Biology: Macromolecules and Life Organization

Characteristics of Life

• Made of Cells: Organisms are composed of one or more cells, which can be prokaryotic (lacking a nucleus and organelles) or eukaryotic (containing a nucleus and organelles). Examples include bacteria (prokaryotic) and plants (eukaryotic).
• Hierarchical Organization: Living things exhibit a complex organization, from atoms to ecosystems. This includes atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms, populations, communities, and ecosystems.
• Reproduction: Organisms reproduce either asexually or sexually, creating new individuals.
• Growth and Development: Organisms increase in size and complexity over time.
• Evolution: Populations of organisms change over time, adapting to their environment.
• Energy Requirements: Organisms require energy to power life processes (e.g., metabolism, movement). Organisms can be photoautotrophs (use sunlight), chemoautotrophs (use inorganic chemicals), or heterotrophs (consume other organisms for energy).
• Homeostasis: Maintaining stable internal conditions despite changing external environments. Examples include shivering when cold or pupils dilating in response to light.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic Cells: Lack a nucleus and membrane-bound organelles.
• Eukaryotic Cells: Contain a nucleus and membrane-bound organelles.

Animal, Plant, and Bacterial Cells

• Animal and plant cells are eukaryotic and multicellular.
• Bacterial cells are prokaryotic and unicellular. They differ in size, complexity, and internal structure.

Biochemistry

Covalent Bonds in Macromolecules

• Covalent bonds hold atoms together in macromolecules by sharing electrons.

Carbon Atoms and Covalent Bonds

• Carbon forms a maximum of four covalent bonds because it has four valence electrons. It needs to share four more electrons to achieve a stable octet configuration.

Monomers and Polymers

• Polymers are long chains of repeating monomers.

Organic Compounds

• Carbohydrates: Function in short-term and long-term energy storage.
  • Monomer: Monosaccharides (e.g., glucose)
  • Polymer: Polysaccharides (e.g., starch, glycogen, cellulose, chitin)
• Lipids: Function in long-term energy storage, insulation, and lubrication, with types like:
  • Triglycerides: Glycerol + fatty acid chains (e.g., oils, body fats)
  • Phospholipids: Phosphate group + two fatty acid chains (e.g., cell membranes)
  • Steroids: Four fused carbon rings (e.g., some hormones, cholesterol)
• Proteins: Function as enzymes, structural components, transport molecules, and more.
  • Monomer: Amino acids
  • Polymer: Polypeptides (proteins)
• Nucleic Acids: Function in storing and transmitting genetic information (DNA and RNA)
  • Monomer: Nucleotides
  • Polymer: Nucleic acids (DNA, RNA)

Structural Formulas

• Specific structural formulas for each class of organic compounds can vary. Key characteristics for differentiation would include the number of carbon atoms, the presence of double or triple bonds, and the general structural shape they form. The ratio of parts (CHOs, or CNH2n+2) in each compound.

Dehydration Synthesis and Hydrolysis

• Dehydration Synthesis: Combining monomers to form a polymer by removing a water molecule.
• Hydrolysis: Breaking a polymer into monomers by adding a water molecule.

Enzymes

• Enzymes: Biological catalysts that speed up chemical reactions by lowering activation energy.
  • Substrate: The molecule upon which an enzyme acts.
  • Active Site: Region of an enzyme where the substrate binds.
  • Activation Energy: The initial energy required to start a reaction.
• Enzyme Specificity: The precise shape of the active site allows only specific substrates to bind.
• Effect on Reaction Rate: Enzymes increase the reaction rate by lowering the activation energy needed. A graph would illustrate a faster reaction with an enzyme.
• Denaturation: Changing the shape of an enzyme's active site, typically by changes in temperature or pH, preventing it from binding to its substrate.

Environmental Factors and Enzyme Activity

• pH and Temperature: Extreme pH or temperature levels can denature enzymes by changing their active site shape.

Enzyme and Substrate Concentration

• Increasing substrate concentration, while enzyme concentration stays constant helps raise the rate of reaction until all enzymes are fully utilized and have a substrate attached. After that, even if more substrate is added, activity will not change. Decreasing substrate will decrease the reaction rate.

Ecosystems and Cycles

Trophic Levels in an Ecosystem

• Producer: Autotrophs that create their own energy (e.g., grass).
• Primary Consumer: Herbivores that eat producers (e.g., bunny).
• Secondary Consumer: Omnivores or carnivores that eat producers or primary consumers (e.g., frogs, some insects).
• Tertiary Consumer: Carnivores that eat primary or secondary consumers (e.g., wolves).

Biotic and Abiotic Factors

• Biotic Factors: Living organisms in an ecosystem.
• Abiotic Factors: Nonliving components of an ecosystem (e.g., sunlight, temperature, water).

Food Chains and Food Webs

• Food Chain: A linear sequence of feeding relationships.
• Food Web: A network of interconnected food chains.

Biomass

• Biomass: The total mass of living and/or once-living organic matter within a given area. Changes in the biomass of one trophic level affect biomass in other trophic levels.

Carbon Cycle

• Carbon Cycle: The natural process where carbon cycles through the atmosphere, land, water, and organisms.
• Processes maintaining CO2 levels: Photosynthesis and cellular respiration.
• Human Alterations: Combustion of fossil fuels increases atmospheric carbon dioxide.

Nitrogen Cycle

• Nitrogen Cycle: The natural process where nitrogen cycles through the atmosphere, soil, water, and organisms.
• Organic compounds requiring nitrogen: Nucleic acids.
• Chemical Forms of Nitrogen: Nitrogen gas (N2), ammonia (NH3), nitrite (NO2-), nitrate (NO3-).
• Microorganisms/Reactions: Nitrogen-fixing bacteria convert N2 to NH3; nitrifying bacteria convert NH3 to NO2- and NO3-; denitrifying bacteria convert NO3- back to N2.

Cell Transport

Plasma Membrane

• Structure: Phospholipid bilayer with embedded proteins, forming a semi-permeable barrier.
• Semi-permeable: Selectively allows certain substances to pass through.
• Hydrophobic and Hydrophilic: Nonpolar "tails" of phospholipids are hydrophobic (repel water) and polar "heads" are hydrophilic (attract water).
• Importance: Regulates the passage of materials in and out of the cell.

Fluid Mosaic Model

• The plasma membrane is a fluid structure with embedded proteins.

Diffusion

• Diffusion: Passive movement of molecules from high to low concentration.

Factors Determining Passive Diffusion

• Size, charge, and polarity of the molecule

Osmosis

• Osmosis: Passive transport of water across a semi-permeable membrane. Water moves from low solute concentration to high solute concentration.

Hypotonic, Isotonic, and Hypertonic Solutions

• Hypotonic: Lower solute concentration outside the cell than inside; water moves into the cell.
• Isotonic: Equal solute concentration inside and outside the cell; no net water movement.
• Hypertonic: Higher solute concentration outside the cell than inside; water moves out of the cell.

Passive vs. Active Transport

• Passive Transport: Requires no energy; moves substances from high to low concentration.
• Active Transport: Requires energy; moves substances from low to high concentration.

Simple vs. Facilitated Diffusion

• Simple Diffusion: Does not require protein channels or carriers.
• Facilitated Diffusion: Uses protein channels or carriers to assist the movement of molecules or ions across a membrane.

Endocytosis and Exocytosis

• Endocytosis: Taking material into the cell by enclosing it in a vesicle.
• Exocytosis: Releasing material from the cell by fusing a vesicle with the plasma membrane.

Neurology

Neuron Structure and Function

• Dendrites: Receive signals.
• Cell Body: Contains nucleus and other organelles.
• Axon: Conducts electrical signals.
• Axon Terminals: Release signals to other cells.

Sodium-Potassium Pump

• Active transport mechanism that maintains a sodium (Na+) and potassium (K+) gradient across a neuron membrane.

Resting Membrane Potential

• The electrical potential difference across the neuron membrane when the neuron is at rest.

Action Potential Transmission

• Action Potential: Electrical signal traveling down the neuron, generated by regulated movement of ions.

Synaptic Transmission

• Neurotransmitter: Chemical messenger released at synapses to transmit signals between neurons.
• Synaptic Vesicles: Membrane-bound sacs containing neurotransmitters in a presynaptic neuron.
• Exocytosis: Process of releasing neurotransmitters from synaptic vesicles to the synaptic cleft.

Membrane Proteins

• Sodium-potassium pump, voltage-gated sodium, potassium, and calcium channels, and ligand-gated channels play roles in producing electrical and chemical signals in neurons.

Cell Energy

Cellular Respiration

• Equation: 6O2 + C6H12O6 → 6H2O + 6CO2 + ATP
• Reactants: Glucose and oxygen.
• Products: Carbon dioxide, water, and ATP.
• Location/Process: Glycolysis (cytoplasm); Pyruvate oxidation, Krebs cycle, and Oxidative phosphorylation (electron transport chain) occur in mitochondria.

ATP Production

• ATP is produced in mitochondria via oxidative phosphorylation (chemiosmosis).

Cellular Respiration Steps

• Glycolysis: Cytoplasm
• Pyruvate Oxidation: Mitochondria
• Krebs Cycle: Mitochondria
• Oxidative Phosphorylation/Electron Transport Chain: Mitochondria

Electron Transport Chain and NADH/FADH2

• NADH and FADH2: Electron carriers that deliver electrons from the Krebs cycle to the electron transport chain to start the ETC at oxidative phosphorylation.

Photosynthesis

• Equation: 6CO2 + 6H2O + sunlight → 6O2 + C6H12O6

Photosynthesis Pigments

• Pigments absorb light energy for photosynthesis (e.g., chlorophyll).

Light-Dependent and Light-Independent Reactions

• Light-dependent: Capture light energy to produce ATP and NADPH, splitting water. Products are O2, ATP and NADPH.
• Light-independent: Use ATP and NADPH to fix carbon dioxide and synthesize glucose, this produces glucose.

Cellular Respiration and Photosynthesis Relationship

• Photosynthesis and cellular respiration are linked; their reactant/products are largely opposite. Electrons are passed and then ultimately create chemical energy known as ATP

Experimental Design

Independent and Dependent Variables

• Independent Variable: The variable that is manipulated or changed in an experiment.
• Dependent Variable: The variable that is measured in an experiment.

Controlling Variables

• Holding some variables constant to ensure the results are due only to the independent variable.

Supporting Claims with Data

• Using data collected from the experiment to support statements, or claims, conclusions, etc.

This quiz explores key concepts in biology, particularly focusing on the hierarchical organization of life, cell types, and the formation of covalent bonds in macromolecules. It also examines the relationship between monomers and polymers and the four major classes of organic compounds. Test your understanding of these essential biological principles.