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Cells
Robert Hooke
Robert Hooke
An English philosopher, architect,
and mathematician.
Took over a commission from the
King of England in which he was
supposed to study insects.
Robert Hooke
Was amazed by the complexity of
tiny life forms like fleas.
Did lots different experiments,
many on himself.
Robert Hooke
Discovered the first “cells” in cork in
1665.
Antonie Von Leeuwenhoek
A Dutch lensmaker. He created his own
microscopes and among other things, observed
pond water.
Von Leeuwenhoek
He made an amazing array of discoveries with tiny
instruments.
The Cell Theory
After years of continued research on the small cells that seemed to make up
everything that is alive. A bunch German scientists proposed what is still
accepted as the cell theory.
Remember the word theory in science doesn’t mean guess. It means the best
possible explanation for the natural world based on repeated experiments.
The Cell Theory
Part 1:
All living things are
composed of cells.
The Cell Theory
Part 2:
Cells are the basic unit
of structure and
function in living things.
The Cell Theory
Part 3:
All cells are produced
from other cells.
The Organelles
Recall way back in the beginning of the unit on classification that prokaryotes and
eukaryotes are different because...
The Organelles
Recall way back in the beginning of the unit on classification that prokaryotes and
eukaryotes are different because...prokaryotes don’t have a nucleus or other
organelles.
The Organelles
In this unit, we are
going to try to
learn all of the
basic organelles
and their
functions.
Organelles are
structures in a cell
that have specific
functions.
The City Analogy
When trying to learn the organelles, it is helpful to have something to compare
them to. There are many options, but we are going to go with a city.
The Cell Wall
The Cell Wall is only
found in plants. Made of
cellulose, it adds strength
and shape and gives the
cell protection. It is like
the wall around a
medieval city.
The Cell Wall
The Cell Wall is only
found in plants. Made of
cellulose, it adds strength
and shape and gives the
cell protection. It is like
the wall around a
medieval city.
Cell Membrane
Just inside the cell wall in plant cells, this is the outer layer on all animal cells. It is
made of two layers of lipids (fat molecules) that are embedded with protein
channels.
Cell Membrane
The entire structure is like a bag around the cell with thousands of tiny openings
made by the protein channels.
Cell Membrane
The protein channels control what can or cannot get in or out of the cell.
Cell Membrane
They work like traffic gates with
guards posted at them.
Nucleus
Usually near the center of the cell the nucleus
will be visible. It is a large round structure
filled with genetic material. We will be
studying the genetic material in much more
detail soon. For now you need to understand
that it is the material that controls the cell and
is passed down from parents.
The nucleus is a membrane filled with
chromatin (genetic material).
Nucleus
The nucleolus is a special part of the nucleus
that makes another organelle called the
ribosome.
Every cell has just one nucleus in it.
Nucleus
The nucleus is like the city government.
Sending out orders on what can and should
happen within the cell.
Mitochondria
In most cells, you will find a bunch of organelles that look like wrinkly beans.
These organelles called mitochondria are special for a couple of reasons. First
off, they provide power to the cell breaking down sugar and turning it into a usable
substance called ATP.
Mitochondria
Mitochondria are also special
because they have their own
genetic material.
The prevailing theory is that
mitochondria are actually a
prokaryotic life form that is
symbiotically associated with
eukaryotes.
Mitochondria
Mitochondria are
like the power
plants in a city.
Endoplasmic Reticulum
This long maze like group of passages caries materials from one part of the cell to
another.
Endoplasmic Reticulum
The endoplasmic reticulum is like the highway system in a city.
Ribosomes
Attached to the endoplasmic reticulum in some areas are little dots called
ribosomes. The ribosomes produce the protein used in the building of the cell.
Ribosomes
Ribosomes are like factories in a city.
Golgi Bodies
The golgi bodies look like a stack of pancakes. They take proteins recently made
by the ribosomes on the endoplasmic reticulum and package them so they can be
moved to the “far” distances of the cell.
Golgi Bodies
The golgi bodies are like the mail service or UPS of the cell.
Chloroplasts
As we learned in the plant unit,
chloroplasts are organelles that
allow for photosynthesis to
happen. Like mitochondria, they
have their own genetic material.
They are green due to be filled
with the chemical chlorophyll.
Chloroplasts
Chloroplasts can be thought of as
solar panels.
They are only found in plants and
some protists.
Vacuoles
The vacuole is a huge organelle in most plant cells. In most animal cells, they are
quite small. They are basically giant bags used to store water, food, or sometimes
waste.
Vacuoles
The vacuole can be
thought of as a water
tower.
Lysosomes
Lysosomes are bag like organelles that look similar to a vacuole. However, they
are filled with strong chemicals that break down anything that they pull inside
themselves. Their job is to break down large food particles, old organelles, or
even invaders.
Lysosomes
Lysosomes can be thought of as the clean up crew of the city. The janitors,
trashmen, plows, etc.
Cytoplasm
The fluid that all of the organelles “float” in is the cytoplasm. It is the filler and
made mostly of water, salt, and protein.