ap biology the cell. ap biology cell characteristics all cells: surrounded by a plasma membrane ...
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AP Biology
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
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Prokaryotebacteria cellsProkaryote
bacteria cellsTypes of cells
Eukaryoteanimal cellsEukaryote
animal cells
- no organelles
- organelles
Eukaryoteplant cellsEukaryoteplant cells
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Types of 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, membrane-enclosed organelle
Cell walls present in fungi and plants only
More complex Membrane bound
organelles present
Prokaryotic vs. eukaryotic cells
AP Biology2005-2006The prokaryotic cell is much simpler in structure, lacking a nucleus and the other
membrane-enclosed organelles of the eukaryotic cell.
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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 gotta 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
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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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smallsubunit
largesubunitRibosomes
Function protein production
Structure rRNA & protein 2 subunits combine 0.08m
RibosomesRough
ER
SmoothER
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Synthesizing proteins
cytoplasm
cisternalspace
mRNA
ribosome
membrane ofendoplasmic reticulum
polypeptide
signalsequence
ribosome
(Free)
(Bound)
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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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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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proteins
transportvesicle
Golgiapparatus
vesicle
smooth ER
rough ER
nuclear porenucleus
ribosome
cellmembrane protein secreted
cytoplasm
Making proteinsPutting it together…
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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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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 cellsonly in animal cells
synthesized by rER, transferred to Golgisynthesized by rER, transferred to Golgi
Where old organelles
go to die!
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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
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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
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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
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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
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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
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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
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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
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Endosymbiosis theory 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
& protectionLynn MargulisU of M, Amherst
1981 | ??
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Food & water storage
plant cellsplant cells
central vacuole central vacuole
contractilevacuole
contractilevacuole
food vacuoles food vacuoles
animal cellsanimal cells
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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
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Vacuoles in plants Functions
storage stockpiling proteins or inorganic ions depositing metabolic byproducts storing pigments storing defensive
compounds against herbivores
selective membranecontrol what comes
in or goes out
AP Biology2005-2006
What limits cell size? Surface to volume ratio
as cell gets bigger its volume increases faster than its surface area smaller objects have greater
ratio of surface area to volume
Why is a huge single-cellcreature not possible?
What cell organelle governs this?
6:1 ~1:1 6:1s:v
AP Biology2005-2006
Limits to cell size Metabolic requirements set upper limit
in large cell, cannot move material in & out of cell fast enough to support life
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What’s the solution?
What process is this?
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AP Biology2005-2006
How to get bigger? Become multi-cellular (cell divides)
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But what challenges do you have to solve now?
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