Intro to Biology

• Common features that define "life" include the ability to reproduce, growth, metabolism, homeostasis, response to stimuli, and adaptation through evolution.
• One of the five unifying themes in biology is the flow of energy through ecosystems.
• The correct order of life's hierarchy of organization from simplest to most complex is: atom, molecule, cell, tissue, organ, organ system, organism.
• The broadest level of taxonomic classification is Kingdom.
• The first step in the scientific inquiry process is making observations.
• It is important to use large sample sizes in scientific experiments to ensure the results are representative and statistically significant.
• A hypothesis is not a well-established explanation for a broad range of phenomena that has been repeatedly tested; a theory is.
• A theory is an explanation supported by evidence, but not considered an absolute fact.
• A key characteristic of pseudoscience is that it is based on untestable hypotheses and lacks empirical evidence.
• A logical fallacy is a flaw in reasoning that undermines the validity of an argument.

Subatomic Particles and Biological Molecules

• A proton carries a positive charge.
• The four elements that are the main components of biological molecules are carbon, hydrogen, oxygen, and nitrogen.
• Carbon, hydrogen, oxygen, and nitrogen react readily with other atoms because they have incomplete outer electron shells, making them highly reactive.
• A trace element is one present in small amounts but essential for life.
• Iron is an example of a trace element required by humans.

Ionic and Covalent Bonding in Water

• Ionic bonding occurs when atoms lose or gain electrons, forming oppositely charged ions that attract each other.
• A covalent bond is found within a water molecule.
• Hydrogen bonds are found between water molecules.
• The polarity of water molecules and hydrogen bonding are the underlying cause for all of water's unique and important properties.
• Biologically significant properties of water include high heat capacity, the ability to dissolve a wide range of substances, and high surface tension.
• Acids are represented by values less than 7, and bases by values greater than 7 on the pH scale.
• An acid increases the concentration of hydrogen ions (H+) in a solution.
• A base decreases the concentration of hydrogen ions (H+) in a solution.

Polymers and Monomers

• Dehydration synthesis (condensation) is used to link monomers together to form polymers.
• Hydrolysis is used to break down polymers into monomers.
• Water is created in the reaction that links monomers to form polymers (dehydration synthesis).
• Water is consumed in the reaction that breaks down polymers into monomers (hydrolysis).
• Amino acids form proteins.
• Monosaccharides form carbohydrates.
• Nucleotides form nucleic acids.
• Fatty acids and glycerol form lipids.

Examples of Biological Molecules

• Cellulose is an example of a carbohydrate.
• Hemoglobin is an example of a protein.
• Phospholipid is an example of a lipid.
• RNA is an example of a nucleic acid.

Glucose, Fructose, and Fats

• Glucose and fructose taste different but have the same molecular formula because they are structural isomers, meaning they have different structural arrangements of atoms.
• High-fructose corn syrup is a sweetener made by converting glucose into fructose.
• Saturated fats have no double bonds between carbon atoms, while unsaturated fats do.
• Saturated fats are solid at room temperature.
• Olive oil is an example of an unsaturated fat.

Protein Structures and Macromolecules

• The primary structure of a protein involves the sequence of amino acids.
• The secondary level of protein structure involves the folding of the polypeptide chain into patterns such as alpha-helices or beta-pleated sheets.
• The tertiary level of protein structure involves the overall 3D shape of a polypeptide chain.
• The quaternary level of protein structure involves the interaction of multiple polypeptide chains to form a functional protein.
• Steroids are an example of lipids.

Domains of Life and Cell Structures

• The three domains of life are Bacteria (prokaryotic), Archaea (prokaryotic), and Eukarya (eukaryotic).
• The nucleus is found in both plant and animal cells.
• The chloroplast is unique to plant cells.
• The mitochondrion produces ATP in both plant and animal cells.

Modern Cell Theory

• Modern cell theory states that all organisms are made up of cells, cells are the basic unit of structure and function in living organisms, and all cells arise from pre-existing cells.
• Membrane-bound organelles are not a characteristic of prokaryotic cells.
• Prokaryotic and eukaryotic cells both have a plasma membrane.
• Prokaryotic cells lack a nucleus, while eukaryotic cells have a nucleus.
• Plant cells have chloroplasts and a cell wall, while animal cells do not.

Cell Membranes and Energetics

• The "fluid mosaic model" describes how the flexible membrane allows some substances to pass while blocking others based on size, charge, and polarity.
• The cell membrane consists of a phospholipid bilayer with proteins embedded, allowing flexibility and selective permeability.
• Functions of proteins in the cell membrane include transporting molecules, acting as enzymes, and serving as receptors.
• A ball rolling down a hill is an example of kinetic energy.
• A compressed spring is an example of potential energy.

Laws of Thermodynamics

• The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted.
• The second law of thermodynamics states that the entropy of an isolated system always increases over time.
• In an exergonic reaction, the reactants have higher potential energy than the products.

Photosynthesis

• The overall reaction for photosynthesis is: 6CO2 + 6H2O → C6H12O6 + 6O2
• The reactants in the overall reaction for photosynthesis are water and carbon dioxide.
• The products in the overall reaction for photosynthesis are oxygen and glucose.
• Key structures in a leaf involved in photosynthesis are mesophyll, stomata, guard cells, veins, thylakoids, grana, and stroma.
• The function of the mesophyll in a leaf is to conduct photosynthesis.
• A redox reaction is a reaction where a molecule gains an electron (reduction) and another loses an electron (oxidation).
• During photosynthesis, carbon dioxide is reduced, and water is oxidized.

Stages and Locations of Photosynthesis

• The two main stages of photosynthesis are the light reactions and the Calvin cycle.
• Light reactions occur in the thylakoid membranes of the chloroplast.
• The Calvin cycle occurs in the stroma of the chloroplast.
• Red and blue light is absorbed by chlorophyll.
• Green light is reflected most by chlorophyll.

Light Reactions and Calvin Cycle Steps

• The basic steps of the light reactions are: light energy is absorbed by chlorophyll, water is split to release oxygen, and ATP and NADPH are produced.
• The products of the light reactions are oxygen, ATP, and NADPH.
• The basic steps of the Calvin cycle is that ATP and NADPH from the light reactions are used to convert carbon dioxide into glucose.
• The products of the Calvin cycle are glucose (or other carbohydrates).

Summary of Photosynthesis

• Photosynthesis occurs in two stages: the light reactions (in the thylakoid membranes), where water is split to produce oxygen, ATP, and NADPH, and the Calvin cycle (in the stroma), where carbon dioxide is fixed into glucose using ATP and NADPH.
• The overall reactants are water and carbon dioxide, and the products are oxygen and glucose.