Biology Keystone Exam Review Notes

Biology Keystone Exam Review

Shared Characteristics of Prokaryotes and Eukaryotes

  • Shared characteristic: Ability to store hereditary information.

Characteristics of All Living Things

  • Living things are made of cells.
  • They possess a universal genetic code.
  • They require a continuous energy flow.
  • They can reproduce independently.
  • They grow and develop.
  • They exhibit hierarchical organization (cells, tissues, organs, organ systems, organism).
  • They respond to stimuli.

Structures Common to Prokaryotic and Eukaryotic Cells

  • Plasma membrane and cytoplasm are common to both.

Prokaryotic vs. Eukaryotic Cells

Prokaryotic Cells

  • Lack a nucleus and membrane-bound organelles.
  • Contain cytoplasm, plasma membrane, cell wall, DNA, and ribosomes.
  • Examples: Bacteria and Archaea.

Eukaryotic Cells

  • Possess membrane-bound organelles.
  • Have a true nucleus with a nuclear envelope.
  • Contain plasma membrane, cytoplasm, DNA, ribosomes, endoplasmic reticulum, Golgi apparatus, nucleolus within the nucleus, vacuoles, and potentially a cell wall.
  • Examples: Protists, Fungi, Plants, Animals.

Size Difference Between Prokaryotic and Eukaryotic Cells

  • Prokaryotic cells are generally much smaller than eukaryotic cells.

Structural Difference

  • Prokaryotic cells lack membrane-bound organelles, which directly relates to their smaller size.

Explanation for Size Difference

  • Lack of organelles results in smaller total cell volume in prokaryotes.
  • Eukaryotic cells, with organelles, can metabolize materials and maintain a larger size.
  • Prokaryotes lack specialization of function due to the absence of organelles.
  • Enzymes in the cytoplasm of prokaryotes perform metabolic functions.
  • Eukaryotic cells exhibit greater division of labor with specialized organelles.

Organelles in Eukaryotic Cells

  • Mitochondria
  • Endoplasmic reticulum
  • Vacuoles
  • Lysosomes
  • Golgi apparatus
  • Nucleus with DNA
  • Nucleolus
  • Ribosomes

Similarities Between Prokaryotic and Eukaryotic Cells (Independent of Size)

  • All cells contain genetic information in the form of DNA.
  • Ribosomes, which translate nucleic acid (RNA) into protein, are present in all cells.
  • A plasma membrane exists in all cells to create an internal environment and facilitate material movement.

Alveoli Structure and Function

  • Alveoli are microscopic air sacs in the lungs of mammals.
  • The structure of the alveoli increases the surface area of the lungs, enabling efficient gas exchange.
  • Membranes are one cell thick to facilitate oxygen and carbon dioxide exchange.
  • Typical human lungs have approximately 700 million alveoli, providing around 70 m^2 of surface area for gas exchange.

Effect of Low Density of Frozen Water in a Lake

  • When water in a lake freezes, it floats, insulating the organisms below.

Properties of Water

  • Water is a polar covalent molecule.
  • It is a universal solvent due to its polarity, dissolving polar covalent compounds (like glucose) and ionic compounds (like salt).
  • Water has a high specific heat, making it slow to heat up and cool down, serving as an insulator in living organisms since their tissue is mostly water.
  • When water freezes, it expands and floats because ice is less dense than water, insulating the water below and keeping it at approximately 4^\circ C.

Carbon's Ability to Form Macromolecules

  • Carbon’s ability to form four bonds makes it uniquely suited to form large, complex, diverse molecules.

Carbon Bonding

  • Carbon has an atomic number of 6.
    • 2 electrons in the first orbital and 4 in the valence orbital.
    • 4 unpaired electrons allow it to form 4 covalent bonds.
  • Carbon can bond with other carbons in chains, rings, single, double, and triple bonds, enabling it to form various molecules.
    • Example: Methane.

Dehydration Synthesis

  • The diagram shows a reaction that forms a polymer from two monomers.
  • This type of reaction is called dehydration synthesis.
  • During dehydration synthesis, a water molecule is removed (–OH from one monomer and –H from another to form H_2O).
  • This joins two monomers to form a polymer.
  • Adding another monomer requires removing another water molecule.
    • Example: Glucose (monomer) forms Maltose (dimer).

Functional Characteristics Distinguishing Proteins from Carbohydrates

  • Proteins have the ability to catalyze biochemical reactions, unlike carbohydrates.

Enzymes

  • Enzymes are proteins and act as biological catalysts.
  • They lower activation energy, allowing chemical reactions to occur at suitable temperatures and rates in an organism’s body.
  • They enter a reaction at an active site to form an Enzyme/Substrate complex.

Protein Composition

  • A protein is a polymer of amino acids.
  • Amino acids join by dehydration synthesis, which removes water to form peptide bonds.
  • There are three main components of an amino acid.

Structural Differences Between Proteins and Carbohydrates

  • Proteins contain C, H, O, and N, while carbohydrates contain only C, H, and O (in a 1:2:1 ratio).
  • Carbohydrates do not contain peptide bonds formed during dehydration synthesis (condensation reaction).

Functional Differences Between Proteins and Carbohydrates

  • Carbohydrates are essential energy molecules for immediate use (simple sugars like glucose) or storage (glycogen in the liver).
  • Proteins are building and regulatory compounds (hormones and enzymes).
  • Muscles and cell membranes contain proteins.

Enzyme Role in Metabolic Reactions

  • Enzymes speed up reactions without being consumed in the process.

Enzyme Regulation

  • Enzymes are organic catalysts that regulate the rate of reactions.
  • They enable reactions under conditions that do not damage a cell.
  • Enzymes are reusable and do not break down under normal conditions.
  • Regulated by temperature, concentration, and pH.

Effect of pH Change on Enzyme Activity

  • A change in pH can alter the rate at which an enzyme catalyzes a reaction.
  • Enzymes have an active site where they interact with the substrate.
  • If the active site is altered (denatured) due to pH changes, it can no longer function.

Energy Transformation in Chloroplasts

  • The green organelle observed in a plant cell is likely a chloroplast.
  • The energy transformation that most likely occurs first within the chloroplast is light to chemical.

Photosynthesis

  • Photosynthesis is the process by which organisms convert light energy into chemical bond energy of glucose.
  • It occurs in the chloroplasts of plant cells.

Similarities Between Photosynthesis and Cellular Respiration

  • Both photosynthesis and cellular respiration include reactions that transform energy.

Photosynthesis vs. Respiration

  • Photosynthesis is like baking a cake: plants take raw materials (CO2 and H2O) and use light energy to make glucose (and release O_2).
  • Respiration is like burning the cake: organisms break down glucose to provide energy for life processes, transferring energy to ATP.
  • All plants undergo both photosynthesis (in the presence of light) and respiration (all the time).
  • All living organisms must go through respiration 24/7.

Molecule Used as Energy Source for Protein Shape Change

  • A protein in a cell membrane changes shape to move sodium and potassium ions against their concentration gradients.
  • ATP was most likely used by the protein as an energy source.

ATP

  • ATP (adenosine triphosphate) is a temporary energy storage molecule.
  • It is a readily usable form of chemical energy.
  • Breaking off the 3rd phosphate releases energy, enabling reactions like changing the shape of a protein.

Energy Transformations in Photosynthesis and Respiration

Photosynthesis

  • CO2 and H2O are transformed using energy from sunlight to create C6H{12}O6 and O2. The captured energy is stored in the chemical bonds of glucose (C6H{12}O_6).

Cellular Respiration

  • O2 and C6H{12}O6 are broken down with a small amount of invested energy to form CO2 + H2O and a large amount of ATP (energy storage molecule).

Relationship Between Photosynthesis and Cellular Respiration

  • They are essentially the reverse of each other.
  • The products of photosynthesis become the reactants for cellular respiration, and vice versa.
  • One