Cells

• Cells


  • Structural and functional units of life
  • Building blocks of all living things
  • Carry out all chemical activities needed to sustain life
• Cells


  • Not all the same
  • Share general structures
  • Organized into three main regions: nucleus, cytoplasm, plasma membrane

  
• Nucleus


  • Control center of the cell
  • Contains genetic material (DNA)
  • Three regions: nuclear membrane, nucleolus, chromatin

  
• Nuclear membrane


  • Barrier of nucleus
  • Consists of a double phospholipid membrane
  • Contains nuclear pores that allow for exchange of material with the rest of the cell
• Nucleoli


  • Sites of ribosome production
  • Ribosomes then migrate to the cytoplasm through nuclear pores
• Chromatin


  • Composed of DNA and protein
  • Scattered throughout the nucleus
  • Condenses to form chromosomes when the cell divides
• Plasma membrane


  • Barrier for cell contents
  • Double phospholipid layer with hydrophilic heads and hydrophobic tails
  • Contains other materials like protein, cholesterol, glycoproteins

  
• Cytoplasm


  • Material outside the nucleus and inside the plasma membrane
  • Includes cytosol, organelles, and inclusions

  
• Ribosomes


  • Made of protein and RNA
  • Sites of protein synthesis
  • Found free in the cytoplasm and attached to rough endoplasmic reticulum
• Endoplasmic reticulum (ER)


  • Fluid-filled tubules for carrying substances
  • Two types: rough ER (studded with ribosomes, site of cellular membrane building materials) and smooth ER (functions in cholesterol synthesis, fat metabolism, drug detoxification)
• Golgi apparatus


  • Modifies and packages proteins
  • Produces different types of packages like secretory vesicles and cell membrane components

  
• Lysosomes


  Contain hydrolytic enzymes that digest non-usable materials within the cell
• Peroxisomes


  • Membranous sacs of oxidase enzymes
  • Detoxify harmful substances
  • Destroy hydrogen peroxide which is toxic to the cell
  • Replicate by pinching in half
• Mitochondria


  • "Powerhouses" of the cell
  • Change shape continuously
  • Carry out reactions where oxygen is used to break down food
  • Provides ATP for cellular energy
• Cytoskeleton


  • Network of protein structures that extend throughout the cytoplasm
  • Provides the cell with an internal framework
  • Three different types: microfilaments, intermediate filaments, microtubules

  
• Centrioles


  • Rod-shaped bodies made of microtubules
  • Direct the formation of mitotic spindle during cell division
• Cellular projections


  • Used for movement
  • Cilia moves materials across the cell surface
  • Flagellum propels the cell
• Cell diversity
• Stages of the cell cycle

  1. Interphase (G1, S, G2)

  2. Mitosis (Prophase, Metaphase, Anaphase, Telophase)
• Interphase


  • Period where cell is busy in respiration, protein synthesis, growth and differentiation
  • Non-dividing stage
  • DNA replication occurs, chromatids are replicated
• Mitosis


  Mother cell divides to produce 2 identical daughter cells with the same amount & quality of genetic material
• Events of cell division

  1. Karyokinesis (division of the nucleus)

  2. Cytokinesis (division of the cytoplasm)
• Stages of mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase