CYTOLOGY: CYTOLOGY: Cell structure and Cell structure and functionfunction

Robert HookeRobert Hooke The first person to The first person to

identify and see identify and see cells. 1665.cells. 1665.

Coined the term “cell”Coined the term “cell”

The cell theoryThe cell theory

Cells are the basic units of lifeCells are the basic units of life.. All living things are made up of cells.All living things are made up of cells. All cells are produced by existing cells.All cells are produced by existing cells.

Cell types.Cell types.

They are either They are either PROKARYOTICPROKARYOTIC or or EUKARYOTICEUKARYOTIC cells. cells.

KaryonKaryon means means ‘kernal’‘kernal’

EuEu means ‘true’ means ‘true’ ProPro means “before” means “before”

Prokaryotic CellsProkaryotic Cells

Kingdoms:Kingdoms:1.1. EubacteriaEubacteria2.2. ArchaebacteriaArchaebacteria

Characteristics:Characteristics:1.1. lacklack a nuclear membrane. a nuclear membrane.2.2. have have nono membrane- membrane-bound organelles.bound organelles.3. “naked” genetic material.3. “naked” genetic material.

Prokaryotic Cell - Bacteria

Eukaryotic CellsEukaryotic Cells Kingdoms:Kingdoms:

1.1. ProtistaProtista

2.2. FungiFungi

3.3. PlantaePlantae

4.4. AnimaliaAnimalia Characteristics:Characteristics:

1.1. havehave a nuclear membrane around a nuclear membrane around genetic material “nucleus”genetic material “nucleus”

2.2. havehave specialized membrane-bound specialized membrane-bound organellesorganelles

8

EukaryotesEukaryotes ProkaryotesProkaryotes

DNADNA linear strands within linear strands within membrane-bound nucleusmembrane-bound nucleus

single circle in “nucleoid single circle in “nucleoid regionregion

SizeSize 5-100 µm5-100 µm 0.2-10 µm0.2-10 µm

OrganizationOrganization often multicellular, some have often multicellular, some have cell walls (no peptidoglycan) cell walls (no peptidoglycan)

usually single-celled, usually single-celled, some have peptidoglycan some have peptidoglycan

cell wallscell walls

MetabolismMetabolism usually need oxygen to existusually need oxygen to exist may not need oxygen to may not need oxygen to existexist

OrganellesOrganelles membrane bound organelles membrane bound organelles like mitochondrialike mitochondria

no organelles, different no organelles, different ribosomesribosomes

ExamplesExamples plants, animals, protists, fungiplants, animals, protists, fungi bacteria, archaeabacteria, archaea

Eukaryotic - Eukaryotic - Animal CellAnimal Cell

Eukaryotic - Plant Cell

Cellular EvolutionCellular Evolution

Current evidence indicates that Current evidence indicates that eukaryoteseukaryotes evolved from evolved from prokaryotesprokaryotes between 1 and 1.5 between 1 and 1.5 billion years ago.billion years ago.

Two theories:Two theories:

1.1. Infolding theoryInfolding theory

2.2. Endosymbiotic theoryEndosymbiotic theory

1. Infolding Theory1. Infolding Theory

The infolding of the The infolding of the prokaryoticprokaryotic plasma plasma membranemembrane gave rise to gave rise to eukaryoticeukaryotic organellesorganelles..

2. 2. Endosymbiotic theoryEndosymbiotic theory EndosymbiosisEndosymbiosis refers to refers to

one species living within one species living within another - the host.another - the host.

TheoryTheory - the movement of - the movement of smaller smaller photosyntheticphotosynthetic (chloroplast)(chloroplast) and and heterotrophic heterotrophic (mitochondria)(mitochondria) prokaryotesprokaryotes into larger into larger prokaryotic host cellsprokaryotic host cells..

CytoplasmCytoplasm

Entire regionEntire region between the between the nuclear membranenuclear membrane and the and the cell (plasma) membranecell (plasma) membrane..

This includes all organelles!This includes all organelles! Buildings, factory layout, matrixBuildings, factory layout, matrix

cytoplasm

CytosolCytosol

The The semi-fluid semi-fluid mediummedium found in found in the the cytoplasmcytoplasm..

This does not This does not include the include the organelles.organelles.

School grounds,School grounds, city area.city area.

NucleusNucleus A A double membranedouble membrane

organelle which organelle which contains the coded contains the coded instructions for making instructions for making proteins.proteins.

Found only in Found only in eukaryoteseukaryotes..

Contains DNA, DNA, also also calledcalled chromatin. chromatin. (Blueprints)(Blueprints)

principal, mayor, control principal, mayor, control centercenter

NucleolusNucleolus Spherical region in Spherical region in

nucleusnucleus.. Produces theProduces the

ribosomesribosomes.. Sometimes more than Sometimes more than

one nucleolus present.one nucleolus present. Training center, machine Training center, machine

shopshop nucleolus

RibosomesRibosomes NuclearNuclear and and cytoplasmiccytoplasmic

organelle.organelle. Composed of Composed of 60% 60%

proteinprotein and and 40% 40% ribosomal-RNA (rRNA).ribosomal-RNA (rRNA).

Site ofSite of protein synthesisprotein synthesis.. Either free or attached.Either free or attached. Machines, teachers, law Machines, teachers, law

enforcersenforcers

Endoplasmic Reticulum Endoplasmic Reticulum (ER)(ER)

Extensive membranous Extensive membranous network of tubules and network of tubules and sacs.sacs.

Two distinct regions:Two distinct regions:

A.A. Rough Rough endoplasmic reticulum endoplasmic reticulum (RER).(RER).

B.B. Smooth Smooth endoplasmic reticulum endoplasmic reticulum (SER).(SER).

Endoplasmic ReticulumEndoplasmic ReticulumA. Rough endoplasmic reticulum (RER).A. Rough endoplasmic reticulum (RER).

1. Studded with 1. Studded with ribosomesribosomes..2. Site of 2. Site of protein modification.protein modification.

Classrooms, assembly line, roadwayClassrooms, assembly line, roadway

B. Smooth endoplasmic reticulum (SER).B. Smooth endoplasmic reticulum (SER).1. Synthesizes lipids, phosolipids and steroids.1. Synthesizes lipids, phosolipids and steroids.2. Detoxifies drugs, alcohol and poisons.2. Detoxifies drugs, alcohol and poisons.

Detox center, water treatment plant, detention Detox center, water treatment plant, detention hall.hall.

Golgi Apparatus, Body or Golgi Apparatus, Body or ComplexComplex

A A stacked, flattened stacked, flattened membranous membranous organelleorganelle of sacs. of sacs.

Modifies, stores Modifies, stores and routes and routes productsproducts from the from the ERER to the to the plasma plasma membranemembrane..

Shipping department, Shipping department, post officepost office

LysosomesLysosomes

Membrane-enclosed bag of Membrane-enclosed bag of hydrolytic hydrolytic enzymesenzymes (digestive enzymes).(digestive enzymes).

Functions:Functions: PhagocytosisPhagocytosis - intracellular digestion - intracellular digestion AutophagyAutophagy - engulfs other cellular organelles - engulfs other cellular organelles ApoptosisApoptosis – Programmed cell death – Programmed cell death

Janitors, recycling binsJanitors, recycling bins

VacuolesVacuoles Large membrane-Large membrane-

enclosed sacs for enclosed sacs for cellular storage.cellular storage.

Three types:Three types:

1.1. Food vacuole Food vacuole (lysosomes attach)(lysosomes attach)

2.2. Contractile Contractile vacuole (Protozoans)vacuole (Protozoans)

3.3. Central Water Central Water Vacuole (mature plant Vacuole (mature plant cells)cells)

Water pump, storage Water pump, storage sheds, refrigerator.sheds, refrigerator.

Cell MembraneCell Membrane The The boundaryboundary of every cell, also called the plasma of every cell, also called the plasma

membrane.membrane. Semi-permeableSemi-permeable, acts as a , acts as a selective barrierselective barrier.. Fence with gates, moat with bridges, security systemFence with gates, moat with bridges, security system

Cell WallCell Wall

Strong fibersStrong fibers surrounding surrounding plant, plant, fungi, some protista fungi, some protista and most bacteria and most bacteria cells.cells.

Composed of Composed of polysaccharides and polysaccharides and proteinsproteins, gives the cell , gives the cell shape.shape.

Boundary lines, open Boundary lines, open fences, structural fences, structural supports.supports.

MitochondriaMitochondria

A A doubled membrane cellular organelledoubled membrane cellular organelle with its with its own own circular DNAcircular DNA found in found in both plants and both plants and animalsanimals..

It is the site of It is the site of cellular respirationcellular respiration, an , an oxygenoxygen requiring process that uses energy extracted from requiring process that uses energy extracted from organic macromolecules (like glucose)organic macromolecules (like glucose) to to produceproduce energy energy for the cell in the form offor the cell in the form of ATPATP..

Power plant, generator, battery.Power plant, generator, battery.

MitochondriaMitochondria

ChloroplastChloroplast

A A doubled membrane cellular organelledoubled membrane cellular organelle with its with its own own circular DNAcircular DNA found found only in plantsonly in plants..

The site of The site of photosynthesisphotosynthesis, a , a carbon dioxidecarbon dioxide requiring process the uses requiring process the uses light energy (sun)light energy (sun) and and waterwater to produce to produce glucose, glucose, which the cell will use for energy. energy.

Cafeteria, restaurants, solar panels.Cafeteria, restaurants, solar panels.

ChloroplastChloroplast

There is always an There is always an exception……exception……

Elysia chlorotica

CytoskeletonCytoskeleton Network of Network of fibersfibers through out the cytoplasm. through out the cytoplasm. Aids in Aids in cellular support and movementcellular support and movement..

• Framework, scaffolding, roadwaysFramework, scaffolding, roadways

Cilia and FlagellaCilia and Flagella

Extensions of the Extensions of the plasma membraneplasma membrane..

Used for movement Used for movement or to move food to or to move food to an oral groove.an oral groove.

Plastids Plastids (I)(I) Primary function of plastidsPrimary function of plastids is to is to

store moleculesstore molecules. . One molecule that they store is One molecule that they store is

pigmentpigment; pigments give fruits ; pigments give fruits and vegetables an orange or red and vegetables an orange or red color.color.

Plastids also store Plastids also store photosynthetic products like photosynthetic products like starchstarch. Chloroplasts are plastids. . Chloroplasts are plastids.

Potatoes, for example, have Potatoes, for example, have many plastids in their cells.many plastids in their cells.

Warehouses, study halls, Warehouses, study halls, storage drums.storage drums.