Comp Exam-Zaidi

four major phases of development

homologous proteins are functionally ____ ex

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)

• 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 ___

higher organisms have several homologs of the same gene: ____ gene regulatory proteins - most important for ____

instructions for producing a multicellular animal contained in the

____ sequences in DNA similar in most organisms, but ____ sequences make one organism different from another and provide uniqueness

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 ____

position specific character of cell is called ____ cells retain ____ of positional value

cellular defferentiation: • asymmetric division: • ex: • symmetric division:

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

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

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:

ultimate result of inductive events is change in ____ ____

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

origin of the nervous system: • neurons are produced in associaiton with ____ cells • CNS is derived from ____ ____ • PNS is derived from ____ ____

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 • ____ → ____ → ____ → ____

last born neurons are on the ____ of the cerebral cortex

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 ____

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 • matrix molecules such as ____ favor axonal outgrowth • matrix molecules such as ____ ____ ____ inhibit growth

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

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 ____

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:

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