Dr. Zaidi Test Three Flashcards
1
Q
What are the universal features of animal development?
A
All organisms begin as a single cell (zygote) Genome of all cells in organism are identical but expression of genes is different Differential gene expression controls development
2
Q
What are the four major phases in development?
A
- Cell proliferation: cells divide and main goal is to survive
- Cell specialization: differentiation begins and cells express different phenotypes
- Cell interaction: cells influence each others behavior
- Cell migration: rearrangements to form layers giving rise to organs and tissues
All happens simultaneousy in diffferent parts of developing embryo
3
Q
What is meant by cells have a memory?
A
Memory is considred the proteins, RNA, lipids, DNA and DNA marks
Cells have records of signals their ancestors received during development
4
Q
Example of how basic machinery for development is similar across all organisms?
A
Homologous proteins are functionally interchangable:
- Protein called Engrailed-1 provides cerebellum development and in mice lacking this protein it can be replaced by the homolog in flies and development occurs normally
5
Q
What is the blasutla, and its signifigance with stem cells?
A
Blastula is a stage in embryonic development when the genome becomes activated and cells divide forming a ball of cells around a hollow cavity.
- inner mass is found in the blastula which contains stem cells
6
Q
What is gastrulation?
A
The blastula undergoes gastrulation to form the gastrula (sheet of epi. cells facing external), which gives rise to the endoderm, ectoderm, and mesoderm.
7
Q
What does the ectoderm give rise to?
A
- Nervous system precursor and epidermis
8
Q
What does the endoderm give rise to?
A
precursor of gut lung and liver
9
Q
what does the mesoderm give rise to?
A
Muscles and CT
10
Q
Where are the “instructions” for producing a multicellular animal found?
A
Within the non coding regions of DNA associated with each gene
11
Q
What serves as binding sites for gene regulatory proteins?
A
Regulatory elements
Regulatory DNA defines the sequential program for development
12
Q
What provides uniqueness to organisms?
A
Noncoding sequences
13
Q
What does it mean for a cell to be determined?
A
Cells are fated to develop into a specialized type despite changes in their environment
14
Q
What does it mean for a cell to be completely undetermined?
A
Can rapidly change due to alterations in its environment
15
Q
What are the two cellular differentiation mechanisms?
A
- Assymetric Division
- Changes in environment after birth
16
Q
What are the mos important environmental cues?
A
Signals from neighobring cells
17
Q
What is inductive signaling?
A
Induction of a different developmental program in cells leading to a different characteristic
18
Q
What are the two types of signaling in inductive signaling?
A
- Short range such as cell to cell contact
- Long range such as hormones or NT
19
Q
What is a morphogen?
A
Type of long range inductive signal that imposes a pattern on a field of cells creating gradients of different concentrations leading to different developmental paths.
20
Q
What forms the gradient produced by morphogens?
A
- localized production of an inducer that diffuses away from the source
- Localized production of an inhibitor that diffuses awasy from source and blocks action of a unifromly distributed inducer
21
Q
What are morphogens on and off system?
A
Antagonists or extracellular inhibitors can bing to the signal or its receptor to block the interaction
22
Q
What is the relationship between lateral inhibition and positive feedback?
A
The cells start out homogenous and symmetrical and the environment imoposes weak asymmetry and positive feedback amplifies the asymmetry. The asymmetry is an all or none irreversible step.
23
Q
What causes diversity in pattern?
A
- Combinatorial control: response of cell to signal with a second signal may be different than if it were just one signal or three.
- Cell memory: effect of a given signal depends on previous experiences
- Sequental induction: signals given at different times
24
Q
What is the ultimate result of inductive events?
A
change in DNA transcription
25
What is the ligand and receptor family for Notch signling pathway?
Delta is ligand Notch is receptor
26
Ligand and receptor for RTK's?
Ligand is EGF and receptor is EGF family
27
What is the receptor and ligand for TGFBeta superfamily?
Receptor is TGFB receptor and ligand is TGFB
28
What is the ligand and receptor for Wnt?
Ligand is Wnt (wingless) receptor is Frizzled
29
What is the ligand and receptor for Hedgehog?
Ligand is hedgehog and receptor is Patched,Smoothened
30
What are the phases of neural development?
1. Different cell types develop independently of each other at different locations in the embryo survival is focus
2. Axons and dendrites grow out along specific routes setting up an orderly network of connections. Goal is to have functional connections
3. Connections are adjusted and refined through interactions with distand regions through electrical signaling. Continues throughout life. If not stimulated synapses dissapear.
31
What germinal layer is the CNS derived from and what structure within that more specifically?
(CNS includes brain spinal cord and retina)
Ectoderm; Neural tube
32
What germinal layer is the PNS developed from and more specifically what structure?
(PNS includes nerves and sensory neurons)
Ectoderm;Neural crest
33
How does the neural tube form?
* Starts with neural groove on dorsal side of embryo
* Groove deepens and neural folds become elevated
* Eventually the folds meet and come together at the midline to from the neural tube
34
How does the neural tube act like a morphogen?
Signaling proteins are secreted from ventral and dorsal side of the tube causing neurons at different positions to express different regulatory proteins
35
Where is BMP and Wnt proteins secreted from?
The roof plate and adjacent cells of the neural tube
BMP is TGFbetal superfamily
36
Where is Sonic Hedgehog secreted from?
Neural tube floor plate and notochord.
Depends on proteoglycans for function
37
Where does the neural crest originate from and how does it form?
Originate at the dorsal end of the neural tube and migrate extensively shortly after or during neurulation to generate different cells of the PNS.
38
What are a few cells types from the neural crest?
1. Neurons and glial cells of PNS
2. Epinephrine producing cells of adrenal gland
3. Skeletal and CT components of head
39
How do neurons migrate?
Radial glial cells act as a scaffold for neurons to crawl on
40
How do the cerebral cortex layers form?
The neurons climb up the radial glial cells and create a layer, as they climb they never settle before another layer. Top layer is the youngest
41
What is the molecular mechanism of neuronal migration?
* Axons and dendrites are indistinguishable and have spiky enlargement called growth cone
* Growth cone crawls trailing the axon or dendrite behind
* Fastest growing neurite becomes axon
42
Growth cone behavior?
* dictated by cytoskeletal macinery
* Growth cones move through filopodia and lamelopodia controlled by monomeric GTPases Rho and Rac
* GC withdrawl from unfavorable surfaces and steer towards favorable ones
43
How do growth cones find their target?
1. Extracellular matrix environment sensed by receptors present on the membrane
2. CHemotactic factors released by neighboring cells can be attractive or repulsive
44
What is the function of an interpolar microtubule?
The plus ends of the MT coming from one pole interac with the plus end from the other pole
45
Viral protein E6 binds to which of the following?
a. p21
b. p53
c. Rb
D.ATM
P53
46
What encodes for Complexes I-V in mitochondria?
Mitochondrial and Nuclear DNA
47
An embryonic cell is cultured and exposed to Retinoic acid leaading it to develop neural traits, it is then exposed to insulin and thyroid hormone and it is observed that the cell becomes an adipocyte. What kind of cell is this?
Committed cell
48
Where is delta and notch found respectively?
Neuron membrane and the inhibited epithelial membrane
49
What is an inhibitory ligand?
a. delta
b. notch
c. breathless
d. frizzled
Delta
50
A growing commissural neuron is unable to initiallly move towards the floor plate. what found on the neuron is most likely missing?
The netrin receptor to receive netrin being released by the floor plate
51
What is not a characteristic of stem cells?
a. self renewal
b. undergo slow divisioin
c. terminally differentiated
d. limitless differentiation
Terminally differentiated
52
Waterproofing of the skin comes from what kind of cells?
Granular cells
53
The stratum spinosum layer of the skin contains numerous \_\_\_.
prickle cells
54
What is associated with remaining stem cell potential in skin cells?
contact with the basal lamina and Beta1 subunit of integrins
55
What could be predicted from a lack of TGFB?
Impaired wound healing
56
What will happen to olfactory transmission if there is an increase in cAMP?
An increase will result in transmission of olfaction
57
Which of the following regarding neurospheres is true?
a. comprised of neural stem cells only
b. .capacity to propagate through generations
c. not dependent on environment
d. B and C
e. all
They have the capacity to propagate through generations
58
Which of the following is a potential implication of the neurosphere?
a. understanding carb metabolism in the frontal lobe
b. understanding effects of oxidative stress in occipital lobe
c. understanding hte protective mechanism of testosterone in the hippocamups
d. all
Understanding the protective mechanism of testosterone in the hippocampus
59
Which of the following regarding endogenous neurogenesis in hte hippocampus is true?
a. learning can be a stimulus
b. antidepressants can be a stimulus
c. decreases with age
d. A and C
e. all
All
60
Which of the following regarding planarian regeneration and neoblasts is true?
a. neoblast alone can regenerate entire planarian body
b. neoblast alone can regenerate only parts of body
c. neoblast alone cannot regenrate the entire body
d. planarian does not have the capacity to repetitively shrink and grow
neoblast cannot regenerate the entire body
61
Which of the following are correctly paired?
a. multipotenet:inner cell mass
b. totipotent: placenta
c. pluripotent: basal lamina
d. pluipotent: trophoblast
Totipotent and placenta
| (B)
62
An ES cell is cultured and harvested and exposed to RA, what tissue would this cell most likely be found in?
Nervous
63
What describes SCeNT most accurately?
a. cells from the ICM are isolated from a blastocyst created from fusion of egg and sperm
b. cells from th eicm are isolated from blastocyst created from fusion of egg and fibroblast
c. fibroblast isolated in culture with Oct4
d. Cell from icm are isolated and exposed to FGF
Cells from the ICM are isolated from a blastocyst created from fusion of egg and fibroblast
64
What matrix molecules favor axonal outgrowth?
Laminin
65
What favors inhibition of axonal growth?
Chondroitin sulfate proteoglycans
66
When netrin binds to its receptor on the neuron what happens to allow the neuron to move?
Opening of calcium channels occurs allowing entry of extracellular calcium leading to activation fo filopodia for movement
67
Where is slit secreted from?
Midline of floor plate to repel growth cones and block entry to the midline (along with semaphorin)
68
What regulates which growth cones synapse and where they synapse?
signals from target tissues when the axonal growth cone reaches the target cells after moving through the narrow track provided by slit and semaphorin
69
How much neurotrphic factor is secreted comared to how many neurons are made, and what occurs to those that do not get the NF?
Neurons are made in excess by roughly 50% and the target cells produces a limited amount of Neurotrphic factors and those that do not get enough die by apoptosis.
(this can be reversed by increasing the number of target cellls and exacerbated by decreasing the number of target cells)
70
What was the first prototypical neurotrphic factor to be identified, what is its receptor and what does it do?
Nerve growth factor
RTK
promotes survivial of specific sensory neurons and sympathetic neurons
71
What are the short term effects of NGF?
effect on growth cone is local direct and rapid and independent of communication with the cell body
72
What is the long term effect of NGF?
effect is on cell survival, mediated by receptor and endocytosis and stimulation of downstream paths
73
Totipotent?
Can develop into anything, including extra-embryonic tissues
(zygote)
74
Pluripotent?
can give rise to all cells of the embryo except extra embryonic tissues. (embryonic stem cells)
75
Multipotent?
(adult stem cells)
can give rise to different cell types of a lineage
76
How is a steady pool of stem cell population maintained?
* asymmetric division: create two cells one that becomes a stem cell and the other that differentiates
* Independent choice: division makes two identical cells but the outcome is influenced by environment
77
What are the drawbacks to asymmetric division of stem cells and why is independent choice more accpetable?
* cant explain how existing stem cells rapidly increase their numbers
* More flexible and explains the sharp increase in stem cells when they are needed, it doesn't have to be 1:1 every time
78
What are founder stem cells?
SC that have a fixed number of divisions and they are controlled by short ragne signals. They define the size of the final structures. They can divide and give rise to one daughter cell that remains a stem cell and a set of cells that have a set of transit amplifying divisions
79
How do transit amplifying cells play a role in the strategy for growth control?
they are programmed to divide a limited number of times
80
What layer in the epidermis has numerous desmosomes that attach tufts of keratin filaments?
Prickle cells (spinosum)
81
Hair follicles undergo cycles of \_\_\_, \_\_\_, \_\_\_\_.
Growth
Regression
Reconstruction- bulge of stem cells
82
If there is an overactivation of hedgehog pathway what can occur?
Cell layer continues to divide even if the cells are no longer attached to the basal lamina, can lead to cancer.
Oppositely if there is a defecit it can lead to loss of sebaceous glands
83
hat occurs if there is an up regualtion of Wnt signaling?
Extra hair follicles to develop giving rise to tumors.
Loss of Wnt would lead to failure of hair follicle development
84
What does notch signaling do in the epidermis?
restricts the size of stem cell population
85
What does lateral inhibition cause in epidermis?
causes neighbors of stem cells to become transit amplifying cells
86
TGFB plays key role in what?
skin wound repair promoting formation of collagen rich scar tissue
87
Describe the structure of an olfactory neuron.
Bipolar neuron with a dendrite that faces the extracellular environment and an axon that travels into the olfactory bulb via olfactory nerve
88
What kind of protein are odorant receptor proteins?
G protein coupled receptor
Golf
89
Describe how olfaction occurs.
* olfactory receptor binds to an odorant molecule
* the receptor activates an intracellular g protein (golf)
* which activates adenylate cyclase producing cAMP
* cAMP opens ion channels resulting in influx of Na and Ca
* Positive ions cause neuron to depolarize causing AP
* AP travels along axon to relay station in brain called glomeruli inside the olfactory bulbs
90
How do olfactory neurons reach the correct glomerulus in the olfactory bulb when regenerated?
Basal stem cells divide and differentiate into olfactory neurons and the odorant receptor proteins help guid axonal growth cone to establish correct connections
91
Where else in the brain is there evidence of stem cells?
* Ventricles of forebrain: lining ventricles continuiously divide and migrate to olfactory bulb
* hippocampus: involved in memory and learning, continuous turnover. NON COMMITTED SC
92
What are neoblasts?
Undifferentiated stem cells that continually differentiate into body cells that are dying by apoptosis, cell corpses are phagocytosed (cell canabolism)
Injection of a single neoblast into an animal that looses ability to undergo cell division can save it
93
What SC are capable of proliferating indefinitely in culture with no restriction of development potential, and where are they cultured from?
Embryonic stem cells - Pluripotent
(cant generate full organism though)
Inner cell mass
94
What occurs if the ES cells are injected into an embryo or adult at later stage when they have not been given cues for proper differentiation?
Teratomas form
95
What is somatic cell nuclear transfer?
Combines cloning methods with embryonic stem cell tech. to produce custom made cells.
* take nucleus from somatic cell and inject it into oocyte and generate a blastocyst to isolate ES cells from
can treat type one diabetes
96
What are problems with SCeNT?
Inefficient need a lot of eggs and challenging not widely available
97
What is induced pluripotent stem cells?
Reprogram somatic cells to act like a pluripotent cell
* uses Oct4, Sox2, Klf4, Myc, Nanog
* Inject one of the five candidate genes into a fibroblast and they form ES like cells and can differentiate into othe cell types
* Low yield
98
What are the challenges of regenerative mediine and transplantation therapy?
* Production of cell in pure form
* Sufficient numbers produced
* Longevity and stability in culture
* delivery method
* proper integration into tissue
* \*tissue immune rejection
* \* genetic and epigenetic aberrations
99
MERRF
MYOCLONUS EPILEPSY WITH RAGGED RED FIBERS
* 90% results from a point mutation in tRNAlys
* myoclonus
* myoclonic epilepsy
* ataxia
* siezures
* dementia
100
MELAS?
Mitochondrial encephalopathy lactic acidosis and stroke like episodes
* Point mutation in tRNAleu (A changes to G)
* onset between 2 and 10
* blindness
* headaches
* anorexia and recurrent vomitting
* lactic acidosis
* RRF
* storke like episodes and siezures
101
KSS
Kearns-Sayre Syndrome
* Deletion or rearrangement and insertions in mtDNA
* Retinitis pigentosa leading to blindness
* cardiac conduction abnormality
* cerebellar ataxia
* cerebral spinal protein level \>100mg/dL
* Onset before 20
102
CPEO
Chronic Progressive External Opthalomplegia
* Ptosis
* RRF
* Caused by mtDNA rearrangements
103
LHON
Leber Hereditary Optic Neuropathy
* Optic nerve not muscle
* acute bilateral or central vision loss leads to blindless
* degeneration of retinal ganglion cell layer and optic nerve
* age of onset is 20-30
* MUTATION IN COMPLEX ONE PROTEINS
