Cell Biology: Structure and Division

Cell Structure:
- Basic unit of life; all organisms are made of cells.
- Two main types: Prokaryotic (no nucleus, e.g., bacteria) and Eukaryotic (nucleus present, e.g., plant and animal cells).
Cell Organelles:
- Nucleus: Control center with DNA.
- Mitochondria: Powerhouse; energy production.
- Ribosomes: Protein synthesis.
- Cell membrane: Semi-permeable barrier.
Cell Division:
- Mitosis: Division of somatic (body) cells for growth/repair.
- Meiosis: Division of gametes (sex cells) for reproduction.

Newton's Laws of Motion:
- First Law: An object at rest stays at rest; an object in motion stays in motion unless acted upon by a force.
- Second Law: Force equals mass times acceleration (F=ma).
- Third Law: For every action, there is an equal and opposite reaction.
Types of Forces:
- Gravity: Pulls objects toward each other.
- Friction: Resists motion between surfaces in contact.
- Tension: Force transmitted through a string or rope.
Motion:
- Speed: Distance traveled per unit of time.
- Velocity: Speed with direction.
- Acceleration: Change in velocity over time.

Major Systems:
- Circulatory: Transports blood, nutrients, gases.
- Respiratory: Exchanges oxygen and carbon dioxide.
- Digestive: Breaks down food, absorbs nutrients.
- Nervous: Controls body functions through signals.
- Musculoskeletal: Supports body structure, enables movement.
Homeostasis: The body's ability to maintain stable internal conditions (e.g., temperature, pH).
Organs and Functions:
- Heart: Pumps blood.
- Lungs: Facilitate gas exchange.
- Brain: Coordinates activities, processes information.

Earth’s Structure:
- Layers: Crust, mantle, outer core, inner core.
- Plate tectonics: Movement of Earth's plates causes earthquakes and volcanoes.
Weather and Climate:
- Weather: Short-term atmospheric conditions.
- Climate: Long-term average of weather patterns.
Solar System:
- Planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
- Sun: Central star providing energy.
- Moon: Earth's satellite affecting tides.

Components:
- Biotic: Living organisms (plants, animals, microorganisms).
- Abiotic: Non-living elements (water, soil, climate).
Energy Flow:
- Producers: Convert sunlight into energy (e.g., plants).
- Consumers: Organisms that eat producers or other consumers.
- Decomposers: Break down dead material, returning nutrients to the soil.
Ecological Relationships:
- Food Chain: Linear sequence of energy transfer.
- Food Web: Complex network of interrelated food chains.
- Biomes: Distinct ecological areas (e.g., forests, deserts, grasslands).

Cells are the fundamental units of life, comprising all living organisms.
Two primary cell types: Prokaryotic (lack a nucleus; e.g., bacteria) and Eukaryotic (contain a nucleus; e.g., plant and animal cells).
Organelles:
- Nucleus: Contains DNA, serving as the control center of the cell.
- Mitochondria: Known as the powerhouse of the cell; responsible for ATP production.
- Ribosomes: Sites for protein synthesis, essential for cellular functions.
- Cell Membrane: Semi-permeable barrier regulating the passage of substances in and out of the cell.
Cell Division:
- Mitosis: Process for the division of somatic cells for growth and repair.
- Meiosis: Specialized division for gametes, leading to genetic diversity in reproduction.

Newton's Laws of Motion:
- First Law: An object remains at rest or in uniform motion unless acted upon by an external force (inertia).
- Second Law: Acceleration is produced when a force acts on a mass, expressed as F=ma.
- Third Law: Every action has an equal and opposite reaction, showing the interaction of forces.
Types of Forces:
- Gravity: Attractive force between masses, critical for keeping objects grounded.
- Friction: Force that opposes motion between two surfaces in contact, affecting movement.
- Tension: Force exerted through a string, cable, or rope when pulled.
Motion:
- Speed: Measure of how fast an object is moving, calculated as distance over time.
- Velocity: Speed with a directional component, providing more detailed motion information.
- Acceleration: Rate of change of velocity over time, indicating how quickly an object speeds up or slows down.

Major Systems:
- Circulatory System: Responsible for transporting blood, nutrients, and gases throughout the body.
- Respiratory System: Facilitates the exchange of oxygen and carbon dioxide.
- Digestive System: Breaks down food into nutrients for absorption and use by the body.
- Nervous System: Coordinates body functions and responses through neural signals.
- Musculoskeletal System: Provides structural support and enables movement.
Homeostasis: The process by which the body maintains stable internal conditions, such as temperature regulation and pH balance.
Key Organs and Functions:
- Heart: Pumps blood, supplying oxygen and nutrients to tissues.
- Lungs: Allow for efficient gas exchange between oxygen and carbon dioxide.
- Brain: Central organ for processing information and regulating body activities.

Earth’s Structure:
- Composed of four main layers: Crust, mantle, outer core, and inner core.
- Plate tectonics theories explain the movement of Earth’s plates, responsible for geological phenomena like earthquakes and volcanic activity.
Weather and Climate:
- Weather refers to short-term atmospheric conditions affecting a specific area.
- Climate represents the long-term average of weather patterns in a region, influencing ecosystems and weather extremes.
Solar System:
- Comprises eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
- The Sun is the central star, providing heat and light essential for life on Earth.
- The Moon acts as Earth’s satellite, influencing tides through gravitational interactions.

Components:
- Biotic factors: Living elements in ecosystems, including plants, animals, and microorganisms.
- Abiotic factors: Non-living components, such as water, soil, and climate conditions.
Energy Flow:
- Producers (e.g., plants) convert sunlight into chemical energy through photosynthesis.
- Consumers obtain energy by eating producers or other consumers.
- Decomposers recycle nutrients by breaking down dead organic matter into the soil.
Ecological Relationships:
- Food Chain: Linear progression of energy transfer from one organism to another.
- Food Web: Complex interconnections of multiple food chains showing how various organisms interact.
- Biomes: Large ecological areas characterized by distinct climates and ecosystems, such as forests, deserts, and grasslands.