C7- A View of the CellC7- A View of the Cell

A View of the CellA View of the Cell

7-1 Discovery of Cells7-1 Discovery of Cells 7-2 7-2 Plasma MembranePlasma Membrane 7-37-3

Discovery of CellsDiscovery of Cells

Anton van Anton van Leeuwenhoek used Leeuwenhoek used the first microscope the first microscope early in the 1600s.early in the 1600s.

It revealed the world It revealed the world of microorganisms of microorganisms and cells which are and cells which are the basic unit of an the basic unit of an organism.organism.

Discovery of CellsDiscovery of Cells

Robert Hooke coined Robert Hooke coined the term cell after the term cell after observing cork under observing cork under a microscope.a microscope.

Hooke’s illustration of cork

Discovery of CellsDiscovery of Cells

1838 Matthias 1838 Matthias Schleiden observed Schleiden observed plant cells.plant cells.

Theodor Schwann Theodor Schwann studied animal cells.studied animal cells.

Ideas were Ideas were summarized in the summarized in the Cell Theory.Cell Theory.

Cell TheoryCell Theory

1. All organisms are made of one or more 1. All organisms are made of one or more cells.cells.

2. The cell is the basic unit of structure 2. The cell is the basic unit of structure and organization in organisms.and organization in organisms.

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

Electron MicroscopesElectron Microscopes

Light Microscopes Light Microscopes 1500X1500X

Dev new EM in 1930s Dev new EM in 1930s & 40s& 40s

Uses beam of Uses beam of electrons to multiply electrons to multiply image 500,000Ximage 500,000X

Lets us see internal Lets us see internal cell structurecell structure

Scanning vs. Transmission EMScanning vs. Transmission EM

Scan surface of cell Scan surface of cell for 3D imagefor 3D image

Study internal Study internal structure of cellstructure of cell

Two Basic Cell TypesTwo Basic Cell Types

All cells contain All cells contain specialized structures specialized structures called called organelles.organelles.

Eukaryotes have Eukaryotes have membrane-bound membrane-bound organellesorganelles

Prokaryotes do notProkaryotes do not Some eukaryotes are Some eukaryotes are

unicellular like unicellular like amoebas.amoebas.

Two Basic Cell TypesTwo Basic Cell Types

Robert Brown Robert Brown observed eukaryotes observed eukaryotes had a prominent had a prominent structure.structure.

Rudolf Virchow said it Rudolf Virchow said it was responsible for was responsible for cell division.cell division.

Eventually the Eventually the structure was called structure was called the nucleus or cell’s the nucleus or cell’s control center.control center.

7.2 Plasma Membrane7.2 Plasma Membrane

Responsible for controlling what goes in and out Responsible for controlling what goes in and out of the cell.of the cell.

Plasma MembranePlasma Membrane

Maintains Maintains homeostasis by homeostasis by selective selective permeability permeability keeping keeping some things in and some things in and keeping others outkeeping others out

Plasma Membrane StructurePlasma Membrane Structure

Phospholipid BilayerPhospholipid Bilayer Glycerol backbone, 2 Glycerol backbone, 2

fatty acids & a fatty acids & a phosphate group phosphate group make a phospholipid.make a phospholipid.

Water is attracted to Water is attracted to the head but not to the head but not to the lipid fatty acids.the lipid fatty acids.

Plasma Membrane StructurePlasma Membrane Structure

Fluid Mosaic Model Fluid Mosaic Model because because phospholipids ripple phospholipids ripple like water with the like water with the currents.currents.

Protein molecules Protein molecules float like boats on the float like boats on the surface in a mosaic surface in a mosaic pattern.pattern.

FlexibleFlexible

Other componentsOther components

CholesterolCholesterol stabilizes the stabilizes the phospholipids by phospholipids by keeping the the tails keeping the the tails from sticking togetherfrom sticking together

Transport proteins Transport proteins span the membrane span the membrane to move needed to move needed substances in and substances in and wastes out of the cell.wastes out of the cell.

7.3 Eukaryotic Cell Structure7.3 Eukaryotic Cell Structure

Each component has Each component has a specific function.a specific function.

They work together to They work together to help the cell survive.help the cell survive.

Cell wall Cell wall fairly rigid fairly rigid part of plant cells, part of plant cells, bacteria & protists bacteria & protists made of cellulose.made of cellulose.

Eukaryotic Cell StructureEukaryotic Cell Structure

NucleusNucleus Cell ControlCell Control Contains directions Contains directions

for making proteins in for making proteins in chromatin.chromatin.

Strands of genetic Strands of genetic material, DNAmaterial, DNA

Chromatin condenses Chromatin condenses to chromosomes to chromosomes before cell divisionbefore cell division

Eukaryotic Cell StructureEukaryotic Cell Structure

NucleolusNucleolus Makes ribosomesMakes ribosomes Ribosomes Ribosomes are are

production site of production site of proteins made by proteins made by direction of DNAdirection of DNA

They’re made of RNA They’re made of RNA and must travel to the and must travel to the cytoplasmcytoplasm to build to build proteins.proteins.

The nucleolus makesThe nucleolus makes ribosomes ribosomes which are which are the site of protein the site of protein synthesis.synthesis.

Ribosomes must Ribosomes must travel out of the travel out of the nucleus to the nucleus to the Cytoplasm Cytoplasm where they where they build the proteins build the proteins according to DNAs according to DNAs direction.direction.

Eukaryotic Cell StructureEukaryotic Cell Structure

CytoplasmCytoplasm Clear, gelatinous fluid Clear, gelatinous fluid

inside a cellinside a cell Ribosomes and RNA Ribosomes and RNA

pass through nuclear pass through nuclear pores in the pores in the nuclear nuclear envelopeenvelope to enter the to enter the cytoplasmcytoplasm

Eukaryotic Cell StructureEukaryotic Cell Structure

Assembly, transport & Assembly, transport & storagestorage

Endoplasmic Endoplasmic reticulum reticulum site of site of cellular chemical cellular chemical reactionsreactions

Highly folded Highly folded membrane which membrane which ribosomes attach to ribosomes attach to (Rough ER) do (Rough ER) do protein synthesisprotein synthesis

Eukaryotic Cell StructureEukaryotic Cell Structure

Each protein has a Each protein has a specific function.specific function.

Smooth ER has no Smooth ER has no ribosomes but makes ribosomes but makes and stores lipids.and stores lipids.

After proteins are After proteins are made they’re sent to made they’re sent to the the Golgi ApparatusGolgi Apparatus

Eukaryotic Cell StructureEukaryotic Cell Structure

Golgi ApparatusGolgi Apparatus Modifies proteins & Modifies proteins &

sorts them into sorts them into packages (packages (vesiclesvesicles) ) for transport to their for transport to their destinationdestination

Eukaryotic Cell StructureEukaryotic Cell Structure

Vacuoles Vacuoles membrane membrane bound compartment bound compartment for temporary storagefor temporary storage

Stores food, enzymes Stores food, enzymes & other needed & other needed materials.materials.

Animal cells may also Animal cells may also have vacuoles usually have vacuoles usually smaller.smaller.

Eukaryotic Cell StructureEukaryotic Cell Structure

Lysosomes Lysosomes contain contain digestive enzymes.digestive enzymes.

Used to digest worn Used to digest worn out organelles, food out organelles, food particles or engulfed particles or engulfed viruses or bacteria.viruses or bacteria.

The membrane The membrane prevents enzymes prevents enzymes from destroying the from destroying the cell.cell.

Eukaryotic Cell StructureEukaryotic Cell Structure

Energy TransformersEnergy Transformers Chloroplasts Chloroplasts capture capture

light energy & convert light energy & convert it to chemical energy.it to chemical energy.

Eukaryotic Cell StructureEukaryotic Cell Structure