Transcript Cell Membranes

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What is this?
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Microscopes

Different types of microscopes
– Light microscope-magnifies images by
focusing light on them
• Most commonly used
• Compound- have two lenses
• Stains may be added to make objects
more visible
– Electron microscopes- magnifies images a
1000X’s more than light microscopes by
focusing a beam of electrons on them
• SEM
• TEM
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A Foot of a Housefly
Using SEM
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Modern Cell Theory
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Cell Theory:
– Cells are the smallest
working units of life
– All living things are made
of cells
– All cells come from preexisting cells
Cheek cells
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Cell Factory
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The cell is like a
factory
– People and machines
perform functions in a
factory
– There are parts of a
cell that also perform
different functions
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Cell Factory
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All factories produce a product.
CELL PRODUCT=PROTEINS
– Cell’s DNA codes for proteins!
– All cells in an organism have the
same DNA, but different cell types
produce different proteins.
– What is needed to build a protein?
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4 Parts of All Cells
1. Cytoplasm- watery
substance inside all cells
 2. Cell membrane (plasma
membrane)- “door” to the
factory that’s made of lipids
and proteins
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– It is a phospholipid bilayer
– Selectively-permeableonly certain things pass
through
– Aids in homeostasis for
stable internal conditions
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Phospholipid Structure
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4 Parts of All Cells

3. Ribosomes -“assembly
line workers”
– They build proteins
– Found all over cell
– Proteins are either used by cell
or shipped out to other cells
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4. Genetic material
– DNA
– RNA
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Two Main Types of Cells
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Prokaryotic
– Bacteria
– Small
– No organelles
except ribosomes
– No nucleus
– Simple
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Eukaryotic
– Anything other than
bacteria, like plants and
animals, have these cells
– Large cells
– Organelles
– True nucleus
– Complex
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Eukaryotic Organelles
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Nucleus-“central office” of the cell that
contains DNA where most cell activity is
started
– DNA carries instructions for how to build
proteins
– Nucleus is surrounded by a porous
membrane. Why?
– The nucleolus, is found in the nucleus and
makes the ribosomes.
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Eukaryotic Organelles
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Mitochondria- “powerhouse” of the cell
– The process of cellular respiration releases
chemical energy from carbs to make ATP when
oxygen is present
– C6H12O6 (glucose) + O2 → CO2 + H2O + energy(ATP)
– Some cells have more than others—why?
– Contain DNA also
Oxygen
and glucose in
Carbon
dioxide,
water, and
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ATP
produced
Eukaryotic Organelles
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Endoplasmic reticulum -“highway” system
throughout inside of cell
– Materials can travel on it throughout the cell
– Rough ER (has ribosomes) vs. Smooth ER
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Eukaryotic Organelles
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Golgi apparatus-“packaging center” of
the cell
– Puts finishing touches on proteins
– Prepares them for shipment out of the cell
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Eukaryotic Organelles
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Lysosome –“recycling center”
– Repairs damaged cell parts.
– Sometimes parts are beyond repair.
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Eukaryotic Organelles
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Vacuoles“storerooms” in
plant and animal
cells.
– What would they
store?
– If they shrivel, so
does the cell
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2 Types of Eukaryotic
Cells

There are two main types of
eukaryotic cells
– Plant-like
– Animal-like
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Plant-like Eukaryotic Cells
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Have:
– Large vacuoles…Why?
– A cell membrane that is
surrounded by a cell wall
• Made of cellulose, a carb
• Gives plant cells support and
structure which protect s cell from
bursting when vacuoles swell with
water
– Chloroplasts so can make own
carbs through photosynthesis
• Chlorophyll-green pigment in
chloroplasts that gathers sunlight
• Have DNA like mitochondria
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Photosynthesis
Source of energy for ALL life on Earth!!!
Reactants
Products
1. Water
1. Oxygen gas
2. Carbon Dioxide
2. Glucose (a carb)
3. Sunlight
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Photosynthesis
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Animal-like Eukaryotic Cells
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Have:
– Only a cell membrane
– No chloroplasts for
photosynthesis so must
consume food for energy
– Small vacuoles
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Endosymbiotic Theory
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Endosymbiotic Theory -mitochondria and
chloroplasts were once prokaryotic cells
that were taken in by other prokaryotes.
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Creation of first eukaryotic “organelles”
Prokaryotes evolved into eukaryotes
Endosymbiotic Theory
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Cell Transport
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Cells need:
WATER
 water, oxygen, and
nutrients to get in
through the cell
membrane so they
WASTE
may use them
 wastes, proteins,
hormones, and other
particles to leave
Cell transport – the
OXYGEN
movement of particles
through the cell membrane into
or out of the cell
NUTRIENTS
CARBON DIOXIDE
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Cell Membranes

ALL CELLS HAVE A CELL
MEMBRANE
 Cell membrane-
two layered
“door” to the factory that’s made
of lipids and proteins
 Selectively-permeable-only
certain things pass through
 Aids in homeostasis—
maintaining stable
conditions within the cell
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Cell Membranes
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Phospholipid Structure
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Each phospholipid of the cell membrane has
two ends:
= “water loving” head
 Hydrophobic = “water fearing” tail
 Hydrophilic
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Cell Membrane Proteins
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Receptor proteins- allow cells to talk to one
another
 Cells send “messages” and others receive them
with receptors.
 Hormones-cellular messages Ex.) Testosterone
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Cell Membrane Proteins
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Marker proteins -gives
your cells an “identity”
 Distinguishes your cells
from other cells
 Blood and tissue types
 Immune system
A marker
A and B
markers
B marker
No marker
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Cell Membrane Proteins
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Channel proteins allow molecules to
pass through the
membrane
 Create a
channel
through the lipids of
the membrane
 Selective about what
passes through
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Natural Movement of
Particles
Things move naturally from
high to low concentrations.
 Spray of
Very low or no
concentration
perfume
 Fart
 Cooking popcorn
 Nutrients in
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bloodstream
Start out highly
concentrated, but
molecules move outward
to areas of low
concentration
High
concentration
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Which container has the highest
concentration of particles?
What would happen to the particles
if we connected containers A and C?
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Natural Movement of
Particles
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Movement of particle across
cells membranes work the same
way
 The cell creates an
environment
inside that may be different from
the outside
 If the concentrations are different
between the inside of the cell and
the outside, particles and
molecules will move until they are
equal inside and out
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are molecules that can pass through
the cell membrane
is a cell membrane
A)
B)
Draw arrows representing which way
the molecules will naturally move
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Particles

Different particles are
transported
differently across the
cell membrane
 The cell membrane is
selective
 Smaller molecules can
pass through
 Larger molecules and
charged molecules
cannot.
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Cell Transport
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Two types of transport of particles
across the cell membrane:
Passive—no energy (ATP)
Active—takes energy (ATP)
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Passive vs. Active Transport
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Passive transport – type of movement of
particles across the cell membrane from high to
low concentrations with no energy (ATP)
needed
 “Paddling with the current”
 Types of passive transport
 Diffusion
 Osmosis
Active transport is just the opposite…low to
high that requires energy
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Passive Transport -Diffusion
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Diffusion – natural
movement of particles
from high to low
concentration
 Passive-no ATP needed
 Occurs until equilibrium is
reached
 This is how some things are
transported through the
cell membrane
High oxygen concentration in blood
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from breathing diffuses into blood cells
Passive Transport -Osmosis
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Why do I care?
Osmosis-diffusion of
water across the cell
membrane from high
to low concentrations
 Passive-no ATP needed
 Water passes easily
through the semipermeable cell
membrane.
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Is There Such a Thing as Too
Much Water?
Water can go through the cell
membrane very easily
 High concentrations of water in your
blood will move into your cells
 Why should I care?
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