Key Concepts in Biology

Cell Theory: All living things are composed of cells; the cell is the basic unit of life; all cells arise from pre-existing cells.
Types of Cells:
- Prokaryotic (e.g., bacteria) - no nucleus, simple structure.
- Eukaryotic (e.g., animals, plants) - has a nucleus and organelles.
Cell Organelles:
- Nucleus: Contains DNA, controls cell activities.
- Mitochondria: Powerhouse of the cell, produces ATP.
- Ribosomes: Synthesize proteins.
- Endoplasmic Reticulum: Rough (with ribosomes) and Smooth (without ribosomes).
- Golgi Apparatus: Modifies, sorts, and packages proteins.

DNA Structure: Double helix, composed of nucleotides (adenine, thymine, cytosine, guanine).
Gene Expression: Process of turning DNA into RNA (transcription) and then into proteins (translation).
Mendelian Genetics:
- Law of Segregation: Alleles separate during gamete formation.
- Law of Independent Assortment: Genes for different traits segregate independently.

Natural Selection: Mechanism of evolution; organisms with favorable traits are more likely to survive and reproduce.
Speciation: Formation of new and distinct species through evolutionary processes.
Evidence of Evolution: Fossil record, comparative anatomy, molecular biology.

Ecosystems: Community of living organisms interacting with their physical environment.
Biomes: Large ecological areas with distinct climates and species (e.g., tundra, rainforest).
Food Chains/Webs: Energy flow in ecosystems; producers → consumers → decomposers.

Organ Systems:
- Circulatory: Transports blood and nutrients.
- Respiratory: Exchanges gases (O2 and CO2).
- Digestive: Breaks down food for energy.
- Nervous: Controls body functions and responses.
Homeostasis: Maintenance of stable internal conditions (e.g., temperature, pH).

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

Bacteria: Prokaryotic microorganisms, can be beneficial (e.g., gut flora) or harmful (pathogens).
Viruses: Non-cellular entities that require a host to replicate; cause various diseases.
Fungi: Eukaryotic organisms that decompose organic material; can be beneficial (e.g., yeast) or harmful (e.g., molds).

Macromolecules:
- Carbohydrates: Energy source and structural elements.
- Proteins: Made of amino acids, perform various functions (e.g., enzymes).
- Lipids: Fats, important for energy storage and cell membranes.
- Nucleic Acids: DNA and RNA, carry genetic information.

Genetic Engineering: Manipulation of an organism’s DNA to achieve desired traits.
CRISPR: A technology for editing genes with precision.
Applications: Medicine (gene therapy), agriculture (GMOs), environmental science (bioremediation).

Cell Theory: Fundamental principles stating all living organisms are made of cells, the cell is the fundamental unit of life, and new cells arise from existing ones.
Prokaryotic Cells: Simple, unicellular organisms without a nucleus; examples include bacteria.
Eukaryotic Cells: More complex cells that contain a nucleus and organelles; examples include animal and plant cells.
Key Organelles:
- Nucleus: Houses DNA and regulates cell activities.
- Mitochondria: Generate ATP through cellular respiration, acting as the cell's energy source.
- Ribosomes: Sites where protein synthesis occurs.
- Endoplasmic Reticulum (ER): Rough ER has ribosomes for protein synthesis; Smooth ER synthesizes lipids.
- Golgi Apparatus: Processes, sorts, and packages proteins for secretion or delivery within the cell.

DNA Structure: Composed of nucleotides in a double helix formation; bases include adenine, thymine, cytosine, and guanine.
Gene Expression: Involves transcription (DNA to RNA) and translation (RNA to protein), crucial for protein synthesis.
Mendelian Genetics: Foundational genetic principles including:
- Law of Segregation: Alleles separate into different gametes during reproduction.
- Law of Independent Assortment: Genes for different traits assort independently during gamete formation.

Natural Selection: Key mechanism driving evolution; advantageous traits enhance survival and reproduction rates in organisms.
Speciation: The evolutionary process that leads to the emergence of new and distinct species.
Evidence for Evolution: Supported by the fossil record, comparative anatomical studies, and molecular biology findings.

Ecosystems: Interactions between communities of organisms and their physical environments.
Biomes: Large ecological areas with unique climates and biodiversity, such as tundras and rainforests.
Food Chains/Webs: Illustrate energy flow in ecosystems starting with producers, followed by consumers, and ending with decomposers.

Organ Systems: Critical systems maintaining physiological functions:
- Circulatory System: Transports blood, nutrients, and gases.
- Respiratory System: Facilitates the exchange of oxygen and carbon dioxide.
- Digestive System: Breaks down food into energy.
- Nervous System: Regulates bodily functions and responses to stimuli.
Homeostasis: The process of maintaining stable internal conditions despite external changes.

Photosynthesis: The process whereby plants convert sunlight into chemical energy, specifically glucose.
Key Plant Structures:
- Roots: Absorb water and nutrients from the soil.
- Stems: Provide structural support and transport materials.
- Leaves: Primary site of photosynthesis.

Bacteria: Prokaryotic microorganisms that can play beneficial roles (e.g., gut flora) or cause disease (pathogens).
Viruses: Non-cellular entities that need a host cell to replicate and can cause various illnesses.
Fungi: Eukaryotic organisms that decompose organic matter; they can be helpful (e.g., yeast) or harmful (e.g., molds).

Macromolecules: Large biological molecules essential for life:
- Carbohydrates: Serve as energy sources and structural components.
- Proteins: Composed of amino acids, they perform a variety of functions, including enzymatic activity.
- Lipids: Fatty molecules essential for energy storage and forming cell membranes.
- Nucleic Acids: Include DNA and RNA, vital for storing and transmitting genetic information.

Genetic Engineering: The alteration of an organism's DNA to introduce or enhance desirable traits.
CRISPR Technology: A revolutionary method for precise gene editing.
Applications: Range from medicine (gene therapy) and agriculture (genetically modified organisms) to environmental science (bioremediation).

Anatomy: Focuses on the structure and organization of living organisms.
Physiology: Studies the functions and processes of different body parts and systems.