Transcript Anatomy & Physiology of the Cell

Cell Organelles
Lindsey Bily
Anatomy & Physiology 2011-2012
Austin High School
Cell Theory
• Developed by Matthias Shleiden
and Theodor Schwann.
• The cell is the fundamental
organizational unit of life.
• All living things are composed of
cells.
Cell Membrane
Cell Membrane
Cell Membrane
• Made up of a
phospholipid bilayer.
• A phospholipid has a
hydrophilic “head” and
a hydrophobic “tail”
• Glycoproteins and
glycolipids attached to
the outer surface and
act as markers “self vs.
non-self”
• Cholesterol is present
to stabilize the
membrane.
Cell Membrane
• Membrane
proteins
are
embedded
and act as
gates or
receptors
for other
chemicals.
Cell Organelles
• “Little Organs”
• Cytoplasm
contains the
organelles and
cytosol.
Endoplasmic Reticulum
• A network of channels in the cytoplasm.
Transports molecules around the cell.
• Rough ER is studded with ribosomes.
• Smooth ER synthesizes lipids.
Ribosomes
They make proteins.
Ribosomes
• Ribosomes on the ER make
proteins for export out of the
cell.
• “Free” ribosomes make
proteins for the cell’s own use.
Golgi Apparatus
• Receive newly
synthesized proteins
and lipids from the ER.
• Modify them so that
they are ready to leave
the cell.
• Carbohydrates,
phosphorus, or lipids
may be added to the
proteins.
Golgi Apparatus
Lysosomes
Vesicles that have detached from the Golgi Apparatus and
Contain enzymes to break down cellular components.
“Cellular Garbage Disposals”
Lysosomes
• White blood cells
engulf cells and
digest them in their
lysosomes.
This picture is of
Staph bacteria (red)
being digested by
lysosomes.
Lysosomes
• This is a
lysosome in
the process of
digesting a
mitochondria!
Peroxisomes
Contain enzymes (peroxidase and catalase) that
detoxify harmful substances that enter the cell.
Usually found in great numbers in kidney and liver
cells.
Mitochondria
• Surrounded by a
double membrane.
• They contain their own
mitochondrial DNA.
• Are thought to have
been free living
bacteria millions of
years ago.
• Site of cellular
respiration to produce
ATP (energy).
The Nucleus
• The largest
organelle.
Usually in the
center in the
cell.
• Contains DNA.
• The nucleolus
contains rRNA
that helps to
form ribosomes.
Cytoskeleton
The cell’s internal supporting framework.
Besides giving the cell shape and structure,
these filamentous elements produce
movements of structures within the cell and
movements of the cell itself.
1. microfilaments
2. microtubules
3. intermediate filaments
Microfilaments
Smallest of the cell fibers.
Very slender strands of proteins.
Actin: They attach the cell membrane and the
nuclear envelope to the cytoplasm.
Myosin: Actin interacts with the thicker (18
nm) myosin microfilaments to produce cell
contractions. This arrangement is abundant
in skeletal muscle cells.
Actin & Myosin
Skeletal Muscle
Intermediate Filaments
Intermediate in thickness between the actin
(thin) and myosin (thick) microfilaments.
They are insoluble and the most durable of
the cytoskeletal components.
Maintain the cell’s shape and anchors the
organelles.
Microtubules
• polymers of tubulin. Microtubules are important for
maintaining cell structure, providing platforms for
intracellular transport, forming the spindle during
mitosis, as well as other cellular processes.
• Microtubules can serve as an anchorage or “footpath”
for proteins that behave as molecular motors. These
specialized proteins, kinesin and dynein produce the
intracellular movements of small structures like
vesicles.
• Microtubules within cilia and flagella produce the whiplike motions of these organelles.
Microtubules
Centrosome & Centrioles
• Centrosome is an area
of cytoplasm near the
nucleus that builds and
breaks microtubules.
• Centrioles are
composed of
microtubules in the
centrosome that are
involved in mitosis.
Cell Extensions
• Projections that extend from the plasma
membrane.
• Microvilli: tiny fingerlike projections that are
involved in absorption. Found in intestinal cells.
• Cilia and Flagella: made of microtubules and
involved in movement.
-Cilia in trachea keep contaminated mucus
from going into the lungs. Cilia in female
reproductive tract keeps the ovum (egg) moving
towards the uterus.
-Flagella on sperm allow it to “swim”.
Ciliated
Trachea
Microvilli
in small
intestine
Flagella on
sperm cells
covering an
egg
Cell Connections
• Cells are held together by nets that surround
groups of cells (ex. Muscle cells), or cells have
direct connections to each other.
– Desmosomes: “spot welds” that hold adjacent
cells together
– Gap Junctions: membrane channels of adjacent
plasma membranes adhere to each other.
• Form gaps or tunnels that join the cytoplasm
of two cells
• fuse two plasma membranes into a single
structure
Tight Junctions: “collars” of tightly fused
membrane. Molecules cannot permeate.
Desmosomes in skin
cells
Gap junctions
(green) between
cardiac cells
Tight Junctions
(green) between
Intestinal
Epithelial cells