EXAM III Final Flashcards
What are two cell phenotypes that cause them to undergo apoptosis?
- Macrophage activation
- DNA fragmentation
- A decrease in the nucleus and volume
- Less adhesion, smaller cytoskeleton and nuclear envelope
Explain the difference between initiator and executioner caspase
Initiator caspase (-8,9) initiates apoptosis by activating the caspase cascade by causing executioner caspase (-3) to actually cleave the downstream targets. (Such as cytoskeleton, inactive endonuclease, proteins, cell adhesion proteins)
Executioner caspase executes apoptosis
Name two ways in which proto-oncogenes become activated to become oncogenes
- Gene amplification, which causes the overproduction of a normal protein.
- Chromosome rearrangement by a nearby regulatory DNA sequence that brings new regulatory sequence that causes overproduction of a normal protein or Creates overactive fusion protein. (I.e. EGF receptor rearrangement can remove the extracellular domain; epidermal growth factor)
- Regulatory mutation which causes an overproduction of a normal protein. (I.e. Promoter mutation)
- Deletion or point mutation in a coding sequence causing a hyperactive protein in normal amounts (I.e. Ras)
Describe the pathology of cancer and how it goes from benign to malignant
A tumor is originally benign. Once it invades a nearby capillary the tumor has become malignant and is capable of entering tissues via the blood vessels. Tumors can also become adhered to the endothelial vessel walls.
Describe polyp and how it develops
A polyp is a precursor to colorectal cancer (APC tumor suppressor gene mutation). They normally take about ten years to develop and if left untreated can become malignant and be cancerous. If the polyp is excised, the patient is cured.
Explain how Gleevec is used in the treatment of anti-cancer therapy
Gleevec is used in chronic myeloid nous leukemia (via Philadelphia chromosome translocation) and binds to the ATP binding site of BCR/Abl, inhibiting tyrosine kinase activity thereby inhibiting cell proliferation
What are the two forms of cell death?
- Necrosis - contents spill out
2. Apoptosis - cell death under physiological conditions (programmed; cells shrink and condense)
T/F; Eliminating lymphocytes after destroying and ingesting microbes is an example of apoptosis
True
T/F; programmed cell death is important for certain cells such as those that are abnormal, non-functional, or potentially dangerous
T
T/F; cytochrome c is a marker of apoptosis
True; released from mitochondria
T/F; apoptosis is an extracellular proteolytic cascade mediated by caspases (proteases)
False; apoptosis is intracellular
T/F; Cysteine is the active site on caspases
True; Cysteine aspartyl specific proteins
T/F; Caspases targets proteins and cleaves them in their sequence where a glycine amino acid residue occurs
False; cleaves where there’s an Aspartic amino acid residue
T/F; pro caspase is an inactive precursor of caspase
True; this is the primary synthesized version of caspase
T/F; the active form of caspase is a heterodimer
True; made up of large and small subunits which forms the heterodimer
T/F; the caspase cascade is reversible
False; it’s actually irreversible
Are death receptors involved in the intrinsic or extrinsic pathway of apoptosis?
Extrinsic
Intrinsic involves cytochrome c from mitochondria
Explain how decoy receptors work in the extrinsic pathway of apoptosis
Decoy receptors contain ligand binding domain (no death domains) which blocks the binding of Fas ligand to the Fas death receptor
Explain how the protein FLIP works in the extrinsic pathway of apoptosis
FLIP is a competitive inhibitor to pro caspase-8,10 death effector domain, thereby inhibiting apoptosis
What are some factors that cause activation of the intrinsic pathway of apoptosis?
Injury
DNA damage
Lack of oxygen, nutrients
Lack of extracellular survival signals
What is the function of cytochrome c in the intrinsic pathway of apoptosis?
Released from intermediate space of mitochondria and binds to adaptor protein to activate procaspases
Define Apaf1
Apoptotic protease activating factor-1; bound by cytochrome c which becomes an apoptosome and activates caspase-9 (initiator caspase_
What are the two types of Bcl2 proteins that control the release of cytochrome c into the Cytosol?
Pro-apoptotic = BH3 and BH123 (Bax, Bak)
Anti-apoptotic = Bcl2 (Bcl-XL, BH1234) = located on cytosolic surface and prevents the aggregation of BH123 (active form)
What is the mechanism of BH3 in the intrinsic pathway of apoptosis?
Pro-apoptotic and located in Cytosol and inhibits anti-apoptotic Bcl2 protein from inhibiting aggregation of BH123 for the release of cytochrome c
Explain the mechanism of IAPs in apoptosis
Inhibitors of Apoptosis bind and inhibit caspases or add ubiquitin to caspases
What it the mechanism of anti-IAPs?
Blocks IAPs by neutralizing them and blocking their functions of inhibiting apoptosis
Can excessive Bcl2 cause cancer?
Yes, because this inhibits apoptosis which would inhibit DNA-damaged cells from dying allowing them to continuing proliferating
List the 3 classification of cancers
- Carcinomas - via epithelial cells
- Sarcomas - via CT and muscle tissue
- Leukemias and lymphomas - via WBCs and their precursors
What is the difference between neovascularization and angiogenesis?
Angiogenesis is the formation of blood vessels from PRE-EXISTING VESSELS
What are the two main classes of cancer critical genes that are the genetic causes of cancer when mutated?
Tumor suppressor genes (loss of function; recessive) - p53, CKI, Rb
Oncogenes (gain of function; dominant) - Bcl2
Which of the following is not involved in cellular function of oncogenes?
A. Cell cycle proteins B. Transcription factors C. Ligands D. Receptors E. Nucleus
Nucleus
List some examples of the two types of tumor suppressor genes; growth restriction and the maintenance of genome integrity
Growth restriction = caspases, Rb, CKI
Maintenance of genome integrity = checkpoint control proteins; DNA repair enzymes/pathways, ATM & ATR (detects DNA damage), Ataxia Telangiectasia
T/F; Cdk and cyclin are proto-oncogenes
True; are usually involved in cell proliferation when bound with CKI(p16)
List some functions of p53 in the regulation of the genome
Tumor suppressor gene
Cell cycle arrest
DNA repair
Apoptosis
Blocks angiogenesis
List some functions of p53 in the regulation of the genome
Tumor suppressor gene
Cell cycle arrest (CKI = p21 = inhibits cell cycle)
DNA repair
Apoptosis (activates BH3, BH123)
Blocks angiogenesis
Define gastrulation
The transformation of a hollow sphere of cells into a structure with a gut
Define gene duplication
When higher organisms have several homologs of the same gene
List the two classes of proteins most important for the development of organisms
- Cell adhesion and cell signaling proteins; layering and talking
- Gene regulatory proteins (the basis for making organisms different from one another; what allows expression)
Completely undetermined vs. Committed cell fates
Completely undetermined cells can change rapidly due to the environment
Committed cells have an idea where they are but can also change with the environment; brain cell that can become microglia, or ependymal, or astrocyte
What is an example of a cell that undergoes long range signaling during inductive signaling during cellular differentiation
Morphogens; BMP, Shh
When a substance diffuses through the extracellular matrix
Short range vs. long range signaling
Short range = cell-cell contact
Long range = substances diffuse through extracellular environment
Symmetric vs. Asymmetric division
Symmetric = daughter cells become different due to environment influences (weak asymmetry)
Asymmetric = granule location within cytoplasm
Define inductive signaling
Environmental signals that come from neighboring cells that induce different development patterns in a homogenous group
(short range vs. long range; morphogens)
Positive feedback and lateral inhibition during symmetrical division
After daughter cells have begun to undergo asymmetry via environmental signals, positive feedback allows strong asymmetry = all or none and irreversible
Self-amplifying
Allowing cells to have memory
Define morphogen
A long range inductive signal that imposes a PATTERN on a field of cells forming gradients of [different] thus allowing for target cells to undergo different developmental pathways
Gradient formed by = Inducer vs. inhibitor
Gradient becomes less the further you remove from a source
What two factors are the response to signaling pathways dependent upon during cell differentiation?
Spatial and time
Define growth cone
An irregular, spiky enlargement at the tip of an axon/dendrite that crawls thru surrounding tissue, trailing the axon or dendrite behind; developing axon-specific proteins forming an axon
Located within the dendrite but doesn’t move; the axon is what moves
What dictates growth cone behavior? What senses the ECM environment?
Its cytoskeletal machinery (filopodia and lamelopodia) containing actin filaments that assemble and disassemble by the action of Rho and Rac monomeric GTPases
Membrane receptors sense the ECM environment
What are two factors that determine the movement and behavior of growth cones? Give some examples
ECM environmental sensed by membrane receptors; homophilic cell adhesions via Ig Superfamily and cadherins
Chemotactic factors via neighboring cells; Slit, Semaphorin, and Netrin
List the 3 chemotactic factors involved in growth cone migration and what type of neuron expresses the receptor?
Attractant = Netrin
Repulsive = Slit & Semaphorin
Commissural neuron contains the Netrin receptor
Explain the pathway of the guidance of a commissural neuron
Commissural axon grows out towards the attractant Netrin with its receptor towards the midline which is then repelled against the midline via Slit (floor plate midline) and Semaphorin (wall of neural tube) with its roundabout receptors and makes its way towards the brain
Makes a 90 degree turn away from the floor plate
ECM Ca2+ entry allows for growth cone movement
Non-commissural neurons don’t contain the receptor and migrate towards the floor plate
Define neurotrophic factors; what is its role in axonal/neuronal growth? What phase?
Factors that are needed for survival released by the target cells that determine where synapses are formed (i.e. Nerve growth factor NGF)
Those that don’t receive enough signals die
PHASE II
What are the 2 rules that synaptic remodeling is dependent upon in retinal/tectal neurons? Race Relations
- Axons from cells in different regions of retina that are excited at DIFFERENT cells compete for tectal neurons
- Axons from neighboring sites excited at the SAME TIME work together to retain and strengthen synapses with tectal neurons
PHASE III
What two factors does activity-dependent synaptic remodeling depend upon?
- Electrical activity
- Synaptic signaling
PHASE III
Synaptic remodeling is based on __________
Functional activity
Layer of skin containing fatty subcutaneous tissue ______
Hypodermis
Layer of skin rich in collagen, providing toughness, containing loose & dense connective tissue _______
Dermis
Layer of skin made up of epithelial cells, forming the outer covering of the skin, creating a water barrier and is continuously repaired and renewed ___________
Epidermis
Skin cells turn over every 30 days by virtue of the presence of stem cells in the basal layers is dependent upon ______
Integrin
This layer of the epidermis forms the waterproof barrier and is the boundary between outer dead and inner metabolically active cells
Granule cell layer
The epidermis is a ________ layer made of ____________
Stratified; keratinocytes
The ________ layer of the epidermis is attached to the basal lamina and are the only dividing cells
Basal cell layer
This layer of the epidermis contains numerous desmosomes that attach tufts of keratin filaments
Prickle cells
The outermost layer of the epidermis is the _________ which are flattened dead cells that are densely packed with keratin containing no organelles
Squame
List the epidermal layer of cells from innermost to outermost
BBPGK
- Basal lamina
- Basal layer
- Prickle layer
- Granule cells
- Keratinized
T/F; epidermal cells undergo change in gene expression while moving up the cellular layers of the skin
True; occurs at each step of differentiation
Cells will end up undergoing partial degradation which is dependent upon partial activation of the apoptotic machinery
Partial degeneration of the epidermal cell layers is dependent upon ________
Partial activation of the apoptotic machinery
Basal lamina adhesion is mediated via ___________
Beta-1 subunit of integrin
Stem cells of the epidermis basal layer provide an ________ supply of fresh differentiated cells every ________ days
Indefinite; 30 days
State 4 characteristics of stem cells
- Not terminally differentiated
- Can divide without a limit
- Undergo slow division
- Gives rise to 1 stem cell and a terminally differentiated cell
T/F; Stem cells are not tissue specific
False; tissue specific
i.e. epidermal stem cells, intestinal stem cells, GI stem cells, etc.
Meaning if you relocate them, they will form whats in their memory, not the new location
What percentage of daughter cells via stem cells keep their stem cell qualities?
50%
Define Independent choice of the division of stem cells
Division makes 2 identical cells allowing for the environment to influence its outcome
3 outcomes = 2 stem cells, 1 SC & 1 differentiated, both differentiated
i.e. bodily needs
During asymmetric division of SC, which daughter cell receives the parental DNA?
The new Stem cell
Define transient amplifying cells
Cells that don’t immediately differentiate; rather they go through division rounds then differentiate
Programmed to divide for a limited number of times once they leave the basal layer
A characteristic of asymmetrical and independent choice division
Which stem cell replication contains drawbacks, rendering us unsure of how existing SCs increase their numbers?
Asymmetric division
Which SC replication is more flexible and explains the sharp increase in SC numbers when needed for repair?
Independent choice
Influenced by environment
What factor determines whether a SC stays a SC or commits to differentiation?
Loss of contact
Beta-1 subunit of integrin
What factor controls the number of SCs?
Contact with basal lamina
_______ of contact preserves SC potential
Maintenance
What does overactive Shh cause in the epidermis? What about a deficiency?
Overactivation causes continuous division even after leaving the basal layer
Def = loss of sebaceous glands
What occurs when Wnt is upregulated in the epidermis?
Grows extra hair follicles
Def = no hair follicles
What does TGF-beta promote in the epidermis?
The formation of collagen rich scar tissue
Repairs skin wounds
What does Notch signaling pathway inhibit in the epidermal renewal system?
Restricts the size of the SC population
Lateral inhibition causes them to become transient amplifying cells
Where are sensory neurons located?
Ear, eye, and nose via ectoderm
Describe the structure of olfactory epithelium
Bipolar neuron with dendrites containing modified cilia facing the external environment that detect external stimulus within supporting cells containing a basal end that makes synapses with neurons that relay the sensory info to specific parts of the brain
What is located on the free surfaces of cilia on the dendrites of olfactory neurons? What type of receptor is this?
Odorant receptor proteins
(olfactory receptors)
GPCR acts via Adenylyl cyclase activating cAMP —> ion channels = Ca2+ —> neuron depolarization —> Glomeruli relay station
Odorant receptor genes that are expressed on olfactory neurons respond to how many numbers of odorant classes?
One class of odorant (organic small molecules)
The receptor recognizes structural features of the odorant
What is the function of glomeruli?
Relay stations in the brain where action potentials run through to response to odorant molecules
1800 glomeruli/bulb in mouse brain
Olfactory neurons expressing same odorant receptor are located in diff places in olfactory epithelium but axons all converge on the same glomerulus
How often do olfactory neurons regenerate? Where are these SC located?
Every month via neural stem cells in the olfactory epithelium = basal SCs in contact w/ basal lamina
What is the function of odorant receptor proteins during axonal guidance?
They allow the growth cone to migrate to and establish connection with the correct glomerulus in the olfactory bulb
Hematopoietic stem cells are an example of
Totipotent SCs
Pluripotent SCs
Multipotent SCs
Multipotent
Only can give rise to RBCs and WBCs
List the 5 sources where we can obtain hematopoietic SCs
- Fetal liver
- Bone marrow
- Peripheral blood
- Umbilical cord
- iPS cells
Stromal SCs (from the bone marrow) can give rise to
Hematopoietic SCs
Hematopoietic Supportive Stroma
Erythroid differentiation is mediated by what hormone?
Erythropoietin
List the 7 stages involved in erythroid differentiation
BPO
- CD34+ cells
- Proerythroblast
- Basophilic Normoblast
- Polychomatic Normoblast
- Orthochromatic Normoblast
- Reticulocyte
- Mature RBC
At which stage of erythroid differentiation does the cell lose its nucleus/DNA material?
Reticulocyte
What types of organs/systems can mesenchymal SCs and adipose SCs (adult SCs) give rise to? What is their potential?
- Bone, fat, cartilage
- Muscle
- Nervous system
- Heart
- Vessels
- Kidney
What two types of mesenchymal SCs have to capability to give rise to chondrocytes, myoblasts, osteoblasts, pancreatic beta-cells and neuronal like cells?
BM-derived mesenchymal SCs
Adipose derived mesenchymal SCs
What is a bone marrow transplant and why would one utilize it?
To transplant and form hematopoietic SCs
There is a lot of research done on transplant outcomes
Lots of info is available about marrow donation experience
From whom would an allogenic transplant be most beneficial for a sick patient?
Are the SCs derived from bone marrow or peripheral blood?
Brother/Sister
Low chance to match with parents
Via peripheral blood bc easier to collect, more rapid hematopoietic recovery and less cost
What are some characteristics of founder SCs?
- Derived from embryo but are adult SC bc they remain in body as adult
- Around in finite/fixed numbers
- Go through a fixed number of divisions
- Controlled by short range signals
- Give rise to transient amplifying cells when generating into an organ/tissue
- Pre-determined
- Divides into SC & differentiated daughter cell/transit amp cell
T/F; transit amplifying cells can give rise to a daughter SC
False; continuing rounds of replication give rise to transit daughter SC that will eventually diff once all rounds of division are complete
When using RA to manipulate embryonic SCs, what tissues can it give rise to?
- Neurons (ectodermal)
- Smooth muscle cells (mesoderm); + dibutyryl cAMP
- Adipocyte; + insulin + thyroid hormone
List the three different protocols that are used to differentiate embryonic SCs from undifferentiated SCs
- Embryoid bodies with no stromal cells or ECM protein medium
- Cells diff on stromal cells with embryonic feeders & LIF to initiate diff
- Cells diff on ECM proteins
This is done to analyze all three types
Which SC type provides a solid theoretical and experimental foundation to solve rejection problems and induce development of specialized cell types?
Embryonic SCs
What is a common disadvantage between both early and mature SCs?
Mature - diff to maintain in cell culture for long periods in lab; limited longevity
Early - difficult to control in lab/ may require many steps to coax into desired cell type
Which SC is unlikely to give an immune response? Which one has more likely for immune rejection?
No immune response advantage = mature SC
Possible immune rejection = embryonic/early
Which SC (early or mature) is easier to extract in lab?
Early
Mature = difficult to find and extract from mature tissues
What is the main basis for somatic cell nuclear transfer (SCNt)?
Nucleus is taken from a somatic cell of a patient and injected into oocyte of a donor replacing the oocyte nucleus
The blastocyst generated from the hybrid oocyte and the embryonic SCs are isolated (ICM)
Done to avoid graft rejection
4 genes that induce adult SCs back to ES like cells
Oxt 3/4
Sox2
Myc
KIF4
Direct gene expression manipulation
Multipotent —> Pluripotent
