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Why Study Cells? Cells are as fundamental to Biology as the atom is to
chemistry.
All organisms are made of cells.
The cell is the simplest collection of living matter that can live.
Everything an organism does occurs fundamentally at the cellular level
Cells are about 90% water, the rest (other 10%) is about…
50% protein
15% carbohydrate
15% nucleic acid
10% lipid
10% other
Contributors to the Cell Theory
Anton Van Leeuwenhoek developed
the first microscope (observed organisms in pond water)
Robert Hooke discovered the cell in 1655
(looked at wood, stems, & thought that
compartments looked like cells
in a monastery—(small rooms)
Other Contributors
Robert Brown 1833 observed that many cells have dark structure near the center— now known to be the nucleus.
Mathias Schleiden stated that all plants are made of cells
Theodore Schawn Stated that animals are made up of cells
Rudolf Virchow stated that all cells come from pre existing cells
The Three Parts of the Cell Theory
1-All living things are made of cells
2-Cells are the basic units of structure and function in living thing
3-All cells come from preexisting cells
Prokaryotic Cells
Has No true nucleus
NO membrane bound
organelles
Have a simple structure and are
smaller in size. Mostly Unicellular (1 cell)
All are Bacteria Eubacteria &
Archeabacteria
Eukaryotic Cells
Has a true Nucleus
Has Membrane bound
Organelles
Are more complex and are larger in
size
Protists, Fungi, Plants, and Animals are all
eukaryotes
Prokaryotic Cells Locomotion Some use flagella
Some use a slime layer
Some don’t move at all
Click on the link below and
read about 5 fun facts about
bacteria (prokaryotes)
BACTERIA FUN FACTS
Bacterial cell wall
Flagellum
Rotary motor
Sheath
How did cells change,
make the transition from
prokaryotic (NO nucleus)
to eukaryotic (TRUE
nucleus) cells?
Endosymbiotic Theory
Endosymbiotic theory suggests that eukaryotes
arose from a symbiotic relationship between
various prokaryotes.
Heterotrophic bacteria became mitochondria.
Cyanobacteria (autotrophic bacteria) became
chloroplasts.
Host cell was a larger prokaryotic cell.
Evidence for this theory is that mitochondria,
centrioles and chloroplasts have their OWN
DNA
Endosymbiosis
Smaller
Prokaryotic
cell
Host cell
Prokaryotic
cell is
engulfed
Symbiosis-Increases
survival of both! CLICK for More on
endosymbiosis
Eukaryotes Eukaryotes arose from
prokaryotes and developed into larger more complex organisms.
Eukaryotes are cells that contain a nucleus and organelles surrounded by a membrane, such as the ER, mitochondria and chloroplasts.
The Nucleus
All eukaryotic cells have a nucleus at some point. This is a membrane-bound structure that contains the DNA (organism's genome). The nuclear membrane has pores or holes in it.
The nucleolus is also in the nucleus where ribosome units are made.
Cytoplasm The cytoplasm is the
AREA between the
nucleus and the cell
membrane.
(the cytosol is the jelly-
like substance filling
the space)
Many chemical
reactions occur here.
Cell membrane Structure & Function
Separates cells from their
environment
Controls what goes in & out of cells
Aids in the protection & support of the cells
Aids in inter cell communication (BETWEEN cells)
Cell membrane Structure & Function
Separates cells from their environment
Controls what goes in & out of cells
Aids in the protection & support of the cells
Aids in inter cell communication (BETWEEN cells)
Cell Membrane Structure & Function Mostly phospholipid bi-layer with the outer part being hydrophilic (phosphate head) and the inner portion very hydrophobic (2 fatty acids)
The hydrophilic heads allow interaction with watery environment inside and out
The hydrophobic inner layers squeeze together and are both stable and fluid
Proteins either move freely w/in the layer & act as channels thru which molecules can OR act like a pump pushing molecules from one side of the membrane to another.
Carbohydrates are attached to proteins, and help cells recognize & interact w/ each other
Cell Wall Found in plants, algae, bacteria,& fungi
Lies OUTSIDE of the cell membrane
Helps protect & support the cell
In plants the primary cell wall is made up of cellulose, makes it elastic so that plant can grow.
In plants with woody stems, a secondary cell wall develops—made up of cellulose & lignin—which makes it rigid.
Ribosomes—Structure & function
Site of protein synthesis (place where proteins are made)
Cells that have high rates of protein synthesis—like the liver have a larger # Ribosomes.
Free Ribosomes are suspended in the Cytosol
Bound Ribosomes are attached to the rough ER.
More about Ribosomes
Made of TWO sub-units that are 60% protein and 40% ribosomal RNA
Free Ribosomes make different proteins than Bound ribosomes (on ER)
They can switch
places as needed
depending on
metabolic needs
of the cell
The endoplasmic reticulum (ER) is where lipids of the cell membrane, along with proteins and other materials are assembled.
Rough ER has ribosomes & Smooth ER has no ribosomes
The ER usually surrounds the nucleus and may reach the cell membrane
Function of the Smooth ER Functions in many different metabolic processes:
Makes Lipid (fats)
Including phospholipids & steroids
Detoxification (lots of smooth ER in liver cells)
Function of the Rough ER Ribosomes are attached to it
Major site of protein synthesis
Makes secretary proteins—
called glycoproteins because they are bound to
carbohydrates (glyco part)
It is also involved in membrane production
Click on link
THE MAKING OF A PROTEIN
Golgi apparatus
collection of Golgi bodies Stacked flattened
sacks Site where cell
products are packaged for export
Proteins are modified by being combined with fats or carbohydrates
Golgi apparatus
Vesicles then pinch off from the Golgi body to be secreted (outside the cell)
Involved in the production of lysosomes
Function of the Mitochondria Site of Cellular Respiration which Converts
Glucose molecules into ATP energy which the cell can use-
C6H12O6 + O2 H2O + CO2 + ATP (energy)
Membrane bound organelle
It is called the power house
of the cell because it is the
site of cell respiration.
Function of the Mitochondria Found in ONLY in ALL Eukaryotic cells &
has its own DNA (remember endosymbiosis)
Chloroplasts are
organelles that
capture sunlight
energy and convert
it into chemical
energy in a process
known as photosynthesis.
Sunlight + H2O + CO2 C6H12O6 + O2
Vacuoles
Found in PLANT and ANIMAL cells
The vacuole acts a container, storing water and dissolved particles
Plants have a large central vacuole for water storage and to maintain turgor pressure
Unicellular organisms can use contractile vacuoles for movement and to maintain homeostasis (water balance)
video
Lysosomes
Are membrane bound sacs of
hydrolytic enzymes
Are used by the cell to digest
(lyse=breakdown)
Macromolecules-like proteins,
polysaccharides, fats, & nucleic acids.
If the cell releases too many Lysosomes it will die because it will eat itself (autolysis).
More about Lysosomes Involved in Phagocytosis—is when a large
molecule engulfs a smaller molecule.
Are often found in white blood cells, used as a immune—defense—mechanism to eat pathogens like viruses and bacteria.
Tay Sach’s, a fatal genetic disease—occurs when a lipid eating enzyme is missing so the fat accumulates in the cells preventing the brain from working.
The cytoskeleton is a network of protein filaments that helps the cell maintain its shape.
It is also involved in movement.
Centrioles Centrioles are
cylindrical bundles of microtubules that function during cell reproduction in animal cells.
Cilia and Flagella
Some eukaryotes have
cilia or flagella for
locomotion or as tissue
to help move stuff along.
Flagella are long whip-
like structures.
Cilia are more numerous
and are “short flagella”.
Eukaryotic differ from
prokaryotic cillia/ flagella
Plant vs. Animal Cells
PLANT
CELL
ANIMAL
CELL Cell membrane
Mitochondria
Golgi apparatus
Nucleus
Cytoskeleton
Ribosomes
Endoplasmic
reticulum
Lysosomes
HAVE:
Cell Wall
LARGE vacuoles
Chloroplasts
DO NOT HAVE:
Centrioles
HAVE:
Centrioles
DO NOT HAVE:
Cell Wall
LARGE vacuoles
Chloroplasts
Turn to page 8 of packet and click on link and complete sheet! When done return to the notes ;-)
cell part QUIZ!
The Cell Membrane As previously mentioned, The cell
membrane is the edge of life, the boundary that separates the living cell from its environment.
It’s almost like the bouncer in the club that is in charge of regulating who goes in and out of the party.
Selectively-Permeable Cell membranes are
always selectively-permeable,
meaning that some molecules
are allowed to pass freely
(diffuse) through the
membrane while others are not.
Made of a phospholipid bilayer,
Also called the “Fluid Mosaic Model”
Phospholipid bilayer or
phosphodigyceride
Head Polar (charged)
Phosphate (PO4)
Hydrophilic (water-loving)
Pointed toward inside & outside of cell
Tails (2) Nonpolar (no charge)
Fatty acid chains
Hydrophobic (water-hating)
Pointed toward middle of membrane
Permeability Vocabulary: Semi-permeable
• Some things can enter the while others can not
• Think of the Bouncer at the club that lets the pretty and the popular students in. But leaves the crazy science teachers outside staring at the door.
Complete Permeable
• Everything can enter the cell.
• An open door
Impermeable
• Nothing can enter the cell.
• Closed and locked door
Types of Transport
Passive Transport
Osmosis Diffusion Facilitated
Diffusion
Active Transport
Endocytosis & Exocytosis
Protein pumps
Types of Transport…diagram
Passive Transport
Requires No ATP
(energy)
Goes with (down)the
concentration gradient (from high-low concentration)
examples:
Osmosis, diffusion & facilitated
diffusion
Active Transport
Requires ATP energy
Goes against (up) the concentration
gradient (from low-high)
examples:
Endocystosis, exocytosis &
protein pumps.
Osmosis and Diffusion Diffusion- movement of materials from an area of high concentration to an area of low concentration.
In cells O2 and CO2 diffuses in and out Click on link
diffusion
Osmosis – diffusion of water which moves from a
high to low concentration. Click on link (be sure to add salt!)
osmosis
Dynamic Equilibrium
Particles move in and out at the same rate, so there is
no overall change and the cell remains in balance
Concentration gradient
The difference in
concentration of
molecules across
a distance in a
solution or in
and out of cells.
Hypertonic, Hypotonic, and Isotonic Solutions (The Power of Osmosis) The concentration of solute in the solution can be
less than the concentration of solute in the cells. The cell is in an hypotonic solution. (hypo = less than normal)
The concentration of solute in the solution can be greater than the concentration of solute in the cells. The cell is in an hypertonic solution. (hyper =
more than normal)
The concentration of solute in the solution can be equal to the concentration of solute in the cells. The cell is in an isotonic solution. (iso = same as normal)
Osmosis Hypotonic Solutions
• Solution has less solute (salt) than the cell
• Water enter the cell
• Cell swells
Hypertonic Solutions
• Solution has more solute than the cell
• Water leaves the cell.
• Cell shrinks
Isotonic solution
• Solute concentration of the solution is equal to that of the cell.
• No net movement of water
• Cell stays the same
Osmosis Diffusion of water through a selectively permeable
membrane.
From high water concentration to low water concentration
Click on link below and take the quiz
OSMOSIS
Facilitated Diffusion Movement of specific molecules across cell
membranes through protein channels or doorways from a high to low concentrations
Is fast and specific, but does not require cell energy.
Glucose
moves
through cell
membranes
this way
Active Transport A material moves from an area of lower
concentration to an area of higher concentration.
REQUIRES the input of cell energy.
THREE main types
1-Protein Pumps-cell membrane protein that “pumps” ions into cell, Na+ K+ pumps enable nerve impulses to move from cell to cell
click on link protein pump
more Active Transport 2-Endocytosis: the process of taking material into
the cell by means of pockets of the membrane.
TWO KINDS Phagocytosis: type of endocytosis where the
cytoplasm surrounds and engulfs large particles “cell eating”
Pinocytosis: “cell drinking”
3-Exocytosis: the removal of cell contents that consists of the membrane fusing with the membrane of the object and forcing the content out the cell. Exiting the cell “cell pooping”
Active Transport
(Requires energy)
Endocytosis “stuff coming into the cell against the gradient”
Phagocytosis
“cell eating”
Pinocytosis
“Cell drinking”
Exocytosis “Stuff leaving the cell
against the gradient
Opposite of endocytosis “getting
rid of waste”
Protein pumps Ex. Sodium-
Potasium pumps
Review ALL Cell Transport Click on link below and review all the forms
of cell transport…have fun!
review! Ready for a quiz??????