THE CELL 3/15/15 HUMAN ANATOMY AND PHYSIOLOGY I THE CELLULAR BASIS OF LIFE

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1 HUMAN ANATOMY AND PHYSIOLOGY I Lecture: M 6-9:30 Randall Visitor Center Lab: W 6-9:30 Swatek Anatomy Center, Centennial Complex Required Text: Marieb 9 th edition Dr. Trevor Lohman DPT (949) tlohman@llu.edu THE CELL CH. 3: THE FUNCTIONAL UNIT OF LIFE THE CELLULAR BASIS OF LIFE The Smallest Living Unit Cell Theory: Generalized or Composite Cell Plasma Membrane Cytoplasm Nucleus Fig 3.2 1

2 THE PLASMA MEMBRANE: STRUCTURE The Fluid Mosaic Model Membrane Lipids Phospholipids Glycolipids Cholesterol Lipid Rafts Fig 3.3 PLASMA MEMBRANE: STRUCTURE Membrane Proteins: Integral Proteins Peripheral Proteins The Glycocalyx Fig CELL JUNCTIONS Tight Junctions: Desmosomes: Gap Junctions: 2

3 THE PLASMA MEMBRANE: MEMBRANE TRANSPORT Passive Processes Osmosis Aquaporins Osmolarity Hydrostatic vs. osmotic pressure Tonicity (Iso, Hyper, Hypo) Fig 3.9 Diffusion Simple diffusion Facilitated diffusion Carrier-Mediated facilitated diffusion Channel-Mediated facilitated diffusion Fig 3.6, 3.7, 3.8 THE PLASMA MEMBRANE: MEMBRANE TRANSPORT Active Transport Primary Active Transport (3.10) Sodium-potassium pump Secondary Active Transport (3.11) Symport system vs. antiport system Vesicular Transport ( ) Endocytosis, Transcytosis, Vesicular Trafficking Fig 3.12 Phagocytosis Pinocytosis Receptor Mediated endocytosis Exocytosis THE PLASMA MEMBRANE: GENERATION OF A RESTING MEMBRANE POTENTIAL Membrane Potential and Resting Membrane Potential Selective Diffusion Establishes Membrane Potential Fig 3.15 Step 1 Step 2 Step 3 Active Transport Maintains Electrochemical Gradients 3

4 THE PLASMA MEMBRANE: CELL-ENVIRONMENT INTERACTIONS Roles of Cell Adhesion Molecules Molecular Velcro The arms Send SOS signals The Mechanical Sensors The Transmitters of intracellular signals THE PLASMA MEMBRANE: CELL- ENVIRONMENT INTERACTIONS Roles of Plasma Membrane Receptors Contact Signaling Chemical Signaling Ligands Catalytic receptor proteins Chemically gated channel-link receptors G-linked receptors Second messengers Cyclic AMP Ionic calcium Fig 3.16 THE CYTOPLASM The Cytosol Organelles Inclusions 4

5 Mitochondria Ribosomes Endoplasmic Reticulum Smooth endoplasmic reticulum Rough Endoplasmic reticulum Golgi Apparatus Trans face Cis face 5

6 Peroxisomes Neutralize free radicals Lysosomes Cytoskeleton Microfilaments Intermediate filaments Microtubules Centrosome Centrioles Fig

7 THE NUCLEUS The Nucleus Multinucleate Anucleate 3 distinguishable regions The Nuclear Envelope Nuclear Pores Nucleoli Chromatin 30% DNA 60% globular histone proteins 10% RNA chains Nucleosomes Chromosomes CELL CYCLE: INTERPHASE/M-PHASE Interphase (Metabolic/Growth Phase) Subphases G1 (gap 1 subphase)/(g0 phase) S Phase G2 (gap 2 subphase) DNA Replication Enzymatic Unwinding Replication bubble forms RNA Primer Formation DNA Polymerase CELL DIVISION Cell Division M (mitotic) phase Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis 7

8 MITOSIS Prophase Early Prophase Chromatin condenses, forms chromosomes Centrosome separation, Mitotic spindle forms Late Prophase Nuclear envelope dissolves Spindle microtubules attach to kinetochores at each centromere Polar microtubules slide past each other forcing the poles apart Fig 3.33 MITOSIS Metaphase Centromeres are at opposite poles of the cell Chromosomes align along the equator of the spindle or metaphase plate Enzymatic separation of chromatids begins ANAPHASE Shortest Mitotic Phase Begins with simultaneous chromatid separation Motor proteins within the kinetochores pull chromosomes toward the poles Polar microtubules continue to expand, pushing the poles further apart 8

9 TELOPHASE Begins when chromosomal movement stops Resembles prophase in reverse Chromosomes unravel and revert to chromatin New nuclear envelopes form and nucleoli reform Mitotic spindle disappears Mitosis ends, and cell is now binucleate CYTOKINESIS Actin ring forms and constricts until cell is pinched in two Begins during late Anaphase Continues beyond Telophase PROTEIN SYNTHESIS Deoxyribose Nucleic Acid DNA is the master blueprint Composed of 4 nucleotide bases A, T, C, G Triplets code for individual amino acids Exons and introns DNA is useless without RNA 9

10 PROTEIN SYNTHESIS RNA Messenger RNA (mrna) The transcript from which protein synthesis is performed Ribosomal RNA (rrna) Building block of ribosomes Transfer RNA (trna) Transport cytoplasmic amino acids to ribosomes PROTEIN SYNTHESIS Transcription Initiation RNA Polymerase Promoter Helix pulled apart Elongation Helix unwound and rewound and as mrna formed Termination Termination signal mrna separation PROTEIN SYNTHESIS Translation Nucleic acid language translated to amino acid language Codons (64 possible) Translation Events Initiation Ribosomal subunit binds to initiating trna which scans for start codon Elongation Codon recognition Peptide bond formation Translocation Termination Stop codon reached Polypeptide chain released 10

11 PROTEIN SYNTHESIS Fig 3.4 Fig 3.39 CH 3: THE CELL Study Guide 11