Comp Exam-Zaidi Flashcards
four major phases of development
- cell division and prolferation: producing many cells from one
- cell differenation and specialization: creating cells with different characeristics
- cell interaction: influences each others behaviors
- cell migration: rearrangement to form layers which give rise to structures such as tissues and organs
all this happens simultaneously in different parts of the developing embryo
homologous proteins are functionally ____
ex
interchangeable
normal mouse lacking engrailed-1 → no cerebellum → drosphilia donated engrailed → cerebellum
conserved mechanisms for development:
- after fertilization the zygote divides ____
- genome is initially ____
- genome becomes active and cells divide and cohere to form a ____ (ball of cells surrounding a hollow cavity)
- blastula then undergoes massive rearrangements to form ____ (has 3 major layers)
- rapidly
- inactive
- blastula
- gastrula
- blastula conists of a sheet of ____ cells facing the external medium
- this sheet give rise to the ____
- ectoderm:
- endoderm:
- mesoderm:
- transformation of blastula (hollow spehre of cells) into a layered structure with a gut caled ___
- epithelial
- ectoderm
- precursor for nervous system and epidermis
- percursor of gut, lung, and liver
- precursor of muscles and connective tissue
- gastrulaution
higher organisms have several homologs of the same gene: ____
gene regulatory proteins - most important for ____
gene duplication
development
instructions for producing a multicellular animal contained in the
non-coding regulatory DNA
____ sequences in DNA similar in most organisms, but ____ sequences make one organism different from another and provide uniqueness
coding
non-coding
cells that are fated to develop into a specialized cell type, despite changes in environment are called ____
cells that can change rapidly due to alterations in environment are called ____ ____
cells that have some attributes of a particular cell type but can change with environment are called ____
determined
completely undetermined
committed
position specific character of cell is called ____
cells retain ____ of positional value
positional value
memory
cellular defferentiation:
- asymmetric division:
- ex:
- symmetric division:
- sister cells born differently ; molecules distributed unequally between daughter cells
- germ cells
- sister cells become different as a result of influences acting on them after their birth (inductive signaling)
inductive signaling:
- most important environmental cues are signals from nieghboring ____
- induction of a different developmental program in select cells in a homogeneous group leading to altered character - ____ signaling
- types of signals:
- ____ range: cell-cell contacts
- ____ range: substances that can diffuse through the extracellular matrix
- cells
- inductive
- short
- long
- short
morphogens:
- morphogen: long range ____ signal that imposes a pattern on a field of cells
- exerts graded effects by forming ____ of different concentrations
- gradient formed by
- localized production of an ____ that diffuses away from its source
- localized production of an ____ that diffsues away from its source and blocks the action of a uniformly distributed inducer
- morphogens need an ____ and ____ system
- inductive
- gradients
- inducer
- inhibitor
- inducer
- on and off
lateral inhibition and positive feedback:
- system starts off ____ and ____
- environment imposes weak ____
- positive feedback ____ effect
- broken asymmetry is ____ or ____ phenomenon
- ____ - once achieved, external signal becomes irrelevant
- ex:
- homogeneous and symmetrical
- asymmetry
- amplifies
- all or none
- irreversible
- delta-notch
ultimate result of inductive events is change in ____ ____
DNA transcription
phases of neural development development:
- phase 1: ____ of neurons → different cell types develop independently at separate locations
- phase 2: ____ of axons and dendrites along specific routes ; ____ formation
- phase 3: ____ of synaptic connections: continues into adult life, occurs through interactions with distant reigosn via electric signals
- genesis
- outgrowth, synaptic
- refinement
origin of the nervous system:
- neurons are produced in associaiton with ____ cells
- CNS is derived from ____ ____
- PNS is derived from ____ ____
- glial
- neural tube
- neural crest
neural crest:
- neural crest cells originate at the ____ end of the neural tube
- migrate extensively during or shrotly after closure of the neural tube - ____
- process
- ____ → ____ → ____ → ____
- dorsal
- neurulation
- proliferate → migrate → aggreagate → differentiate
last born neurons are on the ____ of the cerebral cortex
outside
molecular mechanisms of neuronal migration:
- tip of axon/dendrite has an irregular, spiky enlargement called ____ ____
- one of the growth cones starts migrating fast and develops ____ ____ - this will form the axon
- growth cone behavior is dictated by its ____ machinery
- grow out ____ and ____
- monomeric GTPases ____ and ____ control the assembly/disassebmly of actin filaments which control movement of growth cone
- travel towards targets aong ____ routes
- extracellular matrix environment is sensed by ____ present on membrane
- chemotactic factors are released by neibhboring cells and can be ____ or ____
- growth cone
- axon-specific proteins
- cytoskeletal
- filopodia and lamelopodia
- Rho and Rac
- predictable routes
- receptors
- attractive or repulsive
extracellular matrix (growth cones migration):
- growth cones often follow a path taken by other cells - ____ ____
- mediated by ____ cell adhesion molecules
- two important families
- ____ superfamily
- ____ family
- two important families
- matrix molecules such as ____ favor axonal outgrowth
- matrix molecules such as ____ ____ ____ inhibit growth
- contact guidance
- homophilic
- immunoglobulin
- cadherin
- immunoglobulin
- laminin
- chondroitin sulfate proteoglycans
development of spinal cord:
- ____ neurons of spinal cord receive and relay sensory info from sensory neurons located in the periphery
- ____ clusters of spinal cord neurons develop as motor neurons and send out long axons to connect with muscles
- ____ location has interneurons that connect specific set of nerve cells to each other
- dorsal
- ventral
- intermediate
guidance of commissural neurons:
- ____ is secreted by floor plate and draw neurons towards floor plate
- midline cells secrete ____ , its receptor Roundabout repels growth cones and blocks entry to the midline
- ____ is another repulsive signal that
- growth cone becomes trapped between 2 sets of repellants and travel in a narrow track to the ____
- nectrin
- slit
- semaphorin
- brain
most neurons are made in ____ and up to ____ die after they reach target cell
target cell produces limtied amount of specific ____ factors need for survival
neurons that don’t get enough neurotrophic factors die by:
excesss, 50%
neurotrophic
programmed cell death
adult memory:
synapses are strengthened by external events that cause ____ or more neurons to be activated at the same time
entry of ____ through the glutamate receptor ( ____ receptor) triggers lasting chagne in synaptic strength
individual dendritic ____ remodeled, new spines appear
2
calcium, NMDA
spines
characteristics of stem cells:
- not terminally ____
- can divide without ____
- abilty to ____ themselves
- undergo ____ division
- differentiated
- limit
- renew
- slow
- totipotpency:
- ex
- pluripotency:
- ex
- multipotency:
- ex
- gives rise to all cells of an organism (embryonic and extra-embryonic tissues)
- zygote
- give rise to all cells of the embryo and susequently adult tissues
- embryonic stem cells
- give rise to different cell types of a given lineage
- adult stem cells
maintenance of stem cells:
- asymmetric division:
- independent choice:
- creates 2 cells → one stem cell and one with ability to differentiate
- creates 2 identical cells but outcome is influence by environment
- both can become differentiated, both can remain stem, or combination of the 2
asymmetric division cannot explain how existing stem cells can rapidly increase their ____
numbers
each organ/tissue has fixed number of ____ cell populations programmed to have fixed number of divisions
founder
transit amplifying cells: mixed with stem cells and divide ____
are programmed to divide for a limited ____ of times
frequently
number
adult stem cells need a ____ ____ where they can stay as a stem cell (niche)
specialized microenvironment
epidermis
dermis
hypodermis
outer covering of skin; water barrier
second layer; rich in collagen; tough
fatty subcutatneous layer
cells of the epidermis:
- epidermis is a ____ layer made of ____
- basal cell layer is the only ____ cells in epidermis
- next layer is ____ cells
- next layer is ____ cells which form a waterproof barrier
- forms boundary between inner ____ active strata and ____ dead epidermis cells
- outermost layer is ____ , flattened dead cells densely packed with keratin but no organelles
- stratified, keratinocytes
- dividing
- prickle
- granular
- metabolically, outer
- squame
regulation of epidermal stem cells:
- loss of contact with basal lamina triggers stem cell to ____
- contact with basal lamina is mediated via ____ signaling
- differentiate
- integrin
hair follicle:
- hair grows upward from ____ ____
- ____ glands secrete ____
- stem cells present in ____
- dermal papilla
- sebaceous, sebum
- bulge
upregulation of Wnt signaling causes
underactivation of hedgehog leads to
extra hair follicles to develop (gives rise to tumors)
loss of sebaceous glands
____ plays a key role in repair of skin wounds
TGF-beta
sensory cells present in the senosry epithelium acts as ____ , convering signals from the environment into an electrical form that can be interpreted by CNS
well ____ through evoluation
transducers
conserved
olfactory neurons:
- ____ neurons with a dendrite facing the extracellular environment and an axon that travels along the olfactory nerve to the olfactory ____ in the brain
- many tiny hair-like ____ protrude from the dendrite
- free surfaces of cilia have ____ receptor proteins
- each neuron expresses only one of these genes enabling the cell to respond to only one class of ____
- olfactory receptors are ____
- activated ofactory receptors in turn activate an ____ → ____ → ____ → opens ion channels that results in the influx of ____ and ____ which generates an action potential
- bipolar , bulb
- cilia
- odorant
- odornat
- GPCRs
- Golf → adenylate cyclase → cAMP, sodium and calcium
function of olfactory receptors:
- relay stations in brain called ____
- located in ____ ____, one on each side of the brain
- 1800 glomeruli/bulb in mouse brain
- axons of olfactory neurons (that all express the same odorant receptor) their axons converge on the same ____
- individual olfactory neurons survive for one ____
- regeneration of olfactory receptor cells is one of the only few instance of adult ____ in the CNS
- glomeruli
- olfactory bulb
- glomerulus
- month
- neurogenesis
neurospheres
cluster of neuronal stem cells
can differentitate into neurons and glial cells
evidence for neural stem cells
embryonic stem cells
pluripotency
incapable of generating a full organism
come from inner cell mass of blastocyst
embryonic stem cells:
- ____ → adipocyte
- ____ → neuron
- ____ → macrophage
- ____ → smooth muscle
- ____ → astrocytes and oligodendrocyte
- retinoic acid, insulin, thyroid hormone
- retinoic acid
- macrophage colonly stimulating factor, IL-3,1
- retinoic acid, dibutryryl cAMP,
- fibroblast growth factor
somatic cell nuclear transfer (SCeNT):
- ____ taken from ____ cell of patient and injected into ____ of a donor replacing the oocyte nuclues
- blastocyst generated from this ____ oocyte and ES cell isolated
- nucleus, somatic, oocyte
- hybrid
induced pluripotent stem cell (iPSC):
- adult ____ cells
- expose cells to transcription factors ( ____ , ____ , ____ , ____ )
- low ____
- fibroblast
- Oct4, Sox2, Klf4, Myc
- yield
repair of skin:
- for repopulating damaged area:
- cultured ____ cells from healthy skin regions of patietns used to isolate stem cells
- for immediate replacemnt dermis
- dermis from ____ or artificial matrix used as barrier preventing water loss
- a matrix of ____ and ____ made into a sheet lined with a thin membrane of ____ rubber on the outside
- ____ and blood ____ from patient’s tissue migrate towards the artificial skin and reform the connective tisue underneath
- epidermal
- cadaver
- collagen and glycosaminoglycan, silicone
- fibroblasts and blood capillaries
