AP Biology 2011-2012
Tour of the Cell 1
http://www.studiodaily.com/main
/searchlist/6850.html
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Cytology: science/study of cells
To view cells:Light microscopy
resolving power: measure of clarity
Electron microscopy – electron beam
TEM: to study cell internal ultrastructure
SEM: to study cell surfaces
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To isolate organelles:
Cell fractionation: to separate major organelles
Ultracentrifuge: cell fractionation;
130,000rpm or 1,000,000 g
Cytology: science/study of cells
http://www.youtube.com/watch?v=8BnES4T1RDk
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http://learn.genetics.utah.edu/content/begin/cells/scale/
AP Biology
Cell Size
http://learn.genetics.utah.edu/content/begin/cells/scale/
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Cell Radius 1 2 3 4
SA (r2) 1 4 9 16
V (r3) 1 8 27 64
SA = 4 r2
V = 4/3 r3
SA/V (r2/r3) 1 1/2 1/3 1/4
Cell Size
V > SA
r Vand SA
r SA/V
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Cell Size
As cell size increases, the SA to V ratio
decreases
Rates of chemical exchange may then be
inadequate for cell size
Cell size, therefore, remains small
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Prokaryote
bacteria cellsTypes of cells
Eukaryote
animal cells
- no organelles
- organelles
Eukaryote
plant cellshttp://www.yellowtang.org/animations/cell_features_v2.swf
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Cell Types: Prokaryotic
Nucleoid: DNA
concentration
No organelles with
membranes
Ribosomes:
protein synthesis
Plasma membrane:
(all cells); semi-permeable
Cytoplasm/cytosol (all cells)
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Cell types: Eukaryotic
Nucleus:membrane enclosed organelle
containing chromosomes
Membrane bound organelles of
specialized form and function
Generally larger than prokaryotic cells
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Why organelles? Specialized structures
specialized functions
cilia or flagella for locomotion
Containers
partition cell into compartments
create different local environments
separate pH, or concentration of materials
distinct & incompatible functions
lysosome & its digestive enzymes
Membranes as sites for chemical reactions
unique combinations of lipids & proteins
embedded enzymes & reaction centers
chloroplasts & mitochondria
mitochondria
chloroplast
Golgi
ER
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Cells must work to live! What jobs do cells have to do?
make proteins
proteins control every
cell function
make energy
for daily life
for growth
make more cells
growth
repair
renewal
AP Biology 2007-2008
Building Proteins
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Proteins do all the work!
cells
DNA
proteins
organismRepeat after me…
Proteins do all the work!
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Cells functions Building proteins
read DNA instructions
build proteins
process proteins
folding
modifying
removing amino acids
adding other molecules
e.g, making glycoproteins
for cell membrane
address & transport proteins
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Building Proteins
Organelles involved
nucleus
ribosomes
endoplasmic reticulum (ER)
Golgi apparatus
vesicles
nucleus ribosome ERGolgi
apparatusvesicles
The Protein Assembly Line
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nuclearpores
nuclearpore
nuclear envelope
nucleolus
histone protein
chromosome
DNA
Function
protects DNA
Structure
nuclear envelope
double membrane
membrane fused in spots to create pores
allows large macromolecules to pass through
Nucleus
What kind of molecules need to
pass through?
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DNA
NucleusmRNA
nuclearmembrane
smallribosomal
subunit
largeribosomal
subunit
cytoplasm
mRNA
nuclear pore
production of mRNA
from DNA in nucleus
mRNA travels from
nucleus to ribosome
in cytoplasm through
nuclear pore
1
2
http://www.dnalc.org/resources/3d/12-transcription-basic.html
http://www.dnalc.org/view/15481-Translation-RNA-to-
protein-3D-animation-with-no-audio.html
http://www.youtube.com/watch?v=I9ArIJWYZHI
http://www.youtube.com/watch?v=4jtmOZa
IvS0&feature=related
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Nucleolus
Function
ribosome production
build ribosome subunits from rRNA & proteins
exit through nuclear pores to cytoplasm &
combine to form functional ribosomes
smallsubunit
large subunit
ribosome
rRNA &proteins
nucleolus
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smallsubunit
largesubunitRibosomes
Function
protein production
Structure
rRNA & protein
2 subunits combine 0.08mm
Ribosomes
RoughER
SmoothER
AP Biology membrane proteins
Types of Ribosomes
Free ribosomes
suspended in cytosol
synthesize proteins that
function in cytosol
Bound ribosomes
attached to endoplasmic
reticulum
synthesize proteins
for export or
for membranes
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Endoplasmic Reticulum Function
processes proteins
manufactures membranes
synthesis & hydrolysis of many compounds
Structure
membrane connected to nuclear envelope &
extends throughout cell
http://www.youtube.com/watch?v=PUy_Em5dXmc
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Types of ER
rough smooth
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Smooth ER function
Membrane production
Many metabolic processes
synthesis
synthesize lipids
oils, phospholipids, steroids & sex hormones
hydrolysis
hydrolyze glycogen into glucose
in liver
detoxify drugs & poisons
in liver
ex. alcohol & barbiturates
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Membrane Factory
Build new membrane
synthesize phospholipids builds membranes
ER membrane expands bud off & transfer
to other parts of cell that need membranes
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Rough ER function
Produce proteins for export out of cell
protein secreting cells
packaged into transport vesicles for export
Which cellshave lot of rough ER?
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Synthesizing proteins
cytoplasm
cisternalspace
mRNA
ribosome
membrane ofendoplasmic reticulum
polypeptide
signalsequence
ribosome
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Golgi Apparatus
Which cellshave lots of Golgi?
transport vesicles
secretoryvesicles
Function
finishes, sorts, tags & ships cell products
like ―UPS shipping department‖
ships products in vesicles
membrane sacs
―UPS trucks‖
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Golgi Apparatus
http://www.youtube.com/watch?v=rvfvRgk0MfA
http://www.dnatube.com/video/1594/Protein-Modification-Golgi
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Vesicle transport
vesiclebuddingfrom roughER
fusionof vesiclewith Golgiapparatus
migratingtransportvesicle
protein
ribosome
Regents Biology
DNA
RNA
ribosomes
endoplasmic
reticulum
vesicle
Golgi
apparatus
vesicle
proteinon its way!
protein finishedprotein
Making Proteins
TO:
TO:
TO:
TO:
nucleus
AP Biology
proteins
transportvesicle
Golgiapparatus
vesicle
smooth ER
rough ER
nuclear porenucleus
ribosome
cellmembrane protein secreted
cytoplasm
making proteinsPutting it together…
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Putting it together…making proteins
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AP Biology 2007-
2008
Tour of the Cell 2
AP Biology
Food & water storage
plant cells
central vacuole
contractile
vacuole
food vacuoles
animal cells
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Lysosomes
Function
little ―stomach‖ of the cell
digests macromolecules
―clean up crew‖ of the cell
cleans up broken down
organelles
Structure
vesicles of digestive
enzymes
only in
animal cells
synthesized by rER,
transferred to Golgi
Where old organellesgo to die!
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Lysosomes
white blood cells attack
& destroy invaders =
digest them in
lysosomes1974 Nobel prize: Christian de Duve
Lysosomes discovery in 1960s
1960 | 1974
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Cellular digestion
Lysosomes fuse with food vacuoles
polymers
digested into
monomers
pass to cytosol
to become
nutrients of
cellvacuole
lyso– = breaking things apart
–some = body
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Lysosomal enzymes
Lysosomal enzymes work best at pH 5
organelle creates custom pH
how?
proteins in lysosomal membrane pump H+ ions from
the cytosol into lysosome
why?
enzymes are very sensitive to pH
why?
enzymes are proteins — pH affects structure
why evolve digestive enzymes which function at
pH different from cytosol?
digestive enzymes won’t function well if some leak into
cytosol = don’t want to digest yourself!
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When things go bad…
Diseases of lysosomes are often fatal
digestive enzyme not working in lysosome
picks up biomolecules, but can’t digest one
lysosomes fill up with undigested material
grow larger & larger until disrupts cell &
organ function
lysosomal storage diseases
more than 40 known diseases
example:
Tay-Sachs disease
build up undigested fat
in brain cells
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Lysosomal storage diseases
Lipids
Gaucher’s disease
Niemann-Pick disease
Tay Sachs
Glycogen & other polysaccharides
Farber disease
Krabbe disease
Proteins
Schindler’s disease
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Lysosomal storage disease
Hepatosplenomegaly courtesy
of The National MPS Society,
Inc.
http://www.lysosomallearning.co
m/healthcare/about/lsd_hc_abt_
niemann.asp
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