C

Review Flashcards: Cells, Biomolecules, Water, Enzymes, and Endosymbiosis

Cell Theory and Organelles

  • Cell Theory (core ideas):
    • All living things are composed of cells.
    • Cells come from pre-existing cells (reproduction/division of cells).
    • The cell is the basic unit of life (the smallest unit that can carry out life processes).
  • Prokaryotes vs Eukaryotes (differences summarized):
    • Prokaryotes
    • Do not have a nucleus or membrane-bound organelles
    • Generally smaller in size
    • Simpler organization, older in evolutionary terms
    • Often unicellular
    • Examples: bacteria, archaea
    • Eukaryotes
    • Have a nucleus and membrane-bound organelles
    • Generally larger and more complex
    • Can be unicellular or multicellular
    • Examples: plants, animals, fungi, protists
  • Organelles and their functions (matching the common list):
    • Nucleus: Controls cellular activities; houses genetic material
    • Cell membrane (plasma membrane): Selects what enters or leaves the cell
    • Mitochondrion: Turns food energy into usable energy (ATP)
    • Ribosome: Synthesizes proteins
    • Vacuole: Stores materials
    • Lysosome: Breaks down worn-out parts; involved in cell death
    • Rough Endoplasmic Reticulum (Rough ER): Synthesizes proteins destined for outside the cell or membranes; transports them
    • Smooth Endoplasmic Reticulum (Smooth ER): Synthesizes lipids
    • Golgi apparatus: Modifies, sorts, and packages proteins for secretion or delivery to other organelles
    • Cell wall: Tough, rigid structure; supports plant cells (also in bacteria, fungi, protists)
    • Chloroplast: Carries out photosynthesis; turns light energy into sugars
    • Centriole: Found in animal cells; involved in cell reproduction
  • Key terms definitions (from the Terms list):
    • Polar molecule: A molecule with an uneven distribution of electron density, giving partial positive and negative charges; results in a dipole moment. This often arises when there is a significant difference in electronegativity between atoms in a covalent bond and a bent molecular geometry.
    • Valence electrons: Electrons located in the outermost electron shell (valence shell) that participate in chemical bonding.
    • Ion: An atom or molecule that has gained or lost electrons, resulting in a net positive or negative charge.
  • Additional terms (from Page 2 topic set):
    • Ionic bond: Electrostatic attraction between oppositely charged ions, typically formed from transfer of electrons between metals and nonmetals.
    • Covalent bond: Bond formed by sharing electron pairs between atoms.
    • Hydrogen bond: A weak bond between a hydrogen atom attached to an electronegative atom (like O or N) and another electronegative atom; important in water structure and biomolecule stability.
    • Cohesion: Attraction between like molecules (e.g., water–water).
    • Adhesion: Attraction between unlike molecules (e.g., water–glass).
    • Surface tension (H₂O): The cohesive forces at the surface of a liquid that cause it to behave as if its surface were covered with a stretched elastic membrane.
    • Phagocytosis: A form of endocytosis where the cell engulfs large particles or cells.
    • Endosymbiosis: A symbiotic relationship in which one organism lives inside another; a theory explaining the origin of mitochondria and chloroplasts in eukaryotic cells.
    • Hydrolysis: Chemical breakdown of a compound due to reaction with water.
    • Dehydration synthesis (condensation): Chemical reaction that forms a bond by removing a water molecule; builds larger molecules from smaller ones.
  • Water polarity and its implications (concepts to know):
    • Why water is a polar molecule: Water has a bent geometry and a significant electronegativity difference between oxygen and hydrogen, creating partial negative charge on oxygen and partial positive charges on hydrogens, making the molecule overall polar.
    • Water strider on water: The insect can walk on water due to surface tension created by cohesive hydrogen bonds between water molecules, supporting small, light organisms on the surface; legs distribute weight and reduce wetting.
    • Denting water (surface deformation): When you press on the surface, you disrupt the surface tension and hydrogen-bond network locally; the balance of cohesive forces and the applied pressure creates a temporary dent. The forces involved include surface tension and contact with the substrate.
  • Biomolecules: the four major groups, with monomers and polymers
    • Carbohydrates
    • Monomer: Monosaccharide (e.g., glucose, galactose, ribose)
    • Polymer: Polysaccharide (e.g., starch, cellulose, glycogen, chitin in some contexts)
    • Functions: Quick energy source (fuel), energy storage (starch, glycogen), and structural roles in plants and some organisms (cellulose in plants; chitin in fungi and exoskeletons)
    • Lipids
    • Monomer/Building blocks: Generally glycerol + fatty acids (not a strict repeating unit like other polymers; often form triglycerides, phospholipids, etc.)
    • Polymers (in common sense): Triglycerides, phospholipids, steroids (lipids are not traditional polymers, but they form large, nonpolar biomolecule assemblies)
    • Functions: Long-term energy storage, insulation, components of cell membranes (phospholipids), signaling molecules (steroids and other lipids)
    • Proteins
    • Monomer: Amino acids
    • Polymer: Polypeptides (proteins)
    • Functions: Enzymes (catalysts), structural components, transport, communication, immune defense, movement, signaling
    • Nucleic Acids
    • Monomer: Nucleotides
    • Polymer: Nucleic acids (DNA, RNA)
    • Functions: Store and transmit genetic information, guide protein synthesis
  • Specific examples from the transcript (Page 3 visuals):
    • Nucleic acids: DNA and RNA (polymer examples)
    • Carbohydrate polymers shown: Cellulose (plant cell walls), Chitin (fungi/exoskeletons of arthropods), Chitosan (modified chitin) – polysaccharide examples
  • Quick notes on tests and health context (Unit 1a context):
    • Biomolecule tests (typical classroom assays):
    • Benedict’s test for reducing sugars (carbohydrates)
    • Iodine test for starch (carbohydrates)
    • Biuret test for proteins
    • Sudan III or Sudan IV test for lipids
    • Urine Analysis Lab health implications (relevant to biomolecule content):
    • Presence of large amounts of any biomolecule in urine can indicate health issues (e.g., glucose in urine can indicate diabetes; protein in urine can indicate kidney problems; abnormal lipid metabolites can signal metabolic issues).
  • Biology in context: connection to cells and organisms
    • Biomolecule structure determines function: the arrangement of monosaccharides, amino acids, lipid tails, or nucleotide sequences determines how molecules interact with enzymes, cell membranes, and genetic information flow.
    • Endosymbiotic Theory (summary):
    • What it explains: How eukaryotic organelles (mitochondria and chloroplasts) originated as free-living prokaryotes that were engulfed by ancestral host cells and eventually formed a symbiotic relationship.
    • Who proposed/discovered: The theory was advanced and popularized by Lynn Margulis in the 1960s and 1970s, building on earlier observations.
    • Evidence: Similarities between mitochondria/chloroplasts and bacteria (size, circular DNA, ribosomes), double membranes, autonomous replication (binary fission-like), and genetic similarity to bacterial genes.
  • Quick conceptual recap of the Roles of Major Biomolecule Groups
    • Carbohydrates: immediate energy and structural roles; ring structures in monosaccharides; polysaccharides as storage or support (cellulose, starch) or structural (cellulose in plants, chitin in fungi/arthropods).
    • Lipids: membranes (phospholipids), long-term energy storage (triglycerides), insulation, signaling (steroids).
    • Proteins: a wide range of roles from enzymes to structural support and transport; shape determines function; denaturation disrupts function.
    • Nucleic Acids: genetic information storage and transmission; transcription and translation guide protein synthesis.

Chemical Bonding and Water Properties

  • Water polarity and bonds
    • Water is a polar molecule due to unequal sharing of electrons in the O–H bonds and the bent geometry, giving partial negative charge on oxygen and partial positive charges on hydrogens.
    • Types of bonds:
    • Covalent bonds: sharing of electron pairs between atoms
    • Ionic bonds: transfer of electrons giving ions that attract each other
    • Hydrogen bonds: weak attractions between a hydrogen atom attached to an electronegative atom and another electronegative atom
  • Water-specific properties (why they matter in biology)
    • Cohesion: water molecules sticking to each other via hydrogen bonds
    • Adhesion: water molecules sticking to other substances
    • Surface tension: cohesive forces at the surface create a 'film' that resists external force
    • Water’s unique properties include high specific heat, high heat of vaporization, expansion upon freezing, and being a versatile solvent; these arise from hydrogen bonding and polarity.
  • Endosymbiosis and related terms
    • Endosymbiosis is the concept that some organelles originated as endosymbiotic prokaryotes absorbed by a host cell and became integrated.
    • Phagocytosis is a form of endocytosis where parts of the external environment are engulfed by the cell.
  • Basic lab concepts linked to biomolecules
    • Hydrolysis: breaks chemical bonds with water, separating molecules
    • Dehydration synthesis: forms bonds by removing water, building larger molecules
    • Phagocytosis, hydrolysis, dehydration synthesis are fundamental processes in metabolism and cellular maintenance.

Enzymes and Kinetics

  • What are enzymes?
    • Enzymes are biological catalysts, most of which are proteins (a few RNA-based ribozymes exist).
  • Induced fit model
    • The enzyme active site slightly reshapes to accommodate the substrate, improving catalysis as the substrate binds
  • How enzymes speed up reactions
    • They lower the activation energy (the energy barrier) required for the reaction to proceed, often by stabilizing transition states and providing an optimal microenvironment.
  • Factors affecting enzyme activity
    • Temperature, pH, enzyme concentration, substrate concentration, presence of inhibitors or activators, ionic strength
  • Denaturation
    • Loss of an enzyme’s 3D structure (due to heat, pH, or chemicals), resulting in loss of function
  • Substrate specificity
    • Enzymes typically act on a single substrate or a group of related substrates due to the shape and chemical properties of the active site (lock-and-key or induced-fit concept)
  • Catabolic vs anabolic reactions
    • Catabolic: break down molecules, release energy (e.g., digestion)
    • Anabolic: build up molecules, require energy (e.g., protein synthesis)
  • Diagram labeling prompts (typical enzyme-substrate schematic)
    • Components: active site, enzyme, substrate, enzyme-substrate complex, products
    • Process: substrate binds to active site → enzyme-substrate complex forms → chemical transformation occurs → products released, enzyme is free to catalyze more reactions

Unit 1a Review Guide: Key Concepts and Skills

  • Characteristics of Life (apply to identify living things)
    • Organization (cells; maintain internal order)
    • Homeostasis (maintain stable internal conditions)
    • Metabolism (chemical reactions; energy processing)
    • Growth and development
    • Reproduction
    • Response to stimuli
    • Adaptation/evolution
    • Heredity (DNA-based information transfer)
  • Levels of Organization (define and place examples)
    • Atoms -> Molecules -> Organelles -> Cells -> Tissues -> Organs -> Organ Systems -> Organism -> Population -> Community -> Ecosystem -> Biosphere
    • Smallest level capable of lifelike properties: the cell
    • Given examples, place them within the appropriate level (e.g., tissue vs organ, etc.)
  • Cell Theory (three parts) and origins
    • Parts: 1) All living things are made of one or more cells; 2) Cells arise from pre-existing cells; 3) The cell is the basic unit of life
    • Founders: Matthias Schleiden and Theodor Schwann (co-founders in the 1830s)
    • Term origin: “cell” coined by Robert Hooke (cork cells)
  • Endosymbiotic Theory (summary)
    • Explains origin of mitochondria and chloroplasts in eukaryotic cells
    • Proposed and supported by Lynn Margulis; evidence includes: circular DNA, ribosomes similar to bacteria, double membranes, and autonomous replication
  • Organelles: functions and plant/animal/bacteria presence
    • Know which organelles are present in plants, animals, bacteria; which are unique to bacteria (e.g., cell wall made of peptidoglycan in bacteria), unique to plants (chloroplasts, cell wall with cellulose), unique to animals (centriole in some cells)
    • Ability to identify eukaryotic vs prokaryotic cells from organelle lists or diagrams
  • Microscopes: practical skills
    • Be able to calculate total magnification:
      ext{Total Magnification} = M{ ext{eyepiece}} \times M{ ext{objective}}
    • Understand how to adjust focus and select objectives for different magnifications
  • Biomolecules (structure–function relationships)
    • Review the monomers, polymers, and functions for carbohydrates, proteins, lipids, and nucleic acids
    • Understand how the molecular structure supports biomolecule function (e.g., shape, polarity, hydrogen bonding, covalent linkages)
    • Be able to identify ionic, covalent, and hydrogen bonds and give examples of where each occurs in biomolecules
    • Recognize health implications of biomolecule content in urine and related diagnostics from the Urine Analysis context
  • Enzymes (key concepts)
    • Enzyme type: typically proteins (biomolecules) acting as catalysts
    • What they do: speed up reactions by lowering activation energy; provide specificity for substrates
    • How they do it: active site geometry and induced-fit adjustments; positioning of substrates to facilitate bond breaking/forming
    • Activation energy: energy barrier for a reaction; enzymes lower this
    • Effects of temperature: high temperatures may denature enzymes; optimal temperatures exist for activity
    • Shape importance: the 3D conformation of an enzyme determines substrate binding and function
    • Synthesis vs digestion: anabolic (building) and catabolic (breaking down) reactions, often enzyme-catalyzed

Quick synthesis and connections

  • The transcript outlines a comprehensive review of basic cell biology, biomolecules, and enzyme kinetics that connects structure to function: cell organelles determine how cells operate; biomolecule structures determine their roles in metabolism and cell processes; enzymes regulate biochemical reactions critical for life.
  • The content ties classroom terminology to practical skills (microscope use, analyzing biomolecule tests, understanding endosymbiosis evidence).
  • Practical implications include understanding how disruptions in these processes can indicate health problems (e.g., urine biomolecule content, enzyme function under stress).