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The
Cell
Cell
Structure
and
Function
Early Contributions
• Robert Hooke - First person to see cells, he was
looking at cork and noted that he saw "a great many
boxes. (1665)
• Anton van Leeuwenhoek - Observed living cells in
pond water, which he called "animalcules" (1673)
• Theodore Schwann - zoologist who observed tissues of
animals had cells (1839)
• Mattias Schleiden - botanist, observed tissues of plants
contained cells (1845)
• Rudolf Virchow - also reported that every living thing is
made of up vital units, known as cells. He predicted that
cells come from other cells. (1850 )
The Cell Theory
• 1. Every living
organism is made of
one or more cells.
• 2. The cell is the basic
unit of structure and
function. It is the
smallest unit that can
perform life functions.
• 3. All cells arise from
pre-existing cells.
*Why is the Cell Theory
called a Theory and not a
Fact?
Cells are always small, how small depends on the type of cell
Cells can come in a variety of shapes
Figure 4.3
Single Cheek Cell - at different illuminations
Three Features of Cells
1. Plasma (Cell) Membrane - serves as a barrier, regulates
what enters and leaves the cell
* We go into much more detail in the next chapter on how this works*
Cell Membrane is made of:
a) Phospholipid Bilayer (double layer)
b) Proteins
c) Carbohydrates
Pg 64
2. Genetic Material
1. provides cellular "blueprint" that controls the
functions of the cell
2. In the form of DNA (Deoxyribonucleic acid)
3. DNA is universal for all cells, an all living
things - evidence of common ancestry
4. Chromatin is the complex of proteins and
DNA, it condenses into chromosomes before
cell division
*We will go into much greater detail in a later
unit on GENETICS*
Cytoplasm (cytosol)
1. Located within the
plasma membrane
2. contains water, salts,
and other chemicals
3. organelles float within
this jelly-like substance
Microtubules and
filaments support the
inner structure of the cell
Prokaryote vs Eukaryote Cells
Endosymbiosis theory:
All organelles seem to share many properties with bacteria.
Lynn Margulis proposed endosymbiont hypothesis
(endosymbiosis): that organelles derived from ancient
colonization of large bacteria (became the eukaryotic cell)
by smaller bacteria (became the mitochondria, chloroplast,
etc.) Symbiosis = "living together".
*Mitochondria & Chloroplasts have their own DNA
Animation at Microbiological Concepts
Prokaryote Cells
• no membrane-bound nucleus, chromosomes
grouped together in an area called the
"nucleoid"
• no membrane-bound organelles
• smaller than eukaryotes
• have cell wall and cell
membrane, some have a
capsule on the outside
• ribosomes make protein
• consist of eubacteria and
archaebacteria
• Appendages
include: fimbriae/pili,
flagella
*pili are usually longer and fewer than fimbriae,
both function for attachment and recognition of
host cells (or sexual reproduction)
Figure 4.4a
E. coli
Eukaryote Cells
•
•
•
•
has a membrane-bound nucleus
has membrane-bound organelles in cytoplasm
organelles perform specific functions
much larger than prokaryotes
Organisms within the animal, protist, plant and
fungi kingdoms are all eukaryotes
Do you remember some of the
organelles and their functions?
Quick Recap.......
1. What are the two main types of cells?
2. Which one is larger?
3. Which one does not have a membrane-bound nucleus?
4. What are the three main parts of the cell (that all cells
have)?
5. What are the 3 components of the cell theory?
6. What theory explains how eukaryotes evolved?
It may seem that in these slides there were
quite a few "more on this later.." notes....
That's because cell biology is a huge area, and is divided into
many branches that biologists specialize in...
1) Oncology
2) Microbiology
3) Genetics
4) Paleobiology
5) Pathology
............to name a few
Here's an older video that compares prokaryotes and
eukaryotes and discusses how cells evolved, film by the
Phoenix Learning Group (17 minutes)
And a shorter video on the main parts of The Cell