Their Environment Unit 7 Some Random Cell Facts The average human being is composed of around 100 Trillion individual cells It would take as many as 50 cells to cover the area of a dot on the letter ID: 596193
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Slide1
Cells &
Their Environment
Unit 7Slide2Slide3
Some Random Cell Facts
The average human being is composed of around 100 Trillion individual cells!!!
It would take as many as 50 cells to cover the area of a dot on the letter “
i
”Slide4
Microscopes
In the 1600’s
Anton van Leeuwenhoek
described red blood cells & bacteria from his teeth
1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms
Used a simple microscopeSlide5
Simple Microscope
Little more than a magnifying glass, still with Leeuwenhoek’s skill as a lens grinder he achieved 200x magnification.Slide6
Robert Hooke
In 1665 Robert Hooke, English scientist, used a compound light microscope to examine cork cells
Saw tiny hollow boxes, named the cells after the living quarters of monks
He thought that cells only existed in plants and fungiSlide7
150-200 Year Gap???
Between the Hooke/Leuwenhoek discoveries and the mid 19
th
century, very little cell advancements were made.
This is probably due to the widely accepted, traditional belief in
Spontaneous Generation
.
Examples:
-Mice from dirty clothes/corn husks
-Maggots from rotting meatSlide8
19
th
Century Advancement
Much doubt existed around Spontaneous Generation
Conclusively disproved by Louis Pasteur
+
=
?Slide9
Schleiden & Schwann
Schleiden
looked at plants & concluded that all plants are made of cells.
Schwann
looked at animals & said all animals were made of cellsSlide10
Virchow
All cells come from pre-existing cellsSlide11
These observations led to the
Cell Theory
Slide12
1.
All organisms are composed of one or more cells.
(S & S)
Part 1 of the Cell Theory:Slide13
2.
The cell is the basic unit of function and organization of all organisms.
(S & S)
Part 2 of the Cell Theory:Slide14
3.
All cells are produced by the division of pre-existing cells.
(V)
Part 3 of the Cell Theory:Slide15
Modern Cell Theory
Modern Cell Theory contains 4 statements, in addition to the original Cell Theory:
1. The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division.
2. All cells are basically the same in chemical composition and metabolic activities.
3. All basic chemical & physiological functions are carried out inside the cells (movement,
digestion,etc
).
4. Cell activity depends on the activities of sub-cellular structures within the cell (organelles, nucleus, plasma membrane).Slide16
How Has The Cell Theory Been Used?
The basic discovered truths about cells, listed in the Cell Theory, are the basis for things such as:
Disease/Health/Medical Research and Cures(AIDS, Cancer, Vaccines, Cloning, Stem Cell Research, etc.)Slide17
Some Parting Thoughts
It is amazing to think that the cells that make up our bodies are just as alive as we are. Humans are just an intricately designed community of cells, which must work together to survive.Slide18
Compound microscopes
Microscope that uses a image observed through two lenses.
Used to look at cells & small organisms, magnifies up to 1500X
The magnification is determined by multiplying the two lenses power together.
10 x 40 = 400Slide19
Electron Microscopes
An item is placed in a vacuum and a stream of electrons are aimed at the item. The image is transferred to a computer screen.Slide20
TYPE OF ELECTRON MICROSCOPES
TEM
-
Transmission Electron Microscope
, used to study detailed parts of the cell, magnify hundreds of thousands of times
SEM
-
Scanning Electron Microscope
, 3-D images, but can only see the surface, magnify 60,000X
STM
-
Scanning Tunneling Microscope
, show arrangement of atoms on the surface of a moleculeSlide21
TEM
Bacteria cells
SEM
Sperm cells
STM
Surface of PlatinumSlide22
Prokaryote
Usually a unicellular organism that lacks internal organelles surrounded by membranes.
Has a cell membrane & DNA but
NO NUCLEUS
!
Ex: bacteriaSlide23
Eukaryote
More complex cell, unicellular or multicellular organisms. Has
membrane-bound internal organelles
.
HAS A NUCLEUS!
Ex: plants, animals, fungi, protistsSlide24
Tissue
: A group of cells that function together to perform an activitySlide25
Organ
: Group of 2 or more tissues that function together. (stomach
)Slide26
Organ System
: A group of organs that make a life function efficient. (organism)Slide27
SO…
Cells
form
Tissues
Tissues
form
Organs
Organs
form
SystemsSlide28
Plant & animal cells are EUKARYOTES!
Remember:
All eukaryotes have a
nucleus
!Slide29
3 Differences between plant & animal cells:
1. Plant cells have a cell wall.
2. Plant cells have chloroplasts.
3. Plant cells have 1 large central vacuole and animal cells have many small vacuoles.Slide30
Animal Cell vs. Plant CellSlide31
Why are cells so small?
GEOMETRY!!
Average cell is 50 micrometers in diameter.
As any shape gets larger the interior increases at a faster rate than the surface area (ratio gets smaller as the cell gets larger).Slide32
Cells rely on the surface to allow materials to enter and exit the cell and support the organelles.
Too large a cell results in too little surface area to support the interior.