Discovery of the Cell Robert Hooke: 1665- 1stperson to see a cell Used a microscope to look at a...
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Transcript of Discovery of the Cell Robert Hooke: 1665- 1stperson to see a cell Used a microscope to look at a...
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