AP Bio Unit 2 EXAM

• What is the core structure of cilia and flagella?


  Both have a "9 + 2" pattern of microtubules.
• What is the function of dynein arms in cilia and flagella?


  They are motor proteins that use ATP to facilitate movement along microtubules.
• What is the structure of cilia?


  Cilia are shorter and more numerous than flagella.
• How do cilia function in single-celled organisms?


  Cilia move fluid over the cell surface or propel the organism through water.
• What is the structure of flagella?


  Flagella are longer and fewer in number compared to cilia.
• What is the primary function of flagella?


  Flagella propel cells in liquids by whipping back and forth.
• What are the three major components of the cytoskeleton and their functions?


  • Microfilaments:
  • Structure: Two intertwined strands of actin.
  • Function: Structural support, cell movement, and contraction.
  • Microtubules:
  • Structure: Hollow tubes made from tubulin proteins.
  • Function: Structural support and assist in cellular movement.
  • Intermediate filaments:
  • Structure: Middle thickness.
  • Function: Structural support and maintain organelle positions.
• What is the structure of microfilaments?


  Microfilaments consist of two intertwined strands of actin.
• What is the function of microfilaments?


  They provide structural support and facilitate cell movement and contraction.
• What is the structure of microtubules?


  Microtubules are hollow tubes made from tubulin proteins.
• What is the function of microtubules?


  They provide structural support and help cilia and flagella in cellular movement.
• What is the structure of intermediate filaments?


  Intermediate filaments have a middle thickness compared to microfilaments and microtubules.
• What is the function of intermediate filaments?


  They provide structural support and maintain organelle positions.
• What is the structure of the phospholipid bilayer?


  • Composed of hydrophilic heads and two hydrophobic tails.
  • Arranged in a bilayer with tails facing inward and heads facing outward.
• Why can small nonpolar molecules pass through the phospholipid bilayer?


  They can dissolve easily in the hydrophobic part of the bilayer.
• What type of molecules can pass through the membrane but with more difficulty?


  Small polar molecules can pass but not as easily as nonpolar molecules.
• What type of molecules pass through the membrane slowly?

  Large nonpolar molecules diffuse through more slowly.
• What type of molecules cannot pass through the phospholipid bilayer?


  Large polar molecules cannot pass and need transport proteins.
• Why can't ions or charged molecules pass through the phospholipid bilayer?


  They are strongly repelled by the hydrophobic tails of the bilayer.
• What are the two types of membrane proteins?

  • Integral proteins: Embedded within the membrane and interact with both hydrophobic and hydrophilic environments.
  • Peripheral proteins: Loosely attached to the membrane surface.
• How do membrane proteins allow for portions to be embedded in the membrane and extend into the cell?


  They have amphipathic regions with both hydrophobic and hydrophilic parts.
• What are the hydrophobic parts of membrane proteins made of?


  They are made of nonpolar amino acids that interact with the hydrophobic tails of phospholipids.
• What are the hydrophilic parts of membrane proteins made of?


  They are made of polar or charged amino acids that interact with the hydrophilic heads of phospholipids.
• What is the structure and function of the cell wall?

  • Structure: Made of cellulose microfibrils; primary cell wall is thin and flexible; secondary cell wall adds protection.
  • Function: Provides rigidity, maintains cell shape, and prevents excessive water uptake.
• What is the structure and function of the extracellular matrix?

  • Structure: Network of glycoproteins and proteoglycans providing structural support.
  • Function: Influences cell behavior and eases signal transmission.
• What are the components of the extracellular matrix?


  Collagen and fibronectin are key components.
• What is the function of integrins in the extracellular matrix?


  Integrins connect the ECM to the cytoskeleton, easing signal transmission.
• What are the types of intercellular junctions and their functions?

  • Tight junctions: Seal spaces between cells to prevent leakage.
  • Desmosomes: Provide mechanical adhesion between cells.
  • Gap junctions: Allow ions and small molecules to pass for communication.
  • Plasmodesmata: Channels in plant cells for intercellular communication.
• What is the function of the cell wall in prokaryotic cells?


  It provides structural support and protection.
• What is the function of the plasma membrane in prokaryotic cells?


  It controls the movement of substances in and out of the cell.
• What is the function of the cytoplasm in prokaryotic cells?


  The cytoplasm is where metabolic reactions occur.
• What is the function of the nucleoid in prokaryotic cells?


  The nucleoid is where the cell's DNA is located.
• What is the function of ribosomes in prokaryotic cells?


  Ribosomes are the sites of protein synthesis.
• What is the function of flagella in prokaryotic cells?


  Flagella are long whip-like structures used for movement.
• What is the function of pili in prokaryotic cells?


  Pili help with attachment to surfaces.
• What is the function of the capsule in prokaryotic cells?


  The capsule provides protection and helps the cell stick to surfaces.
• How does cell size relate to surface area and volume?


  • Volume increases cubically while surface area increases quadratically.
  • Downward limits: Cells too small lack space for essential components.
  • Upward limits: Cells too large have decreased surface area to volume ratio, hindering exchange efficiency.
• How do organelles contribute to cellular complexity?


  • Organelles compartmentalize metabolic processes for specialization.
  • They allow multiple processes to occur simultaneously, increasing efficiency.
  • Organelles enable the development of specialized cells in multicellular organisms.
• What is the structure of the nucleus in eukaryotic cells?


  The nucleus is enclosed by a nuclear envelope and contains DNA.
• What is the function of the nucleus in eukaryotic cells?


  The nucleus controls cell activities by regulating gene expression.