E XERCISE 4 The Cell—Anatomy & Division

W HAT IS A CELL ? Structural & functional unit of ALLLLLL living things Different sizes & shapes Different functions Components may vary but have many common features

C ELL C OMPARTMENTS Plasma membrane (plasmalemma) barrier barrier in/out of cell in/out of cellNucleus “control center” of cell “control center” of cell DNA DNACytoplasm Fluid AND other organelles Fluid AND other organelles

F IGURE 4.1 A A NATOMY OF THE COMPOSITE ANIMAL CELL. Nucleus Cytoplasm Plasma membrane

F IGURE 4.1 B A NATOMY OF THE COMPOSITE ANIMAL CELL. Endoplasmic reticulum Nuclear envelope Nucleus Nucleolus Chromatin Mitochondria

C YTOPLASMIC O RGANELLES Chromatin (in nucleus) DNA + proteins—threadlike form DNA + proteins—threadlike form Chromosomes (in nucleus) Before mitosis, chromatin becomes tightly coiled, rod- shaped Before mitosis, chromatin becomes tightly coiled, rod- shapedNucleolus protein & RNA in nucleus protein & RNA in nucleus

F IGURE 4.1 B A NATOMY OF THE COMPOSITE ANIMAL CELL. Endoplasmic reticulum Nuclear envelope Nucleus Nucleolus Chromatin Mitochondria

CHROMATIN NUCLEOLUS Lab Fig. 4-3

Lecture Fig. 3-14

C YTOPLASMIC O RGANELLES Ribosome Made of RNA Made of RNA Protein synthesis Protein synthesis Cytoskeleton (“support beams”) Protein fibers Protein fibers Centrioles: paired cylinders near nucleus Centrioles: paired cylinders near nucleus Microtubules: thin hollow tubes (transport things in the cell, rigidity) Microtubules: thin hollow tubes (transport things in the cell, rigidity) Mitotic spindle forms between centrioles during mitosis

RIBOSOMES MICROTUBULES CENTRIOLES Lab Fig. 4-3

C YTOPLASMIC O RGANELLES Cytoskeleton (“support beams”) Microfilaments: tiny; cell shape Microfilaments: tiny; cell shape Intermediate filaments: medium, cell- stabilizers Intermediate filaments: medium, cell- stabilizers

INTERMEDIATE FILAMENTS MICROFILAMENTS Lab Fig. 4-3

C YTOPLASMIC O RGANELLES WITH M EMBRANES Nuclear membrane (envelope) 2-layered 2-layered Porous: holes for in/out Porous: holes for in/outMitochondria 2-layered membrane with inner folds 2-layered membrane with inner folds Powerhouse of cell Powerhouse of cell Food energy  ATP energy

MITOCHONDRIA NUCLEAR MEMBRANE Lab Fig. 4-3

C YTOPLASMIC O RGANELLES WITH M EMBRANES ER: Canal network continuous with nuclear membrane Smooth endoplasmic reticulum Synthesizes lipids Synthesizes lipids Rough endoplasmic reticulum Ribosomes attached to surface Ribosomes attached to surface Protein synthesis and transport Protein synthesis and transport Lab Fig. 4-3 SMOOTH ER ROUGH ER

C YTOPLASMIC O RGANELLES WITH M EMBRANES Golgi apparatus Cluster of flattened sacs near rough ER Cluster of flattened sacs near rough ER Secretory vesicles Secretory vesicles Secrete contents out of cell Or Lysosome: digestive enzymes (digest foreign material, old cell parts) Peroxisome: oxidase enzymes (use oxygen to detoxify—free radicals, kidney, liver)

SECRETORY VESICLES GOLGI APPARATUS Lab Fig. 4-3

F IGURE 4.3 S TRUCTURE OF THE GENERALIZED CELL. Chromatin Nucleolus Smooth endoplasmic reticulum Cytosol Mitochondrion Lysosome Centrioles Centrosome matrix Microvilli Microfilament Microtubule Cytoskeletal elements Intermediate filaments Peroxisome Secretion being released from cell by exocytosis Golgi apparatus Ribosomes Rough endoplasmic reticulum Plasma membrane Nuclear pore Nuclear envelope Nucleus

T ABLE 4.1 S UMMARY OF S TRUCTURE AND F UNCTION OF C YTOPLASMIC O RGANELLES

C ELL M EMBRANE Phospholipid bilayer Phospholipids Hydrophobic tails Hydrophobic tails Hydrophilic heads Hydrophilic headsCholesterol Lipid, helps stabilize cell membrane Lipid, helps stabilize cell membraneProteins Move around, aid in transport Move around, aid in transport “fluid mosaic model” “fluid mosaic model”

FLUID-MOSAIC MODEL PHOSPHOLIPID BILAYER PROTEINS CHOLESTEROL HYDROPHOBIC TAILS HYDROPHILIC HEADS

F IGURE 4.2 S TRUCTURAL DETAILS OF THE PLASMA MEMBRANE. Polar head of phospholipid molecule Nonpolar tail of phospholipid molecule CholesterolGlycolipid Glycoprotein Peripheral proteins Filament of cytoskeleton Integral proteins Inward-facing layer of phospholipids Outward-facing layer of phospholipids Lipid bilayer containing proteins Glycocalyx (carbohydrates) Extracellular fluid (watery environment outside cell) Cytoplasm (watery environment inside cell)

C ELL D IVISION : MITOSIS InterphaseProphaseMetaphaseAnaphaseTelophaseCytokinesis

Microscope slides also

F IGURE 4.4 T HE INTERPHASE CELL AND THE EVENTS OF CELL DIVISION. (1 OF 2) Centrosomes (each has 2 centrioles) Plasma membrane Nucleolus Nuclear envelope Chromatin Chromosome consisting of two sister chromatids Early mitotic spindle Aster Centromere KinetochoreKinetochore microtubule Spindle pole Polar microtubule Fragments of nuclear envelope Interphase Early Prophase Late Prophase

F IGURE 4.4 T HE INTERPHASE CELL AND THE EVENTS OF CELL DIVISION. (1 OF 2) Centrosomes (each has 2 centrioles) Plasma membrane Nucleolus Nuclear envelope Chromatin Chromosome consisting of two sister chromatids Early mitotic spindle Aster Centromere KinetochoreKinetochore microtubule Spindle pole Polar microtubule Fragments of nuclear envelope Interphase Early Prophase Late Prophase

F IGURE 4.4 T HE INTERPHASE CELL AND THE EVENTS OF CELL DIVISION. (2 OF 2) Metaphase AnaphaseTelophase Cytokinesis Metaphase plate Spindle Daughter chromosomes Nuclear envelope forming Nucleolus formingContractile ring at cleavage furrow

C ELL D IVISION : MITOSIS Interphase Normal cell activities PRIOR to division Normal cell activities PRIOR to division Then it gets the signal to divide Then it gets the signal to divide Copy DNA Copy organelles Copy centrioles Lab Fig. 4-4

C ELL D IVISION : MITOSIS Prophase Chromosomes w/sister chromatids Chromosomes w/sister chromatids Centrioles separated, spindle Centrioles separated, spindle Nuclear membrane breaks down Nuclear membrane breaks down Lab Fig. 4-4

C ELL D IVISION : MITOSIS Metaphase middle middle Lab Fig. 4-4

C ELL D IVISION : MITOSIS Anaphase Chromatids split, to opposite ends Chromatids split, to opposite ends Lab Fig. 4-4

C ELL D IVISION : MITOSIS Telophase Chromatin again Chromatin again Spindle breaks down Spindle breaks down Nuclear membrane Nuclear membrane Lab Fig. 4-4

C ELL D IVISION : MITOSIS Cytokinesis Division of cytoplasm Division of cytoplasm 2 new cells 2 new cells each genetically IDENTICAL each genetically IDENTICAL

R EVIEW F IGURE 4.1

R EVIEW F IGURE 4.2