Cell Division: Mitosis and Meiosis
Cell Cycle Phases
G1 phase: A period of intense metabolic activity. The cell size increases, as do its cytoplasmic structures.
S or synthesis phase: The time when DNA replication occurs.
G2 phase: The period in which the cell prepares to enter division; e.g., chromatin begins to condense.
After phase two, cell division begins.
Example: Escherichia coli can divide roughly every 20 minutes, while human skin cells take about 15 days to divide.
Somatic vs. Sex Cells
Somatic cells: These cells have 46 chromosomes
Read MoreMetabolism, Photosynthesis, and Cellular Respiration
Key Definitions in Metabolism and Energy
Metabolism: The process by which your body converts what you eat and drink into energy.
Energy: The capacity for doing work. It may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other forms.
Chemical Energy: Energy stored in the bonds of chemical compounds. It may be released during a chemical reaction, often in the form of heat (exothermic reactions).
Potential Energy: Stored energy that depends upon the relative position of various
Read MoreCells: The Fundamental Units of Life
Living things are composed of minimal units called cells. All basic chemical and physiological functions—for example, repair, growth, movement, immunity, communication, and digestion—are carried out inside the cell. Depending on the number of cells that form them, living beings can be classified into unicellular and multicellular.
Unicellular Organisms
Unicellular organisms are those formed by a single cell. In this group, the most representative are protozoa, which can only be seen under a microscope.
Read MoreEssential Nutrients and Their Food Sources
Nutrients and Food
Feeding is the selection, preparation, and ingestion of food. It is a conscious and voluntary process.
Nutrition is a set of processes which include digestion (nutrients contained in these foods are extracted), absorption of nutrients (from the intestines to blood), use by cell metabolism to produce energy and matter, and egestion (to eliminate waste products through the excretory system). These are unconscious and involuntary processes.
Nutrient Types
Inorganic Nutrients:
- Water:
Ecosystems: Essential Cycles and Interactions
An ecosystem is defined by the interaction of organisms (biotic factors) with their environment (abiotic factors).
A sustainable ecosystem maintains a balance of resources, environment, and biodiversity over time.
Water’s Role: Water is essential for survival, photosynthesis, nutrient transport, temperature regulation, and habitat.
Components of an Ecosystem
- Biotic Components: Organisms like plants and animals.
- Abiotic Components: Non-living things like water, nutrients (nitrogen, phosphorus), and climate.
Humoral and Cellular Immune Responses Explained
Humoral and Cellular Immune Responses
Humoral Immune-Mediated Replies
Humoral immune response is triggered by B cells in response to a particular antigen, leading to the production of specific antibodies. B cells are formed and differentiate in the bone marrow, where they acquire the capacity to produce antibodies, becoming immunocompetent.
The bone marrow generates millions of genetically distinct B cells, each producing different antibodies that bind to a vast number of different antigens. Some antibodies
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