CytologyCytology

CytologyCytology

is the “study of cells”is the “study of cells”

• Cyto = cell, ology = study ofCyto = cell, ology = study of

The Cell Theory and its Development

Anton van Leeuwenhoek (1632-1723) was the first to Anton van Leeuwenhoek (1632-1723) was the first to adapt lenses to the study of living organisms.adapt lenses to the study of living organisms.

He discovered microorganisms. He discovered microorganisms.

1665 – Robert Hooke

Observed chambers, dead plant cells, in cork.

• Coined the term "cells” in 1665.

Cork Cells

1833 - Robert Brown

• Studied the nucleus. Do all living cells have a nucleus?

Nucleus

Human Cheek Cell

1838 - M.J. Schleiden

• Botanist…. Discovered plants are

made of cells.

Elodea….Typical Plant Cell

1839 - T. Schwann

• Zoologist….discovered animals are made of

cells.

Nerve Cells

1855 - Rudolph Virchow

• “Omnis cellula e cellula”

“All cells are from other

pre-existing cells.”

Discovered while researching cancer cells.

The Cell TheoryThe Cell Theory1. All living organisms are composed of one or more cells.

2. Cells are organisms' basic units of structure and function.

3. Cells come only from pre-existing cells.

How do you measure cells? How do you measure cells?

Cells are measured using “microns”.Cells are measured using “microns”.

A micron is another casual name for a A micron is another casual name for a micrometer.micrometer.

Note: 1.0 Note: 1.0 m = one millionth of a meterm = one millionth of a meter

What limits the size of a cell?What limits the size of a cell?

• Cell volume to surface area ratios favor Cell volume to surface area ratios favor small size... an efficient amount of small size... an efficient amount of

materials must enter and leave the cell.materials must enter and leave the cell.

• Nucleus’ ability to control the cell is Nucleus’ ability to control the cell is limited by the size of the cell.limited by the size of the cell.

Types of CellsTypes of Cells

ProkaryotesProkaryotes

• Lack a nucleus and other Lack a nucleus and other membrane bound membrane bound

organelle.organelle.

First appeared 3.5 BYAFirst appeared 3.5 BYAinclude bacteria include bacteria

and cyanobacteria.and cyanobacteria.

E. coli

EukaryotesEukaryotes

Have a nucleus and membrane Have a nucleus and membrane bound organelle.bound organelle.

First appeared 2.0 BYAFirst appeared 2.0 BYAinclude protists, fungi, plants include protists, fungi, plants

and animals.and animals.

Basic Cell OrganizationBasic Cell Organization

• Cell (Plasma) MembraneCell (Plasma) Membrane

• Nucleus (eukaryotes only)Nucleus (eukaryotes only)

• Cytoplasm (an area!!)Cytoplasm (an area!!)

• Organelles Organelles (structures with specialized functions)(structures with specialized functions)

Animal Cell

Plant Cell

The Cell Membrane The Cell Membrane AKA: Plasma MembraneAKA: Plasma Membrane

• Separates the cell from the Separates the cell from the environment.environment.

• Is “semi-permeable”…… regulates Is “semi-permeable”…… regulates the movement of materials in/out of the movement of materials in/out of

a cell.a cell.

• ALL cells have a plasma membraneALL cells have a plasma membrane

The CytoplasmThe Cytoplasm

• The Cytoplasm is an Area (not stuff) The Cytoplasm is an Area (not stuff) between the plasma membrane and between the plasma membrane and

the nuclear envelope. The cytoplasm the nuclear envelope. The cytoplasm contains the cytosol, nucleus (if contains the cytosol, nucleus (if

present) and cell organelles.present) and cell organelles.

CytosolCytosol• Semi-fluid portion of the cytoplasm (the Semi-fluid portion of the cytoplasm (the

gooey stuff inside the cell)…. gooey stuff inside the cell)…. Composed mostly of water, nutrientsComposed mostly of water, nutrients.

NucleusNucleus• Most conspicuous organelle.Most conspicuous organelle.

• usually spherical, but can be lobed or irregular usually spherical, but can be lobed or irregular in shape.in shape.

• Typically found near the center of a eukaryotic Typically found near the center of a eukaryotic cell…..prokaryotes do not have a nucleus.cell…..prokaryotes do not have a nucleus.

• Control center for the cell.

• Contains the genetic instructions.

Nuclear Envelope… the outer boundary of the

nucleus which gives the shape to the nucleus.

NucleolusNucleolus• Dark area in the nucleus.Dark area in the nucleus.

• 0 - 4 per nucleus.0 - 4 per nucleus.

• Storage area for ribosomes.Storage area for ribosomes.

Chromatin

• DNA and Protein in a “loose” format DNA and Protein in a “loose” format (stringy form of DNA) Will eventually (stringy form of DNA) Will eventually

form the cell’s chromosomes. The DNA form the cell’s chromosomes. The DNA holds the cell’s genetic information.holds the cell’s genetic information.

• Found in the nucleus of eukaryotes and Found in the nucleus of eukaryotes and in the center region of prokaryotes.in the center region of prokaryotes.

The Cell OrganelleThe Cell Organelle• Term means "small organ” Formed Term means "small organ” Formed

body in a cell with a specialized body in a cell with a specialized function.function.

• Keeps various enzymes separated in Keeps various enzymes separated in space. space.

(bags of enzymes)(bags of enzymes)

RibosomesRibosomes

• Structure: made up of protein and RNAStructure: made up of protein and RNA

• No membrane.No membrane.

• Function: site of protein synthesis.Function: site of protein synthesis.

Ribosome LocationsRibosome Locations

• Free in the cytosol…..make proteins for Free in the cytosol…..make proteins for use in cytosol.use in cytosol.

• Attached to the Endoplasmic Attached to the Endoplasmic Reticulum….. make proteins that are Reticulum….. make proteins that are

exported from the cell.exported from the cell.

RibosomesRibosomes

Endoplasmic ReticulumEndoplasmic Reticulum

• Often referred to as ER.Often referred to as ER.

• Stacks of flattened stacks involved in Stacks of flattened stacks involved in the production and transportation of the production and transportation of

proteins, sugars, fats,…..etcproteins, sugars, fats,…..etc

Rough ERRough ER

• Endoplasmic Endoplasmic reticulum with reticulum with

attached attached ribosomes. ribosomes.

The attached The attached ribosomes ribosomes

create proteins create proteins

Smooth ERSmooth ER

• Endoplasmic Endoplasmic Reticulum without Reticulum without

Ribosomes….. Ribosomes….. Responsible for Responsible for

producing lipids and producing lipids and hormones, hormones,

especially in cells especially in cells that export these that export these

substances from the substances from the cell. In liver cells, the cell. In liver cells, the

smooth ER breaks smooth ER breaks down toxins and down toxins and

drugs.drugs.

Golgi ApparatusGolgi ApparatusAKA Golgi bodies or Golgi ComplexAKA Golgi bodies or Golgi Complex

• Structure: flattened sacs arranged in a Structure: flattened sacs arranged in a

stack. (looks like a stack of Pita bread)stack. (looks like a stack of Pita bread)

• 3 to 20 per cell.3 to 20 per cell.

• The Golgi Apparatus package and modify The Golgi Apparatus package and modify proteins and lipids into vesicles (small, proteins and lipids into vesicles (small,

spherical shaped sacs that bud from the spherical shaped sacs that bud from the Golgi apparatus). The vesicles often merge Golgi apparatus). The vesicles often merge

with the plasma membrane to release with the plasma membrane to release contents to the outside of the cell. contents to the outside of the cell.

LysosomeLysosome• Vesicles from the Golgi apparatus Vesicles from the Golgi apparatus

that contain digestive enzymes. that contain digestive enzymes. They breakdown food, cellular They breakdown food, cellular

debris and foreign invaders such debris and foreign invaders such as bacteria.as bacteria.

• Assist with cell death. Assist with cell death. • Not present in plant cells.Not present in plant cells.

PeroxisomesPeroxisomes

• Organelles that breakdown various Organelles that breakdown various substances. During digestion substances. During digestion

0xygen0xygen isis produced and combines produced and combines

with Hwith H22O to form Hydrogen O to form Hydrogen

Peroxide…. a toxin. Peroxisomes Peroxide…. a toxin. Peroxisomes break down Hydrogen Peroxide.break down Hydrogen Peroxide.

MitochondriaMitochondria• Function: Site of Cellular Respiration – Cellular Function: Site of Cellular Respiration – Cellular

Respiration is the release of energy from food to Respiration is the release of energy from food to form ATP…. All cells use ATP as their energy source.form ATP…. All cells use ATP as their energy source.

• ““Powerhouse” of the cell.Powerhouse” of the cell.

• Found in the cytosol.Found in the cytosol.

• Have their own DNA. Can reproduce Have their own DNA. Can reproduce themselves.themselves.

ChloroplastsChloroplasts

• Function: Site of Photosynthesis - chloroplasts Function: Site of Photosynthesis - chloroplasts use of light energy to make food, sugars, from use of light energy to make food, sugars, from

carbon dioxide and water.carbon dioxide and water.

• Contain the green pigment chlorophyll. Contain the green pigment chlorophyll.

• Found in the CytosolFound in the Cytosol

• Have their own DNA. Can reproduce themselves.Have their own DNA. Can reproduce themselves.

Chloroplasts

Enzymes in a crystal

Chromoplasts FunctionFunction: : store plant pigments such as store plant pigments such as

chlorophyll (green) and carotene (orange, red).chlorophyll (green) and carotene (orange, red).

• Found in plants only.Found in plants only.• Classified (named) by color….example: Classified (named) by color….example:

• ““Chloro” means green, therefore a Chloro” means green, therefore a chloroplast is a green plastid that stores chloroplast is a green plastid that stores

chlorophyllchlorophyll• ““Leuco” means white, therefore Leuco” means white, therefore Leucoplasts (AKA Amyloplasts) are Leucoplasts (AKA Amyloplasts) are

white plastids that store starch.white plastids that store starch.

CytoskeletonCytoskeleton• Network of protein fibers and in the cytoplasm.Network of protein fibers and in the cytoplasm.

FunctionsFunctions• Give Cells structure and shape.Give Cells structure and shape.

• Involved in Cell movement.Involved in Cell movement.

• Cytoskeleton is composed of 2 different types of fibers, Cytoskeleton is composed of 2 different types of fibers, which are organized in deceasing diameter….they are:which are organized in deceasing diameter….they are:

1. Microtubules1. Microtubules 2. Microfilaments2. Microfilaments

Microtubule FunctionMaintenance of cell shape.Hold organelles in place.

MicrofilamentsMicrofilaments

• Responsible for Muscle contractions.Responsible for Muscle contractions.

• Cytoplasmic streaming in plants, like Cytoplasmic streaming in plants, like Elodea. Elodea.

• Maintenance and changes in a cell’s shape.Maintenance and changes in a cell’s shape.

Function

Cilia and FlagellaCilia and FlagellaClassified by their lengths and numbersClassified by their lengths and numbers

• Function - to move cells or to sweep Function - to move cells or to sweep materials past a cell.materials past a cell.

• Cilia - short, but numerous.Cilia - short, but numerous.

• Flagella - long, but few (usually only one).Flagella - long, but few (usually only one).

CentriolesCentrioles

• Usually one pair per cell, located close Usually one pair per cell, located close to the nucleus.to the nucleus.

• Found in animal cells only.Found in animal cells only.

• Help in cell division.Help in cell division.

Basal BodiesBasal Bodies

• Same structure as a centriole.Same structure as a centriole.

• Found at the base of the cilia and Found at the base of the cilia and flagellaflagella.

Basal Body

Plant Cell WallsPlant Cell Walls

• All plant cells have a Primary Cell Wall.All plant cells have a Primary Cell Wall.

• Some cells will develop a Secondary Cell Some cells will develop a Secondary Cell Wall.Wall.

Cell WallsCell Walls

• Plant cell walls are made of cellulose Plant cell walls are made of cellulose

( a polysaccharide made of ( a polysaccharide made of -glucose).-glucose).

• Fungi cell walls are made of chitin (a Fungi cell walls are made of chitin (a polysaccharide)polysaccharide)

• Function as the cell's exoskeleton for support and Function as the cell's exoskeleton for support and protection.protection.

Middle LamellaMiddle Lamella

• Thin layer rich in pectin (used to make Thin layer rich in pectin (used to make jelly) found between adjacent plant jelly) found between adjacent plant

cells.cells.

• Glues cells together.Glues cells together.

Vacuoles and VesiclesVacuoles and VesiclesFluid-filled, membrane-bound bodiesFluid-filled, membrane-bound bodies

3 Types of Vacuoles and Vesicles3 Types of Vacuoles and Vesicles• Food vacuolesFood vacuoles

• Central water vacuolesCentral water vacuoles

• Contractile vacuolesContractile vacuoles

The function of the vacuole depends The function of the vacuole depends on the organism.on the organism.

In ProtistsIn Protists single-cell organisms …….“Food” vacuoles single-cell organisms …….“Food” vacuoles

store newly ingested food until the store newly ingested food until the lysosomes can digest it.lysosomes can digest it.

• ““Contractile” vacuoles pump out excess Contractile” vacuoles pump out excess water.water.

Contractile Vacuole

Contractile Vacuole

Food Vacuoles

Central Water VacuoleCentral Water Vacuole

• Large single water containing vacuole Large single water containing vacuole making up to 90% of the cell's volume.making up to 90% of the cell's volume.

• Stores WaterStores Water

• Helps the cells maintain their shapes.Helps the cells maintain their shapes.

Central Water Vacuole

Comparing Plant Cells and Comparing Plant Cells and Animal CellsAnimal Cells

Plant CellsPlant Cells Have cell walls, Have cell walls, chloroplasts, and a chloroplasts, and a

central water vacuole…central water vacuole…animal cells do not!!animal cells do not!!

Animal CellsAnimal CellsHave lysosomes and Have lysosomes and

centrioles…. Plant centrioles…. Plant cells do not!! cells do not!!