Biology 102 Lecture 8: Cell structure and function (Parts 1 and 2)

Biology 102Biology 102

Lecture 8: Cell structure and Lecture 8: Cell structure and function (Parts 1 and 2)function (Parts 1 and 2)

Lecture outlineLecture outline

1.1. History of cell studyHistory of cell study2.2. Basic attributes of cellsBasic attributes of cells3.3. Cell structuresCell structures

I. The history of cell studyI. The history of cell study

A.A. Robert Hooke—1665—coined Robert Hooke—1665—coined the word cell, looked at cork the word cell, looked at cork cellscells

B.B. Antonie van LeeuwenhoekAntonie van Leeuwenhoek• Created optics that could Created optics that could

visualize single cellsvisualize single cells• His technology “lost” for nearly His technology “lost” for nearly

200 years200 years

C. Robert Brown—1831—C. Robert Brown—1831—discovered the "nucleus"discovered the "nucleus"

I. The history of cell studyI. The history of cell study

D. Theodor Schwann—1838—D. Theodor Schwann—1838—viewed animal cells in cartilageviewed animal cells in cartilage1. 1. Cells are the elementary Cells are the elementary

particles of plants and animalsparticles of plants and animals

E. Mattias Schleiden—Cells are the E. Mattias Schleiden—Cells are the fundamental basis of lifefundamental basis of life

F. Virchow—1858—All cells come F. Virchow—1858—All cells come from cellsfrom cells

I. The history of cell studyI. The history of cell study

F. Cell theoryF. Cell theory1.1. All living things are composed All living things are composed

of one or more cellsof one or more cells• What about viruses?What about viruses?

2. Cells are the basic unit of 2. Cells are the basic unit of structure and functionstructure and function

3. All cells come from preexisting 3. All cells come from preexisting cellscells

II. Attributes of cellsII. Attributes of cells

A. Cell sizeA. Cell size1. 1–100µm1. 1–100µm

II. Attributes of cellsII. Attributes of cells

2. Why is there a limit to cell size?2. Why is there a limit to cell size?a. Surface-to-volume ratioa. Surface-to-volume ratiob. Distance from surface to centerb. Distance from surface to center

II. Attributes of cellsII. Attributes of cells

B. Cell typesB. Cell types1. Prokaryotic—no nucleus (or other 1. Prokaryotic—no nucleus (or other membrane-bound organelles) circular membrane-bound organelles) circular DNA, ribosomesDNA, ribosomes

II. Attributes of cellsII. Attributes of cells

B. Cell typesB. Cell types2. Eukaryotic—larger, nucleus, 2. Eukaryotic—larger, nucleus,

linear chromosomes, linear chromosomes, membranous organellesmembranous organelles

III. Cell structureIII. Cell structure

A. A. AllAll cells (prokaryotes and cells (prokaryotes and eukaryotes) possess a plasma eukaryotes) possess a plasma membrane, cytoplasm, genetic membrane, cytoplasm, genetic material and ribosomesmaterial and ribosomes1. 1. Plasma membrane has phospholipid Plasma membrane has phospholipid

bilayer, embedded glycoproteinsbilayer, embedded glycoproteinsa. Isolates cytoplasm a. Isolates cytoplasm

from environmentfrom environmentb. Regulates molecular b. Regulates molecular

movement into and movement into and out of cellout of cell

c. Interacts with other c. Interacts with other cells/environmentcells/environment

III. Cell structureIII. Cell structure

A. All cells possess a plasma A. All cells possess a plasma membrane, cytoplasm, genetic membrane, cytoplasm, genetic material and ribosomes (cont.)material and ribosomes (cont.)2.2. Genetic material—DNA, found Genetic material—DNA, found

in the nucleus (of eukaryotes)in the nucleus (of eukaryotes)• Within cytoplasm of Within cytoplasm of

prokaryotesprokaryotes

3. Cytoplasm—water, salts, organic 3. Cytoplasm—water, salts, organic monomers and polymersmonomers and polymers

a. Contains a. Contains organelles organelles

III. Cell structureIII. Cell structure

B. OrganellesB. Organelles1. 1. RibosomesRibosomes assemble amino acid assemble amino acid

monomers into polypeptide monomers into polypeptide chainschains

a. Associated with a. Associated with the ER in the ER in eukaryoteseukaryotes

b.b. Composed of RNA and proteinsComposed of RNA and proteinsc.c. Both prokaryotes and Both prokaryotes and

eukaryotes have ribosomeseukaryotes have ribosomesd.d. NOTE: NOTE: Other organelles are Other organelles are

present only in eukaryotespresent only in eukaryotes

III. Cell structureIII. Cell structure

B.B. Organelles (cont.)Organelles (cont.)2. 2. Endoplasmic reticulum consists of Endoplasmic reticulum consists of

folded membranes contiguous with outer folded membranes contiguous with outer nuclear membranenuclear membranea.a. Rough ER: protein synthesis and secretionRough ER: protein synthesis and secretionb.b. Smooth ER: lipid synthesis and secretionSmooth ER: lipid synthesis and secretion

3.3. Golgi apparatus: membranous sacs Golgi apparatus: membranous sacs associated with the ERassociated with the ERa.a. Sorts proteins and lipids by destinationSorts proteins and lipids by destinationb.b. Modifies some moleculesModifies some moleculesc.c. Packages these materials, then transports Packages these materials, then transports

them to appropriate locationthem to appropriate location

4. 4. Lysosomes are Golgi-derived vesicles Lysosomes are Golgi-derived vesicles containing digestive enzymescontaining digestive enzymes

Flow of membrane within the cellFlow of membrane within the cell

•Follow pathway of Follow pathway of membrane flowmembrane flow

•NucleusNucleus•ERER•Golgi apparatusGolgi apparatus•Lysosomes (and Lysosomes (and other packets of other packets of materials)materials)•Plasma membranePlasma membrane

III. Cell structureIII. Cell structure

B. Organelles (cont.)B. Organelles (cont.)5. Mitochondria provide energy for 5. Mitochondria provide energy for

cellular functionscellular functionsa.a. Membrane-bound (two Membrane-bound (two

membranes)membranes) Most concentrated in metabolically Most concentrated in metabolically

active cells (i.e. muscles)active cells (i.e. muscles)b.b. Break down molecules to obtain Break down molecules to obtain

their energytheir energy Energy stored “short-term” as ATPEnergy stored “short-term” as ATP

c. Have their own DNA c. Have their own DNA and ribosomes; and ribosomes; self-replicateself-replicate

Structure of a mitochondrionStructure of a mitochondrion

Note: Different reactions occur in Note: Different reactions occur in different parts of the mitochondriondifferent parts of the mitochondrion

Plant cells: Have all the organelles Plant cells: Have all the organelles previously mentioned, and also…previously mentioned, and also…

III. Cell structureIII. Cell structure

B. Organelles (cont.)B. Organelles (cont.)6. Vacuoles6. Vacuoles

a. Large, water-a. Large, water-filled spaces filled spaces (cell sap)(cell sap)

b. Can take up b. Can take up over 90% of over 90% of cell volumecell volume

c.c. Surrounded by tonoplast (a Surrounded by tonoplast (a single membrane)single membrane)

d. Functions:d. Functions:1) Storage of red/blue 1) Storage of red/blue

anthocyanins, acids, salts, anthocyanins, acids, salts, wasteswastes

2) Maintain cell pressure (turgor 2) Maintain cell pressure (turgor pressure)—wiltingpressure)—wilting

Maintenance of turgor pressureMaintenance of turgor pressure

III. Cell structureIII. Cell structure

B. Organelles (cont.)B. Organelles (cont.)7. Chloroplasts7. Chloroplasts

a.a. Note double membraneNote double membraneb.b. Green—contain chlorophyll pigmentGreen—contain chlorophyll pigmentc.c. Stacks of thylakoids (grana) within stroma (fluid)Stacks of thylakoids (grana) within stroma (fluid)

a.a. As for mitochondria, diff. parts have diff. functionsAs for mitochondria, diff. parts have diff. functionsd.d. Have their own DNA and ribosomes; self-replicateHave their own DNA and ribosomes; self-replicate

III. Cell structureIII. Cell structure

B. Organelles (cont.)B. Organelles (cont.)8. Other plastids8. Other plastids

a.a. Storage of materials such as pigments Storage of materials such as pigments and starch (as in potatos)and starch (as in potatos)

III. Cell structureIII. Cell structure

B. Organelles (cont.)B. Organelles (cont.)8. Nucleus is control center of the 8. Nucleus is control center of the

cellcell

III. Cell structureIII. Cell structure

B. Organelles (cont.)B. Organelles (cont.)Functions of the parts of the nucleusFunctions of the parts of the nucleus

a.a. Nuclear envelope (membrane) with Nuclear envelope (membrane) with porespores Water, ions and ATP can pass Water, ions and ATP can pass

through poresthrough pores Other materials are regulated by Other materials are regulated by

“gatekeeper” proteins in the pores“gatekeeper” proteins in the poresb.b. NucleolusNucleolus

Site of ribosome assemblySite of ribosome assemblyc.c. ChromatinChromatin

Between nucleolus and envelopeBetween nucleolus and envelope DNA and protein (DNA and protein (not in nucleolusnot in nucleolus!)!) Replication and transcriptionReplication and transcription

III. Cell structureIII. Cell structure

C. Cell walls in plant cells, C. Cell walls in plant cells, prokaryotic cells, fungiprokaryotic cells, fungi1.1. PlantsPlants

Cell walls of cellulose (Ch. 3)Cell walls of cellulose (Ch. 3)

2.2. FungiFungi Cell walls of chitin (Ch. 3)Cell walls of chitin (Ch. 3)

3.3. Function: support, protectionFunction: support, protection

4.4. NOTE: Animal cells do NOTE: Animal cells do notnot have cell walls!have cell walls!

III. Cell structureIII. Cell structure

D.D. CytoskeletonCytoskeleton1.1. Network of protein fibers to which Network of protein fibers to which

organelles and even enzymes are organelles and even enzymes are attachedattached

Microfilaments Intermed. Fil.Microfilaments Intermed. Fil. Microtubules Microtubules

III. Cell structureIII. Cell structure

Cytoskeleton functionsCytoskeleton functions1.1. Cell shapeCell shape2.2. Organization of cellular structuresOrganization of cellular structures3.3. Cell movementCell movement

Caused by assembly, disassembly Caused by assembly, disassembly and sliding of the filaments and sliding of the filaments

4.4. Organelle movementOrganelle movement Ex: EndocytosisEx: Endocytosis Movement of membrane from ER to Movement of membrane from ER to

Golgi apparatus, etc…Golgi apparatus, etc…

5.5. Cell divisionCell division

III. Cell structureIII. Cell structure

E. E. Cilia and flagella are protein Cilia and flagella are protein microtubule extensions of the microtubule extensions of the plasma membraneplasma membrane1.1. Cilia: short and numerousCilia: short and numerous2.2. Examples: within oviducts to move eggs, Examples: within oviducts to move eggs,

filter-feeding in invertebrates, movement filter-feeding in invertebrates, movement of particles out of respiratory systemof particles out of respiratory system

III. Cell structureIII. Cell structure

2. Flagella: longer and fewer2. Flagella: longer and fewer