Download Cell Membrane

DO NOW:
Why do you think cells weren’t discovered until
1665? Do you think people can ever see cells
with the naked eye? Explain your answer.
Chapter 7.1 Life is Cellular
Objectives:
1. State the cell theory.
2. Describe how the different types of
microscopes work.
3. Distinguish between prokaryotes and
eukaryotes.
LIFE CAN BE FOUND AS…
• SINGLE CELLULAR ORGANISMS
• MULTI-CELLULLAR ORGANISMS
HOW DID WE FIND OUT ABOUT THE CELL?
• Robert Hooke (in 1665)
• 1st person to describe
cells
• Observed cork (plant
cells) with a microscope
ANTON VAN LEEUWENHOEK
• 1673
• First to observe:
– Protists in pond scum
– Blood cells, bacterial cells,
and yeast cells.
• Cells are the basic unit of life!
MATTHIAS SCHLEIDEN
In 1838, concluded that
all plant parts were
made of cells
THEODOR SCHWANN
• In 1839,
–concluded that all
animal tissues were
made of cells
• Schwann cells cover
nerve cells
RUDOLPH VIRCHOW
• In 1858, stated that all
cells could form only
from other cells
Review: Biologists and Their Discoveries
That Led to The Cell Theory
 Matthias Schleiden
• First to observe “cells” by
looking at cork through a
light microscope
• Discovered living organisms
in water through the use of a
simple microscope
• Plants made of cells
 Theodor Schwann
• Animals made of cells
 Rudolph Virchow
• Cells come from existing cells
 Janet Plowe
• Cell membrane is a defined
physical structure
 Robert Hooke
 Anton van Leeuwenhoek
What is the Cell Theory?
• The cell theory states:
–All living things are composed of cells.
–Cells are the basic units of life.
–New cells are produced from pre - existing
cells.
• Is It current?
–YES!
– http://www.youtube.com/watch?v=4OpBylwH9DU&feature=youtu.be
Light Microscopes
• Light passes through a
specimen
• Two lenses form image
• Limitations:
– Magnifies only 1000 times
– Cells are transparent
• Dyes or stains are needed
to help see structures
• Most dyes will kill cell
Electron Microscopes
• Beams of electrons focused by magnetic
fields
• Reveal details 1000 times smaller than light
microscope
• Can only visualize nonliving, preserved cells
and tissues
Cell Size
• Cells are too small to
be seen w/out a
microscope (25um)
• Exceptions
• Amoeba (0.5 mm)
• Human egg cell
• size of a grain of
sand)
• Cell Membrane:
• Cell boundary
• Selectively Permeable
• Cytoplasm:
• Fluid inside cells
• Holds organelles in place
Parts of a Cell
• Organelles: (little organs):
• Structures that perform specific
functions within the cell.
• DNA: Genetic instructions
TWO CATEGORIES FOR
DISTINGUISHING CELL TYPE
• Prokaryotic
• Eukaryotic
PROKARYOTE
•
•
•
•
•
•
Small and simple (0.2 -2.0 µm)
No nucleus
Cell membrane & cytoplasm
Ribosomes
May have cell wall
Grow, reproduce, respond to
change
• May use flagella/cilia for
movement
• Example:
• Bacteria
DNA is floating around
and not in a nucleus!
EUKARYOTE
• Vary in shape
• Highly specialized
• Have a nucleus and
membrane bound organelles
• Cell membrane and
cytoplasm
• DNA is found in the nucleus
• Some single-celled
• Many multi-celled
• Examples:
• All plants, animals, fungi,
and many protists
DNA enclosed in a
nucleus!
Chapter 7.2: Cell Structure & Function
Amoeba
Bacteria
Nerve Cell
Red Blood Cell
Nucleus
• Eukaryotic cells
• Often most
prominent structure
in center of cell
• Controls cell
processes
• Stores DNA
• Codes for new
proteins
Binucleate and Multinucleate Cells:
• Cells with more than
one nucleus
• Examples:
–Cells that destroy
bone
–Some liver cells
–Skeletal muscle cells
Nuclear Envelope
Surrounds
nucleus
• Double
membrane layer
• Pores allow
material to
move in and out
of the nucleus
Chromatin
• Found in Nucleus
• String of DNA
• Condenses to form chromosomes during
cell division
Chromosomes
• Location?
– Nucleus (seen during cell division)
• Description?
– Condensed chromatin
• Function?
– Compacted DNA
– Pass genetic info to following generations
Nucleolus
• Dark spherical mass
inside the nucleus
• Involved in the
Assembly of
ribosomes
Cytoplasm
Gel-like substance
between
membrane +
nucleus
• Holds organelles
• Transport of
materials
Cytoskeleton
Location?
• Nucleus to cell membrane
Description?
• Protein filaments
• Microtubules (cell support)
• Microfilaments (cell division, movement)
Function?
• Maintain shape/support
• Cell movement
• Flagella and cilia
Cilia & Flagella
• Extensions of cell
• Cilia – hair-like
projections
• Flagella- One or two,
longer whip-like
structures
• Cell movement
Flagella
Cilia
Cilia & Flagella
Centrioles
• Found Outside
nuclear envelope
• Only in animal
cells
• They Help
separate
chromosomes
during cell
division
Endoplasmic Reticulum (E.R.)
• Extension from Nuclear
envelope
• Rough E.R. – Ribosomes
• Smooth E.R. – No
ribosomes
• Function?
• Transport materials
• Rough E.R. modify
proteins
• Smooth E.R. make lipids
Ribosomes
• Found In nucleus,
cytoplasm, and
Rough E.R.
• They Produce
proteins based on
instructions found
in DNA
Protein Assembly
Golgi Apparatus
• Found Near E.R. and
nucleus
• Function?
• Further package proteins
after E.R.
• Proteins then sent to
final destinations
• Outside of cell or to
other organelles
Lysosome
• Location?
• Cytoplasm
• Rare in plant cells
• Function?
• Contain enzymes that break down food into
nutrients for cell
• Also a “cell cleaner”
• Break down old organelles
Plant Vacuole
• Location?
• Cytoplasm
• Description?
• Plant cells
• Single, large saclike
structure
• Function?
• Store nutrients
• Pressure in plant vacuole
aid in support of plant cell
(lack of water – wilting)
Vacuoles
• Location?
• Cytoplasm
• Description?
• Animal & Protists
• Multiple vacuoles
• Small saclike structures
• Function?
• Store nutrients
• Remove excess water from
cell (contractile vacuole)
Chloroplasts (Cellular solar plants)
• Location?
• Cytoplasm of
plants
• Some protists &
bacteria
• Function?
• Photosynthesis:
• Use energy
from sunlight to
make glucose
Mitochondria (Cellular power plants)
• Location?
• Cytoplasm
• More in
muscle cells
• Function?
• Cellular
Respiration:
• Release
energy (ATP)
from glucose
Cell Wall
• Location?
• Outer most
boundary in plant,
bacteria and fungi
cells
• Function?
• Support and
protection
• Maintain cell shape
Cell Membrane
• Location?
• Outer boundary of cells
• Function?
• Regulates what enters &
exits
• Supports organelles &
provides barrier
• Construction?
• Lipid bilayer, also containing
proteins and carbohydrates
• Semipermeable
Lesson Overview
Cell Structure
The Properties of Membranes
• Made of phospholipids
• Lipid bilayer (double layer)
• Hydrophobic fatty tails cluster inside
• Hydrophilic heads face out towards
water
Lesson Overview
Cell Structure
The Fluid Mosaic Model:
• Membranes embedded w/ proteins & carbs
• Can move around and “float” among lipids
• Proteins form channels and pumps that help
to move material across the cell membrane
• Organelles:
(4) vesicle
(2) nucleus (3) ribosome
(1) nucleolus
(5) rough E.R.
(6) Golgi apparatus
(7) Cytoskeleton
(8) smooth ER
(9) mitochondria
(10) vacuole
(11) cytoplasm (12) lysosome
(13) centrioles
Plant Cell vs. Animal Cell
DO NOW:
Which of the following best describes a living
cell?
A) A building block
B) A complex factory
C) Can perform all life processes
D) All of the above
Explain your choice.
Objectives:
1. Describe the processes of diffusion and
osmosis.
2. Compare and contrast passive and
active transport.
Types of Cellular Transport

Passive Transport
Cell doesn’t use energy
Diffusion
2. Facilitated Diffusion
3. Osmosis
1.

Active Transport
Cell does use energy
Protein Pumps
2. Endocytosis
3. Exocytosis
1.
Lesson Overview
Cell Structure
Passive Transport:
• Movement of
molecules from one
side of the membrane
to the other
• No additional energy
• Maintains balance in
the cell (homeostasis)
Lesson Overview
Cell Structure
Passive Transport Includes:
• Diffusion
• The movement of solute particles from a
high concentration to low
• Facilitated diffusion
• Using proteins as channels to help pass
certain molecules through the membrane
• Osmosis
• Diffusion of water through the membrane
using aquaporins (water channel proteins)
Passive Transport: Facilitated Diffusion
A
B
 Facilitated diffusion:
Diffusion of specific
particles through
transport proteins
found in the membrane
 Used to transport large, Facilitated Diffusion
diffusion
(Lipid
charged, or water
(Channel
Bilayer)
molecules that can’t
Protein)
regularly pass through
the membrane
Carrier
Protein
Passive Transport: Facilitated Diffusion
Cellular Transport From a
Glucose molecules
High Concentration
Cell Membrane
Low Concentration
Protein
channel
Through a 
Go to
Section:
Transport Protein
Lesson Overview
Cell Structure
Osmosis: An Example of Facilitated Diffusion
• Osmosis: Movement of
water through cell
membranes
• Aquaporins: Transport
proteins that allow water
to pass through the
membrane.
Osmotic Pressure
 Osmotic pressure: Movement of water out of
or into a cell exerting a force.
 For organisms to survive, they must have a way
to balance the intake and loss of water.
 Examples:
 Water and nutrients enter plant cells
through osmosis.
 When a wilted plant is watered, osmosis
makes the plant firm again.
How Organisms Deal with Osmotic Pressure
•Bacteria and plants have cell walls.
•A protist has contractile vacuoles.
•Salt water fish pump salt out of their specialized
gills so they do not dehydrate.
•Fish eggs lack water channels.
•Animal cells are bathed in blood.
•Kidneys keep the blood isotonic by remove excess
salt and water.
Lesson Overview
Cell Structure
Active Transport: Protein Pumps
• Active transport:
Movement from low
concentration to high
• Certain molecules or
ions need special
transport proteins called
protein “pumps,” to
cross the membrane.
• Examples:
• Calcium, potassium,
and sodium ions
Active Transport: Endocytosis

Endocytosis: Taking bulky
material into a cell
•
•
•
•
•
Uses energy
Cell membrane in-folds
around food particle
creating a vesicle
“cell eating”
Forms food vacuole & digests
food
This is how white blood cells
eat bacteria (phagocytosis)
Active Transport:
Endocytosis and Exocytosis
Lesson Overview
Cell Structure
Endocytosis:
Phagocytosis and Pinocytosis
• Phagocytosis:
Cell eating
• Pinocytosis:
Cell drinking
Lesson Overview
Cell Structure
Exocytosis:
• Cells releasing large
amounts of material
from the cell
• The membrane of
the vacuole
surrounding the
material fuses with
the cell membrane,
forcing the contents
out of the cell
Cellular Communication
 Vital for organ systems to work.
 Cells use chemical signals (hormones)
that pass from one cell to another.
 To respond to one of these chemical
signals, a cell must have a receptor to
which the signaling molecule can bind.
 Some cells form connections, or cellular
junctions, to neighboring cells.
Cell Membrane Review
1.All cells have a cell
membrane
2.Functions:
a.Controls what enters
and exits the cell to
maintain an internal
balance called
homeostasis
b.Provides protection and
support for the cell
Cell Membrane Structure
1. Lipid Bilayer: Two
layers of phospholipids
▫ Phosphate head is polar
(water loving)
▫ Fatty acid tails non-polar
(water fearing)
▫ Proteins embedded in
membrane
2. Selectively permeable:
Allows some molecules in
and keeps other molecules
out
Phospholipid
Lipid Bilayer
Structure of the Cell Membrane
Outside of cell
Proteins
Lipid
Bilayer
Transport
Protein
Carbohydrate
chains
Phospholipids
Inside of cell
(cytoplasm)
Go to
Section:
Types of Cellular Transport
•
Passive Transport
Cell doesn’t use energy
1. Diffusion
2. Facilitated Diffusion
3. Osmosis
•
Active Transport
Cell does use energy
1. Protein Pumps
2. Endocytosis
3. Exocytosis
Lesson Overview
Cell Structure
Passive Transport Includes:
• Diffusion
• The movement of solute particles from a
high concentration to low
• Facilitated diffusion
• Using proteins as channels to help pass
certain molecules through the membrane
• Osmosis
• Diffusion of water through the membrane
using aquaporins (water channel proteins)
Passive Transport: Facilitated Diffusion
A
B
• Facilitated diffusion:
Diffusion of specific
particles through
transport proteins
found in the membrane
Facilitated Diffusion
▫ Used to transport
diffusion
(Lipid
large, charged, or
(Channel
Bilayer)
water molecules that
Protein)
can’t regularly pass
through the membrane
Carrier
Protein
Lesson Overview
Cell Structure
Osmosis: An Example of Facilitated Diffusion
• Osmosis: Movement of
water through cell
membranes
• Aquaporins: Transport
proteins that allow water
to pass through the
membrane.
• Why do water molecules
have a tough time
passing through the cell
membrane?
Lesson Overview
Cell Structure
How Osmosis Works
• Isotonic: Same
concentration on
both sides
• Hypertonic:
Concentrated
solution
• Hypotonic: Dilute
solution
http://glencoe.mcgrawhill.com/sites/0042561336/student_view0/chapter3/how
_osmosis_works.html
Osmotic Pressure
Movement of water out of or into a cell exerting
a force.
 For organisms to survive, they must have a
way to balance the intake and loss of water.
 Examples:
 Plasma surrounds red blood cells
 Water and nutrients enter plant cells
through osmosis.
 When a wilted plant is watered, osmosis
makes the plant firm again.
Osmotic Pressure
How Organisms Deal with Osmotic Pressure
•Bacteria and plants have cell walls.
•A protist has contractile vacuoles.
•Salt water fish pump salt out of their specialized
gills so they do not dehydrate.
•Fish eggs lack water channels.
•Animal cells are bathed in blood.
Lesson Overview
Cell Structure
Active Transport: Protein Pumps
• Active transport:
Movement from low
concentration to high
• Certain molecules or ions
need special transport
proteins called:
• protein “pumps,” to
cross the membrane.
• Examples:
• Calcium, potassium,
and sodium ions
Active Transport: Endocytosis
•
Endocytosis: Taking
bulky material into a cell
• Uses energy
• Cell membrane in-folds
around food particle
creating a vesicle
• “cell eating”
• Forms food vacuole &
digests food
•
•
Phagocytosis: Cell Eating
Pinocytosis: Cell
Drinking
 Cells
work best if they have the correct:
 Temperature
 Water levels
 Glucose concentration
 Mechanisms in the body keep the cells in
a constant environment.
 Homeostasis: The maintenance of a
constant environment in the body.
Organism:
`
Anything that can perform life
processes.
Unicellular

organism:
made of a single cell.
All life processes occur in one cell
 These organisms dominate life on earth
in terms of numbers!

Multicellular
 Consist
organisms:
of specialized cells that depend
on each other for the organism to survive.
 Cells
differ in size, shape and
function
 Differences in cells arise from

the way cells are specialized to
perform certain tasks.
Larger
Size
 Prey
for fewer predators.
 Wider variety of prey.
Longer
 Not
Life
limited to life span of a single cell.
Specialization
 Each
type of cell has a particular job
 Organism more efficient
 Cell communication is essential to survival
 Cell
Specialization: Cells throughout
an organism can develop in different
ways to perform different tasks
 Tissue:
Group of cells working together to
perform a specific function.
 Animals have 4 basic types of tissues:




Connective tissue
Epithelial tissue
Muscle tissue
Nerve tissue
 Plants



have 3 types of tissues:
Vascular tissue
Dermal tissue
Ground tissue
 Organ:
Two or more tissues working
together to perform a specific function.
 Ex for animals:

Heart, stomach, intestines, brain, lungs
 Ex

for plants:
Leaves, stems, and roots
 Organ
system: Group of organs working
together to perform a particular function.
 Examples in animals:
 Digestive system
 Respiratory system
 Cardiovascular system
 Examples in plants:
 Leaf systems
 Root systems
 Stem systems
1st level- the cell
 2nd level- tissue (group of similar cells that perform
the same function)
 3rd level- organ (groups of tissues that work
together)
 4th level- organ system (a group of organs that work
together to perform a specific function)

 Structure
is the arrangement of parts in
an organism.
 Function is the job that the part does.
 In organisms, structure and function are
related.
 Vital
for organ systems to work.
 Cells use chemical signals (hormones)
that pass from one cell to another.
 To respond to one of these chemical
signals, a cell must have a receptor to
which the signaling molecule can bind.
 Some cells form connections, or cellular
junctions, to neighboring cells.