ANAPHY Lec

• Contributors to the cell theory

  • Matthew Schleiden
  • Theodore Schwann
  • Rudolf Virchow
• Rudolf Virchow discovered that humans are made up of cells and introduced the principle that all cells came from pre-existing cells
• Cell Theory

  • The cells are the structural units of all living things
  • The human body has 50-100 trillion cells
  • Most cells are composed of carbon, hydrogen, oxygen, and nitrogen
  • Cells are about 60-80% water
  • Cells are believed to be the basic structural and functional units of living organisms
  • The activity of an organism depends on the collective activities of its cells
  • The biochemical activities of cells are dictated by the relative number of specific subcellular structures
  • The continuity of life has a cellular basis
• Modern Cell Theory integrates the principles of genetics and states that hereditary information is passed from cell to the next generation of cells
• Cell Size


  • The diversity of cells may depend on their sizes
  • Cells may come in different sizes depending on what the naked eye could see and depending on the instrument used
  • There are limits in cellular and multicellularity where cells will only grow so big
• Size range of biochemical elements and viruses

  • 1 micrometer to 1 millimeter
  • 0.1 nanometer to 100 nanometers
• Limits in cellular and multicellularity

  Cells will only grow so big and after that, they either remain the same size or they divide into two smaller cells
• Parts of a generalized animal cell

  • Nucleus
  • Plasma membrane
  • Cytoplasm
• Nucleus


  • Control center of the cell, usually located at the central region of the cell, but can be found at the peripheral side in some cells
• Nucleus parts

  1. Nuclear envelope

  2. Chromatin

  3. Nucleolus

  4. Nuclear pores
• Chromatin


  • Threadlike materials composed of DNA and histones, scattered throughout the nucleus when the cell is not dividing, condense to form chromosomes during cell division
• Plasma membrane


  • Also called plasmalemma, serves as a barrier separating cell contents from the surrounding environment, according to the fluid mosaic model
• Fluid mosaic model of the cell membrane

  • Plasma membrane is fluid and not solid, made up of phospholipids arranged tail-to-tail, contains glycerol and fatty acids, hydrophilic head and hydrophobic tails, allows translational movement
• Phospholipid structure


  • Backbone derived from glycerol, contains long carbon molecules called fatty acids, hydrophilic head and hydrophobic tails, allows water molecules to pass through in and out of the cell
• Plasma membrane structure

  • Water molecules can easily pass through in and out of the cell and will not stay at the center of the phospholipid layer heads
  • Cholesterol and protein molecules embedded on the phospholipid layer
  • Molecules found at the surface of the phospholipid layer called peripheral proteins
  • Sugar molecules or carbohydrates scattered in the phospholipid, mostly found in the external layer
  • Sugar groups attached to the phospholipid called glycolipids, sugar groups attached to proteins called glycoproteins
• Cell-to-cell communication


  By way of junctions or collectively known as junctional complexes
• Proteins in the cell membrane

  • Useful for specialized membrane functions such as ion channels, enzymes, receptors for hormones, transporters, channels, carriers, and binding sites
• Sugars in the cell membrane

  • Role similar to glycoproteins, branched sugars attached to proteins in the extracellular space
• Glycocalyx


  • A fuzzy, sticky external layer membrane that reaches the sugar and is found on the cell surface for molecular recognition between cells
• Junctional complexes

  Tight junctions bind cells together into leakproof sheets, desmosomes prevent cells from being pulled apart, gap junctions allow communication between cells
• Cytoplasm is the cellular material outside the nucleus and inside the plasma membrane
• Cytoplasm regions

  • Cytosol, inclusions, organelles
• Many cell organelles are membrane-bound and allow the compartmentalization of their functions
• Mitochondria is known as the powerhouse of the cell, providing energy for all cellular activities
• Mitochondria structure

  • Double-bound membrane, consisting of a double membrane with cristae on the inner membrane carrying out reactions breaking down food into energy
• Mitochondria


  Known as the powerhouse of the cell as it provides energy for all cellular activities
• Mitochondria


  • Consists of a double membrane with cristae on the inner membrane, which carry out reactions using oxygen to break down food into ATP molecules
• Cellular respiration


  Source of energy process where ATP is produced through the breakdown of food using oxygen
• Ribosomes locations

  • Float free in the cytoplasm
  • Attached to the rough endoplasmic reticulum
• Endoplasmic Reticulum


  Fluid-filled tunnels or canals that carry substances within the cell, continuous with the nuclear membrane, with two types - rough ER and smooth ER
• Rough ER

  • Studded with ribosomes, functions in protein synthesis and transport vesicles within cells
• Smooth ER


  • Lacks ribosomes, functions in lipid metabolism and detoxification of drugs and pesticides
• Golgi Apparatus


  Stack of flattened membranes associated with tiny vesicles, modifies and packages proteins from the rough ER
• Lysosomes


  Membranous bags containing digestive enzymes, digest worn-out cell structures, house phagocytes to dispose of bacteria and cell debris
• Peroxisomes


  Organelles made up of membranous sacs of oxidase enzymes, function in detoxifying harmful substances and breaking down free radicals
• Cytoskeleton


  Networks of proteins throughout the cytoplasm, provide internal framework, support organelles, and machinery for intracellular transport
• Types of cytoskeleton

  • Microfilaments
  • Intermediate filaments
  • Microtubules
• Centrioles


  • Rod-shaped bodies made of nine triplets of microtubules, generate microtubules, direct the mitotic spindle during cell division
• Cilia


  Membrane-bound organelles found in eukaryotic cells, slender threadlike projections from cell surfaces
• Types of eukaryotic cells with cilia


  • Most types of eukaryotic cells, certain microorganisms called ciliates