PowerPoint Presentation - Chp 3 Notes

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Chapter 7 - Tour of the Cell
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Cells vary in size but are typically very small.
The more complex the internal components the
larger the cell can be . prokaryote-gteukaryote
cell-gtprotozoan
The small size is a consequence of the cell
volume requiring adequate surface area to support
nutrient demands
1cm sides SA? Vol? Ratio?
2cm sides SA? Vol? Ratio?
3cm sides SA? Vol? Ratio?
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Prokaryotes
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Eukaryotic Animal Cell The basic eukaryotic cell
contains the following 1.plasma membrane
2.cytoplasm (semifluid)
3.cytoskeleton - microfilaments and microtubules
that suspend organelles, give shape, and allow
motion 4.presence of characteristic
membrane enclosed subcellular organelles
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Plasma Membrane Internal Membranes Selectively
permeable barriers
Basic structure makeup is the same. The
specific proteins that are present and in what
concentration will allow different cell types to
respond differently to stimuli and nutrient/waste
identification. Glycocalyx identifies cell type.
(transplant rejection, hashimotos)
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Nucleus - control center
Double membrane surrounding the chromosomes and
the nucleolus. Pores allow specific
communication with the cytoplasm. The nucleolus
is a site for synthesis of RNA used to make up
ribosomes.
Constant chemical communication between the
cytoplasm and the nucleus. Initiation and
cessation of life sustaining chemical reactions
is ordered by the DNA in the nucleus
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Endoplasmic Reticulum - assembly line
Attached to the nuclear envelope for immediate
response to the orders of the DNA. A network of
interconnected membranes forming channels and
pockets (cisternae) within the cytoplasm.
Rough ER Covered with ribosomes (causing the
"rough appearance) which are in the process of
synthesizing proteins for secretion or
localization in membranes.
Ribosome protein RNA complex that is needed for
the synthesis of protein. (free attached)
Smooth ER

• assembly of lipids carbohydrate
• detoxifies toxic chemicals (add OH for
  solubility)
• may store, release recover cell stimulants

What determines amount type of ER in cells?
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The Golgi - Some manufacture packaging for
export Chemicals assembled and acquired from the
ER are placed in a vesicle whose membrane
contains target (docking) chemicals identifying
the final location of its contents (outside cell
or inside organelles)
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Lysosome - digests recycles Made by the golgi,
contains powerful hydrolytic enzymes that digests
organic compounds
H pump in membrane enables the lysosome to lower
pH and digestion started,
Cells deprived of O2 or infected by viruses can
trigger lysosomes to rupture release hydrolytic
enzymes into cytosol (immune system, tadpole
tail, fetal fingers)
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Formation of Lysosomes
The modification and packaging of glycoproteins
glycolipids can establish the glycocalyx on the
plasma membrane
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Endomembrane system A series of closed membranes
within eucaryotic cells that are either
continuous with each other or communicate with
one another via vesicles which are formed at one
surface and move to a second where they are
incorporated.
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Vacuoles
Membrane surrounded "bags" that contain water and
storage materials in plants.

• Contractile Vacuole
• Food Vacuole
• Structural Vacuole
• Storage Vacuole

URL for Contractile Vacuole
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The Mitochondrion - Power generator (Respiration)
Organelle that contains its own DNA and
ribosomes. It makes its own proteins.
EndoSymbiotic Theory. It converts a non-readily
available chemical energy (PGAL) into a usable
form - ATP as long as O2 is readily available
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Cytoskeleton - cell structure
Cytoskeleton revealed by staining with a
fluorescent labeled actin antibody
Cytoskeleton is composed of three main types of
protein fibers, Microtubules, Microfilaments, and
Intermdiate filaments.
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Microtubules and Microfilaments also aid in
cellular transport
Motor proteins (kinesin and myosin) can attach to
the microtubules or microfilaments and with the
use of ATP glide along the surface. As the motor
protein moves along the surface it can drags
organelles through the cytoplasm
Cytoplasmic streaming
The pigment granules move on fixed pathways
inside the chromatophore cytoplasm, following
radially arranged bundles of microtubules. The
process is shown at 24 times the real speed.
Movement is caused by light stimulus to he eye or
emotion. Nerve fibers discharge transmitters that
initiates the movement of the pigment in the
microtubules.
Chrmatophores
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The microtubules can be arranged in elaborate
bundles creating specialized transport structures
(cilia, flagella, centriole)
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Occluding Tight Junctions - keratin proteins fuse
the adjoining membranes in direct contact (no
intracellular space). Weld Anchoring Desmosomes
Adhesion Belts - intermediate filaments
penetrate are shared through the membranes of
both cells. (collagen, keratin) Intracellular
space still present Communication Gap Junctions -
pore like conections that allows cytoplasm to
flow easily between connected cells
(plasmodesmata in plant cells)
Cell Surfaces and Junctions
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Plant Cells are structurally very similar to
animal cells Differences?
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Chloroplast - energy transformer
(Photosynthesis) In the presence of light and
with the use of chlorophyl, the chloroplast
converts CO2 and H2O into carbohydrate. This may
be used for the production of ATP, storage, or
structural material.
Chloroplasts have their own DNA and ribosomes
(endosymbiotic theory) and make their own
proteins. They develop from an undifferentiated
organelle called a Protoplast. Depending on
location in the plant and or the presence or
absence of light, the protoplast may develop into
one of three organelles

• Chloroplast
• Chromoplast
• Leucoplast

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Cell Wall
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Membrane Structure Transport
Functions?
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Cell growth will require formation of additional
membrane and deposition of essential membrane
chemicals. This is accomplished by the
endomembrane system. The Golgi ER work
together to create the key membrane chemicals
which are then concentrated on the inner surface
of vessicles that are released. Vessicle
membranes and the plasma membrane fuse much in
the same way as soap bubbles can fuse.
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Passive Transport All cells require nutrients
and produce waste. Movement of these substances
into and out of the cell at the optimum rate is
essential. What mechanisms insures the proper
exchange (nutrients in and wastes out)?
Molecules own kinetic energy insures movement
from an area of high concentration to an area of
low concentration. The rate at which this
movement will occur depends on?
This type of transport is referred to as Passive.
Why? Organisms without transport systems depend
heavily on this type of movement. What physical
characteristics are typical of those organisms
lacking transport systems?
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Methods of Passive Transport
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Water moves freely between the shifting lipid
molecules. Water will also move from an area of
higher concentration to an area of lower
concentration - Osmosis - diffusion of water
through a selectively permeable barrier
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Active Transport Microtubules Transport
containers filled with basolateral cargo move
along microtubules to the cell periphery
Microtubules responsible for internal cellular
transport were tagged with fluro dyes. Th area
that is brightly colored is the golgi. Small
packets moving to the cell periphery are
vessicles containing golgi or ER
products. Sequence of 100 images. Rate was two
images per second
http//www.mpi-cbg.de/research/simons/Movie.html
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Carrier Proteins can actively transport
substance in or out of cells
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• Endocytosis
• Receptor Mediated Endocytosis (example?)
• Pinocytosis (no receptor - example?)
• Phagocytosis (example?)

Exocytosis (example?)