Exercise 4Exercise 4

The Cell—Anatomy & The Cell—Anatomy & DivisionDivision

What is a cell?What is a cell?

Structural & functional unit of ALLLLLL Structural & functional unit of ALLLLLL living thingsliving things

Different sizes & shapesDifferent sizes & shapes Different functionsDifferent functions Components may vary but have many Components may vary but have many

common featurescommon features

Cell CompartmentsCell Compartments

Plasma membrane (plasmalemma)Plasma membrane (plasmalemma) Separates cell’s contents from outside Separates cell’s contents from outside

environmentenvironment Controls what goes in and out of the cellControls what goes in and out of the cell

NucleusNucleus ““control center” of cellcontrol center” of cell DNADNA

Cytoplasm Cytoplasm Fluid AND other contents Fluid AND other contents outsideoutside the the

nucleusnucleus

PLASMA PLASMA MEMBRANEMEMBRANE

NUCLEUSNUCLEUS

CYTOPLASMCYTOPLASM

Lab Fig. 4-3Lab Fig. 4-3

Cytoplasmic OrganellesCytoplasmic Organelles

Chromatin (in nucleus)Chromatin (in nucleus) DNA + proteins—when not replicating, DNA is DNA + proteins—when not replicating, DNA is

in this threadlike form all over the nucleusin this threadlike form all over the nucleus Chromosome (in nucleus)Chromosome (in nucleus)

When DNA replicates, chromatin becomes When DNA replicates, chromatin becomes tightly coiled, short, rod-shapedtightly coiled, short, rod-shaped

Nucleolus Nucleolus Dense protein & RNA mass in nucleusDense protein & RNA mass in nucleus Forms ribosomes which are then transported Forms ribosomes which are then transported

to cytoplasmto cytoplasm

CHROMATINCHROMATINNUCLEOLUSNUCLEOLUS

Lab Fig. 4-3Lab Fig. 4-3

Lecture Fig. 3-14Lecture Fig. 3-14

Cytoplasmic OrganellesCytoplasmic Organelles

RibosomeRibosome RNARNA Where proteins are madeWhere proteins are made

Cytoskeleton (“support beams”)Cytoskeleton (“support beams”) Protein fibersProtein fibers Centrioles: paired cylinders at right angles Centrioles: paired cylinders at right angles

(important in cell division, makes (important in cell division, makes microtubules)microtubules)

Microtubules: thin hollow tubes (transport Microtubules: thin hollow tubes (transport things in the cell, rigidity)things in the cell, rigidity)

Mitotic spindleMitotic spindle of microtubules forms of microtubules forms between centrioles during cell divisionbetween centrioles during cell division

RIBOSOMESRIBOSOMESMICROTUBULESMICROTUBULES

CENTRIOLESCENTRIOLES

Lab Fig. 4-3Lab Fig. 4-3

Cytoplasmic OrganellesCytoplasmic Organelles

Cytoskeleton (“support beams”)Cytoskeleton (“support beams”) Microfilaments: proteins, important in Microfilaments: proteins, important in

muscle cells; cell-shapemuscle cells; cell-shape Intermediate filaments: proteins, cell-Intermediate filaments: proteins, cell-

stabilizers—resist pulling forcesstabilizers—resist pulling forces

INTERMEDIATE INTERMEDIATE FILAMENTSFILAMENTS

MICROFILAMENTSMICROFILAMENTS

Lab Fig. 4-3Lab Fig. 4-3

Cytoplasmic Organelles with Cytoplasmic Organelles with MembranesMembranes

Nuclear membrane (envelope)Nuclear membrane (envelope) 2-layered2-layered Porous: materials moving to/from Porous: materials moving to/from

nucleus & cytoplasmnucleus & cytoplasm Mitochondria Mitochondria

2-layered membrane with inner folds2-layered membrane with inner folds Powerhouse of cellPowerhouse of cell Transforms energy from food into a form Transforms energy from food into a form

usable by the cell…aerobic respiration usable by the cell…aerobic respiration ATPATP

MITOCHONDRIAMITOCHONDRIA

NUCLEAR NUCLEAR MEMBRANEMEMBRANE

Lab Fig. 4-3Lab Fig. 4-3

Cytoplasmic Organelles with Cytoplasmic Organelles with MembranesMembranes

ER: Canal network continuous with nuclear membraneER: Canal network continuous with nuclear membrane

Smooth endoplasmic reticulum (ER) Smooth endoplasmic reticulum (ER) Synthesizes lipidsSynthesizes lipids

Rough endoplasmic reticulum (ER)Rough endoplasmic reticulum (ER) Ribosomes attached to surfaceRibosomes attached to surface Protein synthesis and transportProtein synthesis and transport

Lab Fig. 4-3Lab Fig. 4-3

SMOOTH ERSMOOTH ER

ROUGH ERROUGH ER

Cytoplasmic Organelles with Cytoplasmic Organelles with MembranesMembranes

Golgi apparatusGolgi apparatus Cluster of flattened sacs near rough ERCluster of flattened sacs near rough ER Proteins made in ER come here to get Proteins made in ER come here to get

packaged and shipped out of the cell or to packaged and shipped out of the cell or to the cell’s cytoplasmthe cell’s cytoplasm

SecretSecretory vesicles: pinch off the golgi, to ory vesicles: pinch off the golgi, to plasma membrane, release contents from the plasma membrane, release contents from the cellcell

Lysosome: sack with Lysosome: sack with digestive enzymesdigestive enzymes ((digest digest foreign material, old cell parts)foreign material, old cell parts)

Peroxisome: sack with oxidase enzymes (use Peroxisome: sack with oxidase enzymes (use oxygenoxygen to to detoxifydetoxify—free radicals, kidney, —free radicals, kidney, liver)liver)

SECRETORY SECRETORY VESICLESVESICLES

GOLGI GOLGI APPARATUSAPPARATUS

Lab Fig. 4-3Lab Fig. 4-3

Cell MembraneCell Membrane

Phospholipid bilayerPhospholipid bilayer PhospholipidsPhospholipids

Hydrophobic tailsHydrophobic tails Hydrophilic headsHydrophilic heads

CholesterolCholesterol Lipid, helps stabilize cell membraneLipid, helps stabilize cell membrane

ProteinsProteins Move around, aid in transportMove around, aid in transport ““fluid mosaic model”fluid mosaic model”

FLUID-MOSAIC MODELPHOSPHOLIPID PHOSPHOLIPID

BILAYERBILAYER

PROTEINSPROTEINS

CHOLESTEROLCHOLESTEROL

HYDROPHOBIC TAILSHYDROPHOBIC TAILS

HYDROPHILIC HEADSHYDROPHILIC HEADS

Cell Division: MITOSISCell Division: MITOSIS

InterphaseInterphase ProphaseProphase MetaphaseMetaphase AnaphaseAnaphase TelophaseTelophase CytokinesisCytokinesis

Cell Division: MITOSISCell Division: MITOSIS

InterphaseInterphase Normal cell activities Normal cell activities

PRIOR to divisionPRIOR to division

Lab Fig. 4-4Lab Fig. 4-4

Cell Division: MITOSISCell Division: MITOSIS

ProphaseProphase Chromosomes Chromosomes

form as sister form as sister chromatidschromatids

Centrioles Centrioles separate, mitotic separate, mitotic spindle formsspindle forms

Nuclear Nuclear membrane & membrane & nucleolus break nucleolus break downdown

Lab Fig. 4-4Lab Fig. 4-4

Cell Division: MITOSISCell Division: MITOSIS

MetaphaseMetaphase Chromatids Chromatids

migrate along migrate along spindle to the spindle to the middle----middle----metaphase metaphase plateplate

Lab Fig. 4-4Lab Fig. 4-4

Cell Division: MITOSISCell Division: MITOSIS

AnaphaseAnaphase Centromeres Centromeres

split & split & chromosomes chromosomes split into 2 split into 2 chromosomes chromosomes which migrate which migrate to opposite to opposite ends of the ends of the cellcell

Lab Fig. 4-4Lab Fig. 4-4

Cell Division: MITOSISCell Division: MITOSIS

TelophaseTelophase Reverse of prophaseReverse of prophase Chromosomes uncoil Chromosomes uncoil

into chromatininto chromatin Spindle breaks downSpindle breaks down Nuclear membranes Nuclear membranes

form @ each endform @ each end Nucleoli appear in Nucleoli appear in

each nucleuseach nucleus

Lab Fig. 4-4Lab Fig. 4-4

Cell Division: MITOSISCell Division: MITOSIS

CytokinesisCytokinesis Division of cytoplasmDivision of cytoplasm Starts at end of telophaseStarts at end of telophase 2 new cells are formed, 2 new cells are formed, each genetically each genetically

IDENTICAL to the “mother” cellIDENTICAL to the “mother” cell