: During prophase I, homologous chromosomes undergo crossing-over, where sections of chromatids exchange places. This results in new combinations of genes on each chromatid.
▪️ Independent Assortment: During metaphase I, how the pairs of homologous chromosomes line up at the metaphase plate is random. This means that different combinations of maternal and paternal chromosomes end up in each gamete.
▪️ Random Fertilization: The fusion of any sperm with any egg during fertilization adds another layer of genetic variability.
4️⃣ Evolutionary Significance:
The genetic variation introduced by meiosis provides raw material for natural selection. Organisms with advantageous genetic combinations are more likely to survive and reproduce, passing on those beneficial genes to their offspring. Over time, this leads to evolutionary changes in populations.
5️⃣ Repair of DNA Damage:
Before entering meiosis, cells undergo DNA repair mechanisms. If there’s damage to the DNA, the processes within meiosis, especially recombination, help correct certain types of damage. This ensures that genetic information passes to the next generation as accurately as possible.
6️⃣ Prevention of Chromosomal Abnormalities:
Gametes receive the correct number of chromosomes. Errors in this process lead to conditions like Down syndrome, where an individual has an extra chromosome 21.
✍️ Summary: meiosis maintains the chromosome number across generations, generates genetic diversity, aids in evolutionary processes, repairs DNA, and prevents chromosomal abnormalities.
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Meiosis has several critical functions in organisms:
1️⃣ Production of Gametes is one of the primary functions. In animals, these gametes are the sperm and egg cells. In plants, meiosis leads to the formation of spores, which then develop into gametophytes that produce gametes.
2️⃣ Halving the Chromosome Number:
The chromosome number of a species remains constant from one generation to the next. By reducing the chromosome number by half, gametes form with a haploid (n) set of chromosomes. When two gametes fuse during fertilization, this restores the diploid (2n) number of chromosomes in the zygote, ensuring genetic stability across generations.
3️⃣ Promotion of Genetic Variation in multiple ways:
▪️Crossing-over: During prophase I, homologous chromosomes undergo crossing-over, where sections of chromatids exchange places. This results in new combinations of genes on each chromatid.
▪️ Independent Assortment: During metaphase I, how the pairs of homologous chromosomes line up at the metaphase plate is random. This means that different combinations of maternal and paternal chromosomes end up in each gamete.
▪️ Random Fertilization: The fusion of any sperm with any egg during fertilization adds another layer of genetic variability.
4️⃣ Evolutionary Significance:
The genetic variation introduced by meiosis provides raw material for natural selection. Organisms with advantageous genetic combinations are more likely to survive and reproduce, passing on those beneficial genes to their offspring. Over time, this leads to evolutionary changes in populations.
5️⃣ Repair of DNA Damage:
Before entering meiosis, cells undergo DNA repair mechanisms. If there’s damage to the DNA, the processes within meiosis, especially recombination, help correct certain types of damage. This ensures that genetic information passes to the next generation as accurately as possible.
6️⃣ Prevention of Chromosomal Abnormalities:
Gametes receive the correct number of chromosomes. Errors in this process lead to conditions like Down syndrome, where an individual has an extra chromosome 21.
✍️ Summary: meiosis maintains the chromosome number across generations, generates genetic diversity, aids in evolutionary processes, repairs DNA, and prevents chromosomal abnormalities.
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Why do 🐢turtles live so long?
There's an evolutionary answer and a biological answer to this question.
✔️The evolutionary answer is relatively straightforward: some natural enemies of turtles, like snakes🐍, birds🦅 and raccoons🦝, love to eat turtle eggs.…
There's an evolutionary answer and a biological answer to this question.
✔️The evolutionary answer is relatively straightforward: some natural enemies of turtles, like snakes🐍, birds🦅 and raccoons🦝, love to eat turtle eggs.…
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Mitosis vs Meiosis: what are main differences and similarities?
Both being vital for cell division in eukaryotes, mitosis and meiosis are however fundamentally different in their functions and outcomes ⬆️.
✅ Similarities
Both mitosis and meiosis:
📍 begin with a single parent cell;
📍 have an interphase stage where DNA replication occurs;
📍 have similar fundamental stages such as prophase, metaphase, anaphase, and telophase.
🆚 Differences
📍 Meiosis ensures genetic diversity and the continuity of species through sexual reproduction, while mitosis facilitates growth, repair, and maintenance of an organism.
📍 Both mitosis and meiosis start out with DNA replication, but with different ultimate goals.
Mitosis has one round of cell division, while meiosis has two rounds.
📍 While mitosis yields two daughter cells that are genetically identical (2n) to the parent cell, meiosis produces four haploid (n) cells that are genetically different from the parent cell.
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Both being vital for cell division in eukaryotes, mitosis and meiosis are however fundamentally different in their functions and outcomes ⬆️.
✅ Similarities
Both mitosis and meiosis:
📍 begin with a single parent cell;
📍 have an interphase stage where DNA replication occurs;
📍 have similar fundamental stages such as prophase, metaphase, anaphase, and telophase.
🆚 Differences
📍 Meiosis ensures genetic diversity and the continuity of species through sexual reproduction, while mitosis facilitates growth, repair, and maintenance of an organism.
📍 Both mitosis and meiosis start out with DNA replication, but with different ultimate goals.
Mitosis has one round of cell division, while meiosis has two rounds.
📍 While mitosis yields two daughter cells that are genetically identical (2n) to the parent cell, meiosis produces four haploid (n) cells that are genetically different from the parent cell.
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What cells have the unique ability to develop into other cell types?
Our body is made up of many different types of cells, most of which are ‘specialized’ – with different functions. E.g., red blood cells are specialized to carry oxygen in the blood, while some gut cells are specialized to absorb nutrients from food.
However, there are also stem cells that have the unique ability to develop into other specialized cell types.
Stem cells are different from other cells in several ways:
✔️ They can divide and renew themselves over a long time
✔️ They are unspecialized, so they cannot do specific functions in the body
✔️ In a developing embryo, they can develop into any type of cell.
✔️ Once the body is grown, they can develop into specific cell types, to replace old or damaged cells.
ℹ️ The concept of a stem cell was first proposed by researchers working on embryonic development in the nineteenth century. They saw such cells as the starting point for biological processes.
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Our body is made up of many different types of cells, most of which are ‘specialized’ – with different functions. E.g., red blood cells are specialized to carry oxygen in the blood, while some gut cells are specialized to absorb nutrients from food.
However, there are also stem cells that have the unique ability to develop into other specialized cell types.
Stem cells are different from other cells in several ways:
✔️ They can divide and renew themselves over a long time
✔️ They are unspecialized, so they cannot do specific functions in the body
✔️ In a developing embryo, they can develop into any type of cell.
✔️ Once the body is grown, they can develop into specific cell types, to replace old or damaged cells.
ℹ️ The concept of a stem cell was first proposed by researchers working on embryonic development in the nineteenth century. They saw such cells as the starting point for biological processes.
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What cells have the unique ability to develop into other cell types? Our body is made up of many different types of cells, most of which are ‘specialized’ – with different functions. E.g., red blood cells are specialized to carry oxygen in the blood, while…
How many types of stem cells are there?
Today, researchers classify three types of stem cells (SC).
The two types of SC ⬆️ are ‘natural’:
1️⃣Embryonic SC supply new cells for an embryo as it grows and develops into a baby. Being ‘pluripotent’, they can change into any cell in the body.
2️⃣ Adult SC replace old or damaged cells as an organism grows. Being ‘multipotent’, they can only change into some cells in the body – not all cell types, because they have already started to specialize, so can only develop further into a specific type of cell.
The third type ⬆️ is ‘artificial’.
3️⃣ Induced pluripotent SC (or ‘iPS cells’) are made in the laboratory. Normal adult cells (often skin cells) can be reprogrammed to become stem cells. This is called ‘inducing’ the stem cells. iPS cells are pluripotent so can, theoretically, like Embryonic SC, develop into any cell type.
ℹ️ In medicine, stem cells are used to replace cells and tissues that have been damaged or lost due to diseases.
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Today, researchers classify three types of stem cells (SC).
The two types of SC ⬆️ are ‘natural’:
1️⃣Embryonic SC supply new cells for an embryo as it grows and develops into a baby. Being ‘pluripotent’, they can change into any cell in the body.
2️⃣ Adult SC replace old or damaged cells as an organism grows. Being ‘multipotent’, they can only change into some cells in the body – not all cell types, because they have already started to specialize, so can only develop further into a specific type of cell.
The third type ⬆️ is ‘artificial’.
3️⃣ Induced pluripotent SC (or ‘iPS cells’) are made in the laboratory. Normal adult cells (often skin cells) can be reprogrammed to become stem cells. This is called ‘inducing’ the stem cells. iPS cells are pluripotent so can, theoretically, like Embryonic SC, develop into any cell type.
ℹ️ In medicine, stem cells are used to replace cells and tissues that have been damaged or lost due to diseases.
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How does the Vangunu giant rat look like?
🐀🏝🇸🇧 The Vangunu giant rat (Uromys vika or U. vika) from the South Pacific island of Vangunu in the Solomon Islands was first described ⬆️ in 2017, when one representative of the species was found dead after loggers took out a section of forest.
✍️ It was the first new species of rodent described in the Solomon Islands in more than 80 years.
⚠️ Due to logging of its lowland forest habitat this one of the world’s rarest giant rodent was considered critically endangered and researchers long feared that it had gone extinct.
❎ For several years, periodic efforts to scientifically identify and document this species were fruitless.
✅ Recently, researchers finally captured images of four of these creatures ⬆️.
🐀🥥🏝 The Vangunu giant rats are about twice the size of common rats, and can chew through coconuts.
🙏🌳🌴 According to scientists, the future of the species relies on the preservation of Zaira primary forests.
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🐀🏝🇸🇧 The Vangunu giant rat (Uromys vika or U. vika) from the South Pacific island of Vangunu in the Solomon Islands was first described ⬆️ in 2017, when one representative of the species was found dead after loggers took out a section of forest.
✍️ It was the first new species of rodent described in the Solomon Islands in more than 80 years.
⚠️ Due to logging of its lowland forest habitat this one of the world’s rarest giant rodent was considered critically endangered and researchers long feared that it had gone extinct.
❎ For several years, periodic efforts to scientifically identify and document this species were fruitless.
✅ Recently, researchers finally captured images of four of these creatures ⬆️.
🐀🥥🏝 The Vangunu giant rats are about twice the size of common rats, and can chew through coconuts.
🙏🌳🌴 According to scientists, the future of the species relies on the preservation of Zaira primary forests.
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What is Peto’s Paradox?
In a multicellular organism, cells must go through a cell cycle that includes growth and division.
Every time a cell divide, it must copy its millions/billion base pairs of DNA, and it inevitably makes some mistakes. These mistakes are called somatic mutations.
If every cell division carries a certain chance that a cancer-causing somatic mutation could occur, then the risk of developing cancer should theoretically increase with both the number of cells and the lifespan of an organism.
However, multiple studies showed that gigantic animals do not only get more cancer than humans, but actually even get less, suggesting that super-human cancer suppression has evolved numerous times across the tree of life. This is the essence and promise of Peto’s Paradox ⬆️.
Peto’s Paradox is named after a British epidemiologist Richard Peto (1943-), who noted the relationship between time and cancer when he was studying how tumors form in mice.
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In a multicellular organism, cells must go through a cell cycle that includes growth and division.
Every time a cell divide, it must copy its millions/billion base pairs of DNA, and it inevitably makes some mistakes. These mistakes are called somatic mutations.
If every cell division carries a certain chance that a cancer-causing somatic mutation could occur, then the risk of developing cancer should theoretically increase with both the number of cells and the lifespan of an organism.
However, multiple studies showed that gigantic animals do not only get more cancer than humans, but actually even get less, suggesting that super-human cancer suppression has evolved numerous times across the tree of life. This is the essence and promise of Peto’s Paradox ⬆️.
Peto’s Paradox is named after a British epidemiologist Richard Peto (1943-), who noted the relationship between time and cancer when he was studying how tumors form in mice.
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How the longest-lived mammals resist cancer?
Massive creatures like whales have roughly 1,000 times the number of cells humans do, but their rates of cancer are much lower. This inconsistency, called Peto’s paradox, has long puzzled scientists.
Bowhead whales ⬆️ are the longest-lived mammals on Earth, with a life span that can exceed 200 years. In 2023, researchers may have discovered one of the keys to their longevity.
In the study, researchers severed both strands of the DNA molecule in cells from humans, cows, mice and bowhead whales. This kind of damage, called a “double-strand break,” is known to increase cancer risk.
The research showed the whales’ ability to repair DNA. Proteins called CIRBP and RPA2 were much more common in bowhead whales and may play a role in this gene repair.
Scientists say, this one of the most important biological discoveries of 2023 can help fight cancer.
ℹ️The bowhead is also the second-largest animal on Earth, reaching over 80,000 kg.
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Massive creatures like whales have roughly 1,000 times the number of cells humans do, but their rates of cancer are much lower. This inconsistency, called Peto’s paradox, has long puzzled scientists.
Bowhead whales ⬆️ are the longest-lived mammals on Earth, with a life span that can exceed 200 years. In 2023, researchers may have discovered one of the keys to their longevity.
In the study, researchers severed both strands of the DNA molecule in cells from humans, cows, mice and bowhead whales. This kind of damage, called a “double-strand break,” is known to increase cancer risk.
The research showed the whales’ ability to repair DNA. Proteins called CIRBP and RPA2 were much more common in bowhead whales and may play a role in this gene repair.
Scientists say, this one of the most important biological discoveries of 2023 can help fight cancer.
ℹ️The bowhead is also the second-largest animal on Earth, reaching over 80,000 kg.
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When were the first books made?
This papyrus fragment ⬆️, unearthed at the Egyptian site of El Hibeh in 1902, began as a bound document dating to 260 B.C. that recorded taxation rates for beer and oil scrawled in Greek letters using black ink.
Having used modern microscopic and multispectral imaging, researchers now believe that it is part of the world’s first book. And, like many of the ancient volumes, it has had many lives.
According to scientists, this sheet of papyrus was first bound within an ancient manunoscript. It was then removed from its binding and sent as a letter to a creditor or a debtor before being transformed once again and reused as wrapping for a mummy during the Ptolemaic period (304–30 B.C.).
The oldest book previously known being from the first or second century A.D., the discovery pushes the origins of bookbinding back by about 400 years and shows that the structure of the book, as opposed to a scroll, existed well before researchers thought.
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This papyrus fragment ⬆️, unearthed at the Egyptian site of El Hibeh in 1902, began as a bound document dating to 260 B.C. that recorded taxation rates for beer and oil scrawled in Greek letters using black ink.
Having used modern microscopic and multispectral imaging, researchers now believe that it is part of the world’s first book. And, like many of the ancient volumes, it has had many lives.
According to scientists, this sheet of papyrus was first bound within an ancient manunoscript. It was then removed from its binding and sent as a letter to a creditor or a debtor before being transformed once again and reused as wrapping for a mummy during the Ptolemaic period (304–30 B.C.).
The oldest book previously known being from the first or second century A.D., the discovery pushes the origins of bookbinding back by about 400 years and shows that the structure of the book, as opposed to a scroll, existed well before researchers thought.
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Why is February 15 important for science?
📌 February 15 is important for modern science as it is Galileo Galilei’s birthday.
📌 Galileo (1564-1642) ⬆️ was an Italian natural philosopher who made several major contributions to scientific progress.
📌 Before Galileo, science was not considered a profession. Typically, people who did ‘science’ were considered natural philosophers and held positions as medical doctors, mathematicians or priests with extra time on their hands.
📌 Galileo was one of the first to express the belief that the basic laws of science could be broken down into mathematics.
📌 🔭 He studied speed and gravity to predict paths of projectile motion. He was among the first to take a closer look at the skies above with a telescope.
📌 His life is generally used as the beginning point of the history of modern science.
📌 His philosophy of observing first, explain second and then observe some more would become the foundation of the modern scientific method.
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📌 February 15 is important for modern science as it is Galileo Galilei’s birthday.
📌 Galileo (1564-1642) ⬆️ was an Italian natural philosopher who made several major contributions to scientific progress.
📌 Before Galileo, science was not considered a profession. Typically, people who did ‘science’ were considered natural philosophers and held positions as medical doctors, mathematicians or priests with extra time on their hands.
📌 Galileo was one of the first to express the belief that the basic laws of science could be broken down into mathematics.
📌 🔭 He studied speed and gravity to predict paths of projectile motion. He was among the first to take a closer look at the skies above with a telescope.
📌 His life is generally used as the beginning point of the history of modern science.
📌 His philosophy of observing first, explain second and then observe some more would become the foundation of the modern scientific method.
Subscribe- t.me/askmenow
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