Transcript Cell Structure and Function

Cell Structure and
Function
Chapter 7
Robert Hooke
Anton van Leeuwenhoek
"I have depicted the leaves at such a
magnitude that you can see the
globules ("tiny spots of different size")
that lay within them. Actually, there are
much more of these spots than I could
depict in the drawing ; they are much
smaller and not given in the right
proportion. After cutting the leaf, those
thin globules showed the very beautiful
lightgreen color my eyes have ever
seen. Some of them were darkgreen
and their color were the black color of
wax alike. Fig. BE is the part of the stem
and the radix within which only very few
green globules could be observed".
--AvL
http://www.euronet.nl/users/warnar/leeu
wenhoek.html
"That what I am
observing is just
what nature, not
by sinfully
defiling myself,
but as a natural
consequence of
conjugal
coitus..."
Birth of Cell Theory

1855- German physician Rudolf Virchow
concluded that new cells could be
produced only from the division of existing
cells
 1883- German botanist Matthias
Schleiden concluded that all plants were
made of cells
 1884- German biologist Theodor Schwann
stated that all animals were made of cells
Cell Theory
 All
living things are composed of cells.
 Cells
are the basic units of structure and
function in living things.
 New
cells are produced from existing cells.
Prokaryotes

Pro- before
 Karyon- “kernel” meaning the nucleus

Cells that do not contain a nucleus
lacking a distinct nucleus, such as
bacteria, (pseudomonas sp)
Pseudomonas sp
Eukaryotes

Eu- true or good
 Karyon- “kernel” meaning nucleus

Cells that contain a true nucleus
HSV 2
HSV 1
Cell Membrane
Nucleus

Contains nearly all the
cell’s DNA and with it,
the coded instructions
for making proteins
and other important
molecules

Controls the cell the
way an office controls
a factory
Ribosomes

Small particles of RNA and protein whose job it
is to assemble proteins for the cell.
 “Factory machine” that follows instructions from
the “boss” (nucleus) to produce proteins
Endoplasmic Reticulum

Site of assembly for
lipid parts of the cell
membrane as well as
proteins and other
materials for export
from the cell
Rough ER

Rough ER is studded
with ribosomes and
works mainly on
proteins
Smooth ER

Smooth ER performs specialized functions with
lipids and detoxification of toxins and drugs

Both types of Endoplasmic Reticulum function
as factory machines producing materials at the
instruction of the head office or boss in the
nucleus
Golgi Apparatus

Modify, sort, and
package proteins for
storage, shipment, or
export from the cell.

Functions as a
customization shop
as well as packaging
and shipping center
for the factory.
Lysosomes

Used for multiple clean-up functions
 Filled with enzymes for breakdown of lipids,
carbohydrates and proteins into small usable
molecules for the cell
 Breakdown “junk” produced in the cell including
old broken organelles
Prions-When Lysosomes Fail
The rogue proteins
associated with Mad
Cow Disease are
resistant to
degradation by
lysosomal enzymes
and so accumulate in
the cell and cause
disease.
Vacuoles

Saclike structure that stores materials such as
water, salts, proteins, and carbohydrates
Plants

In many plant cells there is a single vacuole filled
with liquid. The pressure of the vacuole in the
cell helps support heavy structures such as
leaves.
Cell Walls

Provide support and
protection for the cell
 Cellulose is the main
component of cell
walls
Vacuole
 Holding
space
inside a cell
 May hold food or
water
 Helps maintain
“turgor” in plants
 May help regulate
water or provide
movement in
animal cells
POWER!!!
Mitochondria and Clhoroplasts
 Mitochondira
are organelles that convert
the chemical energy in food into the
compounds the cell uses for energy
 Chloroplasts
are organelles that capture
energy from sunlight and convert it into
chemical energy through photosynthesis
Mitochondrion
“powerhouse of the
cell”
 Contains own DNA

Chloroplast
 Plants
often have both chloroplasts and
mitochondria
 Both have their own DNA
Endosymbiotic Theory
 Mitochondria
and Chloroplasts each
contain their own DNA separate from the
nucleus of the cell
 Some scientists hypothesize that these
organelles were originally prokaryotes that
evolved a symbiotic relationship with other
cells and eventually evolved into
organelles.
Endosymbiotic Theory
Cytoskeleton
• A network of protein filaments that helps the
cell to maintain its shape and provide
assistance for movement
• Supporting structure and transportation
system for the cell-factory
• Made up of microfilaments and microtubules
Cell Membrane
 Regulates
what enters and leaves the cell
and provides protection and support
 Double
 Often
layered lipid bilayer
contains embedded protein
molecules as well as attached
carbohydrates
Concentration

Solution is two substances, one dissolved in the
other
 Concentration of a solution is the mass of solute
in a volume of solution (mass/volume)
12 grams sugar in 3 L water (12g/3L) is 4g/L
12 grams sugar in 6 L water (12g/6L) is 2g/L
The first solution is twice as concentrated as the
second.
Diffusion

Particles move constantly.
 They tend to move from where they are more
concentrated to where they are less
concentrated.
High concentration
Low concentration
Facilitated Diffusion

Particles diffuse across
the cell membrane
through protein
channels.
 Particles are too large
to pass through the
membrane itself.
 Moves down
concentration gradient
 Costs no energy.
Active Transport

Actively pumps
particles from one side
of the cell membrane
to the other
 Requires action and
therefore costs the cell
energy.
 Moves AGAINST the
concentration gradient