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CLASS: Fundamentals 1
8-9-2011
11:00 – 12:00
Cotlin
Scribe: Mathew Owens
Cellular Structure and Organelles
I.
Proof: Gary Cramer
Page 1 of 4
Lysosomes [S 47]
a. Lysosome
i. Membrane bound organelle that contains enzymes that degrade other molecules
A. Contains proteases, lipases, nucleases
a. Lysosomal enzymes are phosphorylated with mannose (a sugar), which targets them for
transport to the lysosome.
ii. Plasma membrane vesicles called endosomes or phagosomes also deliver ingested material to lysosome
for destruction.
A. Ex. LDL is taken up by endosome and then taken to the lysosome for degradation.
iii. PH is about 5-5.5 (acidic environment)
II. Lysosomes [S 48]
a. Lysosomes have many hydrogen pumps that are continually pumping hydrogens into the lysosome.
i. All of digestive enzymes are active at low PH.
A. This is important because you do not want these proteins active everywhere else in the cell.
III. Lysosomes [S 49]
a. On EM’s lysosomes show up as electron dense vesicles. (She said do not worry about this.)
IV. Endocytosis and Endosomes [S 50]
a. Picture of receptor mediated endocytosis.
i. Receptors that specifically grab molecules and take things in.
ii. Endosomes will come in and bind to the receptors and then bring their material to the lysosome.
V. Phagocytosis and Phagosomes [S 51]
a. Vesicles that are much larger same idea they bring in large material and they bring in material to the
lysosome.
VI. Peroxisomes [S 52]
a. Membrane-bound organelle also involved in oxidative reactions
i. Peroxisomes break down fatty acids and lipids.
A. They do not provide energy through oxidation. ( Energy is provided through oxidation in the
mitochondria , Do not get these two confused)
ii. Paroxysmal proteins are synthesized in the cytoplasm and transported into the organelle using a specific
amino acid sequence.
iii. Genetic defects in peroxisomal biogenesis cause several forms of mental retardation.
VII. Peroxisomes [S 53]
a. Picture of peroxisomes, they are the small black dots.
VIII. Mitochondria [S54]
a. Double membrane bound (Inner and outer membrane), powerhouse of the cell (bulk of ATP is synthesized
here)
b. Found all over the cell, clusters are found in locations with high energy demand
i. Ex sperm tails, contractile apparatus of muscles, active transport of membranes, and nerve terminals
c. Also involved with apoptosis (cell death)
d. Have their own DNA and protein synthesizing apparatus and make their own proteins.
e. Mitochondria form differently from other organelles, by pinching in two, they do not divide synchronously with
cell division.
IX. Mitochondria [S 55]
a. Picture of a mitochondria
i. The dense knobs are proteins of the electron transport chain.
X. Organization of Mitochondria [S 56 ]
a. Picture that help depicts between the inner and outer membrane.
XI. Overview of Mitochondrial Functions [S 57]
a. Glycolysis occurs in the cytosol and results in the formation of pyruvate.
i. Pyruvate and Fatty acids are transported into the mitochondria
A. Citric Acid cycle, Krebs cycle, TCA cycle occur in the matrix
ii. She said this was a brief overview, of the functions, and that we will get a more detailed presentation later.
XII. Mitochondria [S 58]
CLASS: Fundamentals 1
8-9-2011
11:00 – 12:00
Cotlin
Cellular Structure and Organelles
a. another picture of the mitochondria. (can be different sizes)
Scribe: Mathew Owens
Proof: Gary Cramer
Page 2 of 4
Cellular structures and Organelles 2
I.
II.
III.
IV.
V.
VI.
Inclusions [S 3]
a. Deposits in cells found in the cytosol
i. Glycogen, lipids, pigments (hemosiderin, melanin), crystals
Proteasome [S 4].
a. Another structure involved with degradation
i. Not part of membrane system
ii. Found in cytosol and nucleus
iii. If the cell does not need protein anymore the protein will be targeted and sent to proteasome
1. Ubiquitin is an amino acid peptide that is used as the signal to direct the protein to the
proteasome.
b. Lysosome vs. Proteasome
i. Lysosome are membrane bound organelle and will receive lots of materials and will have lipases,
nucleases, and proteases
ii. Proteasome is particular for proteins found in the cytosol
The Cytoskeleton [S 5]
a. Is the structural framework of given cell.
i. Composed of three protein polymers:
1. microtubules, active filaments, and intermediate filaments
a. Will help dictate the shape and organization of the cell and also how the cell will
interact with its environment.
Organization of the Cytoskeleton [S 6]
a. Diagram depicting a chain of epithelium.
i. Green =micro tubules
1. Usually run towards the nucleus and outward.
ii. Red = actin
1. Very localized under plasma membrane to help give support.
iii light blue = Intermediate filaments
1. Generally criss cross the cell which helps withstand the pushing and pulling of cells.
Microfilaments, Intermediate filaments, and Microtubules [S 7]
a. Microtubules
i. Rigid column shape structures
b. Intermediate filaments
i. Rope like filaments
c. Microfilaments (ex. actin)
i. Filament disarray
d. Each one of these structures are all polymers of smaller molecules
Microtubules [S 8]
a. Are the largest of the three (microtubules, intermediate filaments, and microfilaments)
b. Are made up of a tubulin dimer (alpha and beta)
i. Very organized and specific in how they are assembled
VII. Microtubules [S 9]
a. Help direct flow in a sense of acting as tracks in the cell.
i. Kinesin-moves vesicles and RNA out along the Microtubules.
ii. Dynein- moves cargo from the cell membrane toward the nucleus.
b. Help form mitotic apparatus and move chromosomes to the poles of the cell. (during mitosis)
VIII. Microtubules [S 10]
a. Microtubules form spindle fibers and are involved in chromosomal movement during mitosis
b. Microtubules are found in the length of axons of neurons and help the axon stay intact.
CLASS: Fundamentals 1
8-9-2011
11:00 – 12:00
Cotlin
Scribe: Mathew Owens
Proof: Gary Cramer
Cellular Structure and Organelles
Page 3 of 4
c. Microtubules are major components of cilia and flagella.
d. Involved with centrioles
i. Anchoring site in the cell
IX. Arrangement of Microtubules [S 11]
X. Picture of Mitosis [S 12]
a. Blue is chromosomes, yellow is microtubules
XI. Structure of Actin filament [S 13]
a. Made up of actin monomers
b. Have a plus and minus end, and specific in how they stack, very dynamic (can be longer or shorter
depending on how long or short they need to be)
XII. Intracellular Actin (Microfilament) [S 14]
a. Actin filaments also help reinforce the surface of the cell by being anchored in the plasma membrane
b. Actin filaments support finger-like projections of the plasma membrane for transporting to increase
surface area for transporting nutrients.
c. Genetic defects in a membrane associated actin binding protein, dystrophin cause most of the common
forms of muscular dystrophy.
d. Provide tracks for the ATP powered motor proteins that produce most cellular movement including
transport of organelles and movement of chromosomes during mitosis.
XIII. Actin [S 15]
a. picture of Actin network
XIV.
Model for cell movement [S 16]
a. Actin is involved with movement of a cell, very dynamic
i. actin’s ability to assemble and disassemble allows the cell to move
XV. Intermediate Filaments [S 17]
a. Static structures, not as dynamic as actin or microfilaments
b. Will have rope like properties, more flexible (help cell be able to stretch)
XVI.
Intermediate filaments [S 18]
a. Flexible, strong intracellular tendons that are used to reinforce cell structure.
b. All intermediate filaments are related to the keratin molecule.
c. Filaments characteristically form bundles that link the plasma membrane to the nucleus.
d. Some reinforce the nuclear envelope.
e. Genetic defects involved with Intermediate filaments.
i. Blistering of skin
XVII. Keratin Filaments in Epithelial Cells [S 19]
a. Picture of epithelial cells stained for keratin.
XVIII. Mechanical strength of filaments [S 20]
a. Graph depicting how intermediate filaments are more likely to withstand forces and not snap under
various levels of tension compared to microtubules and actin filaments.
XIX.
The Cell Cycle [S 21]
a. Diagram of cell cycle
XX. The Cell Cycle [S 22]
a. Eukaryotic cell cycles are divided in two major stages; interphase and mitosis.
i. Interphase- time when cell does not divide
1. G1 is a metabolically active phase
a. Can either enter the Go phase or S phase
2. Go phase is when a cell will not divide for a long period of time.
a. When receives signal that it is time to divide it will move into the S phase
3. S stands for synthesis; this is the stage where the cell replicates its DNA.
a. After the S phase it moves into G2 phase.
4. The G2 phase is a second growth phase; this is when the cell physically bulks up to have
enough material for Mitosis. Also a period of proofreading.
ii. Mitosis – time where cell divides (cytokinesis= cytoplasmic division)
XXI.
Cell Cycle …continued [S 23]
a. Checkpoints and feedback controls coordinate the different phases of the cell cycle to prevent mutations.
b. After DNA replication has occurred, initiation of a new S phase is prevented until the cell has passed
through mitosis.
CLASS: Fundamentals 1
8-9-2011
11:00 – 12:00
Cotlin
Scribe: Mathew Owens
Proof: Gary Cramer
Cellular Structure and Organelles
Page 4 of 4
XXII. Events that occur when a cell divides [S 24]
a. Prophase
i. Where cell assembles, and microtubules attach to chromosomes.
b. Metaphase
i. The chromosomes line up in the middle of the cell.
c. Anaphase
i. The chromosomes are pulled apart towards opposite poles of the cell.
d. Telophase
i. When the cell undergoes a splitting into two daughter cells.
XXIII. Development and Differentation [S 25]
a. Majority of our cells do not divide on a daily basis and are rested in the Go phase.
b. Some cells can never go through mitosis
i. Neurons
ii. Adult Cardiac muscles
c. Some differentiated cells have short life spans and are continually replaced (going through mitosis)
i. Ex. Skin cells
XXIV. Programmed Cell Death (Apoptosis) [S 26]
a. Programmed cell death plays a key role in:
i. Maintenance of adult tissue
ii. Embryonic development
b. Programmed cell death is a process of apoptosis, which is different from accidental death of cell resulting
from acute injury, which is called necrosis.
c. Apoptosis is essential for the health of the organism.
XXV. Events in Apoptosis [S 27]
a. Enzymes associated with this process are called caspases.
b. Caspases digest DNA, cytoplasmic proteins, and organelles.
c. The membrane remains intact until final stages of cell death.
d. Macrophages readily devour the debris of the dying cell and much of the digested material is used in the
building of new cells.
XXVI. Introduction to Histology and Microscopic Techniques
XXVII. Histology
a. Study of microscopic structures of tissues.
b. Four major tissue types
i. Epithelial1. layers of cells that line our skin:
a. Ex. Gi tract, Reproductive Tract
ii. Connective1. cells involved with making matrix
iii. Muscle1. Cardiac, smooth, skeletal
iv. Nerve