Chemistry: Atoms and Chemical Bonds

Subatomic Particles of an Atom

• Atoms are composed of protons, neutrons, and electrons.
• Protons have a positive charge, neutrons are neutral, and electrons are negative.
• Protons and neutrons reside in the atom's nucleus, while electrons orbit the nucleus.

Types of Chemical Bonds

• Ionic Bonds: Occur when one atom loses electrons and another gains them, creating oppositely charged ions that attract each other.
• Covalent Bonds: Formed when two atoms share one or more pairs of electrons. These bonds can be polar (electrons are shared unequally) or nonpolar (electrons are shared equally).
• Hydrogen Bonds: Weak attractions between a slightly positive hydrogen atom of one molecule and a slightly negative atom (often oxygen or nitrogen) of another molecule.

Atoms' Goal and Bonding

• Atoms strive for stability, often achieved by filling their outermost electron shell (valence shell).
• Atoms bond with each other to achieve this stability, sharing or transferring electrons.

Properties of Water

• Water is a polar molecule, meaning it has a slightly positive and a slightly negative end. This polarity allows water to form hydrogen bonds.
• Water has high specific heat capacity, meaning it takes a lot of energy to change its temperature, regulating temperature in organisms.
• Water has a high heat of vaporization, requiring a lot of energy to evaporate, contributing to cooling mechanisms in organisms.
• Water is a good solvent, dissolving many polar and ionic substances (hydrophyllic).
• Water is less dense as a solid than as a liquid; ice floats. This allows aquatic life to survive in frozen bodies of water.

Cell Theory

• Cell Theory postulates that all organisms are composed of cells, that cells are the basic unit of structure and function, and that cells arise from preexisting cells.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic Cells: Lacks a nucleus and other membrane-bound organelles. These cells are smaller and simpler.
• Eukaryotic Cells: Contains a nucleus and other membrane-bound organelles, more complex structures allowing for greater specialization.
• (Note: Visual diagrams are best created separately.)*

Animal vs. Plant Cells

• Similarities: Both have a cell membrane, cytoplasm, and various organelles like mitochondria and ribosomes (e.g., endoplasmic reticulum, golgi apparatus).
• Differences: Plant cells have a cell wall, chloroplasts (for photosynthesis), and a large central vacuole. Animal cells do not.

Organelle Function Matching

• This requires a table/matching activity to best be understood. Organelles (e.g., ribosomes, mitochondria, chloroplasts) function in specific ways; research these separately.

Hierarchy from Atoms to Organisms

• Atoms → molecules → organelles → cells → tissues → organs → organ systems → organisms

Cell Membrane Anatomy and Physiology

• The cell membrane is a phospholipid bilayer with embedded proteins.
• The bilayer forms a barrier between the cell's interior and exterior.
• Proteins conduct specific functions in/out of the membrane.

Macromolecules

• The four main macromolecules are carbohydrates, lipids, proteins, and nucleic acids.

Lipids

• Properties of Lipids: Insoluble in water (hydrophobic), important for energy storage, insulation, and hormone production.
• Types of Lipids: Fats, oils, phospholipids, steroids (visual identification needs visual aids).

Saturated vs. Unsaturated Lipids

• Saturated: Have only single bonds between carbon atoms. Solid at room temperature. (e.g., animal fats)
• Unsaturated: Have one or more double bonds between carbon atoms creating kinks. Liquid at room temperature. (e.g., vegetable oils)

Substance Movement Across Cell Membranes

• Passive Transport: No energy required; Substances move down their concentration gradient (high to low).
• Active Transport: Requires energy; Substances move against their concentration gradient (low to high).
• Examples: Diffusion, osmosis, facilitated diffusion, endocytosis, exocytosis.

Concentration Gradients

• Substances tend to move from areas of high concentration to areas of low concentration.

Endocytosis vs. Exocytosis

• Endocytosis: Cell takes in materials by engulfing them in a vesicle.
• Exocytosis: Cell expels materials by fusing a vesicle with the cell membrane.

Solutions (Isotonic, Hypertonic, Hypotonic)

• Isotonic: Water moves equally in both directions, the concentration of solutes is equal on both sides of the membrane.
• Hypertonic: Water moves out of the cell—the concentration of solutes is higher outside the cell.
• Hypotonic: Water moves into the cell—the concentration of solutes is lower outside the cell.

Feedback Loops

• Negative Feedback: Reverses a change. (e.g., temperature regulation)
• Positive Feedback: Amplifies a change. (e.g., blood clotting). Negative feedback is often more common.

Unit 2 - Energy and Ecosystems

• (Further information on organisms obtaining energy, food webs/chains, energy transfer, carbon cycle, and energy currency needed for this section.)*

Photosynthesis and Cellular Respiration

• Photosynthesis (formula needed): Converts light energy into chemical energy.
• Cellular Respiration (formula needed): Releases stored chemical energy (from glucose) as ATP (energy currency).
• Location: Photosynthesis occurs in chloroplasts, and respiration occurs in the mitochondria.
• Comparison: Photosynthesis stores energy, respiration releases energy—they are opposing processes.

Chemical Energy from Plants

• Chlorophyll captures light energy for photosynthesis.
• Plants use light energy to combine carbon dioxide and water to produce glucose, storing energy.

Polymers and Monomers

• Polymers are large molecules composed of repeating smaller units called monomers.
• Monomers linked by covalent bonds can form complex polymers.

Carbohydrates

• Carbohydrates: Provide energy for cellular processes. (Examples of food sources needed.)

Cellular Oxygen and Energy

• Cellular respiration produces more ATP when oxygen is present. Less ATP is created when oxygen is absent.

Unit 3 – Cell Division and DNA

• (Further information needed for mitosis stages, DNA replication, and cancerous cell development.)*

Mitosis

• Mitosis produces two identical daughter cells from a single parent cell.

Cell Cycle

• Purpose: Growth, repair, and asexual reproduction.

DNA vs. RNA

• DNA: Stores genetic information.
• RNA: Carries out instructions for protein synthesis.

Nucleic Acids

• Structure/properties of nucleic acids, including the monomers (nucleotides).

DNA Replication

• Explains the mechanism and process of DNA replication—must include necessary enzymes.

Complementary DNA Strands

• This requires practice examples.

DNA to Chromosome

• How DNA Condenses: DNA wraps around proteins (histones) to form chromosomes.

Cancer

• Cause of Cancer: Uncontrolled cell growth and division.

Explore the fundamentals of subatomic particles, types of chemical bonds, and the goals of atoms in this chemistry quiz. Understand how protons, neutrons, and electrons interact to form stable compounds, and learn about ionic, covalent, and hydrogen bonds.