Chapter 4
The Cell and Its Environment
Standard 3: Students know and
understand the characteristics and
structure of living things, the
processes of life, and how living
things interact with each other and
the environment.
Introduction to the Cell
Introduction and Evolution of the Cell (26:13)
Vocabulary
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Active transport
Osmosis
Cell theory
Passive transport
Cell wall
Phagocytosis
Diffusion
Pinocytosis
Dynamic equilibrium
Plasma membrane
Endocytosis
Exocytosis
Facilitated diffusion
Transport protein
Fluid Mosaic model
Vesicle
Middle Lamella
Selectively permeable membrane
4.1 Membrane Structure
• Key Terms:
– Cell Theory
– Plasma Membrane
– Selective
Permeability
– Lipid Bilayer
– Membrane proteins
– Fluid mosaic model
E-Coli
• Plasma Membrane
animation
Kingdoms
• On Earth, there are five kingdoms that
include specific organisms that fit into that
kingdom based on similar characteristics.
What are they?
Kingdoms
• On Earth, there are five kingdoms that
include specific organisms that fit into that
kingdom based on similar characteristics.
They are:
– Monera
– Protista
– Plantae
– Fungi (There’s a fungus among us)
– Animalia
Life Inside A Cell
Animal Cell
(3:10)
Plant Cell
Cell Theory
• What are the 3 components of the cell
theory?
Cell Theory
• All organisms are
composed of 1 or
more cells or cell
fragments.
• The cell is the basic
unit of structure and
function in organisms.
• All cells are produced
from other cells.
• So, what are cells
exactly? It’s alive!
Animal cell
(Click on the picture)
Scientists and Cell Theory
• Who was the first scientist to see cells?
• Who was the first scientist to declare that
plants are made up of cells?
• Who was the first scientist to declare that
animals are made up of cells?
Scientists Behind Cell Theory
• Robert Hooke: 1665
– First discovery of cells
• Matthias Schleiden: 1838
– Concluded all plants are
made of cells and cells are
the basis of a plant’s function
• Theodor Schwann: 1839
– All animals are made of cells
• Rudolf Virchow: 1858
– All cells come from other
cells.
Robert Hooke and friends
Click on picture (3:32)
Pick me! Click me!
Plasma Membrane
• What are three properties of the plasma
membrane?
Properties of Plasma Membrane
• All cells live in a fluid environment
• Each cell is a separate unit of life that
receives and releases substances from
their environment through the plasma
membrane.
• Plasma membrane is the cell’s
gatekeeper.
Plasma
Membrane
(1:29)
Selective Permeability
• What is meant by selective permeability?
• What kind of substances can easily pass
in and out of a cell?
Selective Permeability
• The cell’s membrane
selectively lets things in
and out in order to
maintain organization.
• Substances that go in
and out include:
– Amino acids that make
polypeptides.
– Glucose molecules used in
cellular respiration.
– Oxygen in and Carbon Dioxide
out.
Substances go into and
out of the
cell membrane (1:01)
Lipid Bilayer
• Describe the lipid bilayer.
– What is it made of?
– What substances are most likely to pass
through it?
Lipid Bilayer
• Two layers of
phospholipids form
the plasma
membrane.
• Each layer has a
polar head and 2
nonpolar tails.
• Which layer would be
more “friendly” to
water molecules?
Phospholipids on the town
Click on the picture (2:28)
4.2 Membrane Function
• Key Terms:
– Diffusion
• Dynamic equilibrium
– Osmosis
• Hypertonic solution
• Hypotonic solution
– Facilitated diffusion
• Transport proteins
• Channel proteins
• Carrier proteins
– Active Transport
• Pumps
– Endocytosis
• Phagocytosis
• Pinocytosis
• Receptor-aided
– Exocytosis
– Cell Walls
• Middle lamella
Diffusion vs. Osmosis
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What is diffusion?
What is osmosis?
How are they different?
How are they similar?
Diffusion vs. Osmosis
Diffusion
(:39)
Random movement of
particles is called
diffusion.
Particles go from a
greater concentration
to a lesser
concentration to
create a dynamic
equilibrium.
What is dynamic
equilibrium? (6:07)
Diffusion across a membrane (:53)
Osmosis
• Diffusion across a cell
membrane is called
osmosis.
• For any cell to
survive, it must be in
osmotic balance with
its environment.
• Osmotic balance
occurs when
movement of water in
and out of the cell is
equal.
Isotonic, Hypotonic, Hypertonic
• Using the scenario where there is a red
blood cell in the following solutions:
• What is isotonic?
– What happens to the cell?
• What is hypotonic?
– What happens to the cell?
• What is hypertonic?
– What happens to the cell?
TONICITY
Isotonic, Hypertonic and Hypotonic
Solutions
(3:24)
Quick Checkup
• What is the difference between diffusion
and osmosis?
• What is meant by selective permeability?
• Explain dynamic equilibrium.
• Explain what happens to a cell in a
– Hypertonic solution (:35)
– Hypotonic solution (:54)
Facilitated Diffusion
• What are two types of proteins that
facilitate diffusion?
• Which of these uses energy?
• What kind of transport is that called?
• Which of these does not use energy?
• What kind of transport is that called?
Facilitated Diffusion
Channel Protein
Passive Transport System
Channel Protein Action
Carrier Protein
Active Transport System
Carrier Protein Action
Comparison of channel to carrier proteins
Active Transport
• It takes ENERGY for
a cell to move
substances from a
region of lesser
concentration to a
region of greater
concentration.
• Through active
transport, cells use
transport proteins
called pumps.
Transport protein pump
Endocytosis
• What is endocytosis?
• Name the three types of endocytosis and
specifically what type of substance is
transported for each one.
Endocytosis
• Not all substances
enter the cell through
channels.
• A plasma membrane
can enclose a
substance, pinch it off
from the rest of the
membrane and
deposit the material
on the other side.
Endocytosis
(Click here 3:55)
Exocytosis
• What is exocytosis?
• Describe how it works.
Exocytosis
• Exocytosis gets rid of
unwanted particles and
also distributes
substances needed
elsewhere, like
hormones.
• The substance is
enclosed in a vesicle that
travels to the plasma
membrane, breaks open,
fuses with the membrane
and expels the
substance.
Endo and exocytosis review (1:23)
Plant Cells
• How are plant cells different than animal
cells?
• How are plant cells similar to animal cells?
• What is the carbohydrate in a plant cell
that provides structure to a plant?
Plants Have Cell Walls!!!
• Unlike animal cells,
plants have cell walls
made of cellulose.
• Cell walls are made
up of dead cells that
provide protection
and support.
• The middle lamella,
made of pectin, is
sandwiched between
the two primary cell
walls.
Cell walls
(1:53)
Eukaryotic Plant Cells