Introduction toCytology or Cell Biology

How do we observe cells?Light microscopeVisible light passes through objectLens magnify image

Electron microscopeScanning - surface of objectTransmission - sees through objects100,000 X to Millions magnification power

How do we know what happens in each part of the cell?Radioisotopes are used to "trace" different chemical reactions through a cell.

Separate cellular structures with a blender

Centrifuge material and analyze each layer.

People who were important in early cell discovery:

Zacharias Jannsen (1590)Helped invent the First compound microscope

Robert Hooke (1665) Observed dead cork - called them cellsCompound Microscope

Anton Von Leeuwenhoek (1674) - living cells in pond water; one celled organisms -- animalcules

Robert Brown (1831) identifies the nucleus of a cell

Mattias Scleiden (1838) stated that plants are made up of cells

Theodor Schwann (1839)stated that animals are made up of cells

Rudolph Virchow (1858) Studied the pathology of cells. (ability to cause disease)

All cells arise from preexisting cells. New cells can only arise from other living cells by the process of cell division or reproduction

Cell TheoryAll living things are composed of cells

Cells are the fundamental building block of life

All cells come from pre-existing cells (life begets life)

PROCESSES OF CELLSAll life processes involve energy changes.

1. Nutrition - food is needed for energy and building materials.

2. Digestion - breaking down reactions of food into usable parts.

3. Absorption - water, food, ions and other materials

4. Biosynthesis - cells organize many organic substances for cell activity. 5. Respiration - cell energy is released when certain organic molecules are split - energy is used for cell activity.

6. Excretion - waste materials passed from cell to environment

7. Secretion - synthesized molecules which are passed out of a cell and which affect the activities of other cells (vitamins, hormones)

8. Reproduction - cells divide; unicellular - more organisms, multicellular - more cells.

9. Movement - motion of all types; cellular contractions, flowing substances within the cell

10. Egestion - elimination of insoluble compounds and nondigestible particles

Eukaryotic cells advanced cellsHave nucleusPlasma membraneCytoplasm - everything between plasma membrane and nucleusOrganellesFluidCytoskeleton threads of microtubules and microfilaments in cytoplasm

Animal vs Plant CellAnimal cells have unique structuresCentriolesLysosomeFlagellum 1. 2.

3. Plant cells have unique structures Large central vacuoleCell wall 1. 2. Chloroplasts

3.

MitochondrionPlasma MembraneCell WallCentral VacuoleVesicleRibosomesEnvelopeDNA NucleolusCytoskeleton FibresChloroplast Pore Golgi BodySmooth ER Rough sdfERMitochondrion

Centriole

Plasma Membrane

Protein Marker

Sugar Chain Lipid BilayerCholesterol ProteinsEmbedded ProteinOUTSIDE OF CELLINSIDE OF CELL

Cell Membrane Side Profile

Different membranes

All have similar functions & structuresPlasma membrane separates inside of cell from outside of cellOther membrane define organelles to form compartments of eukaryotic cells

Forms a selectively permeable layerLets some things in or out but not allLike a window screen

Nucleus

EnvelopeDouble membranePores to get messages in and outChromatinDNA threadsProtein balls called histones - wrappingNucleolus - site of ribosome production

Nucleus - Structures

Nucleolus where rRNA or Ribosomes are made

Ribosomes

Consists of 2 parts, which are made in nucleus

Make protein in the Cytoplasm

Produce proteins from recipes in the nucleus copied into mRNASome (proteins) will remain in cytoplasmSome will be exported out of cellSome will attach to membranes in cell

Ribosomes are found on the endoplasmic reticulum and in the cytoplasm

Endoplasmic ReticulumRough ERSmooth ER

Rough Endoplasmic ReticulumRough ER - attached to nucleus

Ribosomes stud surface

Produces Membrane proteins - stay in cellSecretory proteins - exported from cell

RER makin Proteins!

Smooth Endoplasmic ReticulumNo ribosomes, so not protein factoriesMore like transport systemMakes steroids, lipidsLiver cells have lots of smooth ERDetoxify chemicalsSupply and demandIncreases tolerance to drugSo higher doses needed for same effect

Golgi apparatus the Post Office of the Cell

Refines, stores and marks molecules for shipmentLooks like stack of hollow pancakesProducts of ER arrive & leave via transport vesiclesMoving from one sac to the nextMolecules get modifiedLabeled and / or storedCalled the cell Post office because it marks and directs products in the cell

Golgi apparatus what it does

Lysosome

Greek for breakdown bodyRecylcerSac of strong digestive enzymesCompartmentalized for safetyCan release to breakdown entire cell suicide sackFunctionsDigest food vacuolesDigest invading bacteriaDigest old organelles

Lysosome

Lysosome

Lysosomal diseasesGenetic disordersRecipe is messed up so protein doesnt workIf recipe for lysosome enzymeWhat should get broken down doesntEx. Tay Sachs Lipids arent broken downBuild up occursEventually causes deathUsually in before age 5

Mitochondria

MitochondriaSite of cellular respirationConversion of food into energy (ATP)ATP is what cells use to make things happen (drive chemical reactions)Double membraneBig bag stuffed in smaller bagFolds of inner bag called cristaeSpace inside inner bag called matrixAlso once free living bacteriaEfficiency - gasoline engines converts 25% of energy mitochondria converts 54% of energy

contains some of its own DNA (amount varies within organisms) believed to evolved from a primitive cell engulfing it and creating a symbiotic relationship DNA in mitochondria obtained only from mother of organism.

Plant Organelles Chloroplasts - in plantsChloroplast1. chlorophyll is green chemical that releases electrons, working like a solar panel in sunlight

2. forms glucose

3. photosynthesis 6CO2 + 6H2 O ---> C6H12 O6 + 6O2

Chloroplasts

Structure of ChloroplastDouble membraneGranaStack of thylakoidsHollow diskWhere sunlight energy is captured and converted to chemical energyStromaThick fluid filling chloroplastContains some DNAOnce free-living bacteria

Cytoskeleton

Actin filamentsMicrotubules

Network of fibers

Give shape to cellsAllow movement of cellMove organelles aroundMade of microtubules and microfilaments

Role of the Cytoskeleton

Cilia

Flagella

9+2 Arrangment in Cilia or Flagella

Basal Body of a Flagella or CiliaNote the triplet rings of tubulin protein

9+0 arrangementNine sets of rings, with no set in middleUsed to set up 9+2 arrangment in cilia or flagella

CentriolesCell reproduction; goes to poles of cell during cell division and helps cell divide

Centrioles at Work in Cell Division

Cell SpecializationDifferent kinds of cells suited for a different activity.

Division of LaborDifferent cells divide their labor each has a specific function and supports each other.

Levels of structure1. Cell2. Tissue3. Organ4. Organ system5. Organism

Tissue Level A group of cells that are alike in structure and activity in an organism muscles

- Skeletal muscle cells motion- Cardiac muscle cells heartbeat- Bones - support- Nerve cells - coordination, perception and automatic body functions

Organ Level several tissues working as a unitheartAnimalsbrain stomachroots Plantsstemleaf

Organ Systemmany organs involved in carrying out a function

digestive nervous skeletal excretory respiratoryendocrine (hormones)circulatory muscularreproductive

Organism complete living thingcell tissueorganorgan systemorganismINCREASING SIZE