Transcript What is a Cell?!

Cells:
The Basic Units of LIFE
Early Discoveries of Life
• The first person to study nature under a
microscope was Anton Van Leeuwenhoek
• Robert Hooke later took bark from a tree and
discovered small chambers he called cells
• Other scientists then began to look at more
plants and animals under microscopes, all
discovering cells were the basic units of all
living things!
What is a Cell?!
It took a long time for people to discover cells
and figure out what they were all about.
They need sophisticated equipment
(microscopes) to be able to see cells.
Every thing we know about cells we call
“cell theory”.
Cell Theory says that…
1. All living things are composed of cells.
2. Cells are the basic units of structure and
function in all living things.
3. New cells are produced from existing cells.
Basic Cell Structure:
• All cells have the same basic structure.
Some are simple and some are very
complex, but we always see…
– Cell Membranes
– Cytoplasm
• Many cells also have a…
– Cell Wall
– Nucleus
Cells come in all shapes and sizes!
There are two types of cells:
Prokaryotic Cells
and
Eukaryotic Cells
These are two distinct types of cells with
STRUCTURAL differences.
Prokaryotes
Bacteria
Eukaryotes
Animal
Plant
Prokaryote Cell
A single celled
organism that does
not have a nucleus. It
does have a cell
membrane and
cytoplasm
Traits of Prokaryotes:
(pro-care-ee-ohts)
1. They do not have a nucleus, and their genetic
material is not stored in the nucleus.
2. They have some organelles, a cell membrane
and cytoplasm but not much else.
3. They are smaller, simper, and less
complicated that eukaryotes.
4. All bacteria are prokaryotes.
(Escherichia Coli and Staphylococcus aureus)
Bacteria may be small but they are powerful!
During the 14th century, 25% or ¼ of Europe was
killed by a killed by a bacteria called the Bubonic
Plague, also called Black Death. This bacteria
was spread through fleas and rodents.
The Black Death was one of the most devastating
pandemics in human history, resulting in the deaths of an
estimated 75 to 200 million people and peaking in Europe
in the years 1346–53. Although there were several
competing theories as to the etiology of the Black Death,
analysis of DNA from victims in northern and southern
Europe published in 2010 and 2011 indicates that the
pathogen responsible was the Yersinia pestis bacterium,
probably causing several forms of plague.
The Black Death is thought to have originated in the arid
plains of Central Asia, where it then travelled along the
Silk Road, reaching Crimea by 1343. From there, it was
most likely carried by Oriental rat fleas living on the black
rats that were regular passengers on merchant ships.
Spreading throughout the Mediterranean and Europe, the
Black Death is estimated to have killed 30–60% of
Europe's total population. In total, the plague reduced the
world population from an estimated 450 million down to
350–375 million in the 14th century. The world population
as a whole did not recover to pre-plague levels until the
17th century.
But at the same time we need
bacteria to live!
1. Bacteria are decomposers and without them all
other organisms would not be able to survive.
2. We use bacteria in our digestive system to
help digest our food. There are approximately
ten times as many bacterial cells as human
cells in the human body!
3. We could not make cheese or yogurt without
bacteria.
Eukaryote Cell
A more complex cell
with a nucleus and
many organelles.
Traits of Eukaryotes: (you-care-ee-othts)
1. They all have a nucleus where the
genetic material of the cell is stored.
2. They have many organelles that work
together to help the cell function, along
with a nucleus, cell membrane, and
cytoplasm.
More traits of Eukaryotes:
(you-care-ee-othts)
3. Eukaryotic cells are much more complex then
prokaryotic cells.
4. They can be just one cell or can make up more
complex multi-cellular organisms.
5.
All plants, animals, fungi, and protists are
eukaryotic cells.
The nucleus!
Prokaryotic cells do not have a
nucleus and eukaryotic cells
do have a nucleus. This
allows eukaryotic cells to make
multi-cellular organisms and
perform more complex
functions.