ZL

The Cellular Level of Organization - Organelles and Cytoplasm (Vocabulary Flashcards)

Cytoplasm

  • Cytoplasm is the material inside the cell excluding the cell membrane, traditionally described as having two components:
    • Cytosol: the intracellular fluid that surrounds organelles
    • Site of many chemical reactions
    • Energy is usually released by these reactions
    • Reactions provide building blocks for cell maintenance, structure, function, and growth
    • Organelles: specialized structures within the cell
  • Nucleus is listed as a major component of the cytoplasm context

Cytoskeleton

  • Network of protein filaments throughout the cytosol
  • Provides structural support for the cell
  • Types of cytoskeletal elements:
    • Microfilaments
    • Intermediate filaments
    • Microtubules

Organelles (key components and roles)

Centrosome

  • Located near the nucleus
  • Consists of two centrioles and pericentriolar material (PCM)
  • Functions as a major microtubule organizing center in many cells

Cilia and Flagella

  • Cilia: short, hair-like projections from the cell surface; move fluids along a cell surface
  • Flagella: longer than cilia; move an entire cell; the classic example is the tail of a sperm cell

Cilia/Flagellum movement (illustrated concepts)

  • Cilium structure and motion involve a power stroke and a recovery stroke
  • Ciliary movement results in movement of liquid across the cell surface
  • Flagellar movement results in propulsion of the entire cell

Ribosomes

  • Sites of protein synthesis

Endoplasmic Reticulum (ER)

  • A network of membranes in the shape of flattened sacs or tubules
  • Rough ER
    • Connected to the nuclear envelope
    • Surface studded with ribosomes
    • Produces various proteins
  • Smooth ER
    • Network of membrane tubules with no ribosomes
    • Synthesizes fatty acids and steroids
    • Detoxifies certain drugs

Golgi Complex

  • Consists of 3-20 flattened, membranous sacs called cisternae
  • Functions: modify, sort, and package proteins for transport to different destinations
  • Proteins are transported by various vesicles

Golgi transport details (pathway overview)

  • Transport vesicle from rough ER to Golgi (entry or cis face)
  • Medial cisterna
  • Transfer vesicles
  • Exit or trans face
  • Secretory vesicles
  • TEM reference for Golgi structure: magnifications can be 6.5 imes 10^{4}x (example from TEM) for details; transverse sections also shown

Processing and Exocytosis (Golgi-RER pathway)

  • Rough ER synthesizes proteins
  • Proteins are packaged into transport vesicles
  • Vesicles fuse with Golgi cisternae and undergo processing
  • Secretory vesicles bud from the Golgi and are routed to the plasma membrane
  • Secreted proteins exit the cell by exocytosis, delivering cargo to the extracellular space

Lysosomes

  • Vesicles that form from the Golgi complex
  • Contain powerful digestive enzymes

Peroxisomes

  • Smaller than lysosomes
  • Detoxify several toxic substances, such as alcohol
  • Abundant in the liver

Proteasomes

  • Continuously destroy unneeded, damaged, or faulty proteins
  • Found in the cytosol and the nucleus

Mitochondria

  • The “powerhouses” of the cell; generate ATP
  • More prevalent in physiologically active cells (e.g., muscles, liver, kidneys)
  • Have inner and outer mitochondrial membranes similar in structure to the plasma membrane
  • Inner membrane folds are called cristae
  • The central fluid-filled cavity is the mitochondrial matrix
  • Self-replicate during times of increased cellular demand or before cell division
  • Contain own DNA
  • Inherited only from the mother

Mitochondria structure (as depicted in figures)

  • Outer mitochondrial membrane
  • Inner mitochondrial membrane
  • Mitochondrial matrix
  • Mitochondrial cristae
  • (Ribosome and enzymes associated with mitochondrial function are located inside)

Nucleus

  • Spherical or oval-shaped structure; usually the most prominent feature of a cell
  • Nuclear envelope: a double membrane that separates the nucleus from the cytoplasm
  • Nuclear pores: numerous openings in the nuclear envelope that control movement of substances between the nucleus and cytoplasm
  • Nucleolus: spherical body that produces ribosomes
  • Genes: hereditary units that control activities and structure of the cell
  • Chromosomes: long molecules of DNA complexed with protein molecules
  • Chromatin: DNA-protein complex within the nucleus when not dividing

Nucleus details (illustrated features)

  • Nucleolus and chromatin organization within the nucleus
  • Nuclear envelope details include multiple layers and pores
  • Presence of polys ribosomes (polyribosomes) associated with translating mRNA

Nuclear architecture and DNA packaging (transverse emphasis)

  • The nucleus contains chromatin that unwinds/condenses as needed
  • During cell division, DNA is packed into chromosomes
  • The nuclear envelope forms around the chromosomes during mitosis

Summary of key terms and relationships

  • Cytoplasm comprises the cytosol and organelles; nucleus is also considered within this context
  • The cytoskeleton provides mechanical support and shapes cell movement via microfilaments, intermediate filaments, and microtubules
  • The endomembrane system (ER, Golgi, lysosomes, vesicles) coordinates protein and lipid synthesis, processing, packaging, and transport
  • Mitochondria generate ATP and contain their own DNA, with maternal inheritance
  • The nucleus houses DNA, transcriptional machinery, and ribosome production through the nucleolus; nuclear pore complexes regulate nucleocytoplasmic transport
  • Exocytosis and endocytosis rely on vesicle trafficking to secrete or internalize materials

Equations and numerical notes in LaTeX

  • Golgi cisternae count: 3-20
  • Centrioles in centrosome: 2
  • Representative magnifications (as seen in TEM/SEM images):
    • TEM: 6.5\times 10^{4}x
    • TEM: 8.0\times 10^{4}x
    • SEM: 3.0\times 10^{3}x
  • Mitochondrial components in brief: inner membrane, outer membrane, cristae, matrix (described verbally rather than a single formula)