Structure and Function

The The cellcell is the is the smallest unit of lifesmallest unit of life that can carry out all the functions of that can carry out all the functions of a living thing.a living thing.

History of the Discovery of History of the Discovery of CellsCells

1500’s: microscope (m.s.) invented by 1500’s: microscope (m.s.) invented by Dutch eyeglass makers (opticians)Dutch eyeglass makers (opticians)

• 1665: Robert Hooke1665: Robert Hooke (English) (English) saw empty “cells” or rooms when saw empty “cells” or rooms when he observed cork under a m.s.he observed cork under a m.s.

Hooke’s drawing of cork as seen through his microscope.

• 1674: Anton van Leeuwenhoek1674: Anton van Leeuwenhoek (Dutch) used hand-held (Dutch) used hand-held m.s.’s to observe organisms and living cells in pond m.s.’s to observe organisms and living cells in pond water and blood.water and blood.

A picture he drew using his microscope. What do you think it is?

Fly eye!

• 1820’s: Rene Dutrochet 1820’s: Rene Dutrochet (French) concluded that (French) concluded that various parts of various parts of organisms (liver, bone, organisms (liver, bone, etc.) are made of cells.etc.) are made of cells.

• 1830’s: Robert Brown (Scottish) discovered the 1830’s: Robert Brown (Scottish) discovered the nucleusnucleus, , or center of the cell.or center of the cell.

1830’s: Felix Dujardin (French) 1830’s: Felix Dujardin (French) discovered discovered cytoplasmcytoplasm, or the clear, , or the clear, jelly-like material in the cell.jelly-like material in the cell.

• 1838: Matthias Schleiden1838: Matthias Schleiden (German) said that (German) said that all all plants and plant parts are made of cells.plants and plant parts are made of cells.

1839: Theodor Schwann1839: Theodor Schwann (German) (German) said that all animals said that all animals and animal parts are made of cellsand animal parts are made of cells. (He later said ALL . (He later said ALL organisms are made of cells.)organisms are made of cells.)

• 1858: Rudolf Virchow1858: Rudolf Virchow (German)(German) said that all cells said that all cells come from preexisting cells.come from preexisting cells.

1970: Lynn Margulis1970: Lynn Margulis

Proposes the idea Proposes the idea that organelles that organelles were once free-were once free-living cellsliving cells

Cell theoryCell theorydeveloped by Schleiden, Schwann, and developed by Schleiden, Schwann, and Virchow, consists of three principles:Virchow, consists of three principles:

Cells are the basic units of all life.Cells are the basic units of all life.

All organisms are made of one or All organisms are made of one or more cells.more cells.

All cells come from preexisting cells.All cells come from preexisting cells.

Exceptions of Cell Exceptions of Cell Theory:Theory: Where did first cell come from?Where did first cell come from?

(Remember Theory of Evolution explanation.)(Remember Theory of Evolution explanation.)

Virus particles have a protein coat and Virus particles have a protein coat and nucleic acid core. They have both living nucleic acid core. They have both living and nonliving characteristics and do not and nonliving characteristics and do not have all the parts of a complete cell.have all the parts of a complete cell.

HIV Hepatitis C West Nile FLUSARS

multicellularmulticellular: : organism made of organism made of many cellsmany cells

unicellularunicellular: : organism made of organism made of one cellone cell

There are two basic types of living things:

How cells vary:How cells vary:

Shape is related to function. Nerve Shape is related to function. Nerve cells can be one meter long, but cells can be one meter long, but very thin.very thin.

Mycoplasms:Mycoplasms: smallest cells cause smallest cells cause respiratory diseasesrespiratory diseases

The largest is an The largest is an unfertilized ostrich unfertilized ostrich egg.egg.

Two types of cellsTwo types of cells

eukaryoteseukaryotes: have a : have a nucleus surrounded nucleus surrounded by a membrane (all by a membrane (all cells except cells except bacteria)bacteria)

prokaryotesprokaryotes: have : have nono definite nucleus definite nucleus (bacteria)(bacteria)

Pro = No: PROKARYOTIC CELLS HAVE NO NUCLEUS!

Basic Cell StructuresBasic Cell Structures

A cell must A cell must have three: have three: cell cell membrane, membrane, nucleus, and nucleus, and cytoplasm.cytoplasm.

Cell MembraneCell Membrane

thin layer of lipid (fats) and protein that thin layer of lipid (fats) and protein that controls what enters and leaves cellcontrols what enters and leaves cell

•made of phospholipids (glycerol, two fatty acids, and phosphate made of phospholipids (glycerol, two fatty acids, and phosphate group) and protein molecules embedded in the lipid layer.group) and protein molecules embedded in the lipid layer.•cell membranes are fluid (lipids and proteins are always in motion) cell membranes are fluid (lipids and proteins are always in motion) forming “mosaics” (called forming “mosaics” (called fluid mosaic model)fluid mosaic model)

CytoplasmCytoplasm

material between the cell material between the cell

membrane and the nucleusmembrane and the nucleus

• made of water and organic compounds made of water and organic compounds organellesorganelles (cell parts) “float” in it (cell parts) “float” in it

• contains contains cytoskeletoncytoskeleton: network of fibers and : network of fibers and tubes extending throughout cytoplasm that gives tubes extending throughout cytoplasm that gives support and helps anchor organelles. It also helps support and helps anchor organelles. It also helps cells change shape.cells change shape.

NucleusNucleus

contains chromosomescontains chromosomes: : most of the cell’s genetic most of the cell’s genetic material. All organisms material. All organisms have a specific number.have a specific number.

Contains Contains nucleolusnucleolus: makes : makes ribosomes, which in turn help ribosomes, which in turn help make proteins in the cell.make proteins in the cell.surrounded by a surrounded by a nuclear nuclear envelopeenvelope, or , or lipid bilayerlipid bilayer..

RibosomesRibosomes make proteins from amino acidsmake proteins from amino acids. They . They

float in cytoplasm or are bound to float in cytoplasm or are bound to membranes. Made by the nucleolus.membranes. Made by the nucleolus.

Endoplasmic reticulumEndoplasmic reticulum (ER) (ER) - - network of membranes that network of membranes that produce and TRANSPORT materials for the cell.produce and TRANSPORT materials for the cell.

rough ERrough ER has has ribosomes on its ribosomes on its surfacesurface- It helps in - It helps in making making proteinprotein secreted by secreted by the cell and new cell the cell and new cell membranes.membranes.

smooth ERsmooth ER has NO has NO ribosomes on itribosomes on it- It - It makes lipids, makes lipids, processes processes carbohydrates, and carbohydrates, and modifies chemicals that modifies chemicals that are toxic to the cellare toxic to the cell..

Golgi apparatusGolgi apparatus (also called (also called Golgi complexGolgi complex or Golgi or Golgi bodiesbodies):): flat, flat,

membrane-membrane-bound sacs bound sacs where where chemicals are chemicals are sorted, sorted, packaged, and packaged, and transportedtransported to to other places.other places.

MitochondriaMitochondria

the “the “powerhousepowerhouse” of ” of the cellthe cell- Changes food - Changes food compounds into a compounds into a usable form of energy usable form of energy (ATP: (ATP: aadenosine denosine ttriripphosphate) for the hosphate) for the cellcell

LysosomesLysosomes

sacs that have sacs that have digestive digestive enzymes to break enzymes to break down large down large moleculesmolecules of of carbs, proteins, carbs, proteins, lipids, and old lipids, and old organelles no organelles no longer useful.longer useful.

VacuoleVacuole

membrane-bound membrane-bound organelle used for organelle used for storagestorage..There is a large, There is a large, central central one in plantone in plant cells (helps to cells (helps to maintain their shape)maintain their shape)There are There are many small many small ones in animalsones in animals..

Types of MovementTypes of Movement ciliacilia: : tiny, hair-like particles tiny, hair-like particles

(ex. paramecium)(ex. paramecium)

flagellaflagella: : large, whip-like taillarge, whip-like tail (ex. (ex. human sperm)human sperm)

Cell DiversityCell Diversity1. 1. Plant CellsPlant Cells

• have a have a cell wallcell wall, a , a tough, rigid outer tough, rigid outer covering that protects covering that protects the cell and helps the cell and helps maintain its shape. maintain its shape.

• Cell walls are also Cell walls are also found in fungi, algae, found in fungi, algae, and bacteriaand bacteria

• chloroplastschloroplasts help make sugars during photosynthesis. help make sugars during photosynthesis.

• They also contain They also contain chlorophyllchlorophyll, the green pigment in plants. , the green pigment in plants. large central vacuolelarge central vacuole

2. 2. Animal CellsAnimal Cells have cytoskeleton have cytoskeleton

but no cell wall for but no cell wall for

support support do NOT contain do NOT contain

chloroplasts may chloroplasts may have have

many very small many very small vacuolesvacuoles

- - semipermeable membranesemipermeable membrane lets certain molecules lets certain molecules pass through and keeps others out. Cells have pass through and keeps others out. Cells have

this!this!

1. 1. Passive Passive transporttransport is the is the movement of a movement of a

substance across substance across a cell membrane a cell membrane

WITHOUT the WITHOUT the input of energyinput of energy..

Cells and Their EnvironmentCells and Their Environment

NO ENERGY!

2. 2. OsmosisOsmosis is the diffusion of water molecules only. is the diffusion of water molecules only.

NO ENERGY!

3. 3. Diffusion,Diffusion, the the most common form most common form

of passive transport, of passive transport, is the movement of is the movement of

substances from substances from areas of HIGH areas of HIGH

concentration to concentration to areas of LOW areas of LOW

concentration.concentration.NO ENERGY!

4. 4. Active transportActive transport uses cellular energy to move uses cellular energy to move substances across a cell membrane. molecules move substances across a cell membrane. molecules move from LOW concentration to HIGH concentrationfrom LOW concentration to HIGH concentration- helps organisms maintain - helps organisms maintain homeostasishomeostasis

USES ENERGY (ATP)!

Bulk MovementBulk Movementused to transport large molecules across membraneused to transport large molecules across membrane

ExocytosisExocytosis takes materials OUT takes materials OUT of the cell.of the cell.

EndocytosisEndocytosis carries materials INTO the cell. carries materials INTO the cell.

PinocytosisPinocytosis (cell “drinking”) is when liquids are moved into (cell “drinking”) is when liquids are moved into

the cell.the cell.

PhagocytosisPhagocytosis (cell “eating”) is when solids are moved into the cell. (cell “eating”) is when solids are moved into the cell.

It’s how some organisms (ex. amoeba) get their food.It’s how some organisms (ex. amoeba) get their food.

Effect of Solution Effect of Solution ConcentrationsConcentrations

HypertonicHypertonic: the concentration of solutes outside is : the concentration of solutes outside is higherhigher than it is inside the cell. than it is inside the cell.

IsotonicIsotonic: the concentration of solutes outside the cell is : the concentration of solutes outside the cell is equalequal to that inside the to that inside the cell. It should be the state of a normal cell.cell. It should be the state of a normal cell.

HypotonicHypotonic: the concentration of solutes outside is : the concentration of solutes outside is lowerlower than it is inside the cell. than it is inside the cell.1. 1. very hypotonicvery hypotonic: the cell has burst due to the large amount of water entering it.: the cell has burst due to the large amount of water entering it.

Let’s take a quiz!!

How many parts can you name?

Now, Check your answers!

Is this a plant or animal Is this a plant or animal cell?cell?

2.

3.

4.

Plant CellPlant Cell

2.

3.

4.

One large vacuole

Chloroplast containing Chlorophyll

Cell Wall

Is this a plant or animal Cell?

A.

B.

C.

D.

E.

F.

G.

Animal CellAnimal CellLet’s Check Your Answers!Let’s Check Your Answers!

A. Nucleus A. Nucleus

B. Mitochondria B. Mitochondria

C. Cell MembraneC. Cell Membrane

D. Smooth ERD. Smooth ER

E. Golgi BodyE. Golgi Body

F. Rough ERF. Rough ER

G. LysosomeG. Lysosome