Chapter 3 Anatomy of Cells

Mosby items and derived items © 2007, 2003 by Mosby, Inc. Slide 1

Chapter 3Chapter 3 Anatomy of Cells Anatomy of Cells

Mosby items and derived items © 2007, 2003 by Mosby, Inc.

Anatomy of CellsAnatomy of Cells

• Cell StructureCell Structure

• Cellular ComponentsCellular Components

Structure Structure

FunctionFunction

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Table 3-2Table 3-2


Functional Anatomy of CellsFunctional Anatomy of Cells

• The typical cell (Figure 3-1) – generic cellThe typical cell (Figure 3-1) – generic cell

Varies in size; all are microscopic (Table 3-1)Varies in size; all are microscopic (Table 3-1)

Varies in structure and function (Table 3-2)Varies in structure and function (Table 3-2)


Typical Cell – Fig. 3-1Typical Cell – Fig. 3-1


Typical or Composite Cell – Fig. 3-1Typical or Composite Cell – Fig. 3-1


Cell StructuresCell Structures

• Plasma membrane—separates the cell from Plasma membrane—separates the cell from its surrounding environmentits surrounding environment

• Cytoplasm—thick gel-like substance inside of Cytoplasm—thick gel-like substance inside of the cell composed of numerous organelles the cell composed of numerous organelles suspended in watery cytosol; each type of suspended in watery cytosol; each type of organelle (“little organ”) is suited to perform organelle (“little organ”) is suited to perform particular functions (Figure 3-2)particular functions (Figure 3-2)

• Nucleus—large membranous structure near Nucleus—large membranous structure near the center of the cellthe center of the cell


Cell MembranesCell Membranes

• Plasma membrane Plasma membrane (Figure 3-3)(Figure 3-3)

• Membranous Membranous organelles – sacs organelles – sacs and canals made of and canals made of the same material the same material as the plasma as the plasma membranemembrane


Cell MembranesCell Membranes

• Structure – is a double layer of phospholipid moleculeStructure – is a double layer of phospholipid molecule PhospholipidPhospholipid

• Heads are hydrophilic (water-loving)Heads are hydrophilic (water-loving)

• Tails are hydrophobic (water-fearing)Tails are hydrophobic (water-fearing)

Cholesterol molecules are scattered among the phospholipids to Cholesterol molecules are scattered among the phospholipids to allow the membrane to function properly at body temperatureallow the membrane to function properly at body temperature

Membrane ProteinsMembrane Proteins

• Controls what moves through the membraneControls what moves through the membrane

• Act as i.d. markersAct as i.d. markers

• Act as receptorsAct as receptors


Cell MembraneCell Membrane

• Membrane FunctionMembrane Function

To keep cellular components inside the cell and To keep cellular components inside the cell and extracellular material outside the cellextracellular material outside the cell

Controls what moves into and out of the cellControls what moves into and out of the cell

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Cytoplasm and OrganellesCytoplasm and Organelles

• Cytoplasm – gel-like internal substance of Cytoplasm – gel-like internal substance of cells that includes many organelles cells that includes many organelles suspended in watery intracellular fluid called suspended in watery intracellular fluid called cytosolcytosol

Cytosol – the watery intracellular fluidCytosol – the watery intracellular fluid

Organelles – “little organs” each have a particular Organelles – “little organs” each have a particular structure and function structure and function

• Know the function of each organelle and be able to Know the function of each organelle and be able to identify it in a generalized figure of the cellidentify it in a generalized figure of the cell


Endoplasmic Endoplasmic Reticulum Reticulum (Figure 3-5)(Figure 3-5)

• FunctionFunction: Synthesis : Synthesis of proteins that will be of proteins that will be excreted from the cell excreted from the cell (rough ER) and (rough ER) and synthesize lipids for synthesize lipids for the cell membrane, the cell membrane, steroid hormones, and steroid hormones, and certain carbohydrates, certain carbohydrates, removes and stores removes and stores CaCa2+ 2+ from the cell’s from the cell’s interiorinterior


Endoplasmic ReticulumEndoplasmic Reticulum

• Two types of ER:Two types of ER:

Smooth ER – do not have ribosomes attachedSmooth ER – do not have ribosomes attached

• Synthesizes certain lipids and carbohydrates and creates Synthesizes certain lipids and carbohydrates and creates membranes for use throughout cellmembranes for use throughout cell

• Removes and stores CaRemoves and stores Ca++++ from cell’s interior. from cell’s interior.

Rough ER – have ribosomes attached to the outer Rough ER – have ribosomes attached to the outer surfacesurface

• Ribosomes synthesize proteins, which move toward the Golgi Ribosomes synthesize proteins, which move toward the Golgi apparatus and then eventually leave the cellapparatus and then eventually leave the cell

• Function in protein synthesis and intracellular transportationFunction in protein synthesis and intracellular transportation


RibosomesRibosomes

• Function: the site of protein synthesisFunction: the site of protein synthesis

Attached to rough ER or scattered in the Attached to rough ER or scattered in the cytoplasmcytoplasm

• Structure: made of two pieces, a large Structure: made of two pieces, a large subunit and a small subunitsubunit and a small subunit

• Ribosomes in the endoplasmic reticulum Ribosomes in the endoplasmic reticulum make proteins for “export” or to be make proteins for “export” or to be embedded in the plasma membrane; free embedded in the plasma membrane; free ribosomes make proteins for the cell’s ribosomes make proteins for the cell’s domestic usedomestic use


Golgi ApparatusGolgi Apparatus

• Function: Synthesizes Function: Synthesizes carbohydrates, processes carbohydrates, processes proteins from the ER; the proteins from the ER; the cell’s “post office”cell’s “post office”

• Structure: cisternae Structure: cisternae stacked on one another stacked on one another and located near the and located near the nucleusnucleus

• Processes protein Processes protein molecules from the molecules from the endoplasmic reticulum endoplasmic reticulum (Figure 3-8)(Figure 3-8)


Figure 3-8. The Cell’s Protein Export SystemFigure 3-8. The Cell’s Protein Export System


LysosomesLysosomes

• Function: Bags of Function: Bags of digestive enzymes break digestive enzymes break down defective cell parts down defective cell parts and ingested particles; a and ingested particles; a cell’s “digestive system”cell’s “digestive system”

• Structure: Made of Structure: Made of microscopic membranous microscopic membranous sacs that have “pinched sacs that have “pinched off” from Golgi apparatusoff” from Golgi apparatus


ProteasomesProteasomes

• Function: Hollow protein cylinders that break down abnormal/misfolded Function: Hollow protein cylinders that break down abnormal/misfolded proteins and normal proteins no longer needed by the cellproteins and normal proteins no longer needed by the cell


PeroxisomesPeroxisomes

• Function: contain enzymes that detoxify Function: contain enzymes that detoxify harmful substancesharmful substances

Often seen in kidney and liver cellsOften seen in kidney and liver cells


MitochondriaMitochondria

• Function: A cell’s “power plant”; the site of ATP synthesisFunction: A cell’s “power plant”; the site of ATP synthesis

• Mitochondrial DNA: Each mitochondrion has a DNA molecule, Mitochondrial DNA: Each mitochondrion has a DNA molecule, allowing it to produce its own enzymes and replicate copies of allowing it to produce its own enzymes and replicate copies of itselfitself


NucleusNucleus

• Definition—spherical body in center of cell; Definition—spherical body in center of cell; enclosed by an envelope with many poresenclosed by an envelope with many pores

• Function: Contains DNA (genetic code) – the Function: Contains DNA (genetic code) – the “brain” of the cell, dictates protein synthesis“brain” of the cell, dictates protein synthesis


Nuclear StructureNuclear Structure• Nuclear Envelope – nuclear membrane, has nuclear Nuclear Envelope – nuclear membrane, has nuclear

pores (controls entrance in and out of the cell)pores (controls entrance in and out of the cell)

• Nucleoplasm – nuclear substanceNucleoplasm – nuclear substance

• Chromatin – the DNA in non-dividing cellsChromatin – the DNA in non-dividing cells

• Nucleolous – found in the nucleus, synthesizes rRNA Nucleolous – found in the nucleus, synthesizes rRNA and combines it with protein to form ribosomesand combines it with protein to form ribosomes


NucleusNucleus

• Contains DNA (heredity molecules), which Contains DNA (heredity molecules), which appear as the following:appear as the following:

Chromatin threads or granules in nondividing cellsChromatin threads or granules in nondividing cells

Chromosomes in early stages of cell divisionChromosomes in early stages of cell division

Functions of nucleus are functions of DNA Functions of nucleus are functions of DNA molecules; DNA determines both structure and molecules; DNA determines both structure and function of cells and heredityfunction of cells and heredity


CytoskeletonCytoskeleton

• Function: acts as a Function: acts as a framework to support framework to support the cell and its the cell and its organelles; involved in organelles; involved in cell movement; forms cell movement; forms cell extensionscell extensions


CytoskeletonCytoskeleton

• Cell fibers – 3 typesCell fibers – 3 types

MicrofilamentsMicrofilaments

Intermediate FilamentsIntermediate Filaments

MicrotubulesMicrotubules


MicrofilamentsMicrofilaments

• Smallest cell fibersSmallest cell fibers ““Cellular muscles”Cellular muscles”

Made of thin, twisted Made of thin, twisted strands of protein strands of protein molecules that lie molecules that lie parallel to the long axis parallel to the long axis of the cellof the cell

Microfilaments can Microfilaments can slide past each other, slide past each other, causing shortening of causing shortening of the cellthe cell


Intermediate FilamentsIntermediate Filaments

• Twisted protein strands slightly thicker than Twisted protein strands slightly thicker than microfilaments; form much of the supporting microfilaments; form much of the supporting framework in many types of cellsframework in many types of cells


MicrotubulesMicrotubules

• Tiny, hollow tubes that are the thickest of the Tiny, hollow tubes that are the thickest of the cell fiberscell fibers

• Function: move things around in the cellFunction: move things around in the cell

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CentrosomeCentrosome

• Also called the microtubule-organizing center Also called the microtubule-organizing center (MTOC)(MTOC)

• Plays an important role during cell divisionPlays an important role during cell division

• The general location of the centrosome is The general location of the centrosome is identified by the centriolesidentified by the centrioles


Cell ExtensionsCell Extensions

• Cytoskeleton that forms projections that Cytoskeleton that forms projections that extend the plasma membrane outward to extend the plasma membrane outward to form tiny, fingerlike processesform tiny, fingerlike processes


Three Types of Cell ExtensionsThree Types of Cell Extensions

• Microvilli – founds in epithelial cells that line Microvilli – founds in epithelial cells that line intestines, increase surface area for absoptionintestines, increase surface area for absoption

• Cilia – short and numerous, move substances Cilia – short and numerous, move substances along the surface of a cellalong the surface of a cell

• Flagella – involved in total cell movement; Flagella – involved in total cell movement; found on human sperm cellsfound on human sperm cells


The Big PictureThe Big Picture

• Review Review

• ConclusionsConclusions

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Chapter 3 Anatomy of Cells