Cell StructuresCell Structures

Cell UnitCell Unit

Discovery of CellsDiscovery of Cells

Robert Hooke (1660’s)– first to observe non-living cells in cork

and named them cells Anton van Leeuwenhoek (1680’s)

– first to observe living cells in lake water and teeth scrapings

The Cell TheoryThe Cell Theory

Developed by Schleiden, Schwann, and Virchow (1800’s)

Important points:– All living things are made of one or more

cells.– Cells are the basic unit of structure and

function in living things.– All cells come from other cells.

2 Basic Types of Cells2 Basic Types of Cells

ProkaryotesProkaryotes (prokaryotic cells) (prokaryotic cells)– Cells that Cells that DO NOTDO NOT have a have a nucleusnucleus– Examples: bacteriaExamples: bacteria

EukaryotesEukaryotes (eukaryotic cells) (eukaryotic cells)– Cells that Cells that DODO have a have a nucleusnucleus and and

other organellesother organelles– Examples: plant cells and animal Examples: plant cells and animal

cellscells

Cell StructuresCell Structures

Specialized structures that perform Specialized structures that perform specific functions in the cell are specific functions in the cell are called organelles.called organelles.

Organelle means “little organ”.Organelle means “little organ”.

Cell WallCell Wall Physical Description: Physical Description: a rigid layer of a rigid layer of

nonliving material that surrounds plant nonliving material that surrounds plant cellscells

Function: Function: protects and supports the protects and supports the cellcell

Type of Cell: Type of Cell: Found in plant cellsFound in plant cells Analogy: Analogy: Walls of schoolWalls of school

Cell MembraneCell Membrane Physical Description: Physical Description: thin, flexible thin, flexible

barrier around the cell (just inside barrier around the cell (just inside the cell wall OR the outside border of the cell wall OR the outside border of animal cells)animal cells)

Function: Function: controls what enters and controls what enters and leaves the cellleaves the cell

Type of Cell: Type of Cell: found in all cellsfound in all cells Analogy: Analogy: the security system of the the security system of the

schoolschool

NucleusNucleus

Physical Description: Physical Description: large organelle large organelle that is usually near the centerthat is usually near the center

Function: Function: controls the cells activitiescontrols the cells activities Type of Cell: Type of Cell: found in all eukaryotesfound in all eukaryotes Analogy: Analogy: the office of a schoolthe office of a school

Nuclear Envelope (Membrane)Nuclear Envelope (Membrane)

Physical Description: Physical Description: Small spherical Small spherical structure within the nucleus that structure within the nucleus that holds in strands of genetic material holds in strands of genetic material (DNA)(DNA)

Function: Function: Hold in genetic instructions Hold in genetic instructions for the cell to do its jobfor the cell to do its job

Type of Cell: Type of Cell: found in all eukaryotic found in all eukaryotic cellscells

Analogy: Analogy: the walls of the officethe walls of the office

ChromatinChromatin

Physical Description: Physical Description: Thin strands of Thin strands of genetic materialgenetic material

Function: Function: The genetic instruction for The genetic instruction for the cell to do it’s jobthe cell to do it’s job

Type of Cell: Type of Cell: found in both eukaryotic found in both eukaryotic and prokaryotic cellsand prokaryotic cells

Analogy: Analogy: the principal him/herselfthe principal him/herself

NucleolusNucleolus

Physical Description: Physical Description: Small dark Small dark structure within the nucleusstructure within the nucleus

Function: Function: Create ribosomesCreate ribosomes Type of Cell: Type of Cell: found in all eukaryotic found in all eukaryotic

cellscells Analogy: Analogy: the substitute teacherthe substitute teacher

CytoplasmCytoplasm

Physical Description: Physical Description: the fluid-like the fluid-like material inside the cell membranematerial inside the cell membrane

Function: Function: contains the organelles; contains the organelles; “cell jelly” and is a site for chemical “cell jelly” and is a site for chemical reactionsreactions

Type of Cell: Type of Cell: found in all cellsfound in all cells Analogy: Analogy: the air inside the schoolthe air inside the school

MitochondriaMitochondria Physical Description: Physical Description: “bean-shaped” “bean-shaped”

organelle that has a folded inner organelle that has a folded inner membranemembrane

Function: Function: breaks down FOOD to breaks down FOOD to release energy for use by the cellrelease energy for use by the cell

Type of Cell: Type of Cell: found in all eukaryotesfound in all eukaryotes Analogy: Analogy: the boiler and generator of the boiler and generator of

the schoolthe school

Endoplasmic Reticulum (ER)Endoplasmic Reticulum (ER) Physical Description: Physical Description: internal internal

membrane systemmembrane system– Rough - has ribosomesRough - has ribosomes– Smooth- no ribosomesSmooth- no ribosomes

Function: Function: assembles parts of cell assembles parts of cell membrane and modifies proteinsmembrane and modifies proteins

Type of Cell: Type of Cell: found in all eukaryotesfound in all eukaryotes Analogy: Analogy: the copy room of a schoolthe copy room of a school

RibosomesRibosomes

Physical Description: Physical Description: tiny, round tiny, round structures either attached to the ER structures either attached to the ER or floating in cytoplasmor floating in cytoplasm

Function: Function: makes proteinsmakes proteins Type of Cell: Type of Cell: found in all eukaryotes found in all eukaryotes

AND some prokaryotesAND some prokaryotes Analogy: Analogy: the teachers in a schoolthe teachers in a school

Golgi Apparatus Golgi Apparatus (aka Golgi Body)(aka Golgi Body)

Physical Description: Physical Description: stack of stack of membranes in the cytoplasmmembranes in the cytoplasm

Function: Function: receives proteins and other receives proteins and other materials from ER; gives proteins the materials from ER; gives proteins the “address” of their final destination“address” of their final destination

Type of Cell: Type of Cell: found in all eukaryotesfound in all eukaryotes Analogy: Analogy: the busses of a schoolthe busses of a school

ChloroplastChloroplast

Physical Description: Physical Description: tubular organelle tubular organelle that contains chlorophyll (a green that contains chlorophyll (a green pigment)pigment)

Function: Function: use energy from SUNLIGHT use energy from SUNLIGHT to MAKE FOOD through to MAKE FOOD through photosynthesisphotosynthesis

Type of Cell: Type of Cell: found in many plant cellsfound in many plant cells Analogy: Analogy: the solar energy panels of a the solar energy panels of a

schoolschool

VacuoleVacuole Physical Description: Physical Description: large, spacious large, spacious

sack in the cytoplasmsack in the cytoplasm Function: Function: stores materials for the cell stores materials for the cell

(water, food, waste, etc…)(water, food, waste, etc…) Type of Cell: Type of Cell: found in all eukaryotes found in all eukaryotes

(usually one large vacuole in plants (usually one large vacuole in plants and many small vacuoles in animals)and many small vacuoles in animals)

Analogy: Analogy: the storage closet of a the storage closet of a schoolschool

LysosomeLysosome Physical Description: Physical Description: small, round small, round

sacks in the cytoplasmsacks in the cytoplasm Function: Function: breaks down large food breaks down large food

particles and old or damaged particles and old or damaged organellesorganelles

Type of Cell: Type of Cell: found in all eukaryotes found in all eukaryotes BUT are very rare in plant cellsBUT are very rare in plant cells

Analogy: Analogy: the janitor of a schoolthe janitor of a school

Plant Cells vs. Animal CellsPlant Cells vs. Animal Cells

Cell WallCell Wall ChloroplastsChloroplasts Lysosomes are Lysosomes are

rarerare 1 Large Vacuole1 Large Vacuole

No Cell WallNo Cell Wall No ChloroplastsNo Chloroplasts Lysosomes are Lysosomes are

commoncommon Several Small Several Small

VacuolesVacuoles

Job of CellsJob of CellsThe main job of all cells is to The main job of all cells is to

make proteinsmake proteins Different cells make different types Different cells make different types

of proteins for different functionsof proteins for different functions Steps of protein production: Steps of protein production:

1)1) RibosomeRibosome

2)2) Endoplasmic ReticulumEndoplasmic Reticulum

3)3) Golgi ApparatusGolgi Apparatus

4)4) Final Destination of the Protein Final Destination of the Protein (may be outside of the cell)(may be outside of the cell)