Topic 1

• Cell Theory


  1. All living things are composed of cells

  2.The Cell in the fundamental unit of life

  3. Cells only arise from pre-existing cells
• Striated Muscle


  Long Cells, (300 mm), multiple nuclei, questions cell theory
• Acetate Fungal Hyphae


  challenges idea that cell is a single unit, multi-nucleated, and continuous cytoplasm. Cell walls composed of Chitin
• giant algae


  challenges that notion that cells must be small, and simple in structure. Size of 5-100mm and complex in form.
• response


  Living things can respond to and interact with the environment
• Homeostasis


  The maintenance and regulation of internal cell conditions, e.g. water and pH
• Growth


  Living things can grow/change
• excretion


  removal of metabolic waste
• reproduction


  living things produce offspring, sexually or asexually
• nutrition


  feeding by either the synthesis of organic molecules (e.g. photosynthesis) or the absorption of organic matter
• SA to Volume Ratio

  A larger SA:Vol ratio can mean that a cell can act more efficiently. For every unit of volume that requires nutrients or produces waste. There is more membrane to serve it
• How to maximize SA to Vol ratio?

  Cells divide, They use membranes to carry out processes, organs will fold up to maximize the ratio
• Rate of Metabolism


  a function of mass/volume
• emergent properties


  when things are added more properties arise
• specialized cells


  All specialized cell and the organs constructed are from differentiation
• Stem Cells


  unspecialized cells that can differentiate into many cell types
• Totipotent


  Can differentiate into any cell
• pluripotent


  Can differentiate into many cells
• multipotent


  can differentiate into a few closely related cells
• unipotent


  Can regenerate,but only into associated cell type
• Stagardt's Macular Distrophy


  A recessive condition for the eyes, stem cells are treated to become retinal cells. Cells attach to the retina and improves central vision
• Lukemia


  Hematopoietic Stem Cells (HSCs) are harvested from bone marrow, peripheral blood or umbilical cord blood

  Chemotherapy and radiotherapy used to destroy the diseased white blood cells New white blood cells need to be replaced with healthy cells. HSCs are transplanted back into the bone marrow HSCs differentiate to form new healthy white blood cells
• Embryonic Stem Cell Structure

  
• Prokaryote Cell Structure


  approximately 0.5 μm

  
• Prokaryotic Reproduction


  Asexually through binary fission.
• Steps of Binary Fission

  1. Two loops attach to membrane

  2. Elongation and pinches off

  3. Two identical cells
• Properties of Prokaryotes


  Their DNA is not enclosed in within a membrane and forms on circular Chromosome

  Their DNA is free; it is not attached to proteins

  They lack membrane-bound organelles. Ribosomes are complex structures within the plasma membrane, but they have no exterior membrane

  Their cell wall is made up of a compound called peptidoglycan

  They usually divide by binary fission, a simple form of cell division

  They are characteristically small in size, usually between 1 and 10 µm
• Eukaryote Cell Structure


  1 micrometer

  
• Nucleus


  Generally Spherical with a double membrane. Pores and holes are present. Contains Chromosomes.
• Mitochondion


  Has a smooth outer membrane. Folds are cristae. Variable Shape. Site of ATP production by aerobic energy
• Free Ribosomes


  80S ribosomes. No membrane, appear as dark granules in cytoplasm. Synthesizes proteins to function in cytoplasm.
• Rough Endoplasmic Reticulum


  Consists of Flattened membrane sacs (cisternae). Located near nucleus. 80S ribosomes are attached to outside of cisternae

  rEr synthesizes transported proteins by vesicles to golgi for modification
• Golgi Apparatus


  Contains cisternae

  No attached ribosomes

  often sited close to plasma membrane

  shorter and more curved than the rER. modifies proteins from the rER , the repackaged in vesicles
• Vesicles


  A single membrane with fluid

  Small

  Transport Materials inside cell
• Lyosomes


  Spherical with single membrane

  Golgi vesicles

  Digestive enzymes from breakdown of:

  food

  unwanted organelles

  cell itself

  High concentration of enzymes, cause this to stain heavily and hence appear dark on micrographs
• Vacuoles


  Single Membrane with fluid inside

  Plant cells vacuoles are large and permanent often occupying cell volume

  In animals vacuoles are smaller and used for various other reasons
• Flagellum


  Thin projection from cell surface. Contain microtubules

  Used to move cell
• Cillia


  Thin projections from cell surface

  Contain Microtubules

  Used to either move cell or the move the fluids next to the cell
• Microtubules


  Small Cylindrical fibers

  Have a variety of functions, part of flagella. Cell division
• Centrioles


  Nine triple miroctubules

  manly found in animal cells not vascular plants of fungi