Download Cell City Analogy

• The Cell Theory grew out of the
work of many scientists and
improvements in the microscope.
Scientists that contributed to the Cell Theory:





Hooke:
Leeuwenhoek:
Schleiden:
Schwann:
Virchow:
• Early studies led to the development of
the cell theory.
The Cell theory has three principles.
1. All organisms are made up of cells
2. All existing cells are produced by other living cells
3. The cell is the most basic unit of life
Cells Have an Internal Structure
•
Cytoskeleton has many
functions
1.
2.
3.
4.
5.
Microtubules give cells
shape; move DNA
Intermediate filaments,
give cells strength
Microfilaments allow
cells to move and divide
Cytoplasm important for
cell structure
Water allows chemical
reactions to occur
Nucleus
Stores genetic information
•
•
•
Nuclear envelope – double
membrane that encloses
DNA
Nuclear Pores –
Nucleolus – contains tiny
organelles for making
proteins
Endoplasmic Reticulum
 Series of folded membranes
“Intracellular Highway”
 Many processes occur on surface and lumen
(interior of membranes)
ex: Production of proteins
and lipids
Endoplasmic Reticulum
• There are two types:
– Rough Endoplasmic
Reticulum (R.E.R.): contain
ribosomes
– Smooth Endoplasmic
Reticulum (S.E.R.): no
ribosomes
Lumen
Ribosome
 Ribosome's link amino
acids to form proteins
 Made of protein and
RNA
 Made in nucleolus;
leave through nuclear
pores
Golgi Apparatus
• Closely stacked membranes
• Package, Sort, and Processes
Proteins from the E.R.
Vesicles
• Membrane-bound sacs pinch off from
E.R. and fuse with Golgi Body; transport
materials
Vacuoles
• Fluid-filled sacs used for storage
• Central vacuole unique to plant cells
– plants shrivel when central vacuoles don’t have enough
water
– Can contain toxins that help the plant survive
Lysosomes
• Contain enzymes inside to digest
material; defend cell from invading
bacteria and viruses
• Surrounded by a membrane; protects
cell from being broken down
Centrosome and Centrioles
• Centrioles are tubes found
in the centrosomes
– Centrioles help divide
DNA.
• Centrosomes make
microtubles which make
spindle fibers
– Centrioles form cilia and
flagella
Plant cells
Have TWO features Animal Cells Do Not
Cell wall: gives
protection, support,
and shape to cell
Chloroplasts:
organelles that
perform
photosynthesis
Cell City Analogy
In a far away city called Grant City, the main export and production product is the
steel widget. Everyone in the town has something to do with steel widget making
and the entire town is designed to build and export widgets. The town hall has the
instructions for widget making, widgets come in all shapes and sizes and any
citizen of Grant can get the instructions and begin making their own widgets.
Widgets are generally produced in small shops around the city, these small shops
can be built by the carpenter's union (whose headquarters are in town hall).
After the widget is constructed, they are placed on special carts which can deliver the
widget anywhere in the city. In order for a widget to be exported, the carts take
the widget to the postal office, where the widgets are packaged and labeled for
export. Sometimes widgets don't turn out right, and the "rejects" are sent to the
scrap yard where they are broken down for parts or destroyed altogether. The
town powers the widget shops and carts from a hydraulic dam that is in the city.
The entire city is enclosed by a large wooden fence, only the postal trucks (and
citizens with proper passports) are allowed outside the city.
KEY CONCEPT The cell membrane is a
barrier that separates a cell from the
external environment. Acts like a fence.
Cell membranes are composed of
two phospholipid layers
• Phospholipids have 3 parts:
– Charged phosphate group
– Glycerol
– Two fatty acid chains
• Label the head
• Label the tail
• Which part is attracted to water?
• Cell membranes are composed of two
phospholipid layers.
– The cell membrane has two major functions.
• boundary
• controls passage
cell membrane
inside cell
outside cell
• Cell membranes are composed of two phospholipid
layers.
– The cell membrane is made of a phospholipid bilayer.
– There are other molecules embedded in the membrane.
Functions
cell membrane
Cholesterol:
carbohydrate
chain
Proteins:
Carbohydrates:
cholesterol
protein
protein channel
protein
Cell membranes are composed of
two phospholipid layers.
– The fluid mosaic model describes the
membrane.
• Fluid: Cell membrane moves, not rigid
– Does not flip, though, outside stays out, inside stays in
• Mosaic: variety of molecules similar to tiles with
different textures and patterns
• Cell membranes are composed of two
phospholipid layers.
– The cell membrane is selectively permeable.
What does selective
mean?
What does permeable
mean?
So, what does
selectively permeable
mean?
• Chemical signals are transmitted across the
cell membrane.
– Receptors bind with ligands and change shape.
– There are two types of receptors.
• intracellular receptor
Examples: Aldosterone
in kidneys
• Chemical signals are transmitted across the
cell membrane.
– Receptors bind with ligands and change shape.
– There are two types of receptors.
• intracellular receptor
• membrane receptor
Examples: red blood cells
carrying carbon dioxide
3.4 Diffusion and Osmosis
KEY CONCEPT Materials move across membranes
because of concentration differences.
3.4 Diffusion and Osmosis
Passive transport does not require energy input from a
cell.
• Molecules can move across the cell membrane
through passive transport.
• There are two types of
passive transport.
• diffusion
• osmosis
3.4 Diffusion and Osmosis
Diffusion and osmosis are types of passive
transport.
• Molecules diffuse down a
concentration gradient.
Where will the
ball roll?
Does it take
energy?
3.4 Diffusion and Osmosis
Diffusion and osmosis are types of passive
transport.
• Osmosis is the diffusion of water molecules across a
semipermeable membrane.
Which direction will
the water molecules
move?
3.4 Diffusion and Osmosis
• There are three types of solutions.
• Isotonic: Iso means equal so…
•
Hypertonic: Hyper = above so…
•
Hypotonic: Hypo = below so…
3.4 Diffusion and Osmosis
Some molecules can only diffuse through transport
proteins.
• Some molecules cannot easily diffuse across the cell
membrane.
• Facilitated diffusion is
diffusion through transport
proteins.
• Move with concentration
gradient!
• No energy required
3.5 Active Transport, Endocytosis,
and Exocytosis
KEY CONCEPT Cells use energy to transport materials
that cannot diffuse across a membrane.
What is different from this picture than the picture in the previous
slides?
3.5 Active Transport, Endocytosis, and Exocytosis
Active transport requires energy input from a cell
and enables a cell to move a substance against its
concentration gradient.
• Active transport is
powered by chemical
energy (ATP).
• Active transport occurs
through transport protein
pumps.
• Cells use active transport
to maintain homeostasis.
3.5 Active Transport, Endocytosis, and Exocytosis
A cell can import and export large materials or large
amounts of material in vesicles during the
processes of endocytosis and exocytosis.
• Cells use energy to transport material in vesicles.
• Endocytosis is the process of taking material into the cell.
• Phagocytosis is a type of endocytosis; engulfs Large
particles
Vesicle
3.5 Active Transport, Endocytosis, and
Exocytosis
• Exocytosis is the process of expelling
material from the cell.
Vesicle