The Cellular LevelThe Cellular Level

Chapter 3Chapter 3

The Cell TheoryThe Cell Theory

1.1. Cells are the building blocks of all Cells are the building blocks of all plants and animals.plants and animals.

2.2. Cells are produced by the division Cells are produced by the division of preexisting cells.of preexisting cells.

3.3. Cells are the smallest units that Cells are the smallest units that perform all vital physiological perform all vital physiological functions.functions.

4.4. Each cell maintains homeostasis Each cell maintains homeostasis at the cellular level.at the cellular level.

5.5. Homeostasis at all other levels Homeostasis at all other levels reflects the combined and reflects the combined and coordinated actions of many coordinated actions of many cells.cells.

I. Studying CellsI. Studying Cells

A.A. CytoCytologylogy- study of the structure - study of the structure and function (fxn) of cellsand function (fxn) of cells

B.B. Cell Biology-Cell Biology- biology + biology + chemistry + physicschemistry + physics

C. Cellular Anatomy C. Cellular Anatomy OverviewOverview

1.1. Sex Cells (Germ/Reproductive)-Sex Cells (Germ/Reproductive)- sperm & egg cellssperm & egg cells

2. 2. SomaSomatic Cells-tic Cells-

All other cells in the body (the All other cells in the body (the focus for most of our studies focus for most of our studies this year)this year)

II. II. Cell MembraneCell Membrane

A.A. AKA AKA Plasma MembranePlasma Membrane or or PlasmalemmaPlasmalemma

B.B. Fxns:Fxns:1.1. Physical Isolation-Physical Isolation-

a.a. Forms outer boundary of cellForms outer boundary of cell

b.b. Separates cell contents from Separates cell contents from extracellular fluid (extracellular fluid (interstitial fluidinterstitial fluid))

c.c. Maintains intracellular environment Maintains intracellular environment for homeostasisfor homeostasis

2.2. Regulation of Exchange-Regulation of Exchange- controls controls what goes in and out of a cell what goes in and out of a cell ((semipermeablesemipermeable))

3.3. Sensitivity-Sensitivity- recognizes and responds recognizes and responds to extracellular changesto extracellular changes

4.4. Structural Support- Structural Support- yupyup

III. CytoplasmIII. Cytoplasm

A.A. Cytosol-Cytosol- intracellular fluid intracellular fluid1.1. Contains dissolved material:Contains dissolved material:

a.a. NutrientsNutrients

b.b. IonsIons

c.c. ProteinsProteins

d.d. Waste productsWaste products

2.2. May contain insoluble material:May contain insoluble material:a.a. GlycogenGlycogen

b.b. Lipid droplets (fat)Lipid droplets (fat)

B. OrganellesB. Organelles

1.1. Structures that perform specific fxns within Structures that perform specific fxns within the cellthe cell

2.2. Nonmembranous OrganellesNonmembranous Organellesa.a. CytoskeletonCytoskeleton

i.i. Internal protein frameworkInternal protein framework

ii.ii. Provides strength and flexibilityProvides strength and flexibility

iii.iii. 4 components:4 components: MicrofilamentsMicrofilaments Intermediate filamentsIntermediate filaments Thick filamentsThick filaments mircrotubulesmircrotubules

b.b. MicrovilliMicrovillii.i. Small projections of the cell Small projections of the cell

membranemembrane

ii.ii. Increase surface area for absorptionIncrease surface area for absorption

c.c. CentriolesCentriolesi.i. Found in pairs in dividing cellsFound in pairs in dividing cells

ii.ii. Form the spindle apparatus, which is Form the spindle apparatus, which is necessary for cell divisionnecessary for cell division

d.d. CiliaCiliai.i. ““beat” rythmically to move beat” rythmically to move

secretions across the cell surface secretions across the cell surface (like a conveyor belt)(like a conveyor belt)

ii.ii. Ex. Cells lining the tracheaEx. Cells lining the trachea

e.e. FlagellaFlagellai.i. Longer than ciliaLonger than cilia

ii.ii. Move a cell through a fluidMove a cell through a fluid

iii.iii. Sperm cells are the only Sperm cells are the only

flagellated human cellsflagellated human cells

f.f. RibosomesRibosomesi.i. Manufacture proteinsManufacture proteins

ii.ii. 2 kinds2 kinds• Free- scattered throughout Free- scattered throughout

cytoplasmcytoplasm• Fixed- attached to endoplasmic Fixed- attached to endoplasmic

reticulumreticulum

3. 3. Membranous Membranous OrganellesOrganelles

a.a. MitochondriaMitochondriai.i. Produce energy for the cell (ATP)Produce energy for the cell (ATP)

ii.ii. The number of mitochondria per The number of mitochondria per cell varies according to the cell cell varies according to the cell type.type.

b.b. Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)i.i. A network of membranes A network of membranes

connected to the nuclear connected to the nuclear membranemembrane

ii.ii. 4 major functions:4 major functions:• Synthesis- proteins, carbohydrates, Synthesis- proteins, carbohydrates,

lipidslipids• StorageStorage• Transport- “highway” of the cellTransport- “highway” of the cell• Detoxification- drugs or toxins can be Detoxification- drugs or toxins can be

absorbed & neutralized in the ERabsorbed & neutralized in the ER

iii.iii. Smooth ER:Smooth ER:• Synthesize lipids & carbohydratesSynthesize lipids & carbohydrates

iv.iv. Rough ER:Rough ER:• Contain attached ribosomesContain attached ribosomes• Modify and package proteins for Modify and package proteins for

transport to the Golgi apparatustransport to the Golgi apparatus

c.c. Golgi ApparatusGolgi Apparatusi.i. Flattened membrane discsFlattened membrane discs

ii.ii. 2 major functions:2 major functions:• Synthesize & package hormones & Synthesize & package hormones &

enzymesenzymes• Renew or modify cell membraneRenew or modify cell membrane

d.d. LysosomesLysosomesi.i. Enzyme-filled vesicles made by the Enzyme-filled vesicles made by the

Golgi apparatusGolgi apparatus

ii.ii. Function in cleaning & recycling Function in cleaning & recycling within the cell:within the cell:• Damaged/old organellesDamaged/old organelles• pathogenspathogens

e.e. PeroxisomesPeroxisomesi.i. Smaller than lysosomes & contain Smaller than lysosomes & contain

different enzymesdifferent enzymes

ii.ii. Absorb & neutralize toxins (like Absorb & neutralize toxins (like alcohol)alcohol)

IV. NucleusIV. Nucleus

A.A. Functions:Functions:1.1. Control center of cellular operationsControl center of cellular operations

2.2. Stores info to control synthesis of all Stores info to control synthesis of all ~100,000 proteins in the human body~100,000 proteins in the human body

3.3. Determines the anatomy and Determines the anatomy and physiology of cells by controlling what physiology of cells by controlling what proteins are made and how muchproteins are made and how much

B.B. Most cells have 1 nucleus Most cells have 1 nucleus

(1 exception= skeletal muscle)(1 exception= skeletal muscle)

C.C. Structure of a typical nucleus:Structure of a typical nucleus:

1.1. Nuclear Envelope Nuclear Envelope a.a. Surrounds nucleusSurrounds nucleus

b.b. Separates it from cytosolSeparates it from cytosol

c.c. Is a double membraneIs a double membrane

d.d. Connected to rough endoplasmic Connected to rough endoplasmic reticulum (RER) in several placesreticulum (RER) in several places

2.2. Nuclear PoresNuclear Pores

a.a. Allow chemical communication Allow chemical communication between nucleus and cytosolbetween nucleus and cytosol

b.b. Large enough to permit the Large enough to permit the movement of ions and small movement of ions and small molecules, but small enough to keep molecules, but small enough to keep DNA and proteins insideDNA and proteins inside

3.3. NucleoplasmNucleoplasm

a.a. Fluid contents of nucleusFluid contents of nucleus

b.b. Contains the nuclear matrix Contains the nuclear matrix (structural support)(structural support)

c.c. Contains ions, enzymes, RNA and DNAContains ions, enzymes, RNA and DNA

4.4. NucleolusNucleolus

a.a. Synthesize ribosomal RNASynthesize ribosomal RNA

b.b. Assemble ribosomal subunitsAssemble ribosomal subunits

c.c. Most prominent in cells that make Most prominent in cells that make large amounts of proteins (liver and large amounts of proteins (liver and muscle cells), because these cells muscle cells), because these cells need lots of ribosomesneed lots of ribosomes

Sorry! Sorry!

We are skipping over translation We are skipping over translation and transcription for now.and transcription for now.

We may come back to the amazing We may come back to the amazing world of genetics later in second world of genetics later in second semester if there is semester if there is time/interest!time/interest!

V. Cell Life CycleV. Cell Life Cycle

On Your Own:On Your Own:

Please read the sections called Please read the sections called “Regulation of Cell Life Cycle” and “Regulation of Cell Life Cycle” and “Cell Division and Cancer”“Cell Division and Cancer”

It’s not super technical, so you should It’s not super technical, so you should be able to understand it and I’m be able to understand it and I’m sure we’ve all known someone w/ sure we’ve all known someone w/ cancer, so it’s worth reading!cancer, so it’s worth reading!

VI. Cell Diversity and VI. Cell Diversity and DifferentiationDifferentiation

A.A. All cells in your body contain all the All cells in your body contain all the information (DNA) needed to be any kind of information (DNA) needed to be any kind of human cell. human cell.

B.B. The skin cells on your big toe have the DNA The skin cells on your big toe have the DNA necessary to be brain cells.necessary to be brain cells.

C.C. However, skin cells have “turned off” genes However, skin cells have “turned off” genes relating to anything other than skin cell relating to anything other than skin cell functions.functions.

D.D. This is called This is called DifferentiationDifferentiation..