Cellular Biology: Structure, Function, and Division
In 1838, Mathias Schleiden and Theodor Schwann proposed the following:
- All living things are formed by one or more cells.
- The cell is the simplest and smallest living thing that exists.
- All cells come from pre-existing cells.
- Every single cell carries out its own actions, although there is coordination between cells.
Cell Structure
- Membrane: The border that separates the cell from the environment. Through the membrane, the cell and the external environment exchange products: substances for nutrition enter,
Local Adaptation, Infectious Diseases, Sexual Reproduction, and Extreme Conditions in Biology
Identifying Local Adaptation in Reciprocal Transplant Experiments
In a reciprocal transplant experiment, researchers could place organisms, like deer mice, with dark and light phenotypes in environments with dark soil and light sand. They would then observe the effect of predation on these different phenotypes. This helps to determine if a phenotype is locally adapted to a specific environment.
Why Bats Transmit Infectious Diseases to Humans and Domestic Animals
Bats make up 20% of all mammal species.
Read MoreBody’s Defense Mechanisms: Barriers, Antigens, and Immunity
Body’s Defense Mechanisms
Barriers: Living organisms have developed an intricate network of defenses to prevent the entry of microorganisms. These defenses, or barriers, may be nonspecific, such as the skin, mucous membranes, and specialized cells that perform phagocytosis in macrophages, transported by blood and lymph. Finally, the response may be specific to that microorganism; this response is called immunity. The skin and mucous membranes are the body’s first defensive structures. The skin is
Read MoreImmune System, Childbirth, and Common Infections: A Detailed Look
The Immune System: A Detailed Look
The macrophages alert the immune system when there is a foreign agent in the following way: by exposing fragments of the antigen on the surface of their cells, they alert the immune system.
Differentiating B Lymphocytes and T Lymphocytes
The B lymphocytes circulate in search of specific antigens in the body. When antibodies unite with the antigens to eliminate them, they send signals to the T lymphocytes to stop multiplying, and the immune response against that particular
Read MoreUnderstanding the Body’s Defense Mechanisms
Mechanisms of Defense (Barriers)
Non-Specific Barriers
These are congenital. We are born with them, and they do not discriminate between pathogens and non-pathogens. They have no memory, which means they do not recognize antigens and are not reinforced after infection.
- The skin is both a mechanical and chemical barrier. The chemical barrier function depends on two glands: sebaceous and sweat glands. Both secrete a fluid that gives the skin a slightly acidic pH, which is very effective against external
Understanding Food, Nutrients, and Biological Processes
Understanding Food and Nutrients
Foods are natural or processed substances containing various nutrients. Humans consume them to satisfy hunger or for other reasons. They can be plant-based, animal-based, liquids, or solids.
Pursuing and obtaining food is fundamental to survival. Therefore, humans have had to adapt to their environment or fight to ensure their survival.
Carbohydrates
Carbohydrates are derived from plants and cereals. They are the primary source of energy for living things. Glucose is
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