Fundamentals of Cell Biology and Human Organ Systems
Levels of Biological Organization
- Tissues
- Sets of specialized cells which have the same function and the same origin.
- Organs
- Structural and functional units of living beings.
- Organ Systems
- Sets of different organs which carry out functions that are independent from each other but coordinated.
- Organism
- The complete unit of the living organism.
Cell Structure and Organelles
- Cellular Membrane
- Consists of lipids and proteins. It surrounds the cell, separating it from its surroundings and allowing various substances
Soil Fertility Management: Chemical, Organic, and Biofertilizer Methods
Understanding Fertilizers and Soil Nutrients
A fertilizer is any natural or synthetic substance (solid, liquid, or gaseous) containing one or more plant nutrients (other than lime) that is applied to the soil or leaves to supply nutrients essential for the growth of plants. The following four main types of fertilizers are recognized:
- Chemical Fertilizers
- Organic Fertilizers or Manures
- Biofertilizers
- Plant Growth Promoting Rhizobacteria (PGPR)
Chemical Fertilizers
Chemical fertilizers are manures or mixtures
Read MoreBacterial Cell Structure, Components, and Growth Kinetics
Bacterial Cell Structure and Components
Cell Envelope
Plasma Membrane
The fundamental barrier defining the cell boundary.
Cell Wall
- Gram-Positive Wall (Gram +)
- Gram-Negative Wall (Gram -)
Organs of Locomotion and Adhesion
- Flagella: Used for motility.
- Pili or Fimbriae: Used for adhesion and conjugation.
Internal Components (Cytoplasm)
The cytoplasm is a gelatinous substance containing essential structures:
- Nucleoid
- Ribosomes
- Inclusion Bodies
External Components
- Capsule: A dense, organized layer.
- Glycocalyx: General
Comparative Biology of Transport Systems in Plants and Animals
Transport in Organisms: Fundamentals
In unicellular and simple multicellular organisms, nutrient uptake and waste removal occur primarily via passive transport mechanisms such as diffusion, osmosis, and facilitated diffusion across the external membrane, facilitated by their small size and high surface area-to-volume ratio.
In complex multicellular organisms, diffusion alone is insufficient to meet metabolic demands due to increased cellular volume and distance. Thus, specialized transport systems
The Human Fertilization Process: From Gamete to Zygote
The Intricate Process of Human Fertilization
Initial Contact and Penetration
The process of fertilization begins with the contact between gametes. This meeting typically occurs in the ampullary region of the fallopian tubes within the female genital tract. First, the sperm must penetrate the corona radiata of the secondary oocyte to reach and make contact with the zona pellucida.
The Acrosome Reaction: Unlocking the Egg
This contact triggers the acrosome reaction in the sperm’s head, releasing enzymes
Read MoreAuxin and Ethylene: Regulators of Plant Growth and Signaling
Phytohormones: Definition and Signaling Principles
What is a Phytohormone?
A phytohormone is a naturally occurring organic molecule produced in plants that acts at low concentrations to regulate growth, development, and responses to environmental stimuli.
- They are signal molecules that coordinate physiological processes such as cell division, elongation, differentiation, flowering, and stress responses.
- Examples include auxins, cytokinins, gibberellins, abscisic acid (ABA), ethylene, brassinosteroids,