Transcript Chp 6 Cells Part1

Tour of the Cell
AP Biology
2007-2008
Types of cells
Eukaryote
animal cells
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Prokaryote
bacteria cells
Eukaryote
plant cells
Why organelles?
 Specialized structures

mitochondria
specialized functions
 cilia or flagella for locomotion
 Containers


partition cell into compartments
create different local environments
chloroplast
 separate pH, or concentration of materials

distinct & incompatible functions
 lysosome & its digestive enzymes
 Membranes as sites for chemical reactions


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Golgi
unique combinations of lipids & proteins
embedded enzymes & reaction centers
 chloroplasts & mitochondria
ER
Cells gotta live!
 What jobs do cells have to do?

building proteins
 proteins control
every cell function

make energy
 for daily life
 for growth

build more cells
 growth
 reproduction
 repair
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Why study protein production?
proteins
cells
DNA
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Repeat after me…
organism
DNA gets the glory, but
Proteins do all the work!
Building Proteins
 Organelles involved
nucleus
 ribosomes
 endoplasmic reticulum
(ER)
 Golgi apparatus
 vesicles

The Protein Assembly Line
nucleus
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ribosome
ER
Golgi
apparatus
vesicles
TO:
endoplasmic
reticulum
nucleus
protein
on its way!
DNA
RNA
TO:
vesicle
TO:
TO:
vesicle
TO:
ribosomes
finished
protein
protein
Golgi
apparatus
Making Proteins
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Putting it together…
nucleus
nuclear pore
Making proteins
cell
membrane
protein secreted
rough ER
ribosome
vesicle
proteins
smooth ER
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transport
vesicle
cytoplasm
Golgi
apparatus
Cells gotta live!
 What jobs do cells have to do?

make proteins
 proteins control
every cell function

make energy
 for daily life
 for growth

build more cells
 growth
 reproduction
 repair
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ATP
Cells need power!
 Making energy
take in food & digest it
 take in oxygen (O2)
 make ATP
 remove waste

ATP
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1960 | 1974
Lysosomes
 Function

Christian de Duve
little “stomach” of the cell
 digests macromolecules

“clean up crew” of the cell
 cleans up broken down
organelles
 Structure

vesicles of digestive enzymes
Where
old organelles
go to die!
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only in animal cells
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

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why is this an adaptation: 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!
But sometimes 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
 ex: self-destruct of cancerous cell
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syndactyly
Fetal development
6 weeks
15
weeks
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When things go wrong…
 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:
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Tay-Sachs disease
build up undigested fat
in brain cells