UNIT 4 will cover cells . These topics are all related to one of the

common characteristics of all living things.

THE CELL

ALL LIVING THINGS ARE COMPOSED

OF CELLS

What the heck is

a cell anyway?

It can also be considered as …

Finally it can be considered as…

Do you remember when we listed

that one of the common

characteristics of all living

organisms was that they had a

cellular nature?

This means they were either

composed of a singular cell

(unicellular) or made up of many

cells (multicellular)

Unicellular Organisms

(Living organisms made up from one cell.)

Multicellular organisms are

composed of many cells. (for example our stomach contains many cells of many different types.)

SO…How is the study of cells related to our

Ecological (Rivers ) Biology? Your Ideas?

All cells are made from the big 4

macromolecules of life. (Do you remember them?)

In some ways cells could be considered

little ecosystems in that…

• They require energy.

• They cycle materials.

• They are interactions

within different parts

of the cell.

In this unit we will explore the

cellular nature of life by focusing on the similarities and differences

between cells of different life forms.

Science in its historical perspective

First…a little history….

A long time ago, people believed in something called Spontaneous

Generation- since at least the time of Aristotle (4th Century BC),

people believed non-living objects can give rise to living organisms.

It was common “knowledge” that simple organisms like worms,

beetles, frogs, and salamanders could come from dust, mud, etc., and

food left out.

BUT THEY WERE WRONG!

Because they were wrong,

we need a story to clarify

and explain the truth.

Once upon a time a long

time ago…

…the microscope was

invented.

(mikros = small; skopo = observe)

HANS AND SON

Sometime about the year 1590,

two Dutch spectacle makers,

Zaccharias Janssen and his

father Hans started

experimenting with these

lenses. They put several

lenses in a tube and made a

very important discovery. The

object near the end of the tube

appeared to be, much larger

than any simple magnifying

glass! They had just invented

the compound microscope.

Galileo Galileo heard of their

experiments and started

experimenting on his

own. He described the

principles of lenses and

light rays and improved

both the microscope and

telescope. He added a

focusing device to his

microscope and went on

to explore the heavens

with his telescopes.

Anton von Leeuwenhoek of Holland became very

interested in lenses while working with magnifying

glasses in a dry goods store. He became so interested

that he learned how to make rounded lenses which

produced greater magnification, and his microscopes

were able to magnify up to 270X!

Leeuwenhoek became more involved in science and

with his new improved microscope was able to see

things that no man had ever seen before.

Anthony Leeuwenhoek (1632-1723) has since been

called the "Father of Microscopy".

Then in 1665 English Scientist Robert Hooke used this new

microscope!

Hooke discovered plant cells -- more precisely, what Hooke saw

were the cell walls in cork tissue. Hooke coined the term "cells":

the boxlike cells of cork reminded him of the prayer cells in a

monastery.

Robert Hooke's sketches of cork

cells.

Check out the dates. While the microscope was rocking back in

1665, it was not until the early 1800’s that the idea of cells was put

together with its relationship to living things!

In 1809 Jean Baptiste Pierre Antoine de Monet Chevalier de

Lamarck, remarked that “No living thing can have life if its

parts are not made of cellular tissue or are not formed by

cellular tissue.”

His theories were largely ignored or

attacked; He never won the acceptance

and esteem of his colleagues, and he

died in poverty and obscurity

• 1838 Schleiden- observed that all plants seemed to be composed

of cells

1839 Schwaan- extended Schleiden's cell theory to animals, stating

that all living things are composed of cells. Came up with the term

“CELL THEORY”

1858 Virchow- German pathologist Rudolf Virchow (1821 - 1902)

altered the thought of cellular biology with his statement that

"every cell comes from a cell“ a theory called BIOGENESIS

From their discoveries:

THE CELL THEORY AROSE…

• THE CELL IS THE BASIC UNIT OF

LIFE.

• ALL LIVING THINGS ARE

COMPOSED OF CELLS.

• ALL CELLS COME FROM OTHER

CELLS.

PERSON GETS

CREDITED

WITH:

Leeuwenhoek

Hooke

Lamarck

Schwaan

Schleiden

Microscope

Found plant/cork cells and

can up with term “cells”

All life is made of cells

Animals have cells

Plants have cells

Cells Size

•Sizes on a microscope are measured in microns. A micron is one

millionth of a meter or 0.001 of a millimeter.

•They range in size

Largest cell = Ostrich egg

Smallest cell= .000001 microns Yikes-tiny!

Average cell size= .5-40 microns

(remember 1 micron = .001 mm)

•Size is restricted: Why? Most cells are small has to do with

simple geometry more than anything else: specifically the

relationship between surface area to volume as a cell gets bigger.

The undisputed largest extant bird egg on earth today is laid by an

ostrich. An average egg weighs about three pounds (1.4 kg), and is

roughly equivalent to about two dozen chicken eggs. It would take

approximately 40 minutes to hard-boil an ostrich egg. The yolk of

an ostrich egg is the largest cell by volume; however, nerve cells

from the spinal cord of a large hooved mammal may be nearly two

meters in length!

Highly magnified view (2000x) of

human pus showing white blood cells

(called neutrophils) with deeply-lobed

purple nuclei.

A culture of rod-shaped

anthrax bacteria (Bacillus

anthracis). Some of the

bacteria have divided by

fission (red arrow).

As the size of a cube

increases, the ratio of

the surface area to

volume gets smaller.

Why would this

surface area to

volume ratio impact

a cell?

Cells have an internal structure

• There are many different cells

• Obviously there is “stuff” inside them.

• Cells are classified into two groups

depending on how that “stuff” is organized.

Cell organelles • Some cells contain organelles.

• Consider that we have internal parts called

organs.

• While some cells just have watery fluid

with molecules inside them (prokaryotic

cells,) others have well defined specialized

parts called organelles (little organs.) These

cells are called eukaryotic cells.

Types of cells • PROKARYOTES

-UNICELLULAR

-ARE THE LARGEST

GROUP OF ORGANISMS

-SIMPLE STRUCTURE

-NO NUCLEUS

-NO MEMBRANE BOUND

ORGANELLES -

APPEARED ABOUT 4

BILLION YEARS AGO- most

primitive

• EXAMPLE: bacteria

& Blue green algae

• EUKARYOTES -MORE ADVANCED

-ALL CELLS IN MULTICELLULAR ORGANISMS ARE EUKARYOTES AND SOME IN UNICELLULAR ORGAN.

- HAVE NUCLEUS

-THESE HAVE MEMBRANE BOUND ORGANELLES

-COMPLEX INTERNAL STRUCTURE

- APPEARED ABOUT 1 BILLION YEARS AGO

EXAMPLE: fish, oak trees, humans, paramecium

PROKARYOTIC CELLS No membrane bound

nucleus. Instead, DNA is in

a circular loop called a

plasmid!

Bacteria cells are very small-

only a fraction of the size of an

animal cell.

Prokaryotes feature 3 major shapes:

spheres, rods, spirochetes.

PROKARYOTIC CELLS

Bacteria serve as

decomposers, act in

the nitrogen cycle,

are agents of

fermentation, and

play an important

role in our own

digestive system.

But they can also

make us SICK!

.

HOW THE EUKARYOTE

FORMED FROM THIS FIRST

BASIC PROKARYOTE… Once upon a time (about one billion years ago), the first eukaryotic cell

came to be. There was a group of primitive bacteria going about their

business when along came a big hungry phagocyte, who ate one of the

bacterium.

Mr. Phagocyte: Yum.

Bacterium: Excuse me.

Mr. Phagocyte: What?

Bacterium: You know, why don't

we join forces and I can help you

and you can help me and we can

become a 'eukaryotic' cell?

Whaddaya say?

Mr. Phagocyte: OK

PROKARYOTE EUKARYOTE

WITHOUT membrane bound WITH membrane

organelles bound organelles

PRO OR EUK

1. Snake cells

2. Human cheek cells

3. Venus fly trap plant cells

4. Blue-green algae

5. Fecal Coliform

6. Salmon cells

7. Salmonella Bacterium cells

EUK

EUK

EUK

PRO

PRO

EUK

PRO

For now think of the cell as an independently functioning unit of life. In

order to perform the many specific tasks there must be many specific

parts. So we will come up with an ANALOGY- The Cell as the City.

THE CELL THE CITY

•Cell membrane is like the _________________

because it determines what comes in and of

the cell/city

•The nucleus is like __________- a storage site

for all the cells information.

•The cytoplasm is like the __________________

in the city. They are the substances in the

cell that carry oxygen, proteins, carbs, and

other substances.

•The mitochondria is like a _____________.

This is where nutrients are converted into

usable cellular energy.

•Ribosomes are the site where protein is put

together. Like the __________ of a city.

City limits, borders

City hall

Land, air, and water

Power plant

factories

•Endoplasmic reticulum are like ___________________________

because they are where the proteins, lipids, and carbohydrates (3 of

the big 4) are processed

•Golgi apparatus are like the _____________________. They are

the parts that modify and package up the cellular materials before

being excreted out of the cell.

•Lysosomes and peroxisomes are the _______________________.

They store strong digestive enzymes (proteins.)

Like a stack of pancakes

Lysosomes under the

microscope

Business district

Post office/UPS/FedEx

Waste removal/sewage plant

•Chloroplasts are analogous to ________________________ found in

green plant cells and some protists. They convert sunlight into

cellular or (chemical) energy.

•Vacuoles are like the city’s _________________. They hold water

and nutrients for the cell. Large central vacuoles usually just found

in plant cells

•Centrioles are like the __________________________ which aid

in cell/movement and division. Found mainly in animal cells.

a solar Power plant

water Supply/warehouses

traffic patterns within the

cell

Cell wall is analogous to ________________________________.

It is found mainly in plants/fungi and provides support to the cell.

Vesicles are like _____________________________ which hold

food and energy molecules for chemical reactions, similar to

vacuoles.

an outside city surrounding highway

Chemical storage/refineries

Cell analogy Project: Can you come up with a creative

analogy for cell organelles in a eukaryotic cell?

A little review…

What cell parts are primarily found in

PLANT cells?

CENTRIOLES

What cell parts are primarily present in

ANIMAL cells?

CELL WALLS, CHLOROPLASTS AND LARGE

CENTRAL VACUOLES

More review LET’S FILL IN THE CHART BELOW WITH 1 WORD

ANSWERS.

CELL PART ONE WORD

FUNCTION

CELL

MEMBRANCE

GOLGI BODIES

VACUOLES

NUCLEUS

LYSOSOME

Click for

answers

POSSIBLE CHART ANSWERS CELL PART ONE WORD

FUNCTION

CELL

MEMBRANCE

regulator

GOLGI BODIES packager

VACUOLES storage

NUCLEUS information

LYSOSOME digestion

Let’s look at some cells

http://www.enchantedlearning.com/subjects/biology/cells/

http://www.enchantedlearning.com/subjects/biology/cells/

CELL MOVEMENT

Cells need to move. Why? Turn to your

table partner and come up with 3 types

of cells and why they might need to

move?

Sperm cells need to

“swim to the egg” to

fertilize it!

White blood cells

need to move

around the body to

help fight

infection!

Plant cells

need to

move from

one plant to

another- like

pollen- so

that it too

can fertilize

another

plant for

reproduction

How do cells move? PLANT CELLS CAN NOT MOVE ON THEIR OWN…THEY RELY ON THEIR

ENVIRONMENT TO MOVE…

EXAMPLES: air, wind, water moving cells from one place to another.

JUST ANOTHER REASON WHY WE NEED TO KEEP OUR RIVERS CLEAN

AND FLOWING!

Some animal cells rely on bodily fluids to move them as well.

Animal cells move

•Cilia= many small hair like structures around the outside of the cell

•Flagella- long whip-like extensions from cell. Propeller-like.

Pseudopod- false foot extension of cell membrane

LET’S EXPLORE

REAL CELLS

What might a cell look like under a microscope?

Will we see all the parts?

What might we see more often in plants than in

animals?

Let’s have a look!