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by Darcy
Plant and Animal Cells
Under the Microscope
1. What indicators were
used to help view some
organelles under the
microscope?
2. What is the structural
difference between cheek
cells and frog’s blood?
How does this affect the
function?
3. What structure did plant
cells have that animal cells
did not?
4. What organelle could be
seen in the spinach cells,
but not the onion cells?
Why?
Cell characteristics
• All cells:
– surrounded by a plasma membrane
– have cytosol
• semi-fluid substance within the membrane
• cytoplasm = cytosol + organelles
– contain chromosomes which have genes in the
form of DNA
– have ribosomes
• tiny “organelles” that make proteins using
instructions contained in genes
Types
Prokaryote
of
cellscells
bacteria
- no organelles
- organelles
Eukaryote
animal cells
Eukaryote
plant cells
Types of cells
 Prokaryotic vs. eukaryotic cells
Prokaryotic cell
• DNA in nucleoid region,
without a membrane
separating it from rest
of cell
• Cell wall present in all
Eukaryotic cell
• chromosomes in
nucleus, membraneenclosed organelle
• Cell walls present in
fungi and plants only
• More complex
• Membrane bound
organelles present
Prokaryotic Cell Structurally Simpler
than Eukaryotic Cells
Eukaryotic Cell: Animal
Eukaryotic: Plant
Cell Membrane
(Covered Extensively in Chapter 7)
Nucleus is the cell’s genetic control
center
Overview: Many cell organelles are connected through
the endomembrane system
Ribosomes make
proteins for use in the
cell and export
Structure:
A. Large Subunit
B. Small Subunit
Function:
- Polypeptide (protein) synthesis
Location:
A. Free: in cytoplasm
B. Attached : bound to ER
The endoplasmic reticulum is
a biosynthetic factory
Structure: Passage ways inside cell
Function:
A.
Rough ER: synthesis of
membrane lipids and proteins,
secretory proteins, and hydrolytic
enzymes; formation of transport
vesicles.
B.
Smooth ER: Lipid synthesis,
detoxification in liver cells,
calcium ion storage.
Synthesis and packaging of a secretory
protein by the rough ER
Golgi apparatus finishes, sorts, and
ships cell products
Golgi Apparatus
• Function
– finishes, sorts, tags & ships cell products
• like “UPS shipping department”
– ships products in vesicles
Which cells
have lots
of Golgi?
• membrane sacs
• “UPS trucks”
secretory
vesicles
transport vesicles
Overview: Many cell organelles are connected through
the endomembrane system
Cellular digestion
• Lysosomes fuse with food vacuoles
– polymers
digested into
monomers
• pass to cytosol
to become
nutrients of
cell
vacuole
 lyso– = breaking things apart
 –some = body
Lysosomes are digestive
compartments
When cells need to die…
• Lysosomes can be used to kill cells when they
are supposed to be destroyed
– some cells have to die for proper development in
an organism
• apoptosis
– “auto-destruct” process
– lysosomes break open & kill cell
• ex: tadpole tail gets re-absorbed
when it turns into a frog
• ex: loss of webbing between your
fingers during fetal development
syndactyly
Fetal development
6 weeks
15 weeks
Review of structures involved in
manufacturing and breakdown
Making Energy
• Cells must convert incoming energy to forms
that they can use for work
– mitochondria:
from glucose to ATP
– chloroplasts:
from sunlight to ATP & carbohydrates
• ATP = active energy
• carbohydrates = stored energy
ATP
+
ATP
Mitochondria & Chloroplasts
• Important to see the similarities
– transform energy
• generate ATP
– double membranes = 2 membranes
– semi-autonomous organelles
• move, change shape, divide
– internal ribosomes, DNA & enzymes
Mitochondria
• Almost all eukaryotic cells have mitochondria
– there may be 1 very large mitochondrion or 100s to
1000s of individual mitochondria
– number of mitochondria is correlated with aerobic
metabolic activity
• more activity = more energy
needed = more mitochondria
What cells would
have a lot of
mitochondria?
active cells:
• muscle cells
• nerve cells
Mitochondria harvest chemical energy
from food
Chloroplasts
• Chloroplasts are plant organelles
– class of plant structures = plastids
• amyloplasts
– store starch in roots & tubers
• chromoplasts
– store pigments for fruits & flowers
• chloroplasts
– store chlorophyll & function
in photosynthesis
– in leaves, other green
structures of plants &
in eukaryotic algae
Chloroplasts convert solar energy to
chemical energy
Mitochondria & chloroplasts are different
• Organelles not part of endomembrane system
• Grow & reproduce
– semi-autonomous organelles
• Proteins primarily from free ribosomes in cytosol & a
few from their own ribosomes
• Own circular chromosome
– directs synthesis of proteins produced by own internal
ribosomes
• ribosomes like bacterial ribosomes
Who else has a circular chromosome not
bound within a nucleus?
bacteria
Endosymbiosis theory
1981 | ??
• Mitochondria & chloroplasts were once
free living bacteria
– engulfed by ancestral eukaryote
• Endosymbiont
– cell that lives within another cell (host)
• as a partnership
• evolutionary advantage
for both
– one supplies energy
– the other supplies raw materials
& protection
Lynn Margulis
U of M, Amherst
Mitochondria and chloroplasts evolved
by endosymbiosis
food vacuoles
Food & water storage
plant cells
central vacuole
animal cells
contractile
vacuole
Vacuoles & vesicles
• Function
– little “transfer ships”
• Food vacuoles
– phagocytosis, fuse with lysosomes
• Contractile vacuoles
– in freshwater protists, pump excess H2O
out of cell
• Central vacuoles
– in many mature plant cells
Vacuoles in plants
• Functions
– storage
•
•
•
•
stockpiling proteins or inorganic ions
depositing metabolic byproducts
storing pigments
storing defensive
compounds against
herbivores
• selective membrane
– control what comes
in or goes out
Putting it all together, try labeling..
animal cells
plant cells
Limits to cell size
• Metabolic requirements set upper limit
– in large cell, cannot move material in & out of cell
fast enough to support life
aa
aa
What process is this?
CH
aa
CHO
O2
CH
aa
CO2
CO2
CHO
CO2
CHO
NH3
O2
NH3
O2
NH3
CHO
CH
O2
NH3
aa
aa
O2
CO2
CH
2005-2006
aa
What’s the solution?
How to get bigger?
• Become multi-cellular (cell divides)
But what challenges do you have to solve now?
CO2
CO2
aa
aa
CO2
CHO
NH3
CO2
O2
NH3
CH
aa
aa
CO2
NH3
CO2
CO2
NH3
NH3
CO2
CH
NH3
NH3
CO2
CHO
O2
NH3
CO2
O2
CH
aa
O2
NH3
CHO
CO2
aa
2005-2006
Cell wall enclose and support plant
cells