Ch 1

• • According to the cell theory, living organisms are composed of cells.
• • Organisms consisting of only one cell carry out all functions of life in that cell.
• • Surface area to volume ratio is important in the limitation of cell size
• • Multicellular organisms have properties that emerge from the interaction oftheir cellular components
• • Specialized tissues can develop by cell differentiation in multicellular organisms.
• • Differentiation involves the expression of some genes and not others in a cell’s genome.
• • The capacity of stem cells to divide and differentiate along differentpathways is necessary in embryonic development and also makes stem cellssuitable for therapeutic uses.
• • Application: Questioning the cell theory using atypical examples, including striated muscle, giant algae and aseptate fungal hyphae.
• • Application: Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism.
• • Application: Use of stem cells to treat Stargardt’s disease and one other named condition.
• • Application: Ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a new-born baby and from an adult’s own tissues.
• • Skill: Use of a light microscope to investigate the structure of cells and tissues, with drawing of cells. Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs.

  Magnification = size of the image / actual size (scale bar).
• • Chlorella or Scenedesmus are suitable photosynthetic unicells
• • name and briefly explain these functions of life: nutrition, metabolism, growth, response, excretion, homeostasis and reproduction. (MR H GREN)
• • Prokaryotes have a simple cell structure without compartmentalization.
• • Eukaryotes have a compartmentalized cell structure
• • Electron microscopes have a much higher resolution than light microscopes
• • Application: Structure and function of organelles within exocrine gland cells of the pancreas and within palisade mesophyll cells of the leaf.

  exocrine gland cells: have cilia to move the cell/ fluid around the cell

  pallisade mesophyll: have chloroplast , cell wall (plants only),

  both have 70s ribosomes in their shared prokaryotic organelles eg. mitochondria
• The prokaryotic ribosome is 70s type and eukaryotic ribosome is 80s type
• • Application: Prokaryotes divide by binary fission

  the DNA is replicated semi conservatively -> the two dna loops attach to the membrane -> membrane elongates and pinches off separating by cytokinesis -> two genetically identical daughter cells
• • Skill: Drawing of the ultrastructure of prokaryotic cells based on electron micrographs.
• • Skill: Drawing of the ultrastructure of eukaryotic cells based on electron micrographs.
• • Skill: Interpretation of electron micrographs to identify organelles and deduce the function of specialized cells.
• • Drawings of prokaryotic cells should show the cell wall, pili and flagella, andplasma membrane enclosing cytoplasm that contains 70S ribosomes and anucleoid with naked DNA.
• • Drawings of eukaryotic cells should show a plasma membrane enclosingcytoplasm that contains 80S ribosomes and a nucleus, mitochondria andother membrane-bound organelles are present in the cytoplasm. Someeukaryotic cells have a cell wall.
• • Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules.
• • Membrane proteins are diverse in terms of structure, position in the membrane and function.
• • Cholesterol is a component of animal cell membranes.
• • Application: Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes.
• • Skill: Drawing of the fluid mosaic model
• • Skill: Analysis of evidence from electron microscopy that led to the proposal of the Davson-Danielli model.
• • Skill: Analysis of the falsification of the Davson-Danielli model that led to the Singer-Nicolson model.
• • Amphipathic phospholipids have hydrophilic and hydrophobic properties
• • Particles move across membranes by simple diffusion, facilitated diffusion, osmosis and active transport.
• • The fluidity of membranes allows materials to be taken into cells by endocytosis or released by exocytosis. Vesicles move materials within cells.
• • Application: Structure and function of sodium–potassium pumps for active transport and potassium channels for facilitated diffusion in axons.
• • Application: Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis.
• • Skill: Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions. eg. put a potato in a solutions of different sucrose concentration, when the mass of the potato makes 0% change the solution is isotonic (the line would cross the x-axis here showing the osmolarity of the potato)
• • Cells can only be formed by division of pre-existing cells
• • The first cells must have arisen from non-living material