Exam 3 Flashcards
Microfilaments (actins)
• support/organize plasma membrane
• Cell shape and division and motility
Microtubules (tubulins)
• organize cytoplasm
• Intracellular transport
• Cell division
• Cilia/flagellae motility
Intermediate filaments (IF proteins)
• strengthen cytoplasm/tissues
• Support nucleus
• Epidermal appendages (hair/nails)
Actin
• medium sized globular proteins (45kDa)
• Six actin gene, including muscle (alpha-actin) and non-muscle (beta and gamma-actin) subtypes
Tubulin
• medium sized globular protein (55kDa)
• Two dozen tubulin genes, alpha, beta, and gamma subunits
• expressed in all cells especially neurons
• binds and hydrolyzes GTP—>GDP
• interacts with motor proteins 
Basic building subunits of microtubules
Heterodimers of Alpha-beta tubulin
Intermediate filament proteins
• 50-200kDa
• 70 gene products categorized into six sub-families
• present in tissue specific manner
Monomers of intermediate filament proteins
Long, linear molecules that assemble during polymerization like threads forming a rope
Tubulin polymers
Tubules formed from Proto filaments that display chemically different ends (polar) 
Types of actins
Muscle— skeletal, cardiac, smooth
Cytoplasmic —beta and gamma cytoplasmic
Types of tubulins
• alpha tubulin, 8 genes
• Beta tubulin, 10 genes
• Gamma tubulin, 2 genes
IF proteins subfamilies
- Acidic keratins
- Neutral/basic keratins
- Vimentin, desmin, GFAP
- Neurofilament IF proteins
- Lamins
- Lens-specific beaded IFs
polarized polymers are formed by:
Actin and tubulin
- subunits are easily added to the plus end, and removed from the minus end 
Actin and tubulin as nucleotide-binding proteins
ATP/GTP and ADP/GDP respectively
ATP and GTP binding stabilize the polymers, and ADP and GDP destabilize the polymers
Dynamic instability
The rapid cycling between microtubule polymerization and depolymerization that occurs continuously in cells 
Actin polymerization is initiated by:
1.) Formin (parallel bundles)
2.) Arp complexes (branching networks)
Tubulin polymerization is nucleated by:
1.) Ring complexes containing gamma tubulin (TURCs)
2.) Alpha and beta tubulin bind to form a heterodimer
3.) Alpha subunit bind to TURC’s beginning the formation of a microtubule (at - end)
4.) TURCs in centrosome
Major phosphorylation sites in an intermediate filament protein (lamin)
PSer-22
PSer-392
PSer-628
IF proteins regulated by:
Phosphorylation —> Depolymerization
Dephosphorylation —> Polymerization
Taxol (paclitaxel)
A clinically useful drug that works by stabilizing microtubules, thereby interfering with mitotic spindle function in dividing cells. Used to treat some types of cancers
Where is actin cytoskeleton?
Localized near plasma membrane, including forming specialized arrays at cell—cell and cell—ECM junctions
Functions of microfilaments
• support an organization
• cell—cell adhesions at adheren junctions 
• cell—ECM adhesion at focal contacts
• regulate gene expression
Actin and myosin interaction
Muscle of the cell
• Controls cell shape
• Drives cytokinesis during cell division
• Drives cell motility
Proteins that link microfilaments to the plasma membrane
1.) talin
2.) catenins
3.) dystrophin
4.) ERM proteins
Myosin
Motor proteins associated with Actin cytoskeleton
Type II myosin
Conventional, they can form bipolar filaments through ability of their long tails to wrap around each other and an anti-parallel orientation
This allows them to pull microfilaments past each other (contraction)
Other types “ unconventional” myosin
Act as monomers or dimers. Do not form bipolar fibers, but bind to different types of cargoes in the cytoplasm
Participate in vesicular trafficking, and interact with Rab small GTPases
Steps of myosin activation
1.) ATP hydrolysis, conformational changes
2.) binding of ATP releases a myosin head from a microfilament
3.) Hydrolysis to ADP plus Pi “cocks” the head, which reattaches to microfilament
4.) Pi released, confirmational change that pulls the microfilament—tightly bound 
Myosin in the absence of ATP
Heads cannot be displaced from tightly binding actin, resulting in rigor mortis 
 Rho family of G-proteins
Promotes stress fiber formation (parallel) 
Rac family of G-Proteins
Promotes lamellipodia formation (peripheral MF network stabilized with filamin)
Cdc42
Promotes filopodia formation (parallel microfilament bundles stabilized with cross-linking proteins that support fingerlike cell extensions)
Focal adhesion
Contains integrins, microfilaments, linking proteins, focal adhesion kinases
Play Central roles in adhesion and cell motility. Communicate status of attachment to ECM
Microvilli
• Increase the absorptive area of the plasma membrane
• are supported by a core bundle of actin microfilaments, but are non-motile
• Prominent in intestinal epithelial
Adherens junctions
1.) Cadherins: IMPs that adhere to each other in the presence of Ca2+
2.) linking (anchor) proteins: alpha and beta-catenins.  Can travel into the nucleus, and function as transcriptional regulators
Sub-plasma membrane-associated microfilaments
• physically support the plasma membrane
• Interact with IMP’s and linking proteins
Actin and muscular dystrophy
Distroglycan complex: IMPs
Dystrophin: linking protein
ECM: laminin and collagen
^^ Mutations in these proteins (esp. dystrophin) weakens the muscle cell membrane leading to cell death
Centrosome 
- the microtubule organizing center (MTOC)
- Nucleates and organizes microtubules - Located near nucleus and Golgi apparatus
• composed of a pair of centrioles
Pericentriolar materials (PCM)
Amorphous material surrounding centrioles. Contains TURC‘s which nucleate microtubule polymerization
Three forms of centrosomes
1.) MTOCs
2.) Basal Bodies
3.) Spindle Poles
Centrosome: Basal bodies
Specialized centrioles that arise through repeated duplication of centrosome centrioles
Migrate to apical (top) region of a cell and nucleate microtubules extension that form cilia and flagellae
Centrosome: spindle poles
Duplicated centrosomes that nucleate the spindle apparatus in dividing cells
Primary Cilium
One per cell, non-motile, 9+0 axoneme, Sensory and signaling functions, formed when cells stop dividing, important in early development
Polycystic kidney disease and obesity causes:
Deficits associated with primary cilium
Microtubule structural proteins
• MAP1,2,4
• Tau
• Plectin
Microtubule motor proteins
• Dyneins
• Kinesins 
Alzheimer’s disease and TAU
TAU hyper phosphorylation is linked to its condensation into neurofibrillary tangles— Aggregates are toxic to brain cells
Dyneins
Move cargo towards the (-) end of MTs
Drives ciliary and flagellar motility
Kinesins
Move cargo toward the (+) end of MTs
Kartagener’s Syndrome (ciliary dyskinesia)
Cilia and flagellae are immotile due to mutations in dynein 
Blistering diseases originate due to:
1.) Auto antibodies produced against normal desmosomal and hemidesmosomal proteins
2.) mutations in IF proteins or other hemi/desmosomes
Pemphigus (bullous pemphigus)
Affects outer layers of skin, auto antibodies to Desmosomal desmogleins 
Blisters are easily ruptured
Pemphigoid (bullous pemphigus)
Effects lower layers of skin (junction of epi-dermis and dermis)
Autoantibodies produced against: ColXVII, BPAG2/BP180, and dystonin (BPAG1/BP230)
Stiff blisters that do not break open easily
Epidermolysis bullosa Simplex
EBS — caused from loss of function mutations in keratin
Nuclear lamina functions
• Physical support for the nuclear envelope
• interconnects nucleus with cytoskeleton and ECM
• organize chromatin
• cell differentiation
• cell cycle and apoptosis
• gene expression
Progeria
Disease of accelerated aging Caused by perturbations in lamin farensylation 
Penicillin and penicillin related compounds
Contain thiazolidine ring, beta-lactam ring, And a variable side chain that dictates it’s microbicidal activity
How penicillin works:
Beta lactam ring Affects penicillin binding proteins by blocking transpeptidation
Naturally derived penicillins
Penicillin G
penicillin V
Penicillinase-sensitive penicillins
Amoxicillin, ampicillin
Penicillinase-resistant penicillins
Dicloxacillin, nafcillin, oxacillin
Do NOT need to pair with beta lactamase inhibitors
Antipseudomonal penicillins
Piperacillin, Ticarcillin
High resistance to drugs
Beta lactamase inhibitors
- Clavulnic acid
- Sublactam
- Tazobactam
They bind to and inactivate the beta lactamases to protect the penicillin drugs
Cephalosporin drugs
Contain beta-lactam ring, broad-spectrum and resistant to Penicillinases, Commonly given via IV, fewer allergic reactions
First generation cephalosporin drugs
• Good against gram positive cocci and a few Gram negative
- cefazolin
- Cephalexin
Second generation cephalosporin drugs
More broad spectrum than first generation, can target more Gram negative bacteria
- Cefaclor
- Cefoxitin
- Cefuroxime
Third generation cephalosporin drugs
Broad spectrum with especially well developed activity against enteric bacteria that produce beta lactamases
- Cefotaxime
- Ceftadime
-  Ceftriaxone— Crosses BBB
Fourth generation cephalosporin drugs
Broad-spectrum for both gram-positive and gram-negative with increased activity against pseudomonas and gram-positive organisms
- Cefapime
Fifth generation cephalosporin drugs
Broad gram positive and gram-negative coverage including MRSA but not pseudomonas
- Ceftaroline
Carbapenems
Have beta lactam ring, used in the hospital setting when other antibiotics aren’t working (side effects: G.I. distress, skin rash, CNS toxicity)
- Doripenem
- Ertapenem
- Imipenem
- Meropenem 
 Cilastatin + imipenem why?
To block renal hydropeptidase in order to decrease the inactivation of the drug in the renal tubules
Non-beta-lactam cell wall targeting drugs
Bacitracin (streptococci/staphylococci), isoniazid (Mycobacterium TB), Vancomycin (Staphylococcal infection), fosfomycin (phosphoric acid agent)
Bacitracin
Narrow spectrum antibiotic produced by a strain of the bacterium bacillus subtilis
Combats superficial skin infection by streptococci and staphylococci
isoniazid
Bacteriocidal to mycobacterium TB, But only against growing cells
Vancomycin
Narrow spectrum antibiotic most effective in treating staphylococcal infections in case of penicillin resistance or allergy
Fosfomycin
Phosphoric acid agent effective as alternate treatment for urinary tract infections caused by enteric bacteria
Oxazolidinones (Linezolid)
• 50S subunit inhibitor
• Bacteriocidal/bacteriostatic
• Inhibits protein synthesis by binding to the 50S subunit, preventing the formation of initiation complex
Oxazolidinones are used against:
Gram-positive bacteria including MRSA and VRE (Vancomycin resistant enterococci) 
Side effects of Oxazolidinones 
Bone marrow suppression (thrombocytopenia), peripheral neuropathy, and serotonin syndrome
Resistance to Oxazolidinones
Resistance via a point mutation in the ribosomal RNA
Aminoglycoside drugs
• 30 S subunit inhibitors
• Bacteriocidal
• Irreversible inhibition of the initiation complex through binding of the 30S subunit. Can cause misreading of the mRNA
• Requires oxygen for optic. Drugs ineffective against anaerobes

Types of aminoglycoside drugs
- Amikacin
- Gentamicin
- Neomycin
- Streptomycin
- Tobramycin
Side effects of the aminoglycoside drugs
Nephrotoxicity, neuromuscular blockade, ototoxicity, teratogen (pregnant women) 
Resistance of aminoglycoside drugs
Resistance via bacterial transferase enzymes that inactivate the drug by acetylation, phosphorylation, or adenylation 
Aminoglycoside drugs used against
• severe gram-negative rod infections
• Synergistic with beta lactamases
Tetracycline drugs
• 30 S Subunit inhibitors
• bacteriostatic

• binds to the 30 S subunit and prevents the attachment of aminoacyl tRNA in the A site
Types of tetracycline drugs
- Doxycycline
- Minocycline
- Tetracycline
Side effects of tetracycline drugs 
G.I. distress, discoloration of teeth and inhibition of bone growth in children, photo sensitivity, NOT used during pregnancy
Resistance of tetracycline drugs
Resistance via decreased uptake or increased efflux out of the bacterial cells by plasmid-encoded transport pumps
Macrolide drugs 
• 50S subunit inhibitors
• bacteriostatic
• inhibit protein synthesis by blocking translocation, bind to the 23S rRNA of the 50S ribosomal unit : bind to E site
Tetracycline drugs used against
Borrelia burgdorferi, mycoplasma pneumoniae, Rickettsia, and chlamydia
Macrolide drugs used against
Atypical pneumonia’s, sexually transmitted infections, gram-positive cocci, and Bordetella pertussis 
Side effects of macrolides 
G.I. motility issues, arrhythmia caused by prolonged QT interval, acute cholestatic hepatitis, rash, eosinophilia, theophylline serum increase, Inhibition of cytochrome P450
Types of macrolides
- Azithromycin
- Clarithromycin
- Erythromycin
Chloramphenicol
• 50 S subunit inhibitor
• Blocks P site, blocks peptidyl transferase
• Bacteriostatic
Chloraphenicol used against:
Meningitis, and rocky mountain spotted fever
Has limited use due to toxicities, continued use in developing countries because of low cost
Chloraphenicol side effects
Anemia, aplastic anemia, grey baby syndrome
Chloramphenicol resistance
Resistance via plasmid-encoded acetyltransferase that inactivates the drug
Clindamycin
• 50 S subunit inhibitor
• Bacteriostatic
• Blocks peptide transfer and translocation at the 50 S ribosomal unit
Clindamycin used against: 
Anaerobic infections, aspiration pneumonia, lung abscesses, and oral infections
Group A strep infections
Clindamycin side effects
C. Diff, Fever, diarrhea
Clindamycin VS metronidazole
Clindamycin treats infections above the diaphragm, well metronidazole treats anaerobic infections below the diaphragm
Dalfopristin/quinupristin
Mechanism:
Combined action is bactericidal for some organisms. Binds 50 S to inhibit translocation
Spectrum:
Reserved for infections caused by multiple drug resistant gram-positive bacteria. Not a first line of treatment
Resistance of  Dalfopristin/quinupristin
• Ribosomal methylation prevents binding of drug to its target.
• Enzymes inactivate the drugs.
• Efflux proteins that pump them out of the cell.
Macrolides/ clindamycin relation to dalfopristin/quinupristin
Cross resistance. Resistance to one of these drugs is equal to resistance to all of these drugs
Side effects of  Dalfopristin/quinupristin
High incidence of althralgias, Inhibits CYP3A4 and is likely to have significant drug interactions
Drugs you not use with newborns
Chloramphenicol
Drugs you do not use in children
Tetracyclines
Drugs you do not use during pregnancy
Tetracycline, aminoglycosides, clarithromycin, chloramphenicol, etc.
Adjust drug based off of elderly renal function
Beta lactams, aminoglycosides
Half-life of these drugs will be increased, retention of drugs increases
Seizures caused by:
Beta lactams, mostly carbapenems
Hepatotoxicity Caused by:
Rifampin
Nephrotoxicity via:
Impenems, Aminoglycosides, vancomycin
 Ototoxicity caused by:
Aminoglycosides, vancomycin
Anemia caused by:
Chloraphenicol
Arthralgia caused by:
Dalfopristin/quinupristin
Superinfection caused by:
Clindamycin, third generation cephalosporin, ampicillin
Causes disulfiram reaction when taken with alcohol:
Second generation cephalosporin with methylthiotetrazole groups
Aminoglycoside + penicillin synergy
Penicillin increases permeability of cell membranes increasing the ability of amino glycosides to enter the cell
Vancomycin + aminoglycoside combination drug
Each alone have some nephrotoxicity. If given together you get marked renal impairment
Penicillin + tetracycline
79% mortality for pneumococcal meningitis
Folic acid synthesis and reduction inhibitors
- Sulfadiazine
- Sulfamethoxazole
- Sulfisoxazole
- Trimethoprim
Cause sensitivities in bacteria that need to synthesize their own dihydrofolic acid
Sulfonamides
• bacterial static
• Competitive inhibitors if dihydropternoate synthase resulting in a disruption of folic acid synthesis
• Inhibits bacterial growth by decreasing nucleotides
Sulfonamide resistance
Comes from altered enzyme, decreased uptake, or increased PABA synthesis
Sulfonamide side effects:
Nausea, vomiting, diarrhea, rash, fever, headache, depression, jaundice, hepatic necrosis, drug induced lupus, and serum sickness-like syndrome
Sulfonamides and G6PD
Sulfonamides can cause a deficiency in G6PD, leading to acute hemolytic anemia
Sulfonamide competition with bilirubin
Competitive inhibitor for bilirubin binding sites on plasma albumin, may increase fetal blood levels of unconjugated bilirubin —kernicterus 
Sulfonamides and warfarin
Sulfonamides displays albumin binding sites for warfarin, increasing the effective activity of the displaced drug
Anticoagulant dosage should be reduced during sulfonamide therapy
Major uses for sulfonamides:
• CNS and ocular toxoplasmosis
• Infection by nocardia bacteria
• Malaria
• UTIs
• Otitis media
Trimethoprim
• bacteriostatic
• Inhibits bacterial dihydrofolic reductase (downstream)
• inhibits purine and DNA synthesis
Major uses for trimethoprim
Primary use is for the prevention of recurrent, uncomplicated urinary tract infections
TMP + SMX
Trimethoprim + sulfamethoxazole 
Bacteriocidal = static + static
• High degree of synergistic activity by inhibiting same pathway
Types of Quinolones
- Ciprofloxacin
- Enoxacin
- Gemifloxacin
- Levofloxacin
- Moxifloxacin
- Nalidixic acid
- Norfloxacin
- Ofloxacin 
Quinolone drugs
• Bacteriocidal
• Inhibit the enzymatic activity of topoisomerase class enzymes: DNA gyrase and topoisomerase IV
• Promote the cleavage of DNA in these enzyme DNA complexes
• Cannot be taken with antiacids
Quinolones are used against:
Aerobic gram-negative bacilli, Particularly members of the family enterobacteriaceae 
What drug is strong enough to use against pseudomonas (P. Aeruginosa)?
Levofloxacin 
Side effects of quinolones
G.I. side effects, confusion, CDF, yeast infection, cartilage damage, arthropathy
tendinitis in those older than 60 also taking prednisone
Metronidazole
• Bacteriocidal
• Inert, activity is determined by the capacity of susceptible organisms to activate the drugs once it enters the cell via passive diffusion
Metronidazole used against:
Anaerobic infections, bacterial septicemia, CNS infections, bacterial vaginosis, acne rosacea
Disulfuram reaction with alcohol + metronidazole 
Disulfiram ethanol reaction due to increased serum acetyl-aldehyde
Metronidazole blocks aldehyde dehydrogenase, inhibiting the oxidation of acetylaldehyde
^^^ hangover feeling results
Rifampin
• Bacteriocidal
• Find bacterial RNA polymerase at the active Center, blocking the elongation of mRNA
Rifampin used against:
Active TB, asymptomatic carriers of Neisseria meningitidis 
Side effects of rifampin
Induction of cytochrome P450, leading to organ rejection, loss of seizure control, and risk of pregnancy if on birth control
Mitochondria DNA is hypermutable
• not bound to histones in a chromatin structure
• Exposed to higher concentrations of ROS
• Balanced by copy number genes, heteroplasmy
MtDNA copy number can be affected by:
Metabolic state, hormones, and drugs
TCA cycle functions:
• oxidized two carbons from acetate to CO2
• Make NADH, FAD2H, and GTP
PDH and the TCA cycle occur in:
The mitochondria
Glycolysis occurs in:
Cytosol
Inherited point mutations in MPC1 can cause:
Lactic acidosis and hyper pyruvatemia (pyruvate—> lactate dehydrogenase)
Four subunits of PDH
E1: pyruvate decarboxylase, TPP
E2: Transacetylase, Lipoate and CoA
E3: dihydrolipoyl dehydrogenase, FAD,
NAH+
X:
PDH Kinases 
Inhibits: pyruvate, ADP
Activates: Hypoxia, acetyl-CoA, and ADH, ATP
PDH phosphatase
Activated by calcium
PDH regulation
Phosphorylation and dephosphorylation of serine residues on E1 alpha subunits
Key regulator of the TCA cycle
Isocitrate dehydrogenase is the key rate limiting enzyme in the TCA cycle
Positive deltaG reactions in the TCA cycle
 citrate—aconitase—> isocitrate
Malate—malate dehydrogenase—> oxaloacetate 
Build up of citrate leads to what other metabolism?
Fatty acid, cholesterol synthesis
Buildup of Malate leads to what other metabolism?
Gluconeogenesis
Citrate synthase
Hydrolyzes the thiolester bond of acetyl Coa to join acetate and oxaloacetate forming citrate
Tricarboxylic acid
Aconitase 
Catalyze is a two step isomerization to convert citrate to isocitrate producing Intermediate aconitate 
Isocitrate dehydrogenase (IDH3)
Catalyzes oxidative decarboxylation for TCA cycle, producing CO2.
IDH1 in the cytosol and IDH2 in the mitochondria catalyze the same reaction but use NADP+/NADPH