cells

• What is the basic unit of life?


  Cell
• What are organelles?


  Specialized structures that perform specific functions
• What does the nucleus contain?


  Genetic material
• What is the cytoplasm?


  Jelly-like substance that holds organelles
• What is another name for the plasma membrane?


  Cell membrane
• What is the function of the cell membrane?


  It encloses the cytoplasm and nucleus
• What is the smallest unit of life?

  Cell
• What are the main functions of the cell?


  • Cell metabolism and energy use (producing ATP)
  • Synthesis of molecules (lipids, proteins, enzymes)
  • Communication (action potential)
  • Reproduction and inheritance (sperm and egg cells)
• What is the outer boundary of the cell called?


  Cell membrane
• What does selectively permeable mean in relation to the cell membrane?


  It allows some substances to pass into or out of the cell
• What is the Fluid-Mosaic Model?


  It describes the arrangement of molecules in the cell membrane
• What are the two regions of phospholipids?


  Polar and nonpolar
• What is the structure of a phospholipid?


  It has a polar head region that is hydrophilic and a non-polar tail that is hydrophobic
• How do lipid-soluble substances move through the cell membrane?


  They can diffuse directly through the phospholipid bilayer
• What is osmosis?


  Diffusion of water across a selectively permeable membrane
• What happens to a cell in a hypotonic solution?


  Water moves into the cell, causing it to swell
• What is the result of a cell in a hypertonic solution?


  Water moves out of the cell, resulting in cell shrinkage
• What is carrier-mediated transport?


  Movement of a substance across a membrane by means of a carrier molecule
• What is facilitated diffusion?


  Movement of substances from a higher to lower concentration with the help of a carrier molecule
• What is the sodium-potassium pump?


  A major example of active transport that moves Na+ out and K+ into cells
• How many potassium ions are moved into the cell by the sodium-potassium pump?


  2 Potassium ions
• How many sodium ions are moved out of the cell by the sodium-potassium pump?


  3 Sodium ions
• What are the two types of transport mechanisms across the cell membrane?

  • Active Transport: requires ATP (e.g., sodium-potassium pump)
  • Passive Transport: does not require ATP (e.g., diffusion, osmosis)
• What is endocytosis?


  Movement of materials into cells by formation of vesicles
• What is exocytosis?


  Secretion of materials from cells using secretory vesicles
• What is the function of ribosomes?


  Site of protein synthesis
• What is the role of the endoplasmic reticulum?


  Forms tubules/sacs throughout the cell and extends from the outer nuclear membrane
• What is the difference between rough and smooth endoplasmic reticulum?

  Rough E.R. is involved in protein synthesis, while Smooth E.R. is involved in lipid synthesis and detoxification
• What does the Golgi apparatus do?


  Modifies, packages, and distributes lipids and proteins
• What are microfilaments?


  Small fibrils formed from protein subunits that support the cytoplasm
• What is the function of intermediate filaments?


  They provide mechanical support to the cell
• What are microtubules?


  Hollow structures formed from protein subunits that support the cytoplasm
• What is the role of the cytoskeleton?


  It holds organelles in place and enables the cell to change shape
• What is the function of the nucleolus?


  It produces ribosomal components
• What do nucleoli consist of?


  Ribosomal RNA and proteins
• What is chromatin?


  Loosely coiled chromosomes found in the nucleus
• How many pairs of chromosomes are found in human cells?


  23 pairs
• What is the nuclear envelope?


  A two-layered membrane that bounds the nucleus
• What are nuclear pores?


  They are openings that allow materials to pass into or out of the nucleus
• What is the function of the mitochondria?


  Energy production