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260 Cards in this Set
- Front
- Back
What are the purposes of membrane trafficking? |
To communicate with other cells and to acquire resources |
|
What are the three basic principles of the Biosynthetic-Secretory and Endocytic pathways? |
1. Polarized trafficking routes 2. Sorting stations 3. Retrieval mechanisms and general balance among routes |
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True or false: both the regulated secretory pathway and the constitutive secretory pathway function in all cells |
False. The regulated pathway only functions in specialized cells |
|
For both of these pathways, how is a mature secretory vessel made? |
By retrieving Golgi components and concentrating cargo |
|
Until when are vesicles stored in the regulated pathway? |
A signal for docking and fusion is given |
|
True or false: regulated secretion provides extra plasma membrane when needed. |
True. |
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Which of the following does not require extra membrane? A. Phagocytosis B. Exocytosis C. Cleavage furrow D. Wound |
B. Exocytosis
|
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Which pathway is the counterbalance for the secretory pathway? |
Endocytic |
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What are the basic steps of endocytosis? |
Invagination, fission |
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What are the three options for an endocytosed vesicle? |
Transcytosis, recycling, degradation |
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True or false: recycling is carried out on the apical domain of plasma membrane |
False. It's carried out on the basal domain; transcytosis takes place on the apical |
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Where does LDL bind? |
To an LDL receptor in a coated pit |
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What happens after endocytosis? |
Uncoating of the vesicle and fusion to the early endosome |
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True or false: the whole LDL + receptor unit is recycled |
False. Only the receptor is |
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How can cells internalize pathogens? |
Phagocytosis |
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Which organelle is an example of a multivesicular complex? |
Late endosome |
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After the v-SNAREs and t-SNAREs have bound, what are the steps for fusion? |
Form stalk, hemifusion, fusion |
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True or false: COPI is the primary driver of vesicle invagination events |
False. Clathrin is |
|
What is the structure of a triskelion? |
3 heavy and 3 light chains |
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What drives fission events and when? |
Dynamin after vesicle invagination events |
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Which complex drives budding events? |
ESCRT |
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True or false: PI(3)P moves with the polyubiquitinated protein from ESCRT-0 all the way to ESCRT-3 |
False. PI(3)P is bound to ESCRT-0 and ESCRT-II, while ESCRT-III is bound by PI(3,5)P; and it's a multiubiquitinated protein |
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What does ESCRT-III do? |
Builds up borders and prevents proteins from diffusing out |
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Virus particles found in the cytoplasm would need which machinery to leave the cell? A. COPI B. Dynamin C. ESCRT D. SNAREs E. Clathrin |
C. ESCRT |
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What is cargo regulated by? |
Signal sequences |
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What is transport machinery regulated by? |
Signaling lipids (PIPs) and small GTPases |
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True or false: a PI(5)P can have a phosphate added to the third carbon to form PI(3,5)P |
False. |
|
True or false: specific PIPs are found at distinct sites in the trafficking network and protein partners will be recruited to these sites |
True. |
|
True or false: GTPase bound to GDP must be phosphorylated to make the complex active |
False. GEF must help exchange GDP for GTP |
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Where does Rab11 localize to? |
Recycling endosomes |
|
How about Rab5A? |
Plasma membrane, clathrin-coated vesicles, early endosomes |
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Rab7? |
Late endosomes |
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How Rab5 recruited to the membrane? |
1. Rab5-GEF exchanges Rab5-GDP 2. Active Rab5-GTP binds to the membrane with its lipid anchor 3. Rab and PI(3)P work together |
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Microtubules are inherently ___________. |
Polarized |
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Each protofilament is made ofheterodimers of the monomericproteins ___________ & ____________. |
a-tubulin and b-tubulin |
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True or false: tubulin monomers bind and hydrolyze ATP |
False. GTP |
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How many filaments make up one microtubule? |
13 |
|
What does gamma tubulin do? |
Nucleates microtubules at the minus end |
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Plus ends grow (FROM/TO) nucleation sites |
From |
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What is dynamic instability? |
How microtubules switch between growing and shrinking to search the full 3D space of the cytoplasm |
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Growing microtubules have a protective cap of __________. |
GTP-bound tubulin |
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True or false: if the GTP cap is lost, growth can never be started again. |
False. If it is regained, growth is resumed |
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In general, to which ends of the microtubule do Dynein and Kinesin move? |
Minus and plus, respectively |
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What motor is likely key for Golgi positioning? A. Kinesin B. Dynein |
B. Dynein
|
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When cAMP levels are decreased in male cichlids, what happens to the melanosomes? |
Kinesin is inhibited and Dynein aggregates the melanosomes to the centre |
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True or false: actin binds and hydrolyzes GTP |
False. ATP |
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True or false: actin is a monomer like microtubules |
False. Microtubules are heterodimers |
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What happens when the rate of addition of Actin-ATP is faster than rate of removal ofActin-ADP? |
A relatively stable "cap" of Actin-ATP subunits can be formed |
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What causes the treadmilling of actin? |
The ATP-ADP polarity |
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What does the ARP complex do? |
Nucleates actin filaments and branches them to form 2D networks |
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What protein chops the network to initiate dissociation? |
Cofilin |
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What do these networks drive? |
Polarized cell movement |
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What creates protrusive machines? |
LArge regions of anchored actin networks |
|
Integrins |
Connect the actin cytoskeleton to extracellular matrix molecules |
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What makes up the integrin? |
a- and b-subunits |
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What acts as an anchor within the cell? |
Vinculin and talin |
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How is the actin cytoskeleton directed to follow a target? |
Chemoattractant receptors orient the actin networks |
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When there are chemoattractants present, where will treadmilling be activated? |
Where the highest concentration activates the most receptors |
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True or false: in epithelial tissue, mechanical stress is supported between cells by cytoskeletal filaments anchored to the matrix and adhesion sites |
False. The stresses are transmitted from cell to cell |
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The extracellular matrix (DIRECTLY/INDIRECTLY) bears mechanical stress |
Directly |
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Where is the epithelial tissue located? |
Lines tissues, surfaces, surrounds organs |
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True or false: connective tissue cells are spread out. |
True. |
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What are epithelial cells directly connected to beneath? |
Minimal extracellular matrix |
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What provides the overall structure in connective tissue? |
Extracellular matrix |
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Connective tissue cells include _________, ___________, and __________. |
Muscle cells, neurons, immune cells
|
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Epithelia are critical for organ ___________ and __________. |
Structure and function |
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In apical to basal order, name the junctional complexes of the epithelial cell. |
Tight, adherens, desmosome, gap junction |
|
Tight junctions |
Seals the gap between epithelial cells |
|
Adherens junction |
Connects actin filament bundle in one cell to that of the next cell |
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Desmosome |
Connects intermediate filaments between cells |
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Gap junction |
Allows the passage of small water-soluble molecules from cell to cell |
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Hemidesmosome |
Anchors actin filaments to extracellular matrix |
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What anchors actin filaments to extracellular matrix? |
Actin-linked cell matrix adhesion |
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What is critical to adhering cells to form epithelia? |
Strong continuous adhesion belts |
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Tight junctions are made up of ________ proteins while adherins are made up of __________. |
Claudin, cadherin |
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True or false: cadherins are membrane proteins |
False. Transmembrane |
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What are the two ways through which cadherin clusters mediate adhesion |
Homophilic interactions between cadherin receptors and links to the actin cytoskeleton |
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True or false: the C terminus of cadherin is on the inside of the cell |
True. |
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What happens if there are no adherens junctions? |
Tissue structure is lost |
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Cadherins are __________ suppressors and the loss epithelial structure is a hallmark of ________. |
Tumour, cancer |
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True or false: the basal side of an epithelial cell faces the organ lumen while the apical side faces the underlying tissue |
False. The opposite |
|
How does the Na+ driven glucose symport work? |
Move glucose from low concentration from lumen to high in the cell; need energy so sodium moves from high to low |
|
What would happen if tight junctions were removed? |
Glucose would freely diffuse between cells and there wouldn't be enough in them |
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Tight junctions are formed from interacting strands of _____________ proteins |
Transmembrane
|
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Claudin is a ___-pass transmembrane _________ essential for _______ junction function. |
4, protein, tight |
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Occludin is a ___-pass transmembrane ___________ needed for ___________ function |
4, receptor, barrier |
|
True or false: claudin and occludin cross both layers of the lipid bilayer |
True. |
|
If occludin were removed, what would happen to the structure of the tight junctions? |
Not much. |
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In C. elegans, what does the sperm entry point act as? |
A primary landmark. |
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Primary landmark |
Used to establish polarity; signals specific structure elaboration |
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Anterior and poster cues form a: A. Positive feedback loop B. Negative feedback loop C. Flip flop device |
C. Flip-flop device |
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____________ junctions are important landmarks for epithelial polarity. |
Adherens |
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Which three proteins act as adherens anchors? |
Arm, a-cat, actin |
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List, in order, the structures made in constructing epithelial polarity. |
1. Apical cue (anchor and actin) 2. Scribble complex forms 3. Tight junction forms 4. Crumbs complex & Par-etc. |
|
Morphogenesis |
The generation of tissue shapes that form organs and bodies |
|
Cell differentiation |
The generation of different types of cells in tissues |
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In adults, multicellular development will occur continually from _______ cells. |
Stem |
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How long does epithelial migration from the bottom of the crypt to the top of the villus in the gut take? |
3-5 days |
|
True or false: non-dividing differentiated Paneth cells of the crypt are stem cells. |
False. |
|
What is the purpose of slowly-dividing stem cells? |
To provide support to the crypt |
|
What do embryogenesis, embryogenesis, organogenesis,and stem cell development share? |
Commonmechanisms of morphogenesis and celldifferentiation. |
|
Zona pelucida |
A jelly-like capsule that houses the pronuclei and the polar body |
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True or false: the polar body is non-viable and will be destroyed |
True. |
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At 2 1/2 days, the fertilized egg has ___ cells and is called the __________. |
8, morula |
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Trophectoderms line the blastocyst and will eventually become _______________ tissue. |
Extra-embryonic |
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What three things does morphogenesis require? |
Internalization of the cells, elongation of the embryo, fine repositioning of the cells |
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Internalization of the cell during _____________ creates the main three germ layers |
Gastrulation |
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Name the stages of gastrulation |
1. Cells start crawling into the inner cavity and become mesoderm cells 2. The endoderm begins to invaginate 3. The ectoderm is on the outside |
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Which tissues, respectively, do the ectoderm, endoderm, and mesoderm form? |
Epidermis/nervous system; gut/lung/liver; muscles/connective tissue/blood vessels |
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What is ingression/delamination? |
A method for cell internalization that involves individual cells separating from the early outer epithelium; epithelial-mesenchymal transition |
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Why are epithelial-to-mesenchymal transitionsdangerous during cancer progression? |
They can cause benign tumours to metastasize by escaping from the epithelium |
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If a chunk of somites were transplanted from a chicken embryo limb to a quail, what would happen? |
Epithelial-to-mesenchymal transitions are tightly regulated so the limb would still form but with a mixture of chicken and quail muscle cells |
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What is invagination/involution? |
When intact epithelial sheets move inside the embryo |
|
What changes are required for this process? |
Microtubules elongate to make columnar cells, apical actin bundles contract to narrow cells' apices |
|
Name a developmental example of this process |
Neural tube development from ectoderm in vertebrates |
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Which TF specifies the cells to undergo mesoderm internalizationin Drosophila? |
Twist |
|
Name the two mechanisms of embryo elongation |
Cell division and cell shape change; convergent extension |
|
How does convergent extension work? |
Lamellopodia crawl on cells, forcing them to converge and then stretch out |
|
True or false: the direction of movement is unregulated |
False. It's regulated |
|
How is the orientation of cell elongation regulated in cell division and shape change? |
The orientation of cellulose microfibrils and driven by turgor pressure |
|
Name the two mechanisms of cell positioning |
Cell sorting; directed cell migration |
|
When cells of the three early germ layers are dissociatedand randomly mixed, the individual cell types re-associateand re-form the germ layers. How? |
The homophilic adhesion between cadherins may group specific cells together |
|
True or false: first-born neurons are deeper in the cortex than last-born |
True. |
|
What kind of cells direct dividing progenitor cells? |
Radial glial cells |
|
How does directed cell migration in the cerebral cortex work? |
DP cells divide, glial cells get longer; DP moves up and implants in the layer of cortical neurons |
|
Where else is directed cell migration required in the nervous system? |
Axon pathfinding |
|
What will the commisural neuron eventually become? |
The spinal cord |
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True or false: axon pathfinding in the neural tube goes from the floor plate to the roof plate |
False. Vice versa |
|
What is the commisural neuron attracted to, and what are the receptors? |
Netrin; DCC netrin receptor |
|
What is the Slit receptor? |
Roundabout |
|
What is the other repellant?
|
Semaphorin |
|
What happens if Slit is removed from the system? |
It won't bind to the Roundabout receptor so the neuron will not grow toward the brain without the repellant |
|
What are the two main mechanisms of cell differentiation? |
Asymmetric and symmetric division |
|
True or false: asymmetric division is when the cells become differentiated by external forces after birth |
False. Specific proteins/combos go to one side of the cell before the split |
|
Direct lateral inhibition |
Cells begin as all the same but some randomly gain an advantage and become differentiated while inhibiting their neighbours from doing the same |
|
The Delta-Notch system is an example of what and how does it work? |
Lateral inhibition; warring cells until one manages to inactivate Notch to activate Delta and become specialized
|
|
True or false: if Notch is turned off, the cell will specialize |
True. |
|
Name the three mechanisms for extrinsic cell differentiation |
Direct lateral inhibition, induction by diffusible signals, regulatory hierarchies |
|
Why don't humans sprout wings? |
Hox genes encode transcription factors with different targets in different species |
|
True or false: cells of the auditory hairs regenerate |
False. |
|
What initiates a nerve impulse on these hair cells? |
When the hair bundle tilts to open the ion channel |
|
What is another type of permanent cells with specific architecture? |
Human photoreceptors |
|
True or false: bone is degraded by osteoclasts and deposited by osteoblasts |
True |
|
How are the fates o stem cell daughters controlled? |
Either through divisional asymmetry or environmental asymmetry
|
|
What is the difference between these? |
Divisional gets factors that promote stemness and original numbers cannot be restored |
|
Stem cells divide (SLOWLY/QUICKLY) |
Slowly |
|
Why do they divide slowly? |
Protects from mutation and telomere depletion |
|
Transit amplifying cells |
Expand cell numbers before final differentiation |
|
The basal lamina provides a _______ for stem cells; from there, the cells ____________ through a linear sequence of cell types. |
Niche, differentiate |
|
Multipotent hemopoietic stem cells differentiate into ______________ and then common ____________ _____________ and ____________ ____________. |
Multipotent hemopoietic progenitors, lymphoid progenitors, myeloid progenitors |
|
In fluorescence-activated cell sorting (FACS), the cells suitable for bone marrow transplant will carry a __________ charge. |
Negative |
|
When a stem cell is to remain a stem cell, what does it bind to? |
The Kit ligand on the stem cell binds to the Kit receptor on the stromal cell; if it doesn't, it becomes a transit amplifying cell and either differentiates or dies |
|
What are the two ways of avoiding immune rejection of embryonic stem cells? |
Somatic cell nuclear transfer and treating some of the patient’s own cells with a factor known to specify ES cell character(e.g. a combination of Oct3/4, Sox2, Myc and Klf4 can convert differentiated cellsinto cells with ES cell characteristics) |
|
Receptor tyrosine kinases |
Enzyme-coupled receptors used in signalling |
|
What do RTKs bind? |
Secreted or cell surface proteins |
|
The RTK domain is in the ___________ of the cell |
Cytosol |
|
Signalling molecules induce the ___________________ of RTKs |
Transautophosphorylation |
|
How does transautophosphorylation work? |
Ligand binding dimerizes the receptor and the kinase domains are brought together and phosphorylate each other |
|
If a receptor tyrosine kinases with a defective kinase domain was expressed together with the normal receptor what would happen? |
The cell would have no response to the signal (dominant negative mutation) |
|
The proteins recruited by RTK have either _____ or ______ domains that bind to ____________ and neighbouring sequences |
SH2, PTB, phosphotyrosine |
|
R7 |
The photoreceptor in Drosophila needed to detect UV light |
|
What are the steps in the Sevenless pathway? |
Boss in the R8 cell is the ligand for Sev RTK; the binding of this ligand activates Sev, then Drk links Sevenless to Sos (Ras-GEF), which activates the Ras protein and downstream signals. |
|
True or false: a mutation at any of these steps would cause the fly to become Sevenless |
True. |
|
Ras |
A monomeric GTPase that is a molecular switch downstream of RTK that leads to cell proliferation or differentiation; in its hyperactive mutant form, it is responsible for 1/3 of human tumours |
|
Active Ras activates MAP kinase kinase kinase, and then what? |
The cascade is phosphorylated (MAP kinase x2 and MAP kinase) until the effector proteins are phosphorylated |
|
How is non-specific cross-talk controlled in yeast? |
Scaffolds bind to specific MAP kinase modules to insulate them |
|
Tyrosine kinase-associated receptors are similar to RTKs, but how do they differ? |
They interact non-covalently with cytoplasmic tyrosine kinase |
|
Receptor __________________ kinases are the largest class of cell surface receptors in plants |
Serine/threonine |
|
___________ signaling stimulatesthe development ofstems, leaves and flowers |
Clv1/Clv2 |
|
True or false: Clv1 and Clv2 get phosphorylated by Clv3 |
False. Clv1 phosphorylates itself and Clv2 |
|
True or false: histidine-kinase-associated receptors are used by all living things |
False. They are not used by animals |
|
CheA |
The histidine kinase that phosphorylates itself on a histidine and transfers the phosphate to an aspartic acid on CheY |
|
If a repellent binds to the chemotaxis receptor in a bacteria but the bacteria is not supposed to tumble, what happens? |
CheZ will remove the phosphate on CheY to stop the tumbling |
|
Choose the correct statement: A. Notch is processed in the extracellular space and cut into two fragments B. The Notch fragment Delta binds to is discarded C. The Notch tail migrates to the nucleus and activates gene transcription |
C. It does and inhibits cell specialization |
|
If hedgehog signaling were inhibited, what would happen? |
The transcriptional activator, Ci, would be sequestered in the cytoplasm, phosphorylated, cleaved and put in a complex with a repressor, and transferred to the nucleus were it would inhibit Hh gene transcription. At the same time, Patched would sequester Smoothened in vesicles since nothing would be bound to iHog (Hh receptor) |
|
What happens when Hedgehog is on? |
Patched transfers Smoothened to the plasma membrane where it releases Ci from the inhibitory complex |
|
Name the four parts of the cell cycle |
G1 (cell growth and partial doubling of organelles), S phase (DNA replication), G2, M phase (mitosis and cytokinesis) |
|
Cdks |
Cyclin-dependent kinases; the traffic lights of the cell cycle |
|
What two things are required for a Cdk to become active (i.e. to give the "green light" for a checkpoint?) |
Cyclin and an activating phosphate |
|
True or false: the same type of cyclin-Cdk checkpoint can be used at multiple points of the cell cycle |
False. There are many different cyclins that bind at different points |
|
Explain how Cdk becomes fully activated. |
Cyclin binds to the T-loop on Cdk to make it partially active, and then a phosphate attaches to the active site of the T-loop to make it fully active
|
|
S-Cdk |
Activity inhibits an inhibitor of the origin recognition complex to promote DNA replication |
|
M-Cdk
|
Phosphorylates (with ATP) multiple targets required to start mitosis |
|
What turns Cdks off? |
Targeted degradation of cyclin |
|
APC |
Anaphase promoting complex; targets M-cyclin to the proteasome for the completion of mitosis |
|
p27 |
A Cdk inhibitor protein (CKI); clamps onto cyclin A or cyclin E of Cdk2 to render it inactive |
|
Wee1 kinase |
Adds inhibitory phosphate to Cdk |
|
Cdc25 phosphotase |
Removes the inhibitory phosphate |
|
Rb |
Blocks G1 progression and S phase by inhibiting cyclin synthesis |
|
How does Rb do this? |
By clamping around E2F |
|
What is the inactive state of Rb? |
When it has two phosphate groups |
|
Loss of both copies of the Rb gene leads to _____ ___________ since it is a ________ ____________ gene. |
Eye cancer, tumor suppressor |
|
Mitogen |
Substance that encourages mitosis |
|
What induces Myc transcription? |
Mitogen signaling via a Ras-MAP kinase signaling cascade
|
|
Myc |
Increases cyclin synthesis and CKI degradation by regulating transcription |
|
What happens when there is too much Myc present? |
Too much replication |
|
Myc is: A. Oncogene B. Tumor suppressor |
A. Oncogene |
|
What adds the activating phosphate to Cdk? |
CAK |
|
What initially activates Cdc25? |
The phosphorylation of M-Cdk |
|
What kind of feedback loop is it when active M-Cdk inhibits Wee1? |
Positive feedback since it is also promoting phosphorylation by Cdc25 |
|
p53 |
Stops the cell cycle in response to damage |
|
What happens when p53 gets phosphorylated? |
Mdm2 detaches and active p53 activates transcription of p21 |
|
p21 |
Cdk inhibitor protein |
|
p53 is A. Oncogene B. Tumor suppressor |
B. Tumor suppressor |
|
Caspase |
Cysteine proteases that cleave target proteins at specific aspartic acid residues and trigger apoptosis |
|
How are caspases activated? |
Inactive procaspases are cleaved at two sites; the prodomains are degraded and the small subunits of two bind to create an active caspase |
|
True or false: caspase 8 is an executioner caspase |
False. Caspase 3 is; caspases 8, 9, and 10 are initiator caspases |
|
True or false: a Fas receptor is an extrinsic signal for a caspase cascade. |
True. |
|
How does Fas work? |
The ligand on the killer lymphocyte binds to the Fas death receptor; FADD and the procaspase attach to form the DISC; procaspase 8/10 is cleaved to form caspase and the cascade is activated; apoptosis is triggered |
|
How is apoptosis triggered intrinsically? |
Apoptotic stiumulus leads to the release of cytochrome c from the mitochondria, which attaches to Apaf1; this oligomerizes and recruits procaspase 9, which cleaves and recruits executioner caspases |
|
True or false: caspase 8 and 9 are used for extrinsic apoptosis signaling |
False. 8 and 10 are used for extrinsic. |
|
How do healthy cells avoid cell death? |
They create lots of decoy receptors that bind the Fas ligand but don't contain death domains (extrinsic) or they mimic initiator caspases without a proteolytic domain |
|
Bcl2 |
Inhibits channel formation in the outer mitochondrial membrane |
|
What happens when there is too much Bcl2? |
Inactivates BH123 and does not allow the release of cytochrome c so may lead to cancer since there would be no cell death |
|
IAPs |
(Inhibitors of apoptosis) block caspase activity in the cytoplasm when procaspases accidentally bump into each other |
|
If apoptosis is supposed to happen but IAPs are present, what happens? |
Anti-IAPs will bind the IAPs and allow the caspases to do their jobs |
|
Name three examples of survival factors that would block apoptosis |
Activated gene regulatory protein transcribes lots of Bcl2; Akt kinase inactivates Bad; MAP-kinase inactivates Hid which normally inhibits IAPs |
|
True or false: tumor cells will have a mixture of which X chromosome is inactivated |
False. All cells will have the same one inactivated |
|
Carcinoma |
Epithelial cell cancers |
|
What is the difference between a benign and a malignant tumor? |
Benign tumors are contained whereas malignant tumors invade the surrounding tissue. |
|
How do cancer cells usually invade other parts of the body? |
Blood vessels or lymphatic vessels |
|
What is the Ames Test and how does it work? |
Tests whether a chemical is a mutagen; mix the test compound and a culture of histidine-dependent Salmonella on an agar plate without histidine and if the culture grows, the compound is a mutagen |
|
True or false: oncogenes are gain of function mutations |
True |
|
True or false: p53 and Rb are oncogenes |
False. They are tumor suppressors and their loss of function can lead to cancer |
|
True or false: tumor suppressor genes are dominant |
False. Recessive |
|
How are oncogenes produced? |
Proto-oncogenes undergo a mutation or gene amplification or chromosome rearrangement |
|
When polarity is lost, metastases ___________. |
Increase |
|
What does Gleevec target and how does it work?
|
The Bcr-Abl protein; binds where ATP normally would and stops phosphate signal for cell proliferation and leukemia |
|
What are the two ways from which cells receive signals? |
Cell-surface and intracellular receptors |
|
What is the main difference between these? |
Cell-surface signals must be hydrophilic whereas intracellulars ones must be hydrophobic |
|
Contact-dependent signaling |
Signals are retained on the cell surface and occurs over short distances |
|
Paracrine signaling |
Signals are released from cells but act locally; movement is restricted |
|
Synaptic signalling |
Neurons extend axons to contact distant targets |
|
Endocrine signaling |
Endocrine cells secrete hormones into the bloodstream for long-range distribution |
|
Signal transduction |
The conversion of extracellular signals into intracellular signals; signal creates a signaling cascade that goes down to the effector proteins |
|
Second messengers |
Small intracellular signalling molecules that bind and alter effector proteins |
|
What are the potential steps of the signal transduction pathway? |
Extracellular signal, scaffold, relay, transduce and amplify, integrate (coincidence detector), spread, anchor, modulate, effector protein activation |
|
SH2 and PTB bind ________________-containing sequences |
Phosphotyrosine |
|
PH domains bind _______________
|
Phosphoinositides |
|
SH3 domains bind _____________-rich sequences |
Proline |
|
What is the difference between synaptic and endocrine signaling specificity? |
The same synaptic signaling molecules can be used in all connections (target-specific) whereas the receptors on the target cells are different for the endocrine pathway.
|
|
What prevents an upstream signal from activating all of the pathways? |
A scaffold; either a designated scaffold, a phosphorylated receptor scaffold, or a PI docking site scaffold
|
|
Coincidence detector |
Only activate downstream signals when two upstream signals are both detected |
|
Biphasic switches promote _______________. |
Differentiation
|
|
The circadian rhythm is an example of a __________ feedback loop with a ________ delay. |
Negative, long |
|
True or false: nuclear receptors are always in the nucleus |
False. They can be in the cytosol, but once they bind to a signalling molecule, they go to the nucleus |
|
Orphan nuclear receptors |
Part of the nuclear receptor superfamily but their ligands are unknown |
|
True or false: the ligand-binding domain of a receptor is closer to the C terminus |
True. |
|
True or false: ion channel transport is active |
False. Passive |
|
Na levels are _______ within the cell, while K levels are ______. |
Low, high. |
|
The cell must contain _________ amounts of positive to negative charges |
Equal |
|
What are the three states of a voltage-gated channel? |
Open, closed, and inactivated |
|
How do chemical synapses transmit signals? |
Synaptic vesicles release neurotransmitters that open ligand-gated ion channels that then depolarize and allow electrical signals to pass through |
|
GPCR |
G-protein coupled receptors are 7 pass transmembrane proteins that respond to proteins, small molecules, and light |
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What are the components of a G-protein and what binds to it? |
Alpha, beta, gamma; GTP/GDP binds the alpha subunit |
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GPCRs signal into the ______________. |
Cytoplasm |
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How does this path get turned on and off? |
GPCR is activated by a small extracellular signal and acts as a GEF on the G-protein and the altered subunits bind downstream proteins. The system is turned off by RGS which acts as a GAP |
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Why do dogs have a better sense of smell than humans? |
They have more types of GPCRs and so can recognize many different odourants |
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IP3 is a hydro_______ molecule that diffuses through the __________while DAG is a hydro________ molecule that diffuses _______ the ________ ____________. |
Hydrophilic, cytoplasm, hydrophobic, plasma membrane |
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How does GPCR signal via calcium? |
GPCR activates production of IP3 and DAG; IP3 goes to the ER and acts as a channel ligand to release Ca and activate protein kinase C |