Download Unit 3 (ch 4)

Bill Nye - Cell
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deo
Discovery of Cells

Robert Hooke, 1665
 Cells in Cork
 Cellulae (little room)
Life 1402: Principles of
Biology
Chapter 4: A Tour of the
Cell
Lecture Objectives:

Know the cell theory of life
 Understand the difference between prokaryotic and
eukaryotic cells
 Appreciate the difference between an animal and plant cell
 Understand the significance of cellular
compartmentalization
 Sketch the basic structure of a cell membrane and identify
its components
 Appreciate the basic functions of various organelles within
the cell and how these structures work together to support
the cell
 Since
the 1600s, scientists have
made many discoveries about the
cells of living things.
Hooke – discovered and named
cells while observing cork (1670)
 Robert
 Anton van Leeuwenhoek (1680?)
• Dutch fabric merchant and amateur scientist
• observed living cells; called some 'animalcules'
 Matthias
•
•
Schleiden (1838)
German botanist
discovered that plants are made of cells
 Theodor
•
•
Schwann (1839)
German zoologist
discovered that animals are made of cells
 Rudolph
•
•
Virchow (1855)
German physician
stated that all living cells come only from
other living cells
 These
discoveries are summarized in the
cell theory.
 The



cell theory states:
All living things are made up of cells.
Cells are the basic units of structure and
function in living things.
New cells are produced from existing cells.
Cell theory
theory – the cell is the
most fundamental and
common unit of living
organisms; therefore, the
definition of life is the presence
of cells.
Cell
Pro- vs. eukaryotic cells
“before”
 Eu – “true”
 Karyote “kernel” or Nucleus
 Prokaryote – no membrane bound nucleus
 Eukaryote – true nucleus
 pro-
A Tour of the Cell

Cells are the basic
unit of all living
things.
 Cells possess a
plasma membrane,
organelles and
cytoplasm
Cytoplasm –
semifluid substance
inside the cell
membrane, between
organelles
Cell Size
 Cell
size and shape is
related to function
 Nerve cells can be
1 meter long
 Ostrich eggs are the
largest single cell
 The largest animal
and plant cells are 100
mm while the smallest
cells are 10mm
 Prokaryotic cells are
between 2 and 8 mm
Cell Size Limits

Surface Area : Volume Ratio
limits cell size
 A cell must absorb all
nutrients and excrete all
wastes through the
membrane surrounding it
 The more volume a cell has
the more it must move
across the membrane
 As a cell grows the volume
increases faster then the
surface area (size of
membrane)
Prokaryotic
Cells
 Prokaryotic
cells have
no clearly defined
nucleus, but do have a
nucleoid region
 The nucleoid region is a
coiled loop of DNA, but
isn’t contained in a
membrane
 Ribosomes are used to
make proteins
Prokaryotic
Cells
A
bacterial cell wall
surrounds the plasma
membrane
 Some prokaryotes have
a sticky layer called a
capsule surrounding
the wall
 Pili may attach the
bacteria to a surface,
while some use flagella
for motility
Eukaryotic Cells
 Eukaryotic
cells are
divided into
compartments or
organelles
 The nucleus is the
most obvious
structure in a
eukaryotic cell
Eukaryotic Cells
 Most
of the cells
chemical activities or
cellular metabolism
are conducted inside
the organelles
 Plant cells contain
some additional
organelles and a
cell wall
Nucleus

The Nucleus is the genetic
control center of a
eukaryotic cell.
 Nuclear DNA is in very
long fibers called
chromatin
 Each fiber of chromatin is
a chromosome
 During cell division,
chromatin condenses so
it is visible
Nucleus
•The nuclear envelope
is the membrane that
surrounds the nucleus.
It contains pores that
control the flow of
material.
•The nucleolus is
responsible for making
ribosomes
Endomembrane System

Organelles that are formed
by interrelated membranes.
 Endoplasmic Reticulum
“Network within the Cell”
Two types smooth and rough
 Rough ER is covered with
ribosomes and is used to
produce membranes.
 Rough ER is also responsible
for making proteins that are
to be secreted by the cell,
such as antibodies.
Golgi Apparatus

The Golgi
apparatus
receives
molecules from
the ER, sorts,
packages and
ships them to the
proper
destination.
Lysosomes
(lyse –
break down, somebody) consist of
digestive enzymes
in a membranous
sac. These are used
to digest nutrient
particles, bacteria
(wbc’s) and recycle
worn out organelles.
 Lysosome
Lysosomes
 Tay-Sachs
and
Pompe’s diseases
are both caused by
a missing gene for
an lysosomal
enzyme making
victims unable to
break down certain
molecules.
Tay-Sach and Pompe’s Disease
 http://www.youtube
.com/watch?v=Seo
PF74QSms
 http://www.youtube
.com/watch?v=BDl
KFFpCnRo
Mitochondria
 Convert
food into
usable a form of
Energy (ATP) for the
cell.
 Mitochondria are made
up of two membranes.
The space between the
two membranes is the
intermembrane space,
while the second
membrane contains the
mitochondrial matrix.
.
Mitochondria
 The
folds in the inner
membrane are cristae.
They increase the
surface area of the
inner membrane.
 Mitochondria have their
own DNA and
reproduce on their own
resembling a
prokaryotic cell. All of
your mitochondria are
inherited from your
mother.
Plant Cells

Being
photosynthetic
plants require a few
more organelles,
including vacuoles
and chloroplasts as
well as a cell wall.
Vacuoles

Vacuoles are mainly
used for water storage,
but can also store
starch or other
nutrients.
Vacuoles

By filling with water the
central vacoule
increases the cell’s
volume putting
pressure on the cell
wall. This is called
turgor pressure and
helps to support plants.
Plants wilt due to a loss
of turgor pressure.
Chloroplasts

Chloroplasts are the organelle of
photosynthesis.
 Chloroplasts are similar to mitochondria in
that they have two membranes, but they also
contain stacks of disks called grana where
chlorophyll traps light energy.
Chloroplasts

As in mitochondria, chloroplasts have their
own DNA and reproduce on their own.
Cilia and Flagella

These structures are
used by cells mainly
for movement.
 Cilia are usually
shorter and too
numerous to count.
 Flagella are usually
longer and few in
number.
Cilia and Flagella

Trachea cells are lined
with cilia that help
move foreign objects
and mucous out of the
lungs.
 Sperm cells have
flagella to make them
motile.