Understanding Genetics: DNA, Genes, and Engineering
Stem Cells
Stem cells retain the ability to renew themselves through self-division. They can differentiate into a range of specialized pluripotent cells, retaining the ability to change into other cells.
Inherited vs. Acquired Characteristics
Inherited variations are received from genes from your parents. Acquired variations are not present at birth; you learn or acquire them throughout your life.
DNA Structure
Deoxyribonucleic acid (DNA) is hereditary material that carries and passes on genetic information.
Read MoreMollusks and Arthropods: Characteristics and Classification
Mollusks: Characteristics and Classification
Mollusks are invertebrates of great importance to humans, providing food and materials for jewelry, among other things. A negative aspect is that some can cause schistosomiasis.
Mollusk Classification
- Monoplacophora: Single shell, found in deep-sea environments.
- Polyplacophora: Shell composed of eight plates, marine.
- Scaphopoda: Conical shell, buried in the seabed sand.
- Gastropoda: May have no shell or a single shell; the most numerous and diverse group (
Characteristics of Life and Cellular Organization
Characteristics of Life
Key characteristics define living organisms:
- Movement: Ability to change position or move internally.
- Responsiveness: Reaction to internal and external changes.
- Growth: Increase in size without changing shape.
- Reproduction: Production of new organisms and new cells.
- Respiration: Obtaining oxygen, removing carbon dioxide, and releasing energy from foods.
- Digestion: Breakdown of food substances into simpler forms.
- Absorption: Movement of substances through membranes and into body fluids.
Cell Division, Nucleic Acids, and Gene Expression
Mitosis
Stages:
- Prophase: Chromatin fibers thicken and shorten to form chromosomes. The nucleolus and nuclear membrane disappear, allowing chromosomes to move freely in the cytoplasm. Mitotic spindles (protein fibers) appear at the cell poles.
- Metaphase: Chromosomes connect to mitotic spindles through centromeres along the cell equator and align, forming the equatorial plate, where sister chromatids are pulled to opposite poles.
- Anaphase: Mitotic spindles break at the equatorial plate and contract,
Water Properties and Homeostasis in the Human Body
Water: Essential for Life and Homeostasis
Water constitutes approximately 60% of the human body. It is distributed as follows: one-third is located outside the cells (extracellular fluid), and the remaining two-thirds are inside the cells.
Cells depend on the internal environment (extracellular fluid) to perform their functions properly. The internal environmental conditions, such as pH, nutrients, and ion concentrations, are crucial for cell life. Maintaining these conditions in a constant state
Read MoreHuman Anatomy: Cells, Tissues, and Body Systems
Histology: Cells and Tissues of the Body
Histology is the microscopic study of tissues, which are composed of specialized cells that work together to perform specific functions. The human body consists of four primary tissue types:
- Epithelial Tissue – Covers and lines surfaces.
- Connective Tissue – Supports and connects different tissues.
- Muscle Tissue – Facilitates movement.
- Nervous Tissue – Conducts nerve impulses.
1. The Cell (Basic Unit of Life)
Cells are the fundamental units of life that make
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