The Cell

Structure and Function
Chapter 4
What importance do
cells have to life?
-Mid 1600’s Started using microscopes
-Robert Hooke- used the scope to look at cork
-Coined the term cells, because of what the cork
looked like under the scope.
-Van Leeuwenhoek- 1st to look at living cells.
-Looked at pond water and saw organisms (very
tiny) living in the water.
1. All living things are made of cells.
2. Basic unit of structure and function.
3. New cells come from existing cells.
- Use fluorescent labels to follow molecules
through cells.
- Can build 3-D cells images of cells and their
-Use light, electrons and high resolution scopes
to see cells, structures, DNA, proteins and
other molecules.
to evolve
Have DNA
3.Simple Cell
4.Ex: Bacteria
1.Cells contain
2.Larger and more
2 Parts
1. Nucleus- Brain of the cell
2. CytoplasmEntire cell outside of the nucleus.
Holds organelles for cell.
Animal Cell
Plant Cell
1. Cell Membrane-thin, flexible outer layer
- lipid bilayer (2 layers of lipids)
- Integral proteins(in membrane)
- Peripheral Protein (touch membrane)
-Mosaic because molecules in
Semi-Permeable Cell Membrane
Gate Keeper- controls what comes in
and out of cell. (picky)
2. Cell Wall- Plant Cells
- made of cellulose
- rigid support for cell/plant
- outside of the membrane
3. Cytoplasm- area between nucleus and
-contains organelles
-jelly-like substance
4. Nucleus- brain of the cell
- surrounded by the nuclear envelope
- double membrane
- contains nuclear pores (sm holes)
- Main Function- store DNA in form of
- during cell division chromatin
coils up to form chromosomes.
- Contains nucleolus
- synthesizes and partially assembles
5. Cytoskeleton- framework of the cell, made of proteins
- 2 structures:
1. microfilaments- (“threads”)
- aid in movement and muscle
2. microtubules- (“straws”)
- assemble/disassemble to
form spindle fibers during cell division.
(extremely important to cells)
6. Cilia and Flagella- hairlike
- on cell surface
- aid movement
Cilia- shorter and numerous
(respiratory system)
Flagella- longer and less numerous
- small structures with specialized function
- Found in the cytoplasm
7. Mitochondrion
- mitochondria (plural)
- “powerhouse” of the cell
- Converts energy from nutrients to ATP
- Double membrane –inner membrane cristae
- has its own DNA (from mother)
-more in active tissue (muscle, liver)
8. Ribosomes- protein synthesis (proteins are made)
- most numerous organelle
- NOT membrane bound
- synthesized and partially made in
- finished being made in cytoplasm
when proteins are made.
- may be “free-standing” or attached to
Endoplasmic Reticulum.
9. Endoplasmic Reticulum (ER)
- “subway” of the cell
- Transports material within cell
- Rough ER- covered with ribosomes
and prepares proteins for transport.
- Smooth ER- no ribosomes
- synthesizes steroids (glands)
- regulates calcium (muscle)
- breaks down toxins (liver)
10. Golgi Apparatus- Made of a series of parallel
- Modifies/ repackages proteins
- manufactures lysosomes
- plays a role in secretion
11. Lysosomes- most common in animals, not plants
- contains digestive enzymes
- help to break down carbs, proteins, lipids
12. Centrioles- found in a pair
- near nucleus
- aid in cell division by aligning
Vacuoles- store food, water, waste (not at same
- plant cells have a large central vacuole
- animals have numerous, smaller
- plant vacuoles perform lysosome job.
14. Chloroplasts- exclusive to plants
- have a double membrane
- captures energy from sunlight and
converts it into chemical energy
during photosynthesis.
- “solar power” in plants
- contains green pigment called
- Type of Chromoplasts- colored plastids
- orange- carotene
Plant Cells
Animal Cells
Cell Wall
No Cell Wall
Cell Membrane
NO Centrioles
Single Large Vacuole
Many small lysosomes
Oblong Shape
Round/Irregular Shape
Nucleus not centrally located
Nucleus usually centrally located
Endoplasmic Reticulum
Endoplasmic Reticulum
Relationships Between Organelles
1. Nucleus (DNA makes RNA)
Nucleolus – Makes Ribosomes
Cytoplasm- Holds Organelles
2. ER- ribosomes attach, transports proteins
3. Proteins modified by GOLGI
4. Golgi manufactures LYSOSOMES
5. Lysosome digest particles, worn out organelles
6. Spare parts from lysosome, ready to use in future
from directions from NUCLEUS
7. MITOCHONDRIA provides energy for ALL
7.3- Cell Boundaries
What is the cell boundary of animal cells?
What is the cell boundary of plant cells?
What role do these structures have?
Cell Boundaries Functions
Cell Membrane- regulates what enters and
leaves the cell.
Cell Wall- Provides support and protection
for the cell.
2 Types of Transport
1. Passive Transport- movement of
molecules/material through the cell
membrane and requires NO energy.
2. Active Transport- movement of
molecules/material through the cell
membrane and REQUIRES energy.
Passive Transport
1. Diffusion- movement of molecules from an
area of high concentration to low
2. Osmosis- movement of solutions across a
3. Facilitated Diffusion- form of diffusion which
requires a carrier protein. Ex: Glucose
- Concentration- amount of solute dissolved in a
- Concentration Gradient- difference in molecule
concentration across a space.
- Movement of molecules from an area of HIGH
concentration to LOW concentration.
Ex: Match being lit.
- Movement is ‘with’ or ‘down’ the gradient
- Molecules move to reach equilibrium.
Diffusion Continued
Movement from high
to low
Diffusion Continued
Kinetic Energy- powers diffusion
- energy of moving particles
- ink dropped into water
- gas exchange in cells (oxygen)
- fragrance of candles in a room
- Movement of water (solutions)
- Cell must have a selectively permeable
- Movement depends on concentration.
(use salt water as an example)
Hypertonic- more solute (salt) [OVER]
Hypotonic- less solute (salt) [Below]
Isotonic- same amounts of solute (equal salt in
the cell and outside of the cell)
Osmosis Continued
of Cell
of Cell
of Cell
Solutions are:
- ate salt, need water
- no salt to absorb water
Osmosis Examples
Plants- “like” HYPOTONIC
- turgor pressure- membrane pushing against
cell wall. Gives us crisp veggies.
Protists- often in HYPOTONIC environment.
- contractile vacuole pumps out excess water
Animals- can be in HYPOTONIC environment.
- cells take on water until they burstCYTOLYSIS
If in HYPERTONIC environment
- Plasmolysis- cells lose water and shrink.
Facilitated Diffusion
- Form of diffusion
- Requires a carrier protein (protein channel)
- Carrier protein binds to molecule and
changes shape to carry molecule across.
- Protein returns to normal shape when
- No ATP (energy) used
- Glucose is best example.
Active Transport
1. Molecular Transport- movement of
molecules from area of lesser to greater
2. Endocytosis- taking in of material into the
cell by infolding of the cell membranes.
3. Exocytosis- forces material out of the cell
through the cell membrane.
Molecular Transport
-Movement of molecules from an area of lesser
higher concentration
- Movement is ‘up’ or ‘against’ the gradient
Paddling up stream
- Normally moves calcium, potassium, and
sodium ions across cell membrane.
- Uses ATP
- Ex: Na/K pumps
- moves 3 Na+ OUT and 2 K+ IN
Endocytosis- “infolding” to allow cells to bring
molecules into it. Cell membrane pinches
around a molecule or fluid.
2 types
1. Phagocytosis- membranes surround LARGE
PARTICLES and pull it in.
2. Pinocytosis- membranes surround FLUIDS
and pull it into the cell
Exocytosis- cells release large amounts of
material from the cell.
- vacuole attaches to cell membrane and
dumps its contents out of the cell.
7-4 Diversity of Cellular Life
- What are the different types of life found
on Earth?
Living Organisms
Unicellular Organisms- a cell is the entire
organism. 1 cell does everything multicellular
organisms do.
Multicellular Organisms- made of many cells
Cell specialization- cells develop in different
ways to perform different tasks.
Cell Specialization
Animal Cells
- Red Blood Cells- transport oxygen
- Pancreatic Cells- produce proteins (enzymes)
- Muscle Cells- humans ability to move
Plant Cells
- Guard Cells- regulates how much carbon
dioxide, oxygen, water vapor is released
through the stomata.
Levels of Organization
CellsTissues- similar cells grouped into units that perform
a particular function.
Ex: muscle, epithelial, nervous and connective
Organs- groups of tissues working together.
Ex: heart
Organ Systems- group of organs that work together.
Ex: Pulmonary system- heart and lungs