Genetics - M2

• Cell Theory


  • All living things are made up of cells
  • Cells are the smallest working units of all living things
  • All cells come from preexisting cells through cell division
• Cell


  The smallest unit that is capable of performing life functions
• Prokaryotes


  • Do not have structures surrounded by membranes
  • Few internal structures
  • One-celled organisms, Bacteria
• Eukaryotes


  • Contain organelles surrounded by membranes
  • Most living organisms
• Cell Membrane


  • Outer membrane of cell that controls movement in and out of the cell
  • Double layer
• Cell Wall


  • Most commonly found in plant cells & bacteria
  • Supports & protects cells
• Nucleus


  • Directs cell activities
  • Separated from cytoplasm by nuclear membrane
  • Contains genetic material - DNA
• Nuclear Membrane


  • Surrounds nucleus
  • Made of two layers
  • Openings allow material to enter and leave nucleus
• Chromosome


  • In nucleus
  • Made of DNA
  • Contain instructions for traits & characteristics
• Nucleolus


  • Inside nucleus
  • Contains RNA to build proteins
• Cytoplasm


  • Gel-like mixture
  • Surrounded by cell membrane
  • Contains hereditary material
• Endoplasmic Reticulum


  • Moves materials around in cell
  • Smooth type: lacks ribosomes
  • Rough type (pictured): ribosomes embedded in surface
• Ribosomes


  • Each cell contains thousands
  • Make proteins
  • Found on ribosomes & floating throughout the cell
• Mitochondria


  • Produces energy through chemical reactions – breaking down fats & carbohydrates
  • Controls level of water and other materials in cell
  • Recycles and decomposes proteins, fats, and carbohydrates
• Golgi Bodies


  • Protein 'packaging plant'
  • Move materials within the cell
  • Move materials out of the cell
• Lysosome


  • Digestive 'plant' for proteins, fats, and carbohydrates
  • Transports undigested material to cell membrane for removal
  • Cell breaks down if lysosome explodes
• Vacuoles


  • Membrane-bound sacs for storage, digestion, and waste removal
  • Contains water solution
  • Help plants maintain shape
• Chloroplast


  • Usually found in plant cells
  • Contains green chlorophyll
  • Where photosynthesis takes place
• Cell Organization


  • The cell is the basic structural and functional unit of life
  • Each cell is a highly organized unit
  • Plasma membrane: forms the outer boundary of the cell
  • Cellular organelles: each performs specific functions
  • Nucleus: contains the cell's genetic material and directs cell activities
  • Cytoplasm: the material between the plasma membrane and nucleus
• Plasma Membrane


  • Plays a dynamic role in cellular activity
  • Separates intracellular substances from extracellular substances
• Fluid Mosaic Model


  • Lipid bilayer
  • Bilayer consists mainly of phospholipids and cholesterol (20%)
• Membrane Protein Functions


  • Marker molecules
  • Attachment proteins (cadherins and integrins)
  • Transport proteins
  • Receptor proteins
  • Enzymes
• Movement Through the Plasma Membrane

  1. Diffusion

  2. Osmosis

  3. Mediated transport

  4. Vesicular transport
• Diffusion


  • The movement of a solute from an area of higher concentration to an area of lower concentration within a solvent
  • At equilibrium, there is a uniform distribution of molecules
• Osmosis


  The diffusion of a solvent (water) across a selectively permeable membrane via diffusion
• Passive Transport


  • Movement of material along a concentration gradient (high concentration ⇒ low concentration)
  • Does not require the expenditure of energy (ATP hydrolysis)
• Primary Active Transport


  1. Three sodium ions (Na+) and adenosine triphosphate (ATP) bind to the Na+-K+ pump, which is an ATP-powered pump

  2. The ATP breaks down to adenosine diphosphate (ADP) and a phosphate (P) and releases energy

  3. The Na+-K+ pump changes shape, and the Na+ are transported across the membrane

  4. Two potassium ions (K+) bind to the Na+-K+ pump

  5. The phosphate is released from the Na+-K+ pump binding site

  6. The Na+-K+ pump resumes its original shape, transporting K+ across the membrane
• Secondary Active Transport


  • A Na+-K+ pump (ATP-powered pump) maintains a concentration of Na+ that is higher outside the cell than inside
  • Sodium ions move back into the cell through a carrier protein (symporter) that also moves glucose
• Vesicular Transport


  1. Endocytosis: the movement of materials into cells by the formation of a vesicle

  2. Phagocytosis: the movement of solid material into cells

  3. Pinocytosis: the uptake of small droplets of liquids and the materials in them

  4. Receptor-mediated endocytosis: involves plasma membrane receptors attaching to molecules that are then taken into the cell

  5. Exocytosis: the secretion of materials from cells by vesicle formation
• Exocytosis


  1. A secretory vesicle moves toward the plasma membrane

  2. The membrane of the secretory vesicle fuses with the plasma membrane

  3. The secretory vesicle's contents are released into the extracellular fluid
• Cell Cycle and Cell Division

  • Cell division is an inherent property of living organisms
  • The growth, differentiation, reproduction and repair take place through cell division
  • There are two types of cell division namely Mitosis and Meiosis
  • The cell capable of undergoing division passes through cell cycle
• Cell Division


  1. Interphase: nondividing, growing phase

  2. M-phase: dividing phase

  3. Karyokinesis: division of the nucleus

  4. Cytokinesis: division of the cytoplasm
• Mitosis and Cytokinesis


  1. Interphase: DNA is found as thin threads of chromatin in the nucleus, DNA replication occurs

  2. Prophase: chromatin condenses into chromosomes, centrioles move, nucleolus and nuclear envelope disappear, microtubules form

  3. Metaphase: chromosomes align in the center of the cell in association with the spindle fibers

  4. Anaphase: the chromatids separate, and each chromatid is then referred to as a chromosome

  5. Telophase: migration of each set of chromosomes is complete, the nuclear envelope forms, the nucleoli form, and cytokinesis continues to form two cells