most cells are too small to see with the naked eye. scientists became aware of cells only after...

Most cells are too small to seeWith the naked eye.

Scientists became aware of Cells only after microscopes Were invented, in the 1600’s.

When the English scientist Robert Hooke used a crude Scope, he saw a bunch of Little boxes he called cells.

Robert Hooke (1635-1703)

10 years after Hooke, AntonVan Leeuwenhoek used a Microscope to view pond Water, and saw tons of

Tiny animals.

Today we know that they are Not animals, but single cell

Organisms.

Leeuwenhoek

Since Robert Hooke 1st Observed cells, microscopes

Have unveiled the details Of cell structure.

There are 2 common kinds ofMicroscopes…

Light microscopes &Electron microscopes

In a light microscope, light Passes through one or more

Lenses to produce an Enlarged image of something.

An electron microscope forms An image of a specimen usingA beam of electrons instead

Of light.

Magnification is the ability toMake an image appear larger.

For example, a magnificationValue of 200X indicates that The object is 200 times its

Actual size.

Resolution is a measure of Clarity of an image.

Both high magnification andGood resolution are needed

To view items clearly.

Light microscopes that have2 lenses are called compound

Light microscopes.

The two lenses are called theObjective and the ocular.

The objective lens is the oneClose to the specimen.

The ocular lens is the one thatYou put your eye on.

Both lenses magnify the image.

To find the total power of theLenses, you multiply the

Power of each lens.

The most powerful light Microscopes magnify up to

2000 times (0.5 μm).

To see past this point you Would have to go to college and

Use the electron microscope.

It took scientists more than 150Years to fully appreciate the

Discoveries of Hooke andLeeuwenhoek.

In 1838 the German botanistMattias Schleiden concluded

That cells make up Entire plants.

A year later, the German Physician Theodor Schwann Concluded that all animals

Are made up of cells.

Rudolf Virchow stated that All cells come from other cells.

All of these studies combined To form the cell theory, Which has three parts…

All living things are composed of one or more cells

Cell are the basic units of structure and function

All cells come from preexisting cells

All cells have the same Common features…

Cell membrane = outer boundary

Nucleus = “center” command center

Cytoplasm – everything between the cell membrane and nucleus

All cells also have ribosomes Which are where proteins

Are made.

All of them also have DNA thatProvide instructions on how

Everything is made and done.

The smallest and simplest cellsAre prokaryotes.

Prokaryotes are single celledOrganisms that lack a nucleus

And other internal stuff.

Bacteria are prokaryotes.

The DNA of a bacteria is Circular and just floating around

In the cytoplasm.

All bacteria have a cell wall.

Some bacteria are also enclosedIn a capsule which allows them

To stick to almost anything.

Many bacteria have flagella,Which are long, threadlike

Structures that enable themTo move around.

Eukaryotic cells are cells thatHave a nucleus.

The nucleus is where the DNA is held.

These cells have many organelles.

An organelle is a structure thatCarries out specific activities.

Many single celled organismsHave cilia that work likeFlagella. (they can also

Have flagella)

The cytoplasm and organellesOf a cell are contained by

Its membrane.

The membrane is made up ofLipids that stick together.

Phospholipids are lipids that areMade up of a phosphate group

And 2 fatty acids.

Same in plants, animals and microorganisms

Lipid bilayer

electron micrograph of a cell membrane at approx. 240,000x

Most all of the eukaryotic Cell functions are controlled

By the cell’s nucleus.

Unlike prokaryotic cells, Eukaryotic cells have a

System of internal organelles.

The endoplasmic reticulum,Or ER, is an extensive systemOf internal membranes that

Move proteins and other Substances through the cell.

The ER is broken into 2 parts,Smooth and Rough.

The rough ER has ribosomesAttached to it and the

Smooth does not.

The Golgi apparatus is a setOf flattened, membrane Bound sacs that serve as

The packaging and Distribution center of the cell.

Lysosomes are small organellesThat contain the digestive

Enzymes for the cell.

Nearly all eukaryotic cells Have mitochondria.

Mitochondria are organelles That harvest energy fromOrganic compounds to

Make ATP.

Mitochondria have their ownDNA and ribosomes.

It is widely accepted that Mitochondria were once

Prokaryotes that got sucked Into eukaryotes and stayed.

Plant cells are eukaryoticCells that have different parts

Than animal cells.

They have cell walls, Chloroplasts and central

Vacuoles.

A cell wall supports and Protects the cell and allows

Plant cells to be stackedOn top of each other.

The cell wall is made up of Proteins and polysaccharides.

We (humans) cannot digestCell walls.

(fiber)

Chloroplasts are organelles That use light energy to

Make carbohydrates From carbon dioxide

And water.

The central vacuole is a largeMembrane bound space that

Stores water and many Substances including ions,

Nutrients and wastes.

When the vacuole is full, it Presses the cytoplasm againstThe cell wall, making the cell

Very rigid.