1. When and where was the first cell born? How did it happen?
2. What are the circumstances that make the appearance of the cell in this earth?
3. What are the differences between prokaryotic and eukaryotic cell? How about plant and animal cell?
1. The origin of the first cell is still a topic of scientific research and debate. However, the prevailing theory suggests that the first cell, or the last universal common ancestor (LUCA), appeared on Earth around 3.5 to 3.8 billion years ago. The specific time and place of its origin are not known with certainty.
The formation of the first cell likely involved a process called abiogenesis, which is the natural creation of life from non-living matter. It is believed that under conditions present on early Earth, organic molecules could have formed from simpler chemical compounds. These organic molecules, combined with other factors such as the presence of water and an energy source, could have led to the formation of primitive cells.
Several hypotheses propose different scenarios for the formation of the first cell. One popular hypothesis is that certain small molecules, like lipids, could have formed naturally and self-assembled into a primitive membrane. This membrane enclosed other organic molecules, creating a boundary between the cell's interior and the external environment. Over time, these primitive cells evolved into more complex forms through processes like genetic mutation and natural selection.
2. The appearance of cells on Earth was influenced by various circumstances, including the presence of suitable chemical compounds, an energy source, water, and a stable environment. Earth's early conditions, such as volcanic activity, lightning, and chemical reactions, likely provided the necessary ingredients for the formation of organic molecules which eventually led to the emergence of cells.
Additionally, the availability of water was crucial for the formation of cells as it provided a medium for chemical reactions to take place and facilitated the transport of nutrients and waste products. The presence of a stable environment allowed these cells to thrive and evolve over time, leading to the emergence of more complex organisms.
3. Prokaryotic and eukaryotic cells differ in terms of their structural complexity and organization.
Prokaryotic cells are simpler and usually found in bacteria and archaea. They lack a membrane-bound nucleus and other membrane-bound organelles. Instead, their DNA is present in the nucleoid region. Prokaryotic cells are typically smaller, have a cell wall, and reproduce through binary fission.
Eukaryotic cells, on the other hand, are found in plants, animals, fungi, and protists. They are more complex and contain a distinct nucleus enclosed within a nuclear membrane. Eukaryotic cells also have various membrane-bound organelles, such as mitochondria, endoplasmic reticulum, and Golgi apparatus. Eukaryotic cells can be much larger and reproduce through processes like mitosis or meiosis.
Plant and animal cells share many similarities as both are eukaryotic cells. However, there are some key differences. Plant cells have a rigid cell wall composed of cellulose, whereas animal cells do not have a cell wall. Plant cells also contain chloroplasts for photosynthesis and large central vacuoles for storage. Animal cells, on the other hand, have specialized structures like centrioles and flagella for different functions.
In summary, the differences between prokaryotic and eukaryotic cells lie in their complexity and presence of certain structures, while the differences between plant and animal cells include the presence of a cell wall and specific organelles.