Chapter 03

• Eukaryotic cell


  One of the two kinds of cells, the other being prokaryotic cell
• Prokaryotic cell


  One of the two kinds of cells, the other being eukaryotic cell
• All living organisms in the kingdom of life are composed of and depend on cells to function normally
• Cells contain organelles to carry out specific functions and contain DNA and RNA
• Cell


  The unit of life that separates itself from its surrounding by a thin partition, the cell membrane
• The word cell was first used by Robert Hooke (1635 – 1703) when he looked at cork with a simple microscope and found what appears to be blocks of materials up the cork
• Modern cell theory


  • All living organisms are composed of cells. They may be unicellular or multicellular
  • Energy flow occurs within cells
  • The cell is the basic unit of structure and function of life
  • All cells have the same basic chemical composition of molecules
  • Heredity information (DNA) is passed on from cell to cell
  • Cells arise from pre-existing cells (they are not derived from spontaneous generation)
• Scientist discoveries


  • Robert Hooke observed slices of cork (empty compartments) and identified and named cells
  • Fanton van Leeuwenhoek used a microscope to observe living cells and could see greater detail due to better lenses
  • Matthias Schleiden proposed that plants are made up of cells
  • Theodor Schwann concluded that all living things are made up of cells
  • Rudolph Virchow proposed that cells came from other living cells by division
• Four common components of cells

  • A plasma membrane
  • Cytoplasm
  • DNA
  • Ribosomes
• Plasma membrane


  An outer covering that separates the cell's interior from its surrounding environment
• Plasma membrane


  • Lipid bilayer composed of phospholipids and cholesterol
  • Proteins extend across or are embedded in either surface of the lipid bilayer
  • The proteins form tiny openings or passageways in the membrane called pores
• Plasma membrane functions


  • Functions as the outer boundary of the cell
  • Controls the entry and exit of substances
  • Receptor proteins function in intercellular communication
  • Marker molecules enable cells to recognize one another
• Nucleus


  The largest organelle, found within the cytoplasm and separated from the cytoplasm by the nuclear membrane
• Nucleus


  • Nuclear envelope: A double membrane that surrounds the nucleus and contains pores to let materials in and out
  • Chromatin: Thin thread-like structures made up of DNA that control cells activities and provide information the ribosomes need to make proteins
  • Nucleolus: Dense bodies consisting of ribosomal RNA and proteins
• Nucleus functions


  • Controls all the cell's activities
  • Controls which proteins are made
• Kingdoms of life


  • Kingdom Animalia: Multicellular eukaryote
  • Kingdom Plantae: Multicellular eukaryote
  • Kingdom Fungi: Mostly multicellular eukaryote
  • Kingdom Protista: Mostly unicellular eukaryote
  • Kingdom Archaea: Unicellular prokaryote
  • Kingdom Bacteria: Unicellular prokaryote
• Eukaryotic cell


  Includes animal cells, plant cells, and fungal cells, and have a true nucleus containing DNA
• Prokaryotic cell


  Includes bacteria and archaea, and have no true nucleus
• Ribosome


  Small grain-like bodies not covered in a membrane, that make proteins by getting instructions for protein production from the DNA in the nucleus
• Endoplasmic reticulum (ER)


  Extends from the nuclear membrane to the cell membrane, found throughout the cytoplasm, and acts as the cell's transportation system
• Rough ER


  • Has bound ribosomes which secrete glycoproteins (proteins covalently bonded to carbohydrates)
  • Membranous tubules and flattened sacs with attached ribosomes
• Rough ER functions


  • Membrane factory for the cell
  • Synthesizes proteins and transports them to Golgi apparatus
• Smooth ER


  • Membranous tubules and flattened sacs with no attached ribosomes
• Smooth ER functions


  • Synthesizes lipids
  • Metabolizes carbohydrates
  • Detoxifies poison
  • Stores calcium
• Golgi apparatus


  Stacks of flat, membrane-covered sacs that sort and modify proteins from the ER to do different jobs, then package them in sacs (called vesicles) that break off and go to the cell membrane or other places within the cell
• Lysosome


  Small, round structures filled with digestive chemicals called enzymes that break down large food molecules, digest waste products, worn-out organelles, and dead or injured cells, and can protect the cell from foreign invaders or act like a "self-destruct" device
• Peroxisome


  Membrane-bound vesicle that serves as one site of lipid and amino acid degradation and breaks down hydrogen peroxide
• Proteasome


  Tube-like protein complex in the cytoplasm that breaks down protein
• Mitochondria


  Rod-shaped structures with a folded inner membrane within an outer membrane, that are the powerhouse of the cell and major sites of ATP synthesis when oxygen is available
• Centrioles


  Pair of cylindrical organelles in the centrosome that serve as centers for microtubule formation, determine cell polarity during cell division, and form basal bodies of cilia and flagella
• Cilia


  Extensions of the plasma membrane containing doublets of parallel microtubules that move materials over the surface of cells
• Flagellum


  Extension of the plasma membrane containing doublets of parallel microtubules that propels spermatozoa in humans
• Microvilli


  Extensions of the plasma membrane containing microfilaments that increase the surface area of the plasma membrane for absorption and secretion, and can be modified to form sensory receptors
• Cell metabolism


  Involves all chemical reactions that occur within a cell, often involving energy transfers where the energy released by one reaction is used in another
• Synthesis of molecules


  Different cells produce various types of molecules including proteins, nucleic acids, and lipids, which determine the structural and functional characteristics of the cells
• Cell communication


  Cells communicate with each other using chemical and electrical signals, such as nerve cells producing chemical signals that muscle cells respond to by contracting or relaxing
• Reproduction and inheritance


  Most cells contain a complete copy of the individual's genetic information, which determines the cell's characteristics, and as a person grows, cells divide to produce new cells with the same genetic information, while specialized gamete cells transmit genetic information to the next generation
• Light microscope


  Allows visualization of general cell features but has limited magnification
• Electron microscope


  Used to study the fine structures of cells in more detail
• Nerve cells produce chemical signals


  1. Nerve cells communicate with muscle cells

  2. Muscle cells respond to chemical signals by contracting or relaxing