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Cells
Early Microscopes
-Lenses and microscopes:
- Late 1500s – Italy: merchants develop magnifying
lenses to examine the quality of cloth
- 1600s – Holland: lenses combined to form
microscopes and telescopes
Early Microscopes
-It was not until the mid-1600s that scientists began to
use microscopes to observe living things
-1665 – Robert Hooke (England) built compound
microscope
- looked at thin sections of cork
- Under the microscope, cork seemed to be made of
thousands of tiny, empty chambers
Early Microscopes
- Hooke called
these chambers
“cells” because
they reminded
him of a
monastery's tiny
rooms, which
were called cells
Early Microscopes
- 1674 – Anton van Leeuwenhoek used a single-lens
microscope to observe pond water
- He used a single-lens microscope
- The microscope revealed a
fantastic world of tiny living
organisms that seemed to be
everywhere
Early Microscopes
- 1838 – Matthias Schleiden concluded that all plants are
made of cells
- 1839 – Theodor Schwann stated that all animals made
of cells
- 1855 – Rudolf Virchow observed onion root tip cells
and concluded that new cells could only be produced by
division of existing cells
The Cell Theory
- It became clear that cells
are the basic unit of life
- The cell theory grew out of
the work of many scientists
and improvements in the
microscope.
The Cell Theory
- The Cell Theory has
three principles:
- All living things
are made of cells
The Cell Theory
- The Cell Theory has
three principles:
- All living things are
made of cells
- Cells are the basic
units of structure and
function in living things
The Cell Theory
- The Cell Theory has
three principles:
- All living things are
made of cells
- Cells are the basic
units of structure and
function in living things
- New cells are produced from pre-existing cells
Prokaryotes vs Eukaryotes
- Cells come in a great variety of shapes and an amazing
range of sizes
- All cells have two characteristics in common
- They are surrounded by a barrier called a cell
membrane
- They contain the molecule that carries biological
information—DNA
Prokaryotes vs Eukaryotes
- Cells fall into two broad categories, depending on
whether they contain a nucleus
- Nucleus:
- A large structure with its own membrane that holds
the cell’s genetic material (DNA)
- The nucleus controls many of the cell's activities
Prokaryotes vs Eukaryotes
- Prokaryotes:
- Cells that do NOT contain
nuclei
- Generally smaller and
simpler
- Do not have
membrane-bound organelles
- Have genetic material that
is not contained in a nucleus
- The organisms we call
bacteria are prokaryotes
Prokaryotes vs Eukaryotes
- Eukaryotes:
- Cells that do contain nuclei
- Generally larger and more
complex
- Display great variety
- Lives as single-celled
organisms
- Large, multicellular
organisms
- Dozens of structures and
internal membranes, and
- Plants, animals, fungi, and
many are highly specialized
protists
- Contain a nucleus in which their genetic
material is separated from the rest of the cell
Prokaryotes vs Eukaryotes
- Similarities between Prokaryotes & Eukaryotes:
- Come in a variety of shapes and sizes
- Both have DNA
- All cells are enclosed by a membrane
- All cells are filled with cytoplasm
- Cells tend to be microscopic
Exploring the Cell
- Researchers use microscopes and techniques more
powerful than the pioneers of biology could have
imagined
- Researchers can use fluorescent labels and light
microscopy to follow molecules moving through the cell
- Confocal light microscopy, which scans cells with a
laser beam, makes it possible to build three-dimensional
images of cells and their parts
Images produced by light microscope
Exploring the Cell
- Electron microscopes are capable
of revealing details as much as
1000 times smaller than those
visible in light microscopes
- Transmission electron microscopes
(TEMs) make it possible to explore
cell structures and large protein
molecules
Exploring the Cell
- With scanning electron
microscopes (SEMs), a pencillike
beam of electrons is scanned over
the surface of a specimen
- The scanning electron microscope
produces stunning
three-dimensional images of cells
Nerve broken
open, revealing
vesicles containing
neurotransmitters
Used
toothbrush
covered in
plague
Typical virus
Prokaryotic vs Eukaryotic
Reading, Video, & Double
Bubble Thinking Map
Prokaryotic Reading
& Coloring Activity
Parts of a Microscope &
Microscope Lab
Animal Cell & Plant
Cell Doodle Notes
Animal & Plant Cell Organelle
Notes along with Flip Picture
Book
Cell Boundaries
- All cells are surrounded by a thin, flexible barrier
known as the cell membrane
- Cell Membrane:
thin, flexible
barrier around a cell;
regulates what enters
and leaves the cell
Cell Boundaries
- The cell membrane
regulates what
enters and leaves the
cell and also provides
protection and
support
- Let’s Review!
- Cell Membranes are made up of LIPIDS
Cell Boundaries
- What two
monomers make up a
LIPID?
- Fatty Acid
- Glycerol
Cell Boundaries
- Draw individual Lipids & Label
their structures
- Fatty Acid (Tails)
Hydrophobic: Hates
Water
- Glycerol (Head)
Hydrophilic : Likes Water
Cell Membrane
- The composition of nearly all cell membranes is a
double-layered sheet called a lipid bilayer
- Lipid Bilayer:
- double-layered sheet that forms the core of nearly
all cell membranes
- hydrophilic heads point out, hydrophobic tails point
inside
Draw & Label the Lipid Bilayer
Extracellular (Outside the cell)
Hydrophilic “Heads”→
Hydrophobic “Tails”→
Intracellular (Inside the cell)
Cell Membrane
- In addition to lipids, most cell membranes contain
protein molecules that are embedded in the lipid bilayer
- Some of the proteins form channels and pumps that
help to move material across the cell membrane
- Carbohydrate molecules are attached to many of these
proteins
- Many of the carbohydrates act like chemical
identification cards, allowing individual cells to identify
one another
Color & Label Cell
Membrane
Cell Walls
- Many cells also produce a strong supporting layer
around the membrane known as a cell wall
- The main function of the cell wall is to provide support
and protection for the cell
- Cell walls are present in many organisms, including
plants, algae, fungi, and many prokaryotes
Cell Walls
- Cell walls lie outside the cell membrane
- Most cell walls are porous enough to allow water,
oxygen, carbon dioxide, and certain other substances to
pass through easily
- Most cell walls
are made from
fibers of
carbohydrate and
protein
Cell Walls
- Plant cell walls are
composed mostly of
cellulose, a tough
carbohydrate fiber
- Cellulose is the
principal component
of both wood and
paper
Cell Wall
Cell Membrane Doodle
Notes
Cell Transportation
- Every living cell exists in a liquid environment that it
needs to survive
- One of the most important functions of the cell
membrane is to regulate the movement of dissolved
molecules from the liquid on one side of the membrane
to the liquid on the other side
Cell Transportation
- The cytoplasm of a cell contains a solution of many
different substances in water
- Concentration:
The mass of solute in a given volume of solution, or
mass/volume
Cell Transportation
- Example:
12 grams of salt in 3 liters of water
Concentration is 12 grams /3 Liters (g/L)
THINK MATH: 12 / 3 is ?
THEREFORE IT IS: 4 g/L
Cell Transportation
- Practice:
12 grams of salt in 6 liters of water
Concentration is 12 grams /6 Liters (g/L)
Final Concentration is : 2 g/L
Cell Transportation
- Which solution is more concentrated?
4 g/L
2 g/L
Cell Transportation
- In a solution, particles move constantly
- Diffusion:
process by which molecules tend to move from an
area where they are more concentrated to an area
where they are less concentrated
- Molecules naturally move from HIGH concentration to
LOW concentration
Cell Transportation
- The solution will eventually reach equilibrium
- Equilibrium:
when the concentration of a solute is the same
throughout a solution
- The substances will be evenly spaced out
- Because diffusion depends upon random particle
movements, substances diffuse across membranes
without requiring the cell to use energy
Cell Transportation
- Even when equilibrium is reached, particles of a
solution will continue to move across the membrane in
both directions
- Most biological membranes are selectively permeable
- Selectively Permeable:
Some substances can pass through the cell membrane
while other substances cannot
Also referred to as semipermeable membranes
Diffusion Station for
Notes
Cell Transportation
- Endocytosis:
- process of taking material into the cell by means of
infoldings, or pockets, of the cell membrane
- Larger molecules and even solid clumps of material
may be transported in through this process
- Two types:
Phagocytosis & Pinocytosis
Cell Transportation
- Phagocytosis:
- process in which
extensions of cytoplasm
surround and engulf large
particles and take them into
the cell
- It means “cell eating”
Cell Transportation
- Engulfing material in this
way requires a considerable
amount of energy
- Due to this, it is correctly
considered a form of active
transport
Cell Transportation
- Pinocytosis:
- process by which a cell
takes in liquid from the
surrounding environment
- Tiny pockets form along the
cell membrane, fill with liquid,
and pinch off to form vacuoles
within the cell
Cell Transportation
- Exocytosis:
- process by which a cell
releases large amounts of
material outside the cell
- The membrane of the vacuole
surrounding the material fuses
with the cell membrane, forcing
the contents out of the cell
Diffusion Lab