THE CELLTHE CELL““The smallest unit that can carry The smallest unit that can carry

out all the processes of life.”out all the processes of life.”

Why are they important?

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Scientists Who Discovered Scientists Who Discovered the Cellthe Cell

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Discovery of the CellDiscovery of the Cell

ROBERT HOOKEROBERT HOOKE First to observe cells.First to observe cells. He examined cork He examined cork

cells.cells. ““These little boxes These little boxes

reminded him of the reminded him of the small rooms in which small rooms in which monks lived, so he monks lived, so he called them cells.”called them cells.”

Discovery of the CellDiscovery of the Cell

Anton van LeeuwenhoekAnton van Leeuwenhoek – First person – First person to examine living cells & father of to examine living cells & father of microscopymicroscopy

Matthias SchleidenMatthias Schleiden – “All plants are – “All plants are composed of cells.”composed of cells.”

Theodore SchwannTheodore Schwann – “All animals are – “All animals are composed of cells.”composed of cells.”

Rudolf VirchowRudolf Virchow – “All cells come from – “All cells come from existing cells.”existing cells.”

The Cell TheoryThe Cell Theory

Schleiden, Schwann, & VirchowSchleiden, Schwann, & Virchow All living things are composed of one All living things are composed of one

or more cells.or more cells. Cells are organisms’ basic units of Cells are organisms’ basic units of

structure & function.structure & function. Cells come from existing cells.Cells come from existing cells.

CELL DIVERSITYCELL DIVERSITY

1. Size1. Size Cells range in size Cells range in size

from .2 um to 2 m.from .2 um to 2 m. Average plant & Average plant &

animal cells are 10 to animal cells are 10 to 50 um in diameter.50 um in diameter.

2. Shape2. Shape Cuboidal & spherical.Cuboidal & spherical.

3. Internal Organization3. Internal Organization Different OrganellesDifferent Organelles

TYPES OF CELLSTYPES OF CELLS EukaryotesEukaryotes – –

Contains a nucleus Contains a nucleus and membrane-bound and membrane-bound organelles.organelles.

ProkaryotesProkaryotes – Lacks – Lacks a nucleus. (bacteria)a nucleus. (bacteria)

OrganelleOrganelle – A cell – A cell component that component that performs specific performs specific functions in the cell.functions in the cell.

ORGANELLESORGANELLES

NucleusNucleus Cell MembraneCell Membrane CytoplasmCytoplasm RibosomesRibosomes Rough Endoplasmic Rough Endoplasmic

ReticulumReticulum Smooth Endoplasmic Smooth Endoplasmic

ReticulumReticulum

Golgi ApparatusGolgi Apparatus MitochondriaMitochondria LysosomesLysosomes Cytoskeleton - Cytoskeleton -

Microtubules & Microtubules & MicrofilamentsMicrofilaments

CiliaCilia FlagellaFlagella

The NucleusThe Nucleus

Directs activities of Directs activities of the cell.the cell.

Contains DNA.Contains DNA. NucleolusNucleolus – synthesis – synthesis

of ribosomes.of ribosomes. Nuclear poresNuclear pores Nuclear envelopeNuclear envelope NucleoplasmNucleoplasm

DNADNA

Deoxyribonucleic acidDeoxyribonucleic acid Encodes information Encodes information

important for the important for the synthesis of proteins.synthesis of proteins.

CYTOPLASMCYTOPLASM

Contains various Contains various organs in the cellorgans in the cell

Gelatin-like fluid Gelatin-like fluid called called cytosolcytosol which which has dissolved salts, has dissolved salts, minerals, and organic minerals, and organic moleculesmolecules

CELL MEMBRANECELL MEMBRANE

Made of lipids & Made of lipids & proteins.proteins.

Provides shape & Provides shape & flexibility.flexibility.

Selectively Selectively PermeablePermeable - a - a complex barrier that complex barrier that keeps out some keeps out some molecules & allows molecules & allows others through.others through.

RIBOSOMESRIBOSOMES

Carry out protein Carry out protein synthesis.synthesis.

Attached ribosomesAttached ribosomes - - attached to Rough attached to Rough ER; produce proteins ER; produce proteins to be exported by the to be exported by the cell.cell.

Free ribosomesFree ribosomes - - produce proteins for produce proteins for the cell.the cell.

ENDOPLASMIC ENDOPLASMIC RETICULUMRETICULUM

Rough Endoplasmic Rough Endoplasmic ReticulumReticulum - (ER) - A - (ER) - A membrane system membrane system covered with covered with ribosomes; aids in ribosomes; aids in protein synthesis.protein synthesis.

Smooth ERSmooth ER - Few or - Few or no ribosomes; no ribosomes; intracellular pathway intracellular pathway for proteins.for proteins.

GOLGIGOLGI APPARATUSAPPARATUS

System of System of membranes.membranes.

Processing, Processing, packaging, & packaging, & secreting organelle secreting organelle of the cell.of the cell.

MITOCHONDRIAMITOCHONDRIA

““Powerhouse of the Powerhouse of the cell.”cell.”

Carries out cellular Carries out cellular respiration.respiration.

LYSOSOMESLYSOSOMES

Contains digestive Contains digestive enzymes.enzymes.

Digests food & Digests food & disease-causing disease-causing bacteria.bacteria.

CYTOSKELETONCYTOSKELETON

Provides a structural Provides a structural framework for the cell.framework for the cell.

MicrotubulesMicrotubules - long, - long, slender protein tubesslender protein tubes

MicrofilamentsMicrofilaments - fine - fine protein threads.protein threads.

CILIA & FLAGELLACILIA & FLAGELLA

Function in movement.Function in movement. Composed of proteins.Composed of proteins. CiliaCilia - small & hair-like; covers entire - small & hair-like; covers entire

surface of the cell.surface of the cell. FlagellaFlagella - long & slender; found singly or in - long & slender; found singly or in

pairs.pairs.

VACUOLESVACUOLES

Store substances Store substances inside the cell.inside the cell.

Plant cells have large Plant cells have large central vacuoles.central vacuoles.

CENTRIOLESCENTRIOLES

Structure that Structure that appears during appears during animal cell divisionanimal cell division

CELL WALLCELL WALL

Only in plant cellsOnly in plant cells Lies outside the cell Lies outside the cell

membranemembrane Supports and protects Supports and protects

the plantthe plant

PLASTIDSPLASTIDS

Convert solar energy Convert solar energy into chemical energy.into chemical energy.

ChloroplastChloroplast - contain - contain green pigmentsgreen pigments

LeucoplastLeucoplast - store - store food, such as food, such as starches.starches.

ChromoplastChromoplast - - synthesize & store synthesize & store other pigments.other pigments.

Plant cells only!!Plant cells only!!

CHLOROPLASTSCHLOROPLASTS

Found in plant cells Found in plant cells onlyonly

Where the energy of Where the energy of sunlight is converted sunlight is converted into chemical energy into chemical energy during photosynthesisduring photosynthesis

Contain green Contain green pigment called pigment called chlorophyllchlorophyll

DIFFERENCES BETWEEN DIFFERENCES BETWEEN PLANT & ANIMAL CELLSPLANT & ANIMAL CELLS

ANIMAL CELLSANIMAL CELLS CentriolesCentrioles Small vacuolesSmall vacuoles

PLANT CELLSPLANT CELLS PlastidsPlastids Large central vacuoleLarge central vacuole Cell WallCell Wall