Transcript Chapter 2 “Cells” Section 1: “Cell Structure Pages 38 – 40

Cells: The
Units of Life
The Cell Theory
Some Random Cell Facts
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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”
Discovery of Cells
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1665- English Scientist,
Robert Hooke,
discovered cells while
looking at a thin slice of
cork.
He described the cells
as tiny boxes or a
honeycomb
He thought that cells
only existed in plants
and fungi
Anton van Leuwenhoek
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1673- Used a handmade microscope to observe
pond scum & discovered single-celled organisms
He called them “animalcules”
He also observed blood cells from fish, birds, frogs,
dogs, and humans
Therefore, it was known that cells are found in
animals as well as plants
150-200 Year Gap???
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Between the Hooke/Leuwenhoek discoveries
and the mid 19th 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 meat
19th Century Advancement
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Much doubt existed around Spontaneous Generation
Conclusively disproved by Louis Pasteur
Pasteur: Ummm, I
don’t think so!!!
?
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+
Development of
Cell Theory
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1838- German Botanist,
Matthias Schleiden,
concluded that all plant
parts are made of cells
1839- German physiologist,
Theodor Schwann, who
was a close friend of
Schleiden, stated that all
animal tissues are
composed of cells.
Development of
Cell Theory
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1858- Rudolf
Virchow, German
physician, after
extensive study of
cellular pathology,
concluded that cells
must arise from
preexisting cells.
The Cell Theory Complete
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The 3 Basic Components of the Cell Theory
were now complete:
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1. All organisms are composed of one or more
cells. (Schleiden & Schwann)(1838-39)
2. The cell is the basic unit of life in all living
things. (Schleiden & Schwann)(1838-39)
3. All cells are produced by the division of
preexisting cells. (Virchow)(1858)
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Modern Cell Theory
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Modern Cell Theory contains 4 statements, in
addition to the original Cell Theory:
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The cell contains hereditary information(DNA) which
is passed on from cell to cell during cell division.
All cells are basically the same in chemical
composition and metabolic activities.
All basic chemical & physiological functions are
carried out inside the cells.(movement, digestion,etc)
Cell activity depends on the activities of sub-cellular
structures within the cell(organelles, nucleus, plasma
membrane)
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How Has The Cell Theory Been Used?
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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.)
Parts of the Cell: Organelles
COMMON CELL TRAITS
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A cell is the smallest unit that is capable of
performing life functions.
2 Types of Cells
COMPARING CELLS
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The size & shape of a
cell relates to its
function. (job it does)
Prokaryotic Cells
(proh KAYR ee yah tihk)
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cells without membranebound structures
EX: bacteria
pond scum
Eukaryotic Cells
(yew KAYR ee yah tihk)
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cells with membranebound structures
EX: animals, plants,
fungi and protists
CELL WALL
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protects the cell
gives shape
is made of cellulose
A cell wall is found in plants, algae, fungi, & most
bacteria.
CELL MEMBRANE
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Outer covering, protective layer
around ALL cells
For cells with cell walls,the cell
membrane is inside the cell wall
Allows food, oxygen, & water
into the cell & waste products
out of the cell.
CYTOPLASM
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gelatin-like inside cell membrane
constantly flows
aka protoplasm
CYTOSKELETON
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scaffolding-like
structure in cytoplasm
helps the cell maintain
or change its shape
made of protein
NUCLEUS
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Directs all cell activities
Contains instructions
for everything the cell
does
These instructions are
found on a hereditary
material called DNA
Usually the largest
organelle
NUCLEAR MEMBRANE
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separates nucleus from
cytoplasm
controls movement of
materials in & out of
nucleus
NUCLEOLUS
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Aka “little nucleus”
Found in the nucleus
CHROMATIN
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contains genetic code that controls cell
made of DNA & proteins
CHLOROPLASTS
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Green organelles that
make food
found only in plant cells
CHLOROPHYLL
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A green pigment that
gives leaves & stems
their color
Captures sunlight energy
that is used to produce
food called glucose
Glucose is a type of sugar
MITOCHONDRIA
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Organelles that release
energy from food
This energy is released by
breaking down food into
carbon dioxide
AKA the powerhouse b/c
they release energy from
food
Some muscle cells have
20,000 mitochondria
RIBOSOMES
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Make proteins
Float freely or attached to
the endoplasmic reticulum
(ER)
Ribosomes are made in the
nucleolus
ENDOPLASMIC RETICULUM
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A series of folded membranes
that move materials (proteins)
around in a cell
like a conveyor belt
Smooth ER – ribosomes not
attached to ER
Rough ER – ribosomes
attached to ER
GOLGI BODIES (GAWL jee)
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Stacked flattened
membranes
Sort and package
proteins
VACUOLES
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Temporary storage
spaces
Store food, water,
waste
LYSOSOMES (LI suh sohmz)
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The word "lysosome" is Latin for "kill body."
The purpose of the lysosome is to digest things.
They might be used to digest food or break
down the cell when it dies.
Break down food molecules, cell wastes & worn
out cell parts
FROM CELL TO ORGANISM
Cell
The basic unit of life
Tissue
Group of cells working together
Organ
Group of tissues working together
Organ System
Group of organs working together
Organism
Any living thing made of 1 or more cells
NAME THE ORGANELLE
a. Nucleus
b. Chloroplast
c. Golgi body
d. Mitochondria
1- Nucleus
2- Chromosomes
3- Mitochondria
4- Ribosomes
5- Chloroplasts
6- Vacuoles
7- ER
8- Cell
Membrane