Discovery of the CellRobert Hooke: 1665-1stperson to see a cellUsed a microscope to look at a piece of corkSaw small, empty “boxes”which reminded him of the small rooms monks lived in called cells.These “cells”weren’t alive.

From Robert Hooke's Micrographia (1667 ed.). National Library of Medicine

1st Living Cells Anton van Leeuwenhoek1st person to see and describe living cells: 1673Made his own microscopesCould magnify 200 times!Described the things he observed as “Animalcules”Wrote many description of his discoveries to the Royal Society in LondoMany of his drawings and descriptions are very accurate even today

From the 1stobservation of the cell by Hooke and Leeuwenhoek it took 150 years to develop a theory that explained them.A lot of reasons for the length of time.Not many people had access to microscopes.Problems with making lenses.Previous knowledge/thoughts about where life came from (spontaneous generation).Development of technology to make lenses allowed for more people to study cells.

Cell Theory Developement

The Cell Theory1.All Living things contain a cell or cells.2.Cells are the basic unit of structure and

function of lifeAnything smaller than a cell can’t be alive

3.Cells come only from other cells.Disproved spontaneous generation.

Two Basic Types of Cells

Prokaryotes&

Eukaryotes

PROKARYOTIC CELLSOnly Unicellular (Single Celled)

DO NOT have a NUCLEUS

Examples include:The Kingdom Monera – Bacteria Only

PROKARYOTIC CELLSDO NOT have a NUCLEUSDO NOT have membrane bound organelles

Information about Prokaryotics

Important FactsEvolved 4 billion years agoNo membrane bound nucleus or organelles

Some have flagella – whip like tailSome have cilia – short, hair like extension

Pro = Before Karyon = Nucleus

Eukaryotic Cells

Only Unicellular or Multicellular

DO HAVE a NUCLEUS

Examples include:The Kingdom Protista, Fungi, Plantae, and Animalia

Eukaryotic Cell

Information about Eukaryotics

Important FactsEvolved 3 billion years later than bacteriaHave membrane bound nuclei and organellesMore complex than ProkaryotesSome unicellular organisms can have flagella

or ciliaEu = True Karyon = Nucleus

What is inside of animal and plant cells?

There are two main types of eukaryotic cells

animal and plant cells

What is inside the eukaryotic cell?

Cell OrganellesOrganelle= “little

organ”Found only inside

eukaryotic cellsEverything in a cell

except the nucleus is cytoplasm

Cell MembraneBoundary of the cellMade of a phospholipid bilayerPart is hydrophobic (water fearing) and part is

hydrophillic (water loving)

The NucleusControl center of

the cellContains DNASurrounded by a

double membraneUsually the easiest

organelle to see under a microscope

Usually one per cell

What is inside the nuclear envelope?

Inside the NucleusChromatin

granular material inside nucleus

Consists of DNA bound to proteins

Chromosomes –what chromatin condenses

to formContains the genetic

nformationNucleolus

Small dense region where assembly of ribosomes begins

Endoplasmic ReticulumA.k.a. “ER”Connected to

nuclear membraneHighway of the cellRough ER: studded

with ribosomes; it makes proteins

Smooth ER: no ribosomes; it makes lipids

RibosomeSite of protein synthesisFound attached to

rough ER or floating free in cytoplasm

Produced in the nucleolus

Two parts to the ribsomeLarge and small subunits

that act together“reads” messagner RNA

and makes polypeptides (proteins)

Golgi ApparatusLooks like a stack

of platesActs like the post

office of the cellModifies, stores and

sorts packages (proteins)

Lysosomes

Garbage disposal of the cell

Contain digestive enzymes that break down wastes

Mitochondria“Powerhouse of the cell”Structure – organelle

with double membranes; the inner membrane has many folds

Cellular respiration occurs here to release energy for the cell to use

Bound by a double membrane

Has its own unique strand of DNA

VacuolesLarge central

vacuole usually in plant cells

Many smaller vacuoles in animal cells

Storage center for the cellcontainer for water,

food, enzymes, wastes, pigments, etc.

CytoskeletonActs as skeleton and

muscleProvides shape and

structureHelps move

organelles around the cell

Made of three types of filamentsMicrotubulesActin filamentsIntermediate filaments

CentrioleAids in cell divisionUsually found only in

animal cellsMade of microtubules

There are additional organelles in plant cells not found in

animal cells

ChloroplastFound only in plant cellsStructure – thylakoid

membranes are stacked; they contain pigments such as chlorophyll

Contains the green pigment chlorophyll

Convert solar energy into chemical energy through photosythesis (makes glucose)

Bound by a double membrane

CHLOROPLAST

Cell WallFound in plant and

bacterial cellsRigid, protective

barrierLocated outside of

the cell membraneMade of cellulose

Movement of Molecules Diffusion –movement of molecules from HIGH to LOW

concentrationsDoes not require energyOsmosis – the diffusion of water

Movement through a membraneFacilitated diffusion -when substances move across

a membrane through specialized protein channels

Active transportActive

transport –movement of molecules in the cell against the gradient (from LOW to HIGH)Requires

energy

Vocabulary to Know

Isotonic = same solute as water

Hypotonic = less solute, more wtaerHypertonic =more solute, less water

Concentration DeterminationMolecules will move until they are equal on each side of the membrane

They will continue to pass back and forth and forth across the membrane staying equal on both sides

hypertonic/hypotonic solutions are determined by comparison of solute on each side of the membrane

Why are cells so small?

The surface of a cell, its membrane, is the site of exchange between its interior and its external environment. This surface must allow sufficient exchange to support the contents of the cell. As an object increases in size its volume increases as the cube of its linear dimensions while surface area increases as the square. As these cubes illustrate the surface area to volume ratio of a small object is larger than that of a large object of similar shape. This ratio limits how large cells can be.

Cell SpecializationCells develop in

different ways to perform different tasksStem cells

Levels of organizationCellsTissuesOrgansOrgans

systems