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125 Cards in this Set

  • Front
  • Back
6 Types of intermediate filaments
1. Keratins - epithelial, hair, nails
2. Desmin - muscle cells
3. Vimentin - embryo, fibroblasts, leukocytes, endothelial cells
4. Glial Fibrillary Acidic Protein - astrocytes, Schwann Cells, oligodendrocytes
5. Neurofilaments - neurons
6. Nuclear Lamins - nucleus of all cells
Drugs that act on actin
Cytochalasin ABCDE - secreted by fungi; bind to ends of actin filaments and prevent further polymerization

Phalloidin - from mushroom; binds to actin filaments and stabalizes them against depolymerization
Molecules required for actin polymerization
Ca 2+, ATP, G-Actin
Functions/Types of Actin Bundles
1. Contractile: ex. cleavage furrow (myosin)
2. Gel-like network: ex. cell cortex (filamin)
3. Parallel: ex. core of microvilli Ivillin, fimbrin)
4. Focal Contact for Cell Attachment: ex. stress fiber (alpha-actin, talin, vinculin)
5 functions of Intermediate Filaments
1. structural support
2. deformable 3D framework
3. anchor nucleus
4. adaptable connection between cell membrane and cytoskeleton
5. framework for maintenance and reorganization of nuclear envelope
What are the "bones and muscels" of the cell
Intermediate filaments
They have no contractility and no polarity
Mainly a crosslinking function
What molecules are required for microtubule assembly
Mg 2+, GTP, MAPs
Tubulin Binding Drugs
Colchicine, Colcemid: inhibit addition of tubulin to microtubules
Vinblastine, Vincristine: cause tubulin aggregates to form
Taxol: Stabalizes microtubules
What is the function of MAPs
Organize microtubules and affect their stability
Describe the structure of the nuclear pore
3 rings - cytoplasmic, middle, and nucleoplasmic
8 spoke like structures that connect cyto. and middle rings
nuc. ring has protruding basket
middle ring contains transporter
Where are ribosomes produced
Fibrillar center
inactive DNA in nucleolus
Pars Fibrosa
RNA in nucleolus
Pars granulosa
maturing ribosomal subunits in nucleolus
nucleolar matrix
involved in nucleolar organization
A. Kinetochore
B. Kinetochore microtubule
C. Astral microtubule
D. Polar microtubules
E. Chromosome
F. Pole, centrosome
G. Spindle
H. Aster
I. Zone of Interdigitation
Name the structures
Describe how chromosomes seperate during anaphase
It's the assembly and disassembly of microtubules that allows chromosomes to seperate
What are nucleoporins and what are the two types
Nucleoporins are the proteins that line the nuclear pore complex and are responsible for the transport of all macromolecules. Importins transport molecules into the cell and exportins transport molecules out of the cell.
What is Kinesin
One of the motor proteins responsible for chromosome movement
What are three common types of membrane lipids
1. Phospholipids
2. Glycolipids
3. Cholesterol
What is the general structure of a phospholipid and why is it amphipathic
The fatty acid side chains can be the same or different and the alcohol is not always present
What is the general structure of a glycolipid and why is it amphipathic
Similar to a phospholipid, a sugar takes the place of the phosphate group. Fatty acid tails are hydrophobic and sugar is hyfrophilic
What is the general structure of cholesterol and why is it amphipathic
The hydroxol group is hydrophilic while the rest of the molecule is hydrophobic
What are 6 functions of the plasma membrane
1. Regulate nutrient and ion transport into the cell
2. Regulate transport of waste out of the cell
3. Maintain correct chemical conditions in the cell
4. Provide a site for lipid based chemical reactions
5. Interact with other cells or the ECM (extra cellular matrix)
6. Detect and transduce signals from environment to cell
What type of molecules can pass directly through the lipid core of the membrane and which cannot
Can: Steroid hormones, Gases, small uncharged polar molecules, water and urea depending on the concentration gradient

Cannot: Large uncharge polar molecules, ions, charged polar molecules
What are the features of a peripheral membrane protein
loosely associated with membrane

Do no enter or span the lipid core

removed with mild conditions (salt/pH)
What are the features of an integral membrane protein
Tightly associated with the membrane, enetering or spanning the lipid core

Removed only with harsh conditions (detergents)

Contains one more stretch of 20-25 hydrophobic residues arranged in an alpha helix to span the lipid core
Why is the hydrophobic alpha helix perfectly suited to span the lipid core
It has hydrophobic residues

All of the hydrogen bonds are intramolecular and are therefore not available to interact with the hydrophobic core
What are the four types of lipid anchors
1. Farnesylation
2. Palmitoylation
3. Myristoylation
4. Glycosylphosphatidylinositol (GPI) Anchor
How do lipid anchors work
Hydrophobic molecules that are covalently linked to a protein. The hydrophobic molecule is embedded in the hydrophobic core of the plasma membrane, thus anchoring the protein at the membrane. Importatn for recognition and signaling proteins.
How does cholesterol affect membrane fluidity with relation to Tm (phase transition or melting temp.)
Below Tm: Increases fluidity, kinked structure disrupts the tight and orderly packing of the lipid side chains

Above Tm: Decrease fluidity, limits the free movement of the lipid side chains due to its planar shape
5 Reasons membrane fluidity is important
1. Influences arrangement of of proteins and lipids
2. Foster assembly/disassembly of protein subunits and signaling complexes int he membrane
3. Changes membrane permeability
4. Excessive fluidity can lead to membrane destruction
5. Altering fluidity can alter membrane and/or cell function
How does fatty acid saturation affect membrane fluidity
Desaturated fatty acids have more kinks which disrupts tight packing thereby increasing fluidity and lowering the Tm compared to saturated fatty acids
How does the length of the fatty acid chain affect membrane fluidity
Longer acyl side chains increase the Tm
What are the four basic tissue types
1. Epithelial
2. Connective Tissue
3. Muscle
4. Nerve
What are the 4 types of junctions of the epithelial lateral membrane
Zonulae Occludentes
Zonulae Adherentes
Maculae Adherentes (Desmosomes)
Gap Junctions
Zonulae Occludentes
Tight junctions, most apically located, prevent movement of membrane proteins from apical to basolateral domain, fuse plasma membranes of adjacent cells to prevent water-soluble molecules from flowing in between, can be tight or leaky
Zonulae Adherentes
belt like junctions that adhere adjoining epithelial cells to each other, located just basal to the zonulae occludentes, the integral protein cadherin fills intercellular space and bind a bundle of actin filaments inside cell by alpha actinin and vinculin. Extra cellular regions of cadherins from adjoing cells bind to each other. This junction not only links the cell membranes of two adjoining cells but also thier cytoskeletons
Maculae Adherentes
Desmosomes - weld like junctions along the lateral cell membranes of epithelial cells that help to resis shearing forces. Attachment plaques of adjoing cells are located on the cytoplasmic side of the membrane. Intermediate filaments insert into plaque and extend into cytoplasm. The intercellular region is filled with the extra cellular region of a cadherin type transmembrane linker protein that binds the two cells in the presence of Ca 2+
Gap Junctions
Nexus or communication junctions: mediate intercellular communication by permitting the passage of various substances between adjacent cells.
^ molecules of the transmembrane protein connexin form a connexon - an aqueous pore through the plasma membrane to the intercellular space

Connexons from adjoing cells fuse
3 specializations of the basal surface of epithelial cells
1. Basal Lamina
2. plasma membrane enfoldings
3. hemidesmosomes
What is the structure and function of hemidesmosomes in epithelial cells
Attach the basal cell membrane to the underlying basal lamina. An attachment plaque composed of desmoplakins is presenton the cytoplasmic side of the membrane. The cytoplasmic side of the transmembrane linker proteins of the integrin family attach to the plaque while their extracellular part bind to laminin and type IV collagen of the basal lamina. Keratin tonofilaments insert into the plaques on the cytoplasmic side
What are the main differences between exocrine and endocrine glands
Exocrine glands secrete their products via ducts onto the epithelial surface from which they originated.

Endocrine glands have lost their connection to their originating epithelium and secrete their products into the blood or lymph
List and describe the four modes of exocrine secretion
1. holocrine: the entire cell disintigrates and releases its product (sebaceous gland)

2. Merocrine: exocytosis, secretory vesicle fuses with membrane and realeases content w/o loss of cytoplasm, most common (sweat, salivary, pancreas, goblet cells)

3. Apocrine: secretion is pinched off cell with some of cytoplasm n cell membrane (lipid portion of milk of mammary gland)

4. Cytocrine: whole cell is secreted (ovary and testis)

2. Merocrine
What are the three parts of connective tissue
cells, ground substance, and fibers
What is the function of connection tisue
connects all the other cells of different tissue types both mechanically and medtaboloically, provides and maintians form of body
What germ layer does connective tissue derive from
3 classes of connective tissue
embryonic, proper, special
embryonic connective tissue
mucoid connective tissue (umbilical cord)
Connective tissue proper (4 types)
Areolar - loose packing and surrounds blood vessels

Dense connective tissue - 1. dense irregular (dermis, organ, capsules, periosteum), 2. dense regular (tendons, ligaments), elastic (ligamentum nuchae of the neck and flava)

reticular tissue - lymphatic tissue, bone marrow; delicate network of reticular fibers

adipose tissue - subcutaneous n omentum
Special connective tissue (3 types)
cartlidge, bone, blood
7 Functions of onnective tissue
1. mechanical support - structural support to organs, packing material (nature's mortar), rigid structural support ( cartilidge and bone)
2. mechanical protection - bony and cusion
3. energy storage and temp regulation (fat)
4. metabolic support - regulates exchange of metabolites between blood and tissue
5. transport of material - blood and lymphatics
6. protection against infection - immune system works in CT
7. repair after injury
stroma (def.)
general term for connective tissue of an organ
Parenchyma (def.)
general term for functional part of organ
3 classes of cells of connective tissue
fixed, wandering, associated
5 types of fixed cells of connective tissue
fibrocytes, mesenchymal, reticular, adipose, brown adipocytes

responsible for the synthesis and maintenance of the extracellular maintenance
4 tyes of wandering cells
macrophages, mast cells, plasma cells. leukocytes

transient cells that migrate into connective tissue
3 types of associated cells
endothelial, smooth muscle, pericytes

cells associated with blood vessels that are always within CT
Fixed cell of the CT
Most common cell in CT proper

Appearance - vesicular nucleus w/nucleolous, can't see cytoplasm, hard to identify

Secretory cell - stuff of extracellular matrix

fibroblast is still dividing and laying down new matrix, fibroblasts do not divide and only maintain existing matrix
Mesenchymal cell
cell of embryonc CT, looks like fibroblast and has same function but only present in embryonic tissue

Reticular Cell
Found in Retucular CT
Has processes that form around reticula fibers
forms cell covered fiber framework

Secretory - matrix proteins
Adispose Cells
Found in CT
2 types - white and brown
white Morphology - large cell, signet ring, unilocular, forms in subcutaneous fascia
white fuction - lipid storage
white pathology - hypercellular obesity (increased # of adipose cells) and hypertrophic obesity (increased vol. of adipose cells)

brown morphology - small, multilocular, many mitochondria
brown function - provides heat by uncoupling oxidation process from ATP production (THERMOGENIN)
brown location - newborns: mediastinum, aorta, axilla between scapula
Lipid storage enzymes
lipoprotein lipase - breaks down lipids into free fatty acids and glycerols for storage as triglyceride

hormone sensitive lipase - breaks down triglycerides into free fatty acids for circulation
Wandering cell of CT
Primary functions are phagocytosis and antigen presentation
Lots of lysosomes and phagolysosomes
ID w/phagocytosis of vital dye
Part of mononuclear phagocyte system which develop from Granulocytic-Monocyte Stem Cell

*When a monocyte leaves the blood for the CT, it becomes a macrophage, name depends on where it is
Mast Cell
Wandering cell of CT
Morphology - very granular, hard to see nucleus
Granules - mediators of inflammatory respone in response to IgE (Paracrine secretion)
Location - along capillaries in mucosal membranes in resp, digestive, and urinary tracts
What is in the granules of Mast Cells
histamine, heparin, eosinphilic chemotaxic factor, neutrophilic chemotaxic factor, leukotrienes, cytokines
Anaphylactic Shock
Too much release of Mast cell granules causes extreme sytemic inflamation and can couse death within hours due to migration of fluid into CT which causes bp to drop and smooth muscle contraction (lungs)
Plasma Cell
Wandering cell of CT
Morphology - nucleus is located to one side (eccentric) w/ cartwheel appearance of heterochromatin, many RER (to produce IgG)

Produced from B-Cells and only found in CT under normal conditions
3 types of extracellular fiber
collagen fibers, reticular fibers, elastic fibers
Type I Collagen

Dermis, tendon, organ, capsule, bone, dentin (most common)
Type II Collagen
resists pressure

hyaline and elastic cartlidge
Type III Collagen
delicate support meshwork

lymphatic system, spleen, liver, lung, cardiovascular system
Type IV Collagen
Attachment, filtration

Basal Lamina
Collagen disease caused by lack of vittamin C which is required for hydroxylation of proline
Ehlers-Danlos, Type VII
Collagen disease due to procollagen peptidase change

hyperflexible joints, dislocations, soft skin
Ehlers-Danlos, Type IV
Due a deficiency in Type III Collagen

Aneurysms and intestinal rupture common
Elastin fibers in alveoli force air out. Emphysema is a lung disfunction caused by the breakdown of elastic fibers in the alveoli
Marfan's Syndrome
Caused by poor microfibril formation in elastic fibers. Tendency to rupture aorta and other blood vessels
3 components of ground substance and thier functions
proteoglycans - viscosity, slippery

interstitial fluid - disspersion of nutrients and waste

glycoproteins - adhesion molcules
Types of GAGs
non sulfated - hyaluronic acid

sulfated - keratan sulfate (cartilage), heparin sulfate (basement membrane), chondroitin-6-sulfate (cartilage, bone, skin), Chondroitin-4-sulfate (artilage, bone, skin), dermatin sulfate (dermis)
Protein core with sulfated glycosamines (GAGs) attached, bottle brush appearance
Pull water into ground substance
Hyaluronic Acid
non sufated, long chain, neg charged, atracks cations and pulls in water, slippery
Has gel-like consisency that resists compression
forms a physical barrier to prevent migration of bacteria
inhibits cell adhesion and facilitates cell migration
free proteoglycan
Syndecan and Fibrocan
membrane bound proteoglycans
core protein with branched sugars
adhesion molecules that bind to other molecules like heparin sulfate and collagen IV
fibronectin, lamin, tenascin, entatin, nidogen
intrstitial fluid
water, tissue fluid
metabolic support of CT
Transport between BVs and parenchyma
bound by proteoglycans and hyaluonic acid
abnormal build up of interstitial fluid in ECM
BLocked lymphated
Blocked venous return
Increased vascular permeability
liver disease
Basement Membrane
Light microscopy term
Located in ECM on basal aspect of epithelium cells
Surrounds all cells (muscle, epithelium, nerve) EXCEPT connective tissue cells
EM description of basment membrane
Lamina Lucida
Lamina Densa - Collagen Type IV
Lamina Reticularis - fine reticular fibers (Type III Collagen) that bind to Lamina Densa
Basil Lamina
EM term to describe the portion of the basement membrane containing the Lamina Lucida and Lamina Densa
Function of Basement Membrane/Basal Lamina
Physical attachment of cells to ECM via ntegrin at the cell surface, the glycoproteins fibronectin, laminin and perlecan, and intactin in the lamina lucida and Collagen IV in the lamina densa and Collagen III in the lamina reticularlis

Acts as macromolecular filter for interstitial fluid being forces ou of and back into capillaries
Why is cell motility important
Wound Repair
Junctional vs Nonjunctional adhesion
Junctional adhesions have specifin morphologically defined regions of the cell membrane

Nonjunctional Adhesions
How does a cell know where to leave a blood vessel to reach a site of infection
Extravasation - process of attaching to endothelial lining followed by migration of the cell through the capillary wall
How do cells move through the ECM
Diapedesis - process of migrating through ECM
What are the 4 steps of Extravasation
1. Activation of endothelial cells causes P-Selectine to be displayed on surface
2. Trapping: P-selectin temporarily binds to selectin receptors on leukocytes via H-bonding, causing cell to roll and slow down and bind PAF
Adhesion: Activated integrin on leukocyte binds to ICAM of endothelial cell covalently
4. Migration:cell sticks lamellapodia or pseudopodia through to basement membrane and then pulls itself through. Leuk. secretes metalloproteases which breaks apart cellular junctions to slip through
How is integrin activated and inactivated
Integrin on the leukocyte membrane undergoes a conformational change when the PAF receptor on the leukocyte binds to PAF (platelet activating factor) on the endolthelium. This allows the integrin to bind to ICAM (intracellular adhesion molecule) on the epithelial cell
What are the 2 types of Diapedesis
Slow moving: occurs inn fibroblasts and growth cones of neurons (during development)

Mast moving: occus in leukocytes and macrophages, can see cytoplasmic streaming
What are the 4 steps of diapedesis
1: Extension of lamellipodia (podosomes)
2. Adhesion: formation of focal contacts, attaches cell to substrate which gives cell a point to pull against and holds cell in places
3. Cytoplasmic flow forward, cytoskelitin shifts, cytoplasm goes from gel to sol
4. retraction with footprint, trailing edge thins, forms retraction fiber, "snaps" to leave footprint
How does cell membrane move forward during diapedesis (3 possib le mechanisms)
1. cytoskeleton elements, actin filaments, are bound to membrane by myosin I. Microfilaments grow, polymerize under influence of profilin to push membrane ahead
2. Myosin I w. plasma membrane attached to it. Microfillaments extended w.o. profilin, but still push membrane forward
3. MyosinI attaches plasma membrane to cytoskeleton and <yosinI moves forward within the membrane to shift microfilaments forward
How does cell know which direction to go during diapedesis
chemotaxtic factors (released by mast cells)
Calcium concentration gradient
S Phase
Replication of nuclear DNA
Cells contain the diploid (2n) amount of DNA before S phase and 4n after
Duplicate chromosomes consist of 2 identical sister chromatids
phaseMetabolism of RNA, regulatory proteins and enzymes necessary for mitosis to take place
DNA is analyzed for possible errors and correcte4d before mitosis
Cell has two complete diplod sets of chromosomes
Cell divides
G1 phase
Cell volume is restored to normal (2n)
Metabolism of RNA, regulatory proteins, and enzymes necessary for DNA replication
Cells can withdrq from the cell cycle into G0 and stop dividing for long periods of time or indefinetley
Experimental Systems for Cell Cyle research
biochemical analysis of animal eggs and embryos
identification of yeast cell division cycle mutants
mammalian cell fusion experiments
Mitosis Promoting Factor (MPF)
identified from analysis of xenopous eggs
required for progression from G2 into miosis
reguired for chromatin condensation, nuclear envelope breakdown, fragmentation of ER and GOlgi, reorginization of microtubules to form mitotic spindleprotein synthesis required for activity
A complex of cyclin b and M-Cdk (cyclin dependant kinase)
CYclin B
Identified in sea urchin embryos
Cyclin B cyclically increases and decreases during post fertilization period
Rise and fall just before cleavage
parallels MPF activity
Protein synthesis required for activity
Cdc 25
Promotes progress through cell cycle, activates MPF
Deficit leads to elongated cells that don't divide
Wee 1
Inhibits MPF, inhibits progression through cell cyle
Defecit leads to very small cells that divide to quickyly
S phase specific cell cyle promoting factor, diffusible
Identified by mammaliam fusion experiments
Critical for preventing re-replication
Cyclin dependent kinases (Cdks)
activity rises and falls through the cell cycle and lead to cyclic changes in the phosphorylations of intracellular proteins that initiate or regulate the mahor events of the cell cycle
bind to Cdks to cyclically regulate their activity. Cdks are dependent on cyclins for their activity . Cyclin levels undergo a cycle of synthesis and degrdation with each cell cycle
How are cyclins regulated through the cell cycle
Proteolysis - Ubiquitin dependent

List and describe the stages of the cell cycle
1. Interphase
a. G1: Cell vol. is restored to normal (2n), cell prepares for DNA replication, cells can enter G0 from here and stop dividing
b. S Phase: Replication of nuclear DNA (4n)
c. G2 phase: cell gets ready for mitosis, dna is analyzed for possible errors and corrected, cell is 4n
2. Mitosis
List and describe the stages of mitosis
Prophase: chromosomes condense and spindle apparatus forms
Prometaphase: nuclear envelope disappears
Metaphase: chromosomes line up on the metaphase plate
Anaphase: The chromosomes split and begin to move to the poles
Telophase: Cytokenesis occurs, the chromosomes uncoil and the nuclear envelope reforms
How and why are Xenopus eggs used to study the cell cycle
Why: The eggs are the size of BBs and the embryos are relatively large. After being laid by the female they are "dormant" waiting to be fertilized. After fertilization they undergo rapid synchronous cell division. This dormant period and fertilization period can be tightly controlled and manipulated in the lab.

How: Substances can be injected into the egg to determine their effect on the cell cycle. Or, cell extracts can be prepared from the egg to create a cell-free experiment in the test-tube
What are two types of yeast and how are they used to study the cell cycle
Saccharomyces cervevisiae - budding yeast
Schizosaccaromyces pombe - fission yeast
Conditional mutants in the cell cycle are identified, i.e. temperature sensitive mutants - gene product is active aat he permissive temperature and inactive at the restrictive temperature. Cells can be grown at the permissive temperature and then switched to the restrictive temperature to look at the effects of loss of that particular gene product.

Cell division cycle (cdc) mutants will be halted at a specific stage of the cell cycle at the restrictive temperature
How are mammaliam cell fusion experiments used to study the cell cycle
Cells at different stages of the cell cycle can be fused to look at the resulting effects on the cell cycle. For exampleWhen an S-phase cell and a G1-phase or G2 are fused, the s-phase nucleas will drive the G1 nucleus into s-phase, but not the G2. This indicates that there is a block to re-replication
Mitosis Promoting Factor (MPF)
A factor that initiates mitosis
Required for: chromatin condensation, nuclear envelope breakdown, fragmentation of the ER and Golgi, Reorganization fo microtubules to form the mitotic spindle
A complex consisting of cyclin B and M-Cdk (cyclin dependant kinase)
Levels rise and then fall just before division
Regulated by Wee1 Kinase (-) and CD25 Phophatas (+)
How do Cyclin dependent kinases (cdks) function in the cell cycle
activity rises and fall through the cell cycle
leads to cyclic changes in the phosphorylation of intracellular proteins that intitiate or regulate the major events of the cell cycle.
Depemdent on cyclins for their activity.
Associate successively with different cyclins to trigger different events in the cell cycle
How do cyclins function in the cell cycle
bind to Cdks to cyclically regulate their activity.
Required for Cdk activity
Undergo a cycle of synthesis and degredation with each cell cycle.
What are the 4 classes of cyclins
G1/S cyclins - bind Cdks at the end of G1 and commit the cell to DNA replication
S cyclins - bind cdks during s phase and are required for the initiation of DNA replication
M cyclins - promote the events of mitosis
G1 cyclins - help promote passage through start or the restriction point in late G1
How is Cdk activity suppressed
1. phosphorylation in the active site of Cdk inhibits cyclin-Cdk activity; Wee1 phosphorylates, Cdc25 dephosphorylates

2. Cdk inhibitor proteins (CdkIs) bind to the cyclin-Cdk complex and change the conformation of the active site rendering it inactive
How are cyclin levels controlled
1. Proteolysis via a ubiquitin dependent system
a. SCF ubiquinates G1/S cyclins and some CKIs to control S phase initiation
b. APC (anaphase-promoting complex) ubiquinates M Cyclins and other regulators of mitosis

2. transcription