Basic Concepts in Biology

Definition: Biology is the study of living organisms, their structure, function, growth, evolution, and interactions with their environment.

Cell Theory:
- All living organisms are composed of cells.
- The cell is the basic unit of life.
- All cells arise from pre-existing cells.
Cell Types:
- Prokaryotic Cells: Simple, no nucleus (e.g., bacteria).
- Eukaryotic Cells: Complex, with a nucleus (e.g., plants, animals, fungi).
Cell Organelles:
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Powerhouse, produces ATP.
- Endoplasmic Reticulum: Synthesis of proteins (rough ER) and lipids (smooth ER).
- Golgi Apparatus: Modifies, sorts, and packages proteins.
- Chloroplasts: Site of photosynthesis in plant cells.

DNA Structure: Double helix made of nucleotides (A, T, C, G).
Genes: Segments of DNA that code for proteins.
Chromosomes: Structures made of DNA and protein; humans have 46 (23 pairs).
Mendelian Inheritance: Principles of heredity, including dominant and recessive alleles.

Natural Selection: Mechanism of evolution where organisms better adapted to their environment tend to survive and reproduce.
Speciation: The formation of new and distinct species in the course of evolution.

Ecosystem: A community of living organisms and their physical environment.
Biomes: Large ecological areas characterized by specific climates and types of flora and fauna (e.g., desert, rainforest).
Food Webs: Complex networks of feeding relationships among organisms.

Homeostasis: The process by which organisms maintain a stable internal environment.
Metabolism: Sum of all biochemical reactions within an organism; includes catabolism (breaking down) and anabolism (building up).
Transport Mechanisms:
- Passive Transport: Movement of molecules without energy (e.g., diffusion).
- Active Transport: Movement of molecules requiring energy (e.g., sodium-potassium pump).

Photosynthesis: Process by which plants convert light energy into chemical energy (glucose).
Plant Structure:
- Roots: Absorb water and nutrients.
- Stems: Support plant and transport materials.
- Leaves: Main site of photosynthesis.

Body Systems:
- Circulatory System: Transports blood, nutrients, gases.
- Respiratory System: Facilitates gas exchange (oxygen and carbon dioxide).
- Nervous System: Controls body activities by transmitting signals.

Microorganisms: Includes bacteria, viruses, fungi, and protists.
Roles:
- Decomposers in ecosystems.
- Some are pathogenic (cause diseases).
- Others are beneficial (e.g., gut microbiota).

Applications: Genetic engineering, cloning, and therapeutic uses (e.g., insulin production).
Tools: CRISPR, PCR (Polymerase Chain Reaction), and recombinant DNA technology.

These notes provide a concise overview of fundamental concepts in biology, useful for studying and understanding the discipline.

The study of life, encompassing structure, function, growth, evolution, and interactions with the environment.

Cell Theory states all living organisms are made of cells, cells are the fundamental unit of life, and all cells arise from pre-existing cells.
Prokaryotic cells are simple, lack a nucleus (e.g., bacteria), while eukaryotic cells are complex with a nucleus (e.g., plants, animals, fungi).
Organelles are specialized structures within cells with specific functions:
- Nucleus houses genetic material (DNA).
- Mitochondria are the powerhouses, producing cellular energy (ATP).
- Endoplasmic reticulum is involved in protein synthesis (rough ER) and lipid synthesis (smooth ER).
- Golgi apparatus modifies, sorts, and packages proteins.
- Chloroplasts are the site of photosynthesis in plants.

DNA, the carrier of genetic information, has a double helix structure composed of nucleotides (adenine, thymine, cytosine, guanine).
Genes are segments of DNA that code for specific proteins, determining traits.
Chromosomes are structures composed of DNA and protein, with humans having 46 (23 pairs).
Mendelian inheritance explains how traits are passed from parents to offspring, including concepts of dominant and recessive alleles.

Natural selection is the driving force of evolution, favoring organisms with traits better suited to their environment for survival and reproduction.
Speciation is the process of forming new and distinct species through evolutionary changes.

An ecosystem comprises a community of living organisms and their physical surroundings.
Biomes are large ecological regions characterized by specific climates and types of flora and fauna (e.g., desert, rainforest).
Food webs are complex networks showing feeding relationships between organisms in an ecosystem.

Homeostasis is the process by which organisms maintain a stable internal environment, essential for proper function.
Metabolism encompasses all biochemical reactions occurring within an organism. Catabolism breaks down molecules, while anabolism builds them up.
Transport mechanisms move substances across cell membranes:
- Passive transport doesn't require energy (e.g., diffusion).
- Active transport requires energy (e.g., sodium-potassium pump).

Photosynthesis allows plants to convert light energy into chemical energy (glucose) using chloroplasts.
Plant structure is specialized for different functions:
- Roots absorb water and nutrients from the soil.
- Stems provide support and transport water and nutrients throughout the plant.
- Leaves are the primary site of photosynthesis.

Body systems work together to maintain life:
- Circulatory system transports blood, nutrients, and gases.
- Respiratory system facilitates gas exchange (oxygen and carbon dioxide).
- Nervous system controls and coordinates body activities through signal transmission.

Microorganisms are microscopic living organisms including bacteria, viruses, fungi, and protists:
- Decomposers play a crucial role in ecosystems, breaking down organic matter.
- Some are pathogens, causing diseases.
- Others are beneficial, aiding in processes like digestion (gut microbiota).

Genetic engineering involves manipulating genetic material for various applications.
Cloning creates genetically identical copies of organisms.
Therapeutic uses of biotechnology include producing essential proteins like insulin.
Tools used in biotechnology include CRISPR, Polymerase Chain Reaction (PCR), and recombinant DNA technology.