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• Knowledge of science and scientific literacy are relevant for thinking creatively about scientific issues and integrating those ideas into decision-making
• Biology is the scientific study of life

Characteristics of Life

• Cells are the smallest unit of life, capable of independent function and reproduction
• All living things are composed of cells
• Cells use DNA, as the chemical material of genes
• Cells require energy and building materials for growth, maintenance, and repair
• Living things create and maintain order
• Regulation keeps living things in order
• All organisms grow and develop
• Organisms respond to their environment
• Reproduction
• Evolution

Scientific Method

• Make an observation
• Formulate a hypothesis
• Make a prediction based on the hypothesis
• Conduct an experiment to test the prediction
• Draw a conclusion based on the experimental results
• A control group does not receive treatment and serves as a baseline for comparison
• Replication in experimental design requires more than one subject in both control and experimental groups
• A scientific theory is a comprehensive idea supported by extensive evidence and scientific reasoning

Variables

• Identify the independent and dependent variables in a hypothesis
• Interpret graphical data from a simple experiment

Chemistry & Macromolecules

• Matter is anything that occupies space and has mass, existing as a solid, liquid, or gas
• Life is comprised of carbon, hydrogen, oxygen, and nitrogen

Atomic Structure

• Protons are in the nucleus and have a positive charge
• Neutrons are also in the nucleus and are neutral
• Electrons have a negative charge and circle the nucleus in shells at different energy levels
• The first electron shell holds 2 electrons, and the second holds up to 8
• An atom's behavior is determined by how its electrons interact with other atoms
• Atoms are most stable when their outer shell is full

Elements

• If the outer shell is not full, atoms will form bonds with other atoms to fill it
• Atomic number is the number of protons in an atom's nucleus, found at the top left of the atomic symbol
• Atomic mass is the number of protons plus the number of neutrons, found at the bottom middle of the atomic symbol
• A compound occurs when a molecule contains one or more different types of atoms

Bonding

• An atom is the smallest unit of matter that retains properties of an element
• An ion is a charged atom
• A molecule is made up of atoms held together by chemical bonds
• A compound is when a molecule contains one or more different types of atoms
• An element is a substance that cannot be broken down chemically into any other substance
• Ionic bonds occur when an atom loses or gains electrons and becomes charged
• The attraction between the opposite charges holds ions together and fills the outer shell
• Covalent bonds occur when two atoms share one or more pairs of outer-shell electrons, filling their outer shells

Covalent Bonds

• There 2 types are: Polar and Non Polar
• Covalent bonds are the strongest bond
• Nonpolar bonds share bonds equally
• The weakest bond occurs when a slightly positive ion attracts to a slightly negative ion

Water

• Hydrogen bonds form when water molecules get near each other, and oppositely charged regions attract
• Hydrogen bonds give water structure and stabilize nucleic acids

Water Characteristics

• Cohesion: A result of hydrogen bonding, water molecules "stick" together
• High Heat Capacity: Because of hydrogen bonding, water can resist temperature change and absorb/store large amounts of heat
• Low density as a solid: water changes from liquid to solid, H bonds push molecules farther apart, lowering density
• Good Solvent: can dissolve polar and ionic compounds
• Solution: liquid consisting of 2+ mixed substances
• Dissolving agent: the solvent
• Dissolved substance: the solute

Acids and Bases

• Acids have more H+ ions than OH- ions and are very reactive
• Bases have more OH- ions than H+ ions, binding to H+ and neutralizing acids
• Buffers absorb excess H+ ions to prevent max acidity and release H+ ions to prevent max basicity
• pH describes how acidic/basic a solution is based on the concentration of H+ ions
• Ranges from 0 (highest H+ concentration) to 14 (lowest H+ concentration)
• The pH of 7 is neutral, with H+ = OH-

Macromolecules

• Carbohydrates are composed of monosaccharides and provide fuel for cells
• Glycogen is carbohydrates' temporary storage, and fat is their long-term energy storage
• Lipids contain more C-H bonds than carbs and provide more stored energy than carbs
• Triglycerides are fats made of glycerol and 3 fatty acids
• Proteins are protein polymers made of amino acids.
• Examples are enzymes, and used for body structure, health protection, regulate cells, contract muscles, transport oxygen to body
• Nucleic acids are made of nucleotides and include DNA/RNA

Proteins

• The order of bases in a DNA molecule determines what protein to make
• Nucleic acids carry genetic info and direct the production of proteins

Lipids

• Saturated fats contain no C=C double bonds, forming straight/tightly packed chains that are solid at room temperature
• Unsaturated fats have one C=C bond, are loose, and liquid at room temperature
• Protein structure is important because if it is not folded correctly, it will not work, and minor changes can cause malfunctions
• Denaturation occurs when unfavorable temperature and pH changes cause a protein to lose its shape and function
• Enzymes speed up chemical reactions and use activation energy to initiate the reaction

Cells

• Microscopes provide the resolution to visualize cells too small to see with the naked eye
• Resolution is the minimum distance between two points that allows distinguishing them as separate
• Higher resolution results in a clearer image

Cells: Prokaryotic

• Smaller
• No membranous organelles or nucleus
• Includes bacteria and archaea
• First cells on earth
• Metabolically diverse

Cells: Eukaryotic

• Bigger
• Have membranous organelles and a nucleus
• Physical separation of compartments
• Different chemical reactions can occur at the same time

Cell Structures

• Plasma membrane
• Cytoplasm
• DNA
• Ribosomes
• Animal cells have many vacuoles, don't contain chloroplast, and don't have a cell wall
• Plant cells have one vacuole, contain chloroplast, and have a cell wall
• Phospholipids have two regions: a polar/hydrophilic head and a non polar/hydrophobic tail
• Form bilayers of cells when placed in water, with the head outside the membrane and the tail inside the membrane.
• Proteins: fingerprint for identification by other cells, helps membrane's flexibility, binds to external chemicals, gives passageway for other cells to pass through, and accelerate interactions on membrane
• Carbohydrates: cell recognition markers
• Cholesterol: important for membrane fluidity
• The plasma membrane separates living cells from nonliving surroundings and provides a barrier
• The plasma membrane also allows certain molecules to pass through and interact with the environment and neighboring cells

Transport Mechanisms

• Simple diffusion: molecules move from an area of high concentration to an area of low concentration
• Facilitated diffusion: molecules still move to an area of low concentration, but need help from a transport protein
• Osmosis: water diffuses from a high concentration area to a low concentration area to equalize the concentration of water inside/out of the cell
• Always diffuse toward hypertonic concentration
• In a hypertonic fluid (concentration outside cell >), the cell loses water
• In a hypotonic fluid (concentration outside cell < in), the cell gains water
• Active transport: molecules can't move up the membrane without energy input

Permeability

• O2 and CO2 can freely pass through the plasma membrane because of their small size and neutral charge
• Nonpolar molecules freely pass because the membrane interior is also nonpolar

Solutions

• An isotonic solution has an equal solute concentration outside and inside the cell, meaning water movement is equal in both directions
• A hypotonic solution has a concentration of lower solute outside the cell than inside, so water moves into the cell
• A hypertonic solution has a concentration of higher solute outside the cell than inside, so water moves outside the cell

Organelles

• Nucleus: stores hereditary info & info needed to create proteins
• Contains chromatin (DNA associated with proteins) & nucleolus (stores ribosome which makes protein from RNA attaching to it)
• Ribosomes: protein factories; found throughout cytoplasm, bound to endoplasmic reticulum
• Rough endoplasmic reticulum: Assembly Line; folds/packages proteins, studded with ribosomes that produce proteins
• Smooth Endoplasmic Reticulum: assembly line; Synthesizes lipids and detoxifies waste molecules
• Golgi Apparatus: post office; processes/packages proteins, lipids, & molecules and runs carbohydrate synthesis
• Lysosomes: garbage disposal; uses sacs that contain enzymes to digest/recycle cell waste
• Mitochondria: powerhouse; does cell respiration, convert energy from food into chemical (ATP)
• Cytoskeleton: movers/shapers; gives cell shape/support & movement, transport organelles/vesicles, cell contents/chromosomes, heals wounds, and moves past cells using cilia (short structures that beat to move) and flagella (long structures)
• Cell Wall: Protective Barrier; gives structure/protection, prevents water loss, not present in animal cells
• Vacuoles: Storage Sacs for nutrients; breaks down waste, deters predators, sex reproduction, & physical support
• Chloroplasts: Photosynthesizers; perform photosynthesis by converting light energy to chemical glucose, only found in plant cells.
• Two types of organelles have theories of endosymbiosis: Chloroplast & Mitochondria
• Endosymbiosis explains the origin of mitochondria/chloroplasts inside eukaryotic cells, while invagination explains the origin of the nucleus and other organelles