PDF's Flashcards
Cytogenetic analysis of cells from retinoblastomas showed that the region around
chromosome _____ often had an abnormal structure
13q14
The Rb protein is ______ in rapidly proliferating cells at S or
G2 of the cell cycle, but is _________ in non-proliferating cells in G0 of G1 of the cell
cycle.
b
hyperphosphorylated
hypophosphorylated
The hypophosyphorylated form of the RB protein functions to ____
repress cells into the S phase
RB protein is an oncogene or tumor suppressor?
TS
What phosphorylates the RB protein?
CDKs
The RB protein is a target for many animal tumor viruses such as
SV40 and HPV
viruses drive a quiescent cell into the S phase
of the cell cycle and to proliferate by producing a viral protein(s), SV40 T antigen (T stands for
transforming) or HPV E7 protein, that binds to and inactivate the RB protein.
The ____ gene is a tumor surpessor in Familial Adenomatous Polyposis (FAP)
APC
Incidence of FAP
1/10,000
The APC gene is on chromosome ___
5q
The APC gene encodes a cytoplasmic protein that regulates the localization of ____-
beta catenin
beta catenin is kept at the plasma membrane by being bound to ___ in normal cells
E-cadherin
When the APC is lost in FAP patients, ________________.
Beta-catenin goes to the
nucleus to produce transcription of oncogenes like c-myc
ICF and ECF: Na+
ICF: 14 mM
ECF: 140 mM
ICF and ECF: K+
ICF: 145 mM
ECF: 5 mM
ICF and ECF: Cl-
ICF: 5 mM
ECF: 145 mM
ICF and ECF: A-n
ICF: 126
ECF: 0
ICF and ECF: H20
ICF and ECF: 55,000 mM
Osmolarity
the total concentration of solute particles: for example, a 1 M solution of CaCl2 gives a 3 osM solution (3 solute particles/molecule dissolved).
Nernst equation
E=-60/(valence elections)*log([ ]o/[ ]i)
Driving force of an ion
difference between Vm and Eion
3 SNARE proteins
VAMPs
Syntaxin
SNAP25
Structure of VAMPs
transmembrane domain at one end with a helical domain in it
Structure of Syntaxin
transmembrane domain with helical domain
Structure of SNAP25
No TM domain, two helical domain, fatty acid binding region that acts like a membrane binding domain
All vesicles contain _____, while all target membranes contain _______ and ______.
VAMPs
Syntaxin and SNAP25
Enzyme that regulates dissociation of SNARE proteins
NSF protein (hexamer that uses 6 ATP to for a barrel and twist)
Refolding of syntaxin is mediated by ____
Sec1
Main primary active transporters
NA/K
CA++
H+
Two basic types of secondary active transporters
Cotransporters- same direction
Antiport or exchange- opposite direction
Examples of cancers inherited in autosomal dominant fashion
Familial adenomatous polyposis
familial retinoblastoma
Familial breast and ovarian cancer
Wilms tumor syndromes
Examples of cancers inherited in autosomal recessive fashion
xeroderma pigmentosa
ataxia-telangiectasia
bloom’s syndrome
Fanconi’s anemia
Function of HPV E7 protein
bind and inactivate the RB protein
Sporadic cases of retinoblastoma are usually ______
unilateral
unlikely to occur in both retinas
BRCA2 is allelic with _____
the Fanconi’s anemia D1 gene, FANCD1
“Hotspots” in p53 mutations
Certain p53 point mutations are found more frequently than others in human cancers. These mutations are called “hotspots
Viruses that inactivate p53 (and also Rb)
Adenovirus E1B
HPV E6
The retroviral RNA genome consists of ______
two identical strands held together by a tRNA molecule
In a retrovirus: gag encodes for \_\_\_ env for \_\_\_\_ pol for \_\_\_\_\_ v-onc
internal virion proteins
virus membrane glycoproteins
virus polymerase
v-onc gives ability ro rapidly proliferate and form tumors
4 examples of v-onc’s
v-src: rous sarcoma virus
v-erb: avian erythroblastosis virus
v-abl: Abelson leukemia virus
v-myc: usually fused to gag gene, neoplastic transformation of cells
The products of oncogenes typically mimic
hormones or growth stimulating factor
The proto-onc or c-onc genes are involved in _______. What type of changes are responsible for these effects?
The proto-onc or c-onc genes are involved in spontaneous malignancies that have nothing to do with a retrovirus.
Either quantitative changes (too much protein) or qualitative changes (overactive or unregulated protein) in the proto-oncogene are responsible for these effects.
Difference between c-src and v-src
c-src has a different carboxy-terminal amino acid sequence that v-src and has numerous introns that do not exist in v-src
Difference between c-myc and v-myc
c-myc also has many introns not present in v-myc, although the coding sequences are nearly identical (7 amino acid changes
Human bladder cancer mutation
c-ras
Oncogene found in neuroblastomas
N-myc
Oncogene that codes for an integral membrane protein kinase that is amplified in about 20% of breast cancers
erbBw or HER2/neu
monoclonal antibodies specific for the protein product of the HER2/neu/erbB2 oncogene
Herceptin
Why do drugs that inhibit “normal” cellular proteins (c-myc, c-abl, etc.) kill only the cancer cells?
cancer cells but not normal cells have become dependent or “addicted” to the overexpressed oncogene. This referred to as “oncogene addiction
Diagnostic criteria for LFS (3)
- A probandwith a sarcoma diagnosed before 45 years of age AND
- A first-degree relative with any cancer under 45 years of age AND
- A first-or second-degree relative with any cancer under 45 years of age or a sarcoma at any age
How do you test for LFS?
Direct sequencing of p53 (either only hotspots or entire gene)
The major causes of death in patients with VHL are_______ and________
Metastatic RCC
CNS hemangioblastomas
Von Hippel-Lindau disease is classified based on presence or absence of _________ and type of ___________.
Pheochromocytoma (adrenal gland tumor)
VHL mutation
Type 1 VHL disease is due to ____
total or partial loss of VHL
Type II VHL disease is due to
VHL missense mutation
VHL chromosomal location
short arm of chromosome 3
Actions of VHL protein
Regulation of HIF
suppression of aneuploidy
maintenance of primary cilia
stabilization of macrotubules
HIF-alpha is hydroxylated by
proline and asparagine hydroxlase
Hydroxylated HIF-alpha is___
ubiquinated by WT VHL and undergoes proteosomal degredation
When VHL is mutated HIF ____ and activates ____ (4)
accumulates
VEGF, PDGF, TGF alpha and Beta
3 classes of lipids in a membrane
phospholipids
sphingolipids
cholesterol
Two important properties of channels
- most are selective
2. some channels contain molecular gates
The “patch clamp” technique is used to _____
see individual ion channels at work
molecules can cross membranes through _____ or ______
channels or transporters
3 mechanisms to solve problem of volume contro (due to movement of water)
- make cell impermeable to water
- build a strong wall around cell
- balance the osmotic force osmotically
What does the Van’t Hoff equation tell you?
quantitative relationship between osmotic suction and the pressure one has to exert in order to balance it
Solution that makes a cell shrink
hypertonic
Solution that makes a cell swell
hypotonic
Time course of volume change when immersed in 600 mosM glycerol (+) with 300 Anion in cell
Cell will initially shrink but will later fill with water and burst
What does the Nernst equation tell you?
Equilibrium potential
What does the membrane potential depend on?
Relative permeability
What is the driving force of a cell?
the difference between Vm and Eion
Causes of hyperkalemia
Injuries that disrpt cell membranes
attack of red blood cells
Diagnosis of hyperkalemia
EKG to detect arrhythmias
Treatment of acute hyperkalemia
C BIG K
Calcium, Bicarbonate, Insulin + Glucose, Kayexalate
What does Kayexalate do?
Ion exchanger- gives up sodium for potassium ions
In regards to Inflammatory Bowel disease, smokers are at increased risk for ______
Crohn’s disease
In regards to IBD, former smokers and nonsmokers are at increased risk for_____
ulcerative colitis
Fistulas are ____ in Crohns but ____ in UC
common
rare
Inflammation is _____ in Crohn’s and _____ in UC
transmural
mucosal
Pattern in Crohn’s vs. UC
discontinuous vs continuous
Hematochezia (blood in stool) is ____ in Crohn’s but ____ in UC
rare
common
Location of Crohn’s vs. UC
Ileum vs Rectum
Mechanism of insulin release
: glucose enters the cell through the GLUT2 transporter, undergoes glycolysis, leading to an increase in the intracellular ATP to ADP ratio. This change closes the ATP-sensitive potassium channel, preventing outward leak of potassium ions. The resultant buildup of intracellular potassium (because there are other sodium/potassium channels actively antiporting against the gradient) depolarizes the membrane, activating a voltage-gated calcium channel and leading to calcium influx. The increased intracellular calcium ion concentration leads to exocytosis of preformed insulin-containing secretory granules
Half life of insulin
5 minutes
Two cardinal sins of DKA management
Prematurely stopping insulin infusion
Failing to use enough dextrose
How does dehydration occur in DKA?
Excess glucose in filtrate-> kidney cannot absorb as much water
Mechanism of potassium depletion in DKA
aldosterone released in response to dehydration-> sodium is retained at the expense of potassium ions
Despite the fact that a DKA patient may present with hyperkalemia, they will have _____.
low potassium levels in cells and have greater potassium needs
Cerebral edema in DKA clinical manifestations
mental status changes; headache; Cushing’s triad (hypertension, bradycardia, irregular respirations); or fixed, dilated pupils
Treatment of cerebral edema in DKA
elevate head of bed
hyperventilating the patient
giving IV mannitol (not metabolized) or hyertonic saline
Glucose transporter
Example of facilitated diffusion
transport glucose in either direction while burning no energy
Once in the cell, glucose in phosphorylated to G-6-P
What pump is responsible for moving calcium out of the cell
Na/Ca pump
Digitalis
extract that can help the heart beat stronger by blocking the Na/K pump and indirectly inhibitinf the Na/Ca exchanger
Na/H exchange carrier
secondary active transport system, in which the inward leak of Na+ drives the outward pumping of H+.
What pump bring chloride ions to the ICF?
Na/K/2Cl
While certain studies suggest the existence of a _____ pump, it likely does not exist.
H/K
Voltage gated channels of the KV, NaV and CaV families have______ membrane-spanning domains, each of which contains _________
4
6 alpha helices (S1 through S6)
_____ helices have ______ at every ______ position that sense voltage
S4
positively charged residues (lys or arg)
third position
The “P loop” between ____ and ____ helices forms the _____
S5 and S6
ion conducting pathway
Neurotransmitter receptors directly coupled to ion channels
Ionotropic
Examples of an ionotropic receptors (2)
pentameric ligand gated channels
Ionotropic glutamate receptor
Pantameric ligand gated channels are _____ and contain _____. _____ is the alpha helix that assembles around the central ion conducting pathway.
heteropentameric
4 transmembrane alpha helices (M1-M4)
M2
Ionotropic glutamate receptors are ____
tetrameric ligand gated channels
NMDA receptors
NMDA receptors bind:
two of the four subunits bind glutamate and the other two bind glycine.
Chloride channels (CLC family)
dimer- each su has an ion permeation pathways
Aquaporin water channel
tetramer w 4 water pores and a central pore
Rank selectivity between the following channels: Na, K, Ca, nicotinic AChR
K > Na > Ca > nicotinic
In regards to epithelial cells, the Na/K pump is ALWAYS located on the _____ membrane and is the driving force for nearly all transport
basolateral
The apical membrane is ______ to sodium
highly permeable
TransPD = Vm (_____) – Vm (______)
basolateral
apical
The key to understanding epithelial secretion in general and the main defect in those diseases is a _______ channel in the ________ membrane. in a resting cell this channel is _____
chloride
apical
closed
What activates the Cl channel on the apical membrane of epithelia?
in GI tract- digestion
Pathogens (cholera)
Most important chloride channel on the apical membrane of epithelia
Cystic fibrosis transmembrane conductance regulator (CFTR)
Most important function of the kidney
get rid of non-volatile wastes
How does the kidney get rid of extra water?
hypothalamus stops secreting vasopressin-> removes aquaporins from apical membranes
What determines the threshold voltage in an action potential?
The point at which sodium and potassium CURRENTS are exactly equal and opposite
What is gained by having voltage-gated potassium channels?
Faster repolarization
Two types of refractory periods
Absolute
Relative
What is accommodation mean in regards to action potentials?
If an axon is depolarized slowly, it may fail to generate an action potential, even if depolarized beyond what had been threshold for a rapid depolarization. In other words, the axon accommodates to the slow, steady stimulus
What is the safety factor in regards to action potentials and why is it important?
axons have more than enough Na channels to do the job; their safety factor of transmission is 5-10 times the minimum required for successful propagation.
Important for: branching of axons, speed of transmission
small diameter fibers have ____ threshold to external stimulation, conduct action potentials at ____ velocities, and have ____ safety factor for conduction.
High
lower velocities
low
Pain fibers have ____ diameters
small
Strongly associate allele in MS
HLA-DRB1
Virus and MS
EBV- infection late in life is bad
Drug that improves walking in MS patients
Dalfampridine
The typs of Nups
membrane anchored
scaffolding
barrier
Barrier Nups contain regions enriched in _____
phenylalanine/glycine repeats
NLS
rich in lysine
NES
Rich in leucine
NTF2
specific transporter for Ran GDP
NXF1/NXT1
transporters for mRNA and Ribosomal RNA
Low Ran GTP levels in ____
Cytoplasm
High Ran GTP levels in _____
nucleus
Six major functions of the ER
(1) synthesis of lipids (phospholipid, ceramide, and cholesterol; primarily in the smooth ER), (2) control of cholesterol homeostasis (cholesterol sensor and synthesis), (3) storage of Ca+2 (rapid uptake and release), (4) synthesis of proteins on membrane bound ribosomes (rough ER), (5) co-translational folding of proteins and early posttranslational modifications, and (6) quality control.
Protein that recognizes ER signal sequence
Signal recognition particle (SRP)
Chaperone protein involved in ER lumen
BiP
Type I membrane protein
amino terminal in ER lumen
Importance of N linked glycosylation
- keeps proteins from aggregating
1. monitor unfolded proteins
Major functions of Golgi (4)
(1) Synthesis of complex sphingolipids from the ceramide backbone, (2) Additional post-translational modifications of proteins and lipids (most notably, glycosylation and sulfation), (3) Proteolytic processing, (4) Sorting of proteins and lipids for post-Golgi compartments.
Sulfation occurs where in the Golgi?
trans Golgi and trans Golgi network
Two major routes of endocytosis
- phagocytosis
2. pinocytosis
Phagocytosis is carried out by ____ and _____
macrophages and neutrophils
Pinocytosis is usually associated with specific uptake of ____ and _____
ligands and receptors
Vesicles involved in endocytosis are typically formed by ____ or _____
clathrin coat proteins or caveolae
LDLRs are clustered on the membrane because ___
an adaptor protein complex AP2 binds the receptor and also binds clathrin
Caveolae are small endocytic vesicles that form ______
without coat proteins
Caveloae are especially important for membrane domains know as ____
Lipid rafts
Protein for caveolae formation
Caveolin
Each caveolae structure contains how many caveolin
144
The UPS is responsible for ____ degradation
rapid
Autophagy is mainly involved in degradation of _____ protein
long-lived
Enzyme in ER that allows formation of disulphide bonds
ERp57
thiol oxidoreductase
Proteins in the ER involved in holding misfolded proteins there until they are properly folded
calnexin (TM) and calrericulin (Soluble protein in ER lumen)
Calnexin and calreticulin bind proteins if there is a ___ attached
Glucose
After one round of calnexin/calreticulin, glucose is removed. If not correctly folded ___ adds glucose back on
glucosyltransferase
The proteasome cuts up polypeptides into ____ AA segments
short 7-9 AA
the _____ of the proteasome is where proteolytic cleavage takes place
central cylinder
Th two caps of the proteasome recognizes ____ and uses ____ to unfold the protein
Polyubiquitin
ATP
Three ligase enzymes involved in ubiquination
E1. E2, and E3
A chain of ___ ubiquitins is needed for proteosomal degradation
4
Interferon gamma induces transcription of
three novel beta subunits for proteasome (form immunoproteosome)
pH of lysosome
5
___________ plasma membrane proteins are targeted for endocytosis and are transferred via the late endosome/multivesicular body to the lysosome for degradation.
monoubiquinated
Necrosis
Mitochondria swell-> starve cell of ATP-> plasma membrane’s opn pumps fail-> water fills cell-> cell bursts
Intensely proinflammatory
Defining morphologica feature of apoptosis
Collapse of nucleus
Chromatin becomes super condensed
Cells shrink
An apoptotic cell tears itself apart into ____
apoptotic bodies
Cell that eats apoptotic bodies
phagocyte
Why is a phagocyte important?
ensure that the apoptotic cell gets taken up by a healthy cell, before it has had a chance to spill its dangerous, proinflammatory contents.
Apoptosis in cells is accompanied by changes in which phospholipid in the plasma membrane?
PS
What happens to PS in an apoptotic cell?
Scramblase exposes it on the cell exterior
What happens when PS is exposed on the cells exterior?
Phagocytic cells recognize and digest cell
A macrophage recognizes an apoptotic cell and releases ____, which is anti-inflammatory. Thus, removal of apoptotic cells is ___
TGFB
silent
low-dose radiation _____ lymphocytes; rather, it ______
does not kill
induces them to kill themselves
Normally the mitochondrial membrane is guarded by
Bcl-2 and Bcl-Xl
When a cell receives an apoptotic signal ___ and ____ make the mitochondrial membrane permeable to _____
Bax and Bak
cytochrome C
Proteins that replace Bcl-2 and Bcl-Xl during apoptosis
Bim and PUMA
Cytochrome C activates ____, which activates _____, which activates ______
Apaf-1
Caspase 9
Caspase 3
Caspase 9 is a ___ caspase, while caspase 3 is an ___
signal
executioner
_____ are responsible for surveillance of the surfaces of all body cells.
Cytotoxic (killer) T cells (CTL)
CTL-> ___-> which then_____-> ______-> ____-> ____
upregulates FasL engages and cross links with Fas or CD95 CD95 activates FADD Caspase 8 Caspase 3
autoimmune lymphoproliferative syndrome (ALPS) mutation
Fas or FasL
Protein related to Caspase 8 that competes with FADD and inhibits apoptosis
FLIP
viral form in herpes
In the other CTL mechanism, the killer cell secretes ____ and a _______ that together deliver apoptosis-inducing molecules to its intended target
granzymes
pore making protein (perforin)
Why are lymphocytes so susceptible to radiation?
a damage lymphocyte can lead to autoimmunity or lymphoma
Example of receptor family karyopherins
karyopherin beta
interacts directly with cargo and FG Nups
Example of adapter Karyopherins
karyopherin alpha
have specific binding sites for specific cargos and receptor family karyopherins
Specific transporter for Ran GDP
NTF2
Transporters for mRNA and rRNA
NXF1/NXT1
____ relieves binding affinity for Ran-GTP/Karyopherin binding, allowing _____ to activate Ran’s intrinsic GTPase
Ran BP1
RanGAP1
Durin RanGTP facilitated export ____ exchanges GTP for GDP
NTF2
Cholera exhibits >____ serogroups including ____
> 200
O-specific polysaccharide (OPS) of LPS
The ___ of cholera supports colonization.
Pili (TCP)
The cholera toxin subunits
1 alpha
5 beta
Receptor of cholera toxin
ganglioside GM1
Cholera toxin increases ____ production, which induces the ____ to secrete ____
cAMP
CFTR
Cl-
Patients with blood group ____ are more susceptible to severe cholera infections
Blood group O
3 main types of autophagy
- macroautophagy
- microautophagy
- chaperone mediated autophagy
Autophagy is induced during times of ____
nutrient stress
You can monitor autophagy by attaching GFP to ____
LC3
Genes that regulate autophagy
Atg
Very “druggable”
Why can you not always be certain that an observed effect was autophagy related when you knockout an ATg gene?
All known autophagy regulators also do other things independent of autophagy
Autophagic process
- induction
- vesicle nucleation (phagophore)
- V expan (omegasome)
- cargo transporting (LC3 and p62)
- vesicle closure (autophagosome)
- V fusion with endosome (amphisome)
- V fusion with lysosome (autolysosome)
If Beclin 1 binds to Bcl-2/Bcl-Xl->
No autophagy
Beclin-1 interacts with BCL-xl via a ___ domain
BH3
BH3 mimetic that disrupts Beclin-1-Bcl-xl interaction
ABT 737
Rapamycin ____ autophagy
increases
AA recognition sequence in chaperone mediated autophagy
KFERQ
Describe rationale behind autophagy’s protective action against neurodegeneration
Autophagy degrades the aggregate-prone proteins (perhaps after they have started to form small aggregates).
IV insulin 2 purposes in treatment of DKA
decrease blood glucose halting ketoacidosis (takes longer)
Insulin actions in liver (4)
+ glucose uptake, glycogen synthesis
- gluconeogenesis
- ketogenesis
+lipogenesis
Insulin actions in muscle (2)
+ glucose uptake, glycogen synthesis
+ protein synthesis
Insuliin actions in adipose tissue (3)
+ glucose uptake
+ triglyceride uptake
+ lipid synthesis
3 types of cytoskeleton fibers
microtubules
actin
intermediate filaments
Domains in microtubules
alpha, beta, and gamma
2 steps in microtubule formation
- Heterodimer formation
2. protofilaments binding to one another
Polymerization of microtubules is on the ____ end
plus
The ___ cap on the plus end of microtubules stabilizes them
GTP
Microtubule severing protein mechanisms (2)
GTP-> GDP
or cut them
