Chapter 2Chapter 2

CellCell

History of CytologyHistory of Cytology

Anton Van LeeuwenhoekAnton Van Leeuwenhoek – invented – invented microscope – discovered the microscope – discovered the presence of presence of cellcell while observing a while observing a drop of rainwaterdrop of rainwater. .

Robert HookeRobert Hooke – invented a compound – invented a compound microscope – coined the word “cell” – microscope – coined the word “cell” –

Robert BrownRobert Brown - he discovered the - he discovered the nucleusnucleus of the cell.of the cell.

Matthias Scheiden (Matthias Scheiden (BotanistBotanist) & Theodore ) & Theodore Schwann (Schwann (ZoologistZoologist) concluded that plants ) concluded that plants and animals are made up of cells.and animals are made up of cells.

Rudolf VirchowRudolf Virchow – Considered cells – Considered cells as the basic units of structure and as the basic units of structure and function – discovered the process of function – discovered the process of cell divisioncell division – cells came from the – cells came from the division of pre-existing cells.division of pre-existing cells.

Walter FlemingWalter Fleming – he discovered – he discovered aster formationaster formation and condensation of and condensation of the the chromatinschromatins

Peirre-Joseph Van BenedenPeirre-Joseph Van Beneden – he – he discovered discovered meiosismeiosis..

History of CytologyHistory of Cytology

Parts of the Parts of the Cell TheoryCell Theory

(Rudolf Virchow)(Rudolf Virchow) The cell is the unit of structure in The cell is the unit of structure in

all living things. all living things. The cell is the unit of function in The cell is the unit of function in

all living things. all living things. All cells come from preexisting All cells come from preexisting

cells. cells.

Generalized Functions of the Generalized Functions of the CellCell

IrritabilityIrritability – the ability to respond – the ability to respond to stimuli. to stimuli.

ContractilityContractility – the ability to – the ability to change shape.change shape.

AbsorptionAbsorption – is the imbibitions of – is the imbibitions of substances for assimilation by substances for assimilation by the cellthe cell

Secretion & ExcretionSecretion & Excretion – are – are processes involved when the cell processes involved when the cell excludes material. excludes material.

RespirationRespiration – the process involved – the process involved in the release of energy through the in the release of energy through the biological oxidation of food. biological oxidation of food.

ReproductionReproduction – is the increase in – is the increase in the number of cells through cell the number of cells through cell division. division.

Generalized Functions of the Generalized Functions of the CellCell

Cell SizeCell Size

MacroscopicMacroscopic – cells that are big – cells that are big enough to be seen by unaided enough to be seen by unaided eyes. eyes. Example Example

Frog’s egg cellFrog’s egg cell Chicken eggChicken egg

MicroscopicMicroscopic - - ExampleExample

Liver cell – 7 micronsLiver cell – 7 microns Blood cellBlood cell

ShapeShape

SphericalSpherical – – round or ovalround or oval

SquamousSquamous – flat – flat & tile-like& tile-like

CuboidalCuboidal – – Square & Square & equidimensionalequidimensional

ColumnarColumnar – – rectangular, rectangular, uprightupright

FusiformFusiform – – Tapering at both Tapering at both endsends

ShapeShape

StellateStellate – Star- – Star-likelike

SpiderlikeSpiderlike – – oval shaped oval shaped surrounded with surrounded with cytoplasmic cytoplasmic extensionsextensions

ShapeShape

NetlikeNetlike –, –, Branching & Branching & interlacinginterlacing

FilamentousFilamentous – – Threadlike & Threadlike & longlong

AmorphousAmorphous – – irregular, no irregular, no definite shapedefinite shape

ShapeShape

Animal CellAnimal CellNuclear poreNuclear Membrane

NucleolusChromatins

Nu

cle

us

Centriole

Pinocytic Vesicle

Lysosome

Cytoplasm

Cell MembraneVacuole

Ribosomes

Mitochondrion

SmoothEndoplasmicReticulum

Golgi Complex

RoughEndoplasmicReticulum

Nucleoplasm

Cell membraneCell membrane

--selectively regulates the materials selectively regulates the materials moving to and from the cellmoving to and from the cell

Cell WallCell Wall

– – present only in plant cellspresent only in plant cells StructureStructure

   - a non-living secretion of the cell membrane,    - a non-living secretion of the cell membrane, composed ofcomposed of cellulosecellulose

      - cellulose fibrils deposited in alternating - cellulose fibrils deposited in alternating layers for strengthlayers for strength

      - contains pits (openings) that make it totally - contains pits (openings) that make it totally permeablepermeable

FunctionFunction    - provides protection from physical injury   - provides protection from physical injury    - together with vacuole, provides skeletal    - together with vacuole, provides skeletal supportsupport

NucleusNucleusThe nucleus consists of The nucleus consists of

the nuclear envelope, the nuclear envelope, nucleolus, chromatin, nucleolus, chromatin, and nucleoplasm.and nucleoplasm.

Nuclear EnvelopeNuclear Envelope Structure Structure

-two unit membranes -two unit membranes with a fluid-filled spacewith a fluid-filled space

--nuclear poresnuclear pores present present -outer membrane may -outer membrane may

be continuous with be continuous with endoplasmic reticulumendoplasmic reticulum

Function Function -selectively permeable -selectively permeable

to control movement to control movement in or outin or out

-contains nuclear -contains nuclear contentscontents

ChromosomesChromosomes

Structure Structure -composed of -composed of

long thin long thin strands of DNAstrands of DNA

Function Function -contains -contains

instructions instructions that control cell that control cell metabolism and metabolism and heredityheredity

NucleolusNucleolus

Structure Structure -non-membraneous -non-membraneous

matrix of RNA matrix of RNA (ribonucleic acid)(ribonucleic acid) and and proteinprotein

Function Function - instructions in DNA - instructions in DNA

are copied hereare copied here - works with - works with

ribosomes in the ribosomes in the synthesis of proteinsynthesis of protein

CentrioleCentriole

Structure Structure - nine triplets of - nine triplets of

microtubules form microtubules form one centrioleone centriole

- two centrioles form - two centrioles form one centrosomeone centrosome

Function  Function  - forms spindle - forms spindle

fibres to separate fibres to separate chromosomes chromosomes during cellduring cell divisiondivision

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER)

Structure Structure - sheets of unit - sheets of unit

membrane with membrane with ribosomes on the on the outsideoutside

- forms a tubular - forms a tubular network throughout network throughout the cellthe cell

   Function Function - transports - transports

chemicals between chemicals between cells and within cellscells and within cells

- provides a large - provides a large surface area for the surface area for the organizationorganization of of chemical reactions chemical reactions and synthesisand synthesis

RibosomeRibosome

Structure Structure - non-membraneous, - non-membraneous,

spherical bodies spherical bodies composed ofcomposed of RNA RNA (ribonucleic acid) and (ribonucleic acid) and protein enzymesprotein enzymes

Function Function - site of protein - site of protein

synthesissynthesis

Golgi ApparatusGolgi Apparatus

Structure Structure - stacks of flattened - stacks of flattened

sacs of unit membrane sacs of unit membrane - vesicles pinch off the - vesicles pinch off the

edgesedges

Function Function - modifies chemicals to - modifies chemicals to

make them functionalmake them functional - secretes chemicals in - secretes chemicals in

tiny vesiclestiny vesicles - stores chemicals- stores chemicals - may produce - may produce

endoplasmic reticulumendoplasmic reticulum

MitochondrionMitochondrion Structure Structure - composed of modified double unit - composed of modified double unit

membrane (protein, lipid)membrane (protein, lipid) - inner membrane infolded to form - inner membrane infolded to form cristaecristae Function Function - site of cellular respiration ie. the release - site of cellular respiration ie. the release

of chemicalof chemical energy from foodenergy from food Glucose  +  Oxygen  ------>Glucose  +  Oxygen  ------> Carbon Dioxide  +  Water  + Energy (ATP)Carbon Dioxide  +  Water  + Energy (ATP)

LysosomeLysosome

Structure Structure - membrane bound bag - membrane bound bag

containing hydrolytic containing hydrolytic enzymesenzymes

- hydrolytic enzyme = (water - hydrolytic enzyme = (water split biological catalyst)split biological catalyst) i.e. using water to split i.e. using water to split chemical bondschemical bonds

Function Function - break large molecules into - break large molecules into

small molecules bysmall molecules by inserting inserting a molecule of water into the a molecule of water into the chemical bondchemical bond    

Microfilaments/NeurotubulesMicrofilaments/Neurotubules

- system of transport for - system of transport for materials within a neuron and materials within a neuron and may be used for structural may be used for structural supportsupport

VacuoleVacuole

StructureStructure    - a single layer of unit membrane    - a single layer of unit membrane enclosing fluid inenclosing fluid in a sacka sack

FunctionFunction    - produces turgor pressure against    - produces turgor pressure against cell wall for supportcell wall for support    - stores water and various chemicals   - stores water and various chemicals    - may store insoluble wastes   - may store insoluble wastes

food vacuolefood vacuole -stores and digests food-stores and digests food contractile vacuolecontractile vacuole -pumps out wastes and -pumps out wastes and

excess water from the excess water from the cellcell

ChloroplastChloroplast

StructureStructure    - composed of a double layer of modified membrane    - composed of a double layer of modified membrane (protein, chlorophyll, lipid)(protein, chlorophyll, lipid)    - inner membrane invaginates to form layers called "grana"   - inner membrane invaginates to form layers called "grana" (sing., granum) where chlorophyll ((sing., granum) where chlorophyll (greengreen) is concentrated) is concentrated

Function - site of photosynthesisFunction - site of photosynthesis                                                                                       chlorophyllchlorophyll

  Carbon Dioxide + Water   Carbon Dioxide + Water ------------------->-------------------> Glucose + Oxygen Glucose + Oxygen + + radiant energy   (food)radiant energy   (food)

ChromoplastsChromoplasts have carotenoids, which impart have carotenoids, which impart redred-to--to-yellowyellow colors to plant parts, but no chlorophyll. colors to plant parts, but no chlorophyll.

AmyloplastsAmyloplasts have no pigments. They store starch have no pigments. They store starch grains in plant parts such as potato tubers.grains in plant parts such as potato tubers.

Two Types of vacuoleTwo Types of vacuole

1. Food vacuole1. Food vacuole -stores and digests food-stores and digests food 2. Contractile vacuole2. Contractile vacuole -pumps out wastes and excess -pumps out wastes and excess

water from the cellwater from the cell

Nucleus control center of the cell contains DNA which directs the synthesis of proteins by the cell

Mitochondrion carries on the process of cell respiration converting glucose to ATP energy the cell can use

Endoplasmic Reticulum transport channels within the cell

Ribosome found on the endoplasmic reticulum and free within the cell  responsible for the synthesis of proteins for the cell

cell membrane selectively regulates the materials moving to and from the cell

Food Vacuole stores and digests food

Contractile vacuoleContractile vacuole pumps out wastes and excess water from the cell

Chloroplastfound in plant cells and algae  carries on the process of photosynthesis

Cell wall surrounds and supports plant cells

Some Cell Organelles

Cell Organelle Function

nucleuscontrol center of the cell contains DNA which directs the synthesis of proteins by the cell

mitochondrioncarries on the process of cell respiration converting glucose to ATP energy the cell can use

endoplasmic reticulum transport channels within the cell

ribosomefound on the endoplasmic reticulum and free within the cell  responsible for the synthesis of proteins for the cell

cell membrane selectively regulates the materials moving to and from the cell

food vacuole stores and digests food

contractile vacuole pumps out wastes and excess water from the cell

chloroplastfound in plant cells and algae  carries on the process of photosynthesis

cell wall surrounds and supports plant cells

Plant Cell Animal CellPlant Cell Animal Cell

Vacuole

Thylakoidmembrane

Starch grain

Ch

loro

plast

Plasmodesmata

Cell Wall

THE ENDTHE END NEXT MEETING - EXAMNEXT MEETING - EXAM

http://www.cellsalive.com/http://www.cellsalive.com/cells/cell_model.htmcells/cell_model.htm