Transcript Chapter3 - sshsanatomy

Chapter 3
Anatomy of
Cells
Cell Theory
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All living things are composed of one or
more cells.
Cells are the basic units of structure and
function in living things.
New cells are produced from existing
cells.
In 1839 German Scientists
Theodor Schwann and Matthias
Schleiden suggested that cells
were the basic unit of life and that
all living things came from cells
Functional Anatomy
• Refers to study of structure as they relate
to function
The World of
Microscopy
Light Microscope
• Also referred to as the optical
microscope
• Uses visible light and a system
of lenses to magnify images of
small samples.
• Limit of 2000 times greater
Skin
cells
Anton Van Leeuwenhoek
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Dutchman
Commonly known as "the Father of
Microbiology“
Considered to be the first
microbiologist.
Didn’t invent but did improve the light
microscope.
He was first to observed single celled
organisms which he called
animalcules
Robert Hooke
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Englishman
Known as "the father of
microscopy“
Coined the term "cell" due to the
fact that what he was looking at
reminded him of a monk’s cell in a
monastery
Published a book in 1665 titled
Micrographia
Electron Microscope
• Uses a particle beam of
electrons to illuminate a
specimen and create a
highly-magnified image.
• Can obtain much higher
magnifications of up to 2
million times.
• First prototype built in
1931
Fly foot
Transmission Electron Microscope
TEM
• Electrons are emitted
by an electron gun
• Images are called
transmission electron
micrographs
Hair
Scanning Electron Microscope
SEM
• Beam of electrons
scan the surface and
are reflected from the
surface
• Gives illusion of depth
Dust mite
Single hair
cell from
frog’s ear
Principle of Complementarity of
Structure and Function
• An organ's structure cannot be studied
without understanding how it functions in
the living system
• An organ's function cannot be studied
without understanding it’s structure in the
living system.
Cell Types
Nerve Cell
• Surface sensitive to
stimuli
• Long extensions
• Detects changes in
internal or external
environment
• Transmit nerve
impulses from one
part of the body to
another
Muscle Cell
• Elongated and
threadlike
• Has tiny fibers that
slide together
forcefully
• Made to contract or
shorten
• Used in movement of
body parts
Red Blood Cells
• Contains hemoglobin
• Transports oxygen in
the blood stream
RBC with
malaria
Gland Cells
• Contain sacs that
release secretion to
outside of the cells
• Releases substances
such as hormones,
enzymes, mucous
and sweat.
Exocrine gland
Immune Cells
• Main function is to
destroy “nonself” cells
such as cancer or
bacteria.
• Some have outer
membranes that can
engulf other cells
• Some can
manufacture
antibodies
• Some can destroy
other cells
T cell
Composite Cell
• Typical cell
• Cells have many
similarities
3 Main Cell Structures
• Plasma membrane
• Cytoplasm
• Nucleus
Cell Structures
• Plasma membrane surrounds the cell
• Inside cell is composed gel-like substance
called cytoplasm
• Cytoplasm is made up of various
organelles and a watery fluid called
cytosol or intracellular fluid
• Nucleus is in the center of cell and is not
part of cytoplasm.
Review
1. What important concept was purposed by
Schleiden and Schwann?
2. Give example of how cell structure
relates to its function.
3. Three main cell structures
Cell Membranes and Organelles
• Made of lipids, protein and other
molecules
• Each cell has various membranous
organelles which are sacs and canals
made from the same material as the
plasma membrane (See Table 3-2 page
77)
Membranous Structures
• Plasma membrane
• Endoplasmic
Reticulum (ER)
• Golgi Apparatus
• Lysosomes
• Peroxisomes
• Mitochondria
• Nucleus
Nonmembranous Structures
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Ribosomes
Cytoskeleton
Cilia and flagella
Nucleolus
Fluid Mosaic Model
• Model of cell membrane structure composed of a
lipid bilayer with scattered proteins; often
described as a sea of lipids with protein icebergs.
Fluid and moves around with a flowing changing
pattern of arrangement.
Plasma
Membrane
Plasma Membrane/Cell Membrane
• Bi-layer of phospholipids
• Hydrophobic tails and
Hydrophilic heads
Cholesterol
•Steroid lipid that mixes with
the phospholipids.
•Stays fluid enough to
function at body
temperature.
•Without it cell membranes
would break far too easily
•Forms fence like material
that allows lipid soluble
molecules to pass through
Membrane Proteins
•Act like gates allowing water
soluble molecules through
membranes.
•Glycoproteins are formed
•Glycoproteins have carbohydrates
attached to them acting like
identification markers
•Some are receptors that react to
things such as hormones
•Carry molecules across membrane
in a process known as signal
transduction
See Table 3-3 page 80
Cytoplasm
• Gel-like internal substance
• Contains suspended structures
• Highly differentiated into organelles
and cytosol
Organelles
Endoplasmic Reticulum (ER)
• Endoplasm means cytoplasm is
located toward the center of the cell
• Reticulum means network
• ER however is located throughout the
cell as seen by electron microscopes
• ER walls are basically the same
molecular structure as the plasma
membrane
• Function in protein synthesis
Endoplasmic Reticulum (ER)
• Allows intracellular transport of molecules
• Proteins move through canals toward the
golgi apparatus
• Two types: Rough and Smooth
Rough ER
• Ribosomes on the surface of the
membrane make it rough
• Proteins are synthesized, enter
the canal and move toward the
Golgi apparatus and eventually
leave cell.
Smooth ER
• No ribosomes on
walls
• Smooth ER
believed to
synthesize lipids
and
carbohydrates
Ribosomes
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Protein factories: Protein synthesis
Many are attached to rough ER
Can not be seen with a light microscope
Made of two subunits. A large one and a small
one (figure 3-6 page 82)
Ribosomes
• Each subunit contains a ribonucleic acid
(RNA) bonded to a protein (rRNA, mRNA,
tRNA)
• Working ribosomes function in groups called
polyribosomes.
• Polyribosomes look like a string of beads
under the electron microscope.
Golgi Apparatus
• It is a membranous organelle
• Has several canals called cisternae
• Process and packages protein molecules
for export out of cell
• Proteins are packaged into membranous
bubbles called vesicles
Golgi Apparatus
Lysosomes
• Lysosomes have membranous walls.
• Vesicles that have been pinched off from the
Golgi apparatus
• Filled with enzymes capable of breaking
down cell components
• Lysosomes destroy cells by digesting them
• They are the cellular garbage disposal of the
cell
• White blood cells
Peroxisomes
• Membranous organelle
• Detoxify the cell
• Contain peroxidase and catalase
Mitochondria
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Membranous organelle
Called “the power house” of the cell
Produce ATP for cell energy use
Have 2 membrane walls
Inner wall folded into cisternae
Outer membrane has enzymes in it
Number of mitochondria in a cell has been
linked to the cell’s activity
Mitochondria
Other Organelles
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Box 3-2 Page 81
Originally just listed as inclusions
Barrel
Compartment for Peptide Loading (CPL)
Caveola
Review
• List 3 functions of the plasma membrane
• Identify 3 organelle and give functions
• Distinguish between membranous and
nonmembranous structures
Cytoskeleton
Cytoskeleton
• Cell’s internal supporting framework
• Made up of rod-like pieces that support
and allow movement
• Has muscle-like groups of fibers that
move the cell or cell parts
Cell Fibers
• Form 3D irregularly shaped lattice or
scaffolding
• Appear to support ER, mitochondria
and free floating ribosomes
• They have microfilaments,
intermediate filaments and
microtubules
• See page 85
Microfilaments
• Smallest cell fibers
• Often serve as
“cellular muscle”
• Made of thin twisted
strands of protein
molecules
• Some can slide past
one another causing
shortening of the cell,
such as in muscle
fibers
Intermediate Filaments
• Twisted protein strands
• Thicker than microfilaments
• Form much of the supporting framework
Microtubules
• Thickest fibers
• Hallow tubes
• Protein subunits
arranged in spiral
fashion
• Engine of the cell,
due to aid in
movement of cell
parts or even the cell
itself
Centrosomes
• Near nucleus
• Coordinates the
building and breaking
of microtubules
• Moves chromosomes
around in cell during
cell division
Cell Extensions
• Microvilli, cilia and flagella
• Projections that extend the plasma
membrane outward
• Assist in movement and absorption
• Increases cell surface area
Microvilli
• Found in epithelial cells found in intestines
and other areas
• Used where maximum absorption is
required
Cilia and Flagella
• Have cylinders made
of microtubules at
their core
• Each cylinder is
composed of 9 double
microtubules
arranged around 2
single microtubules in
the center
• Aids in movement
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Nucleus
Occupies the central portion of the cell
Nuclear substance is known as nucleoplasm
Nuclear membrane is called nuclear envelope
Cell membrane seems to be extension of the ER
The non-membranous nucleolus is in the nucleus, it
contains the nucleic acid RNA instead of DNA
• Functions in control and regulation of the cell
Nucleolus
• Membraneless body
• Inside nucleus
• “programs” the formation of ribosomes
thus playing essential role in their
formation
DNA and Chromosomes
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Chromosomes are
tightly coiled DNA
molecules.
Humans have 46
chromosomes
Cell Connections
Desmosomes
• Small spot welds that hold adjacent cells
together
• Skin cells are held together this way
• Holds together like hook and loop of velcro
• Anchored internally by intermediate
filaments of cytoskeleton.
Gap Junction
• Membrane channels of adjacent plasma
membrane adhere to each other.
• They form gaps or tunnels connecting 2 cells
• They fuse 2 plasma membranes into a single
structure
• Advantages are certain molecules can pass
directly from one cell to another and
• Heart muscles cells are joined by Gap junctions
Gap Junction
• Electrical impulses
can travel over many
cell membranes in a
row without stopping.
• Heart muscle cells
are joined by gap
junctions.
Tight Junction
• Joined by collars of
tightly fused
membrane
• Entire sheet of cells
can be held together
like a six pack of soda
(only tighter)
• Molecules can not
permeate
• Found in intestines