Cells!!!!

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sparked by just the right combination of
physical events chemical processes
Origin of Life
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• The evolutionary tree of life can be documented
  with evidence.
• The Origin of Life on Earth is another story

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The Origin of Life is a Hypothesis

• Special Creation
• Was life created by a supernatural or divine
  force?
• not testable
• Extra-terrestrial Origin
• Was the original source of organic (carbon)
  materials comets meteorites striking early
  Earth?
• testable
• Spontaneous Abiotic Origin
• Did life evolve spontaneously from inorganic
  molecules?
• testable

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Conditions on early Earth

• Reducing atmosphere
• water vapor (H2O), CO2, N2, NOx, H2, NH3, CH4,
  H2S
• lots of available H its electron
• no free oxygen
• Energy source
• lightning, UV radiation, volcanic

low O2 organic molecules do not breakdown as
quickly
Whats missingfrom thatatmosphere?
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Origin of Organic Molecules

• Abiotic synthesis
• 1920Oparin Haldane propose reducing atmosphere
  hypothesis
• 1953Miller Urey test hypothesis
• formed organic compounds
• amino acids
• Adenine
• Show Miller Urey Animation

CH4
H2
NH3
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Stanley Miller
University of Chicago
produced -amino acids -hydrocarbons -nitrogen
bases -other organics
Why was this experimentimportant??!
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Organic monomers/polymer synthesis

• These molecules served as monomers of building
  blocks for the formation of more complex
  molecules, including proteins nucleotides.
• Joining of the monomers produced polymers with
  the ability to replicate, store transfer
  information.
• The RNA World hypothesis proposes that RNA could
  have been the earliest genetic material.

RNA DNA template?
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Evidences of Life
Deep Sea Vents Stromatolites
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Key Events in Origin of Life

• Origin of Cells (Protobionts)
• lipid bubbles ? separate inside from outside
• ? metabolism reproduction
• Origin of Genetics (1st Genetic Material!)
• RNA is likely first genetic material
• multiple functions encodes information
  (self-replicating), enzyme, regulatory molecule,
  transport molecule (tRNA, mRNA)
• makes inheritance possible
• makes natural selection evolution possible
• Origin of Eukaryotes
• endosymbiosis

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How might the first cells have originated?

• Hypothesis chemical evolution or the
  chemosynthetic theory life developed from
  non-living materials eventually, by the process
  of natural selection, over hundreds of millions
  of years, became able to self-replicate and
  metabolize.

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This hypothesis presumes that at least 4 steps
happened to bring about this chemical evolution

• The abiotic (nonliving) synthesis and
  accumulation of small organic monomers like amino
  acids or nucleotides
• The Joining of monomers into polymers.
• The self-assembly of molecules into droplets that
  had chemical characteristics inside different
  from the environment outside.
• The ability to replicate

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First Eukaryotes
2 bya

• Development of internal membranes
• create internal micro-environments
• advantage specialization increase efficiency
• natural selection!

nuclear envelope
endoplasmicreticulum (ER)
plasma membrane
infolding of theplasma membrane
nucleus
DNA
cell wall
plasma membrane
Prokaryotic cell
Prokaryotic ancestor of eukaryotic cells
Eukaryotic cell
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1st Endosymbiosis

• Evolution of eukaryotes
• origin of mitochondria
• engulfed aerobic bacteria, but did not digest
  them
• mutually beneficial relationship
• natural selection!

internal membrane system
aerobic bacterium
mitochondrion
Endosymbiosis
Eukaryotic cell with mitochondrion
Ancestral eukaryotic cell
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2nd Endosymbiosis
Eukaryotic cell with mitochondrion

• Evolution of eukaryotes
• origin of chloroplasts
• engulfed photosynthetic bacteria, but did not
  digest them
• mutually beneficial relationship
• natural selection!

photosyntheticbacterium
chloroplast
mitochondrion
Endosymbiosis
Eukaryotic cell with chloroplast mitochondrion
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Theory of Endosymbiosis

• Evidence
• structural
• mitochondria chloroplasts resemble bacterial
  structure
• genetic
• mitochondria chloroplasts have their own
  circular DNA, like bacteria
• functional
• mitochondria chloroplasts move freely within
  the cell
• mitochondria chloroplasts reproduce
  independently from the cell

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Molecular genetic evidence from existing and
extinct organisms indicates all organisms on
Earth share a common ancestral origin of life
Molecular building blocks are common to all life
forms
Common genetic code are shared by all modern
organisms.
Metabolic pathways are conserved across all
currently recognized domains (bacteria, archea,
eukarya)
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The Universal Tree of Life
1. Last common ancestor of all living things.
2. Possible fusion of bacterium with archea
making eukaryotes
3. Symbiosis of mitochondrial ancestor with
ancestor of eukaryotes
4. Symbiosis of chloroplast ancestor with
ancestor of green plants
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Cambrian explosion

• Diversification of Animals
• within 1020 million years most of the major
  phyla of animals appear in fossil record

543 mya
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FUNCTIONS OF LIFE
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In order to perform these functionswhat do we
need?

• CELLS!!!!

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Parts of the Cell Theory

• All organisms are composed of one or more cells.
• Cells are the smallest units of life
• Cells can only come from pre-existing cells.

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Evidence to support cell theory

• Through the use of microscopes scientists have
  amassed even more credibility on the part of
  cells being the smallest unit of life.
• As of this date we have not been able to find an
  organism that is not made of at least one cell.
• Louis Pasteur performed experiments to support
  the principle that all cells come from other
  cells.

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Various Microscopes Used Today
Light Microscope
Electron Microscope (EM)
Scanning Electron Microscope (SEM)
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Whats the Difference between the TEM and SEM?
Transmits a beam of electrons through a thin
section of a specimen.
Perceives the excited electrons coming off of the
surface or the gilded surface of a specimen.
How do EMs get Such high magnification
resolution?
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How has biology been limited by available
technology in the past?
What kinds of things were correctly postulated
before the technology we have today?
How are scientists still limited by available
technology?
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http//learn.genetics.utah.edu/content/cells/scale
/
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PROKARYOTIC VS EUKARYOTIC CELLS UNDER THE
MICROSCOPE
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BESIDES SIZE..WHAT ELSE IS DIFFERENT BETWEEN
PROKARYOTE CELLS AND EUKARYOTE CELLS?
GET TOGETHER WITH A PARTNER AND COME UP WITH AS
MANY DIFFERENCES AS POSSIBLE. THE WINNERS GET
CANDY!!!
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• PROKARYOTIC

• EUKARYOTIC

• Smaller simpler
• Less than 10µm in diameter
• DNA in ring form without protein
• DNA is free floating
• No mitochondria
• 70S (svedberg unit) ribosomes
• No internal compartmentalization to form
  organelles
• Thought to be the 1st cells on Earth.
• Reproduce by Binary Fission
• EX BACTERIA

• Bigger more complex
• More than 10µm
• DNA with proteins as chromosomes/chromatin
• DNA enclosed in nucleus
• Mitochondria is present
• 80S ribosomes
• Internal compartmentalization present to form
  many types of organelles.
• EX EVERYTHING EXCEPT
• BACTERIA

Svedberg unit amount of time it takes the
ribosomes to be centrifuged to form a pellet
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PROKARYOTIC CELL
What do you think the functions are?
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• Capsule - Found in some bacterial cells, this
  additional outer covering protects
  the cell when it is engulfed by other organisms,
  assists in retaining moisture, and helps the
  cell adhere to surfaces and nutrients.
• Cell Wall - Outer covering of most cells that
  protects the bacterial cell and gives
  it shape.
• Cytosol - A gel-like substance composed mainly of
  water that also contains enzymes,
  salts, cell components, and various organic
  molecules located in the cytoplasm. It
  is where organelles are found
• Cell Membrane or Plasma Membrane - Surrounds the
  cell's cytoplasm and regulates the
  flow of substances in and out of the cell.
• Pili - Hair-like structures on the surface of the
  cell that attach to other bacterial cells.
  Shorter pili called fimbriae help bacteria attach
  to surfaces.
• Flagella - Long, whip-like protrusion that aids
  in cellular locomotion.
• Ribosomes - Cell structures responsible for
  protein production.
• Plasmids - Gene carrying, circular DNA structures
  that are not involved in
  reproduction.
• Nucleiod Region - Area of the cytoplasm that
  contains the single bacterial
  DNA molecule.

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What do membrane-bound organelles do for the cell?

• They give the cell compartments in which to
  perform certain functions, under specific
  conditions, with all the materials needed in one
  location.

How do you think prokaryotic cells perform
cellular functions without compartmentalized
cells?

• They have folds in their plasma membranes that
  act as compartments.

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CELL PARTS FUNCTIONS
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NUCLEUS
WHAT PARTS ARE IN THE NUCLEUS?
DNA, mRNA, histone proteins surrounding DNA, free
floating nucleotides, ribosomal subunits around
the nucleolus
WHATS THE FUNCTION?
To protect the DNA
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WHAT CAN YOU EXPECT FROM CELLS THAT DONT HAVE A
NUCLEUS AROUND THEIR DNA, SUCH AS PROKARYOTES?
BECAUSE THE DNA IS EXPOSED, PROKARYOTES HAVE A
MUCH HIGHER RATE OF DNA MUTATION.
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RED BLOOD CELLS DO NOT HAVE A NUCLEUS AT
MATURITY. HOW DO THEY FUNCTION WITHOUT IT?
AT MATURITY THEY HAVE ALL THE PROTEINS ENZYMES
NEEDED FOR THE REMAINDER OF THEIR SHORT LIFE SPAN
HOW DO RED BLOOD CELLS REPRODUCE?
THEY DONT. NEW RBCS ARE MADE IN BONE MARROW
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If mature red blood cells have no nucleus or DNA
why do forensics need blood for DNA analysis?
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NUCLEOULUS
THE NUCLEOLUS IS ALSO DNA BUT HAS A SEPARATE
NAME, EVEN THOUGH IT IS NOT A SEPARATE
COMPARTMENT.
WHY DO YOU THINK THIS REGION HAS ITS OWN NAME?
IT APPEARS AS A DENSE REGION ON A LIGHT
MICROSCOPE WAS ORIGINALLY THOUGHT TO BE A
DIFFERENT COMPARTMENT, BUT WITH IMPROVED
TECHNOLOGY IT WAS RECOGNIZED AS A HIGHLY
STRUCTURED REGION OF DNA WITH CONSTANT ACTIVITY
THE DENSITY IS DUE TO THE PRESENCE OF GRANULES
FIBERS HOLDING THE RIBOSOMAL DNA IN PLACE.
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RIBOSOMES
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ENDOPLASMIC RETICULUM
SMOOTH
Synthesizes lipids detoxifies drugs and poisons.
ROUGH
Helps synthesize proteins to be exported from the
cell.
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GOLGI APPARATUS (AKA GOLGI COMPLEX)
Center of manufacturing, warehousing, sorting,
and shipping
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LYSOSOMES
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VACUOLES
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MITOCHONDRIA
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CHLOROPLASTS
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HOW ARE THE MITOCHONDRIA AND CHLOROPLASTS SIMILAR
TO PROKARYOTIC CELLS?
BOTH HAVE THEIR OWN DNA
SIZE
THEY REPRODUCE IN A SEMIAUTONOMOUS MANNER
THEY ARE NOT PART OF THE ENDOMEMBRANE SYSTEM
SOME PROTEINS NEEDED ARE MADE BY THEIR RIBOSOMES
LOCATED IN THEIR MEMBRANE OTHER PROTEINS ARE
BROUGHT IN FROM THE CYTOSOL
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Why might we do a mitochondrial DNA test?

• It is most effective in determining siblings
• Mitochondrial DNA is past on by mom only so all
  siblings will have the same mitochondrial DNA.
• US military uses it for identification of
  skeletons from old war zones.
• Highly preserved compared to nucleus DNA

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Why do mitochondria chloroplasts have so many
membranes in them?
For increased surface area used for the energy
conversion processes that occur in these
organelles.
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PLASTIDS- in plant cells not animal cells

• Leucoplasts- energy storage
• Chromoplasts- color centers
• Chloroplasts- essential for photosynthesis

Are colorless and store starch (amylose)
-mostly in roots tubers
Have pigments that give flowers and fruits their
color
Contain green pigment (chloropyll) along with
enzymes various molecules that aid them in
photosynthesis
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PEROXISOMES
Seedlings have peroxisomes in order to convert
fatty acids to sugar until it is able to
photosynthesize.
Produces hydrogen peroxide by transferring
hydrogen to oxygen. -use oxygen to
breakdown fatty acids (send to mitochondria for
cellular respiration fuel) -in liver
cells they detoxify alcohol other harmful
compounds by transferring hydrogen from the
poisons to oxygen. Once hydrogen peroxide is
made, other enzymes within the peroxisome changes
it to water.
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CENTRIOLES
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CYTOSKELETON
SUPPORT, MOTILITY, AND REGULATION
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Microtubules(originate from centrosomes)

• Help determine/maintain cell shape (by
  resisting compression)
• Involved in cell movement (flagella, cilia)
• Involved in the position of organelles within the
  cell
• function like tracks within the cell, on which
  cargoes of materials like vesicles or organelles
  can be transported
• Involved in the movement of chromosomes during
  cell division.

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Antimitotics

• Cancer fighting drugs that inhibit microtubes
  from breaking down and reassembly.

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Microfilaments

• Maintain cell shape (bearing tension)
• Responsible for gross changes of cell shape
• Pseudopodia
• Muscle contractions
• Cleavage during cell division
• Phagocytosis.

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MICROFILAMENTS
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Intermediate Filaments(keratin filaments)

• Permanent structures in the cell
• Helps maintain rigid cell shape
• Anchor organelles in fixed positions when
  necessary (EX nucleus)

Warningviewer discretion advised
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Epidermolysis bullosa simplex or EBS
People with a rare mutation in their keratin
genes that prevents proper assembly of keratin
filaments have skin cells that rupture from even
slight pressure
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How are microtubules different from intermediate
filaments?

• Unlike intermediate filaments all microtubules
  are made up of a single kind of protein called
  tubulin.
• Microtubules are assembled in such a way that
  they have a polarity (that is, one end is
  different from the other).
• Microtubules are rapidly
• assembled and broken down
• many times within a short
  span of
• time, while intermediate
  filaments
• are more stable.

MICROTUBULES INTERMEDIATE
FILAMENTS
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MOTOR PROTEINS
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CELL WALL
EXTRACELLULAR STRUCTURE
MUCH THICKER THAN PLASMA MEMBRANES (ranging from
0.1micrometers to several micrometers)
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Outermost regions of various cell types
Cell Outermost part
Bacteria Cell wall of peptidoglycan
Fungi Cell wall of chitin
Yeasts Cell wall of glucan and mannan
Algae Cell wall of cellulose
Plants Cell wall of cellulose
Animals No cell wall, plasma membrane secretes a mixture of sugar proteins called glycoproteins that forms the extracellular matrix
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Extracellular Matrix (ECM) of Animal Cells
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Intercellular Junctions

• How cells adhere to each other, interact with
  each other, and communicate with each other.

• PLANTS
• PLASMODESMATA
• CYTOSOL PASSES THROUGH BETWEEN CELLS ALLOWING
  WATER AND SMALL SOLUTES TO PASS FROM CELL TO CELL.

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• Animals

Cells pressed together bound together by specific
proteins. Prevent leakage of extracellular fluid
Like rivets, they fasten cells together.
Intermediate filaments anchor desmosomes in the
cytoplasm.
Cytoplasmic channels from one cell to the
next. Like plasmodesmatas in plants
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CELL FRACTIONATION
Producing pure components of a mixture of cell
parts. The process involves two basic steps
-disruption of the tissue -lysis
of the cells, followed by
centrifugation
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Variations among Eukaryotic Cells

• Plant cells

• Animal cells

• Exterior of cell includes cell wall
• Have chloroplasts
• Possess large vacuole thats centrally located
• Store carbohydrates as starch
• Do not contain centrioles
• Has a fixed often angular shape

• Exterior of cell includes plasma membrane
• No chloroplasts
• Vacuoles are usually not present or are very
  small
• Store carbohydrates as glycogen
• Have centrioles
• Is flexible and more likely to be rounded in
  shape.

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Cell Reproduction Differentiation

• Multi-cellular organisms usually start as 1 cell.
• Cells reproduce at a rapid rate and go through
  differentiation.
• This occurs to produce all the required cell
  types that are necessary for the organisms
  well-being.
• Genes on a chromosome allow for this process to
  occur.
• All cells contain all of the genetic information
  to make the entire organism.
• Each cell becomes a specific type of cell
  depending on which DNA segment becomes active.

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Stem Cells

• Retain the ability to divide and differentiate.
• Plants have these cells in their meristematic
  tissue (near root stem tips).
• Gardeners take cuttings from stems or roots to
  grow a new plant.
• In the 1980s, pluripotent (embryonic stem cells)
  were found in mice.
• Problem stem cells cant be distinguished on
  appearance. They can only be isolated based on
  behavior.

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Research on using stem cells

• To replace differentiated cells lost due to
  injury and disease.
• EX Parkinsons Disease Alzheimers disease are
  caused by loss of brain cells.
• EX Certain types of diabetes deplete the
  pancreas of essential cells.
• Using tissue specific stem cells
• Blood stem cells replace damaged bone marrow

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GOLGI APPARATUS
NUCLEAR ENVELOPE
PLASMA MEMBRANE
NUCLEUS
ROUGH ER
SMOOTH ER
LYSOSOME
MITOCHONDRIA
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PILI
NUCLEOID
PLASMA MEMBRANE
CELL WALL
RIBOSOMES
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Cell membrane
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DESCRIBLE THE CELL PARTS THAT WOULD BE FOUND IN
GREATER NUMBERS IN
STOMACH CELLS
rough ER for secretion
LIVER STORAGE CELLS
vacuoles for storage
POTATO CELLS
vacuole for starch storage
WHITE BLOOD CELLS
lysosomes to breakdown engulfed pathogens
MESOPHYLL (PLANT LEAF) CELLS
chloroplasts for photosyntheis
MUSCLE CELLS
LIVER DETOX CELLS
mitochondria for ATP
peroxisomes smooth ER to break down toxins
ADIPOSE CELLS
vacuoles for storage
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How do cells recycle?

• Endomembrane system
• Cycle phospholipids
• Lysosomes, peroxisomes, rough ER
• Breakdown macromolecule parts reassemble them
• Cytoskeleton
• Constant flow of assembling de-assembling
  subunits.

Why are cells so efficient at recycling?
For the same reasons developing countries are
good at recycling limited resources and limited
energy