Comp Exam-Zaidi

Question 1

four major phases of development

Answer 1

1. cell division and prolferation: producing many cells from one
2. cell differenation and specialization: creating cells with different characeristics
3. cell interaction: influences each others behaviors
4. 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

Question 2

homologous proteins are functionally ____

ex

Answer 2

interchangeable

normal mouse lacking engrailed-1 → no cerebellum → drosphilia donated engrailed → cerebellum

Question 3

conserved mechanisms for development:

1. after fertilization the zygote divides ____
2. genome is initially ____
3. genome becomes active and cells divide and cohere to form a ____ (ball of cells surrounding a hollow cavity)
4. blastula then undergoes massive rearrangements to form ____ (has 3 major layers)

Answer 3

1. rapidly
2. inactive
3. blastula
4. gastrula

Question 4

• 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 ___

Answer 4

• epithelial
  
  • ectoderm
• precursor for nervous system and epidermis
• percursor of gut, lung, and liver
• precursor of muscles and connective tissue
• gastrulaution

Question 5

higher organisms have several homologs of the same gene: ____

gene regulatory proteins - most important for ____

Answer 5

gene duplication

development

Question 6

instructions for producing a multicellular animal contained in the

Answer 6

non-coding regulatory DNA

Question 7

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

Answer 7

coding

non-coding

Question 8

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 ____

Answer 8

determined

completely undetermined

committed

Question 9

position specific character of cell is called ____

cells retain ____ of positional value

Answer 9

positional value

memory

Question 10

cellular defferentiation:

• asymmetric division:
  
  • ex:
• symmetric division:

Answer 10

• 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)

Question 11

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

Answer 11

• cells
• inductive
• • short
    
    • long

Question 12

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

Answer 12

• inductive
• gradients
• • inducer
    
    • inhibitor
• on and off

Question 13

lateral inhibition and positive feedback:

1. system starts off ____ and ____
2. environment imposes weak ____
3. positive feedback ____ effect
4. broken asymmetry is ____ or ____ phenomenon
5. ____ - once achieved, external signal becomes irrelevant
6. ex:

Answer 13

1. homogeneous and symmetrical
2. asymmetry
3. amplifies
4. all or none
5. irreversible
6. delta-notch

Question 14

ultimate result of inductive events is change in ____ ____

Answer 14

DNA transcription

Question 15

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

Answer 15

• genesis
• outgrowth, synaptic
• refinement

Question 16

origin of the nervous system:

1. neurons are produced in associaiton with ____ cells
2. CNS is derived from ____ ____
3. PNS is derived from ____ ____

Answer 16

1. glial
2. neural tube
3. neural crest

Question 17

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
  
  • ____ → ____ → ____ → ____

Answer 17

• dorsal
• neurulation
• • proliferate → migrate → aggreagate → differentiate

Question 18

last born neurons are on the ____ of the cerebral cortex

Answer 18

outside

Question 19

molecular mechanisms of neuronal migration:

1. tip of axon/dendrite has an irregular, spiky enlargement called ____ ____
2. one of the growth cones starts migrating fast and develops ____ ____ - this will form the axon
3. growth cone behavior is dictated by its ____ machinery
   
   1. grow out ____ and ____
   2. monomeric GTPases ____ and ____ control the assembly/disassebmly of actin filaments which control movement of growth cone
   3. travel towards targets aong ____ routes
      
      1. extracellular matrix environment is sensed by ____ present on membrane
      2. chemotactic factors are released by neibhboring cells and can be ____ or ____

Answer 19

1. growth cone
2. axon-specific proteins
3. cytoskeletal
   
   1. filopodia and lamelopodia
   2. Rho and Rac
   3. predictable routes
      
      1. receptors
      2. attractive or repulsive

Question 20

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

Answer 20

• contact guidance
• homophilic
  
  • • immunoglobulin
      
      • cadherin
• laminin
• chondroitin sulfate proteoglycans

Question 21

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

Answer 21

• dorsal
• ventral
• intermediate

Question 22

guidance of commissural neurons:

1. ____ is secreted by floor plate and draw neurons towards floor plate
2. midline cells secrete ____ , its receptor Roundabout repels growth cones and blocks entry to the midline
3. ____ is another repulsive signal that
4. growth cone becomes trapped between 2 sets of repellants and travel in a narrow track to the ____

Answer 22

1. nectrin
2. slit
3. semaphorin
4. brain

Question 23

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:

Answer 23

excesss, 50%

neurotrophic

programmed cell death

Question 24

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

Answer 24

2

calcium, NMDA

spines

Question 25

_characteristics of stem cells:_ 1. not terminally \_\_\_\_ 2. can divide without \_\_\_\_ 3. abilty to ____ themselves 4. undergo ____ division

Answer 25

1. differentiated 2. limit 3. renew 4. slow

Question 26

* totipotpency: * ex * pluripotency: * ex * multipotency: * ex

Answer 26

* 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

Question 27

_maintenance of stem cells:_ 1. asymmetric division: 2. independent choice:

Answer 27

1. creates 2 cells → one stem cell and one with ability to differentiate 2. creates 2 identical cells but outcome is influence by environment 1. both can become differentiated, both can remain stem, or combination of the 2

Question 28

asymmetric division cannot explain how existing stem cells can rapidly increase their \_\_\_\_

Answer 28

numbers

Question 29

each organ/tissue has fixed number of ____ cell populations programmed to have fixed number of divisions

Answer 29

founder

Question 30

transit amplifying cells: mixed with stem cells and divide \_\_\_\_ are programmed to divide for a limited ____ of times

Answer 30

frequently number

Question 31

adult stem cells need a ____ \_\_\_\_ where they can stay as a stem cell (niche)

Answer 31

specialized microenvironment

Question 32

epidermis dermis hypodermis

Answer 32

outer covering of skin; water barrier second layer; rich in collagen; tough fatty subcutatneous layer

Question 33

_cells of the epidermis:_ 1. epidermis is a ____ layer made of \_\_\_\_ 2. basal cell layer is the only ____ cells in epidermis 3. next layer is ____ cells 4. next layer is ____ cells which form a waterproof barrier 1. forms boundary between inner ____ active strata and ____ dead epidermis cells 5. outermost layer is ____ , flattened dead cells densely packed with keratin but no organelles

Answer 33

1. stratified, keratinocytes 2. dividing 3. prickle 4. granular 1. metabolically, outer 5. squame

Question 34

_regulation of epidermal stem cells:_ 1. loss of contact with basal lamina triggers stem cell to \_\_\_\_ 2. contact with basal lamina is mediated via ____ signaling

Answer 34

1. differentiate 2. integrin

Question 35

_hair follicle:_ 1. hair grows upward from ____ \_\_\_\_ 2. ____ glands secrete \_\_\_\_ 3. stem cells present in \_\_\_\_

Answer 35

1. dermal papilla 2. sebaceous, sebum 3. bulge

Question 36

upregulation of Wnt signaling causes underactivation of hedgehog leads to

Answer 36

extra hair follicles to develop (gives rise to tumors) loss of sebaceous glands

Question 37

\_\_\_\_ plays a key role in repair of skin wounds

Answer 37

TGF-beta

Question 38

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

Answer 38

transducers conserved

Question 39

_olfactory neurons:_ 1. ____ neurons with a dendrite facing the extracellular environment and an axon that travels along the olfactory nerve to the olfactory ____ in the brain 2. many tiny hair-like ____ protrude from the dendrite 3. free surfaces of cilia have ____ receptor proteins 1. each neuron expresses only one of these genes enabling the cell to respond to only one class of \_\_\_\_ 4. olfactory receptors are \_\_\_\_ 1. activated ofactory receptors in turn activate an ____ → ____ → ____ → opens ion channels that results in the influx of ____ and ____ which generates an action potential

Answer 39

1. bipolar , bulb 2. cilia 3. odorant 1. odornat 4. GPCRs 1. Golf → adenylate cyclase → cAMP, sodium and calcium

Question 40

_function of olfactory receptors:_ 1. relay stations in brain called \_\_\_\_ 1. located in ____ \_\_\_\_, one on each side of the brain 2. 1800 glomeruli/bulb in mouse brain 2. axons of olfactory neurons (that all express the same odorant receptor) their axons converge on the same \_\_\_\_ 3. individual olfactory neurons survive for one \_\_\_\_ 4. regeneration of olfactory receptor cells is one of the only few instance of adult ____ in the CNS

Answer 40

1. glomeruli 1. olfactory bulb 2. 2. glomerulus 3. month 4. neurogenesis

Question 41

neurospheres

Answer 41

cluster of neuronal stem cells can differentitate into neurons and glial cells evidence for neural stem cells

Question 42

embryonic stem cells

Answer 42

pluripotency incapable of generating a full organism come from inner cell mass of blastocyst

Question 43

embryonic stem cells: 1. ____ → adipocyte 2. ____ → neuron 3. ____ → macrophage 4. ____ → smooth muscle 5. ____ → astrocytes and oligodendrocyte

Answer 43

1. retinoic acid, insulin, thyroid hormone 2. retinoic acid 3. macrophage colonly stimulating factor, IL-3,1 4. retinoic acid, dibutryryl cAMP, 5. fibroblast growth factor

Question 44

_somatic cell nuclear transfer (SCeNT):_ 1. ____ taken from ____ cell of patient and injected into ____ of a donor replacing the oocyte nuclues 2. blastocyst generated from this ____ oocyte and ES cell isolated

Answer 44

1. nucleus, somatic, oocyte 2. hybrid

Question 45

_induced pluripotent stem cell (iPSC):_ 1. adult ____ cells 2. expose cells to transcription factors ( ____ , ____ , ____ , ____ ) 3. low \_\_\_\_

Answer 45

1. fibroblast 2. Oct4, Sox2, Klf4, Myc 3. yield

Question 46

_repair of skin:_ 1. for repopulating damaged area: 1. cultured ____ cells from healthy skin regions of patietns used to isolate stem cells 2. for immediate replacemnt dermis 1. dermis from ____ or artificial matrix used as barrier preventing water loss 2. a matrix of ____ and ____ made into a sheet lined with a thin membrane of ____ rubber on the outside 3. ____ and blood ____ from patient's tissue migrate towards the artificial skin and reform the connective tisue underneath

Answer 46

1. 1. epidermal 2. 1. cadaver 2. collagen and glycosaminoglycan, silicone 3. fibroblasts and blood capillaries