Key Concepts in Biology

Prokaryotic Cells:
- No nucleus, simpler structure (e.g., bacteria).
- DNA is circular and found in the nucleoid.
Eukaryotic Cells:
- Have a nucleus and organelles (e.g., plants, animals).
- DNA is linear and organized into chromosomes.

Carbohydrates: Provide energy and structural support.
- Monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), polysaccharides (e.g., starch).
Proteins: Functions include catalysis, structure, and transport.
- Made of amino acids.
Lipids: Store energy, form cell membranes, and signal molecules.
- Include fats, oils, and phospholipids.
Nucleic Acids: Store and transmit genetic information.
- DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

DNA Structure: Double helix formed by nucleotides (adenine, thymine, cytosine, guanine).
Gene Expression: Process by which information from a gene is used to synthesize a functional gene product (usually proteins).
Mendelian Genetics:
- Principles of inheritance (dominant vs. recessive traits).
- Punnett squares to predict genotype ratios.

Natural Selection: Mechanism of evolution; organisms better adapted to their environment tend to survive and reproduce.
Speciation: Process by which new species arise.
Common Descent: All living organisms share a common ancestor.

Ecosystems: Interactions between organisms and their environment.
Biomes: Large geographic biotic communities (e.g., desert, rainforest).
Food Chains and Webs: Energy flow through trophic levels (producers, consumers, decomposers).

Organ Systems:
- Circulatory, respiratory, digestive, nervous, and reproductive systems.
Homeostasis: The maintenance of stable internal conditions.

Photosynthesis: Process by which plants convert light energy into chemical energy.
Plant Structures: Roots, stems, leaves, flowers, and fruits.

These notes cover foundational concepts in biology, designed to provide a quick reference and facilitate understanding of the subject.

All living organisms consist of cells; they are the fundamental unit of life.
Cells originate from pre-existing cells, emphasizing continuity in biological processes.

Prokaryotic Cells: Lack a nucleus; simpler structure, e.g., bacteria. Contains circular DNA located in the nucleoid region.
Eukaryotic Cells: Possess a nucleus and organelles, found in plants and animals. DNA is linear, organized into chromosomes.

Carbohydrates: Vital for energy and structural integrity, categorized into monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), and polysaccharides (e.g., starch).
Proteins: Serve various functions including catalysis, structure, and transport; composed of amino acids linked by peptide bonds.
Lipids: Primarily for energy storage, cellular membrane formation, and signaling; examples include fats, oils, and phospholipids.
Nucleic Acids: Essential for genetic information storage and transmission; include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

DNA Structure: Comprises a double helix formed by nucleotide pairs: adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).
Gene Expression: Involves the transcription of DNA into mRNA, followed by translation into proteins, producing functional gene products.
Mendelian Genetics: Explores inheritance patterns, distinguishing between dominant and recessive traits; utilized Punnett squares for predicting genotype ratios.

Natural Selection: A driving force in evolution where organisms that are better suited to their environments are more likely to survive and reproduce.
Speciation: The process leading to the emergence of new species from common ancestors.
Common Descent: The concept that all living organisms share a common ancestor, underpinning the unity of life.

Ecosystems: Comprised of interactions among living organisms and their physical environment, emphasizing the dynamic nature of ecosystems.
Biomes: Large geographic areas characterized by distinct climate and biological communities, such as deserts or rainforests.
Food Chains and Webs: Describe energy transfer and nutrient flow through interconnected trophic levels: producers, consumers, and decomposers.

Organ Systems: Include circulatory, respiratory, digestive, nervous, and reproductive systems, collaborating for maintaining body functions.
Homeostasis: The process of regulating internal conditions to maintain steady state despite external changes, crucial for survival.

Focuses on microorganisms—bacteria, viruses, fungi, and protozoa—and their roles in health, disease development, and biotechnological applications.

Photosynthesis: The process wherein plants convert sunlight into chemical energy, producing glucose and oxygen as byproducts.
Plant Structures: Comprise essential components such as roots (anchorage), stems (support), leaves (photosynthesis), flowers (reproduction), and fruits (seed dispersal).

Ethology: The scientific study of animal behavior in natural settings, observing instinctual and learned behaviors.
Animal behaviors can be categorized into instinctive (innate responses) and learned (acquired through experience and interaction).