Key Concepts in Biology: Cells and Genetics

Cell Theory: All living organisms are made of cells; cells are the basic unit of life; all cells arise from pre-existing cells.
Prokaryotic vs. Eukaryotic Cells:
- Prokaryotic: No nucleus, smaller, unicellular (e.g., bacteria).
- Eukaryotic: Nucleus present, larger, multi/unicellular (e.g., plants, animals).
Cell Organelles:
- Nucleus: Control center of the cell.
- Mitochondria: Powerhouse, ATP production.
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum: Synthesis and transport (Rough ER with ribosomes, Smooth ER without).

DNA Structure: Double helix, made of nucleotides (A, T, C, G).
Chromosomes: DNA packaged into structures; humans have 46 chromosomes.
Gene Expression: Process by which information from a gene is used to synthesize a functional gene product (proteins).
Mendelian Genetics: Study of heredity, principles such as dominance, segregation, and independent assortment.

Natural Selection: Mechanism of evolution; organisms better adapted to their environment tend to survive.
Speciation: Formation of new species through processes like allopatric or sympatric differentiation.
Fossil Record: Evidence of evolution over time, documenting changes in species.

Ecosystem: Community of living organisms interacting with their physical environment.
Biomes: Large ecological areas on Earth, defined by climate and vegetation (e.g., tundra, desert, rainforest).
Food Chains/Webs: Represent trophic levels and energy flow through ecosystems.

Homeostasis: Regulation of internal conditions (temperature, pH) despite external changes.
Organ Systems: Groups of organs working together (e.g., circulatory, respiratory, digestive systems).
Metabolism: All chemical reactions in an organism; includes catabolism (breaking down) and anabolism (building up).

Macromolecules: Four main types - carbohydrates, proteins, lipids, nucleic acids.
Enzymes: Biological catalysts that speed up chemical reactions.
Metabolic Pathways: Series of interconnected biochemical reactions (e.g., glycolysis, Krebs cycle).

Protein Synthesis: Process of using DNA to make proteins through transcription (DNA to RNA) and translation (RNA to protein).
Genetic Engineering: Manipulating genes for practical purposes (e.g., CRISPR technology).

Immune System: Body's defense system against pathogens.
Types of Immunity:
- Innate: Non-specific, rapid response.
- Adaptive: Specific, slower response, develops memory.

Photosynthesis: Process by which plants convert sunlight into energy (glucose); occurs in chloroplasts.
Plant Structures: Roots (absorption), stems (support), leaves (gas exchange).

These notes encapsulate the pivotal aspects of biology, offering a structured overview for study and review.

Cell Theory explains that all living things are composed of cells, which are the fundamental unit of life and arise from pre-existing cells.
Prokaryotic cells lack a nucleus, are smaller in size, and typically exist as single-celled organisms, represented by bacteria.
Eukaryotic cells, in contrast, contain a nucleus, are larger, and can be single-celled or multicellular, encompassing animals and plants.
Cell organelles are specialized structures within cells that perform specific functions. The nucleus is the control center of the cell, containing genetic material. Mitochondria generate energy (ATP) for the cell, earning them the nickname "powerhouses". Ribosomes are responsible for protein synthesis. The endoplasmic reticulum (ER) is involved in the synthesis and transport of molecules.

DNA is a double helix structure composed of nucleotide building blocks (adenine (A), thymine (T), cytosine (C), and guanine (G)).
Chromosomes are structures containing packaged DNA; humans have 46 chromosomes.
Gene expression refers to the process of converting information from a gene into a functional product, typically a protein.
Mendelian genetics studies inheritance patterns, focusing on principles like dominance, segregation, and independent assortment.

Natural selection is the driving force behind evolution, where organisms with traits better suited to their environment are more likely to survive and reproduce.
Speciation is the formation of new species through processes like allopatric speciation (geographic isolation) or sympatric speciation (evolution within the same geographic area).
The fossil record provides evidence of evolutionary changes over time, showing how species have evolved and changed.

An ecosystem encompasses a community of living organisms interacting with their physical environment.
Biomes are large ecological areas characterized by distinct climate and vegetation types, examples include tundra, desert, and rainforest.
Food chains/webs illustrate trophic levels and the flow of energy through ecosystems.

Homeostasis is the maintenance of stable internal conditions (temperature, pH) despite external changes.
Organ systems are groups of organs that work together to perform specific functions (e.g., circulatory, respiratory, digestive systems).
Metabolism refers to all chemical reactions within an organism, including catabolism (breaking down molecules) and anabolism (building up molecules).

There are four major types of macromolecules: carbohydrates, proteins, lipids, and nucleic acids.
Enzymes are biological catalysts that accelerate chemical reactions within cells.
Metabolic pathways are series of interconnected biochemical reactions, examples include glycolysis and the Kreb's cycle.

Protein synthesis is the process of making proteins from DNA through transcription (DNA to RNA) and translation (RNA to protein).
Genetic engineering involves manipulating genes for specific purposes using techniques like CRISPR technology.

The immune system defends the body against pathogens.
Innate immunity is non-specific and provides a rapid response, while adaptive immunity is specific, slower, and develops memory.

Photosynthesis is the process plants use to convert sunlight into energy (glucose), occurring in chloroplasts.
Plant structures include roots for absorption, stems for support, and leaves for gas exchange.