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LS 1 Final
not cumulative, lectures after 2nd midterm
35
Biology
Undergraduate 1
03/11/2008

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Term
important traits to distinguish protostomes
Definition
dorsal brain connected to a ventral nerve cord
Term
What unites protostomes?
Definition
nephrozoa - they all have exretory system. [kidneys or something like it]
Term
2 categories of protostomes
Definition
ecdysozoa and lopophores
Term
lophophore
Definition
bryozoans and brachiopods - tentacle like structures around their mouths to guide in plankton
Term
Ecdysozoa growth?
Definition
shedding exoskeleton [molting or ecsysis]
Term
ecdysozoans include?
Definition
insects,spiders, and crustaceans
Term
limitations on ecdysozoan growth
Definition
-exoskeleton made of chitin or secondarily laid down in calcium carbonate
-Limbs are armored and so muscles have to attach between those joints and on internal surfaces
Term
Constraints during ecdysozoan growth
Definition
-Growth can’t be continuous
-must occur through numerous cycles of deposition of the exoskeleton followed by molting or disassembly of it
Term
instar
Definition
ecdysozoan between molts while it is in larval stage; resembles the one before it
Term
types of molting
Definition
complete and incomplete metamorphosis
Term
complete metamorphosis
Definition
insect development in which egg, larval, pupal, and adult stages occur, each differing greatly in morphology
Term
pupal stage in ecdysozoan
Definition
after last larval instar, stays inactive to avoid harsh weather, hardens quickly, and all pigmentation occurs rapidly
Term
animal hemisphere
Definition
region of egg where sperm enters
Term
zygote
Definition
a single diploid cell that has just undergone nuclear fusion – the nucleus of the sperm fuses with genetic material of egg to form genetic nucleus of ________
Term
blastula, blastocoel
Definition
results from early cell division; hollow cavity inside called ______
Term
blastula, blastocoel
Definition
results from early cell division; hollow cavity inside called ______
Term
dorsal; ventral
Definition
animal pole; vegetal pole
Term
gastrula
Definition
continuous growth of cells in various regions of ______ are becoming differentiated into endoderm, mesoderm and ectoderm
Term
archenteron
Definition
[primitive gut] becomes endoderm in gastrula
Term
movements due to cytoskeleton
Definition
The actin fiber of the cell can move expand or contract and they create furrow that grows deep enough for the two cells to form on either side. Eventually 2 daughter cells will form due to __________
Term
cleavage plane
Definition
separate cytoplasm into 2 separate compartments [each with its own cytoplasmic content]
Term
sea urchins
Definition
have complete cleavage where a plane of separation cuts completely through the dividing cell and all subsequent mitosis is the same.
Term
distribution of yolk in zygote
Definition
more yolk is found in vegetal pole then animal pole and results in different cell size [small at animal pole].
Term
incomplete cleavage
Definition
lots of yolk at vegetal pole,so it isn't cut in two -- results in mitotic activity on top so embryonic activity happens above the yolk
Term
superficial cleavage[peculiar to protostomes]
Definition
cytopasmic contents are distributed evenly and mitosis occurs, numerous nuclei are produced but no plane of separation - happens at the early stage
Term
syncitium
Definition
fungi; single cell with multiple nuclei [nuclear divisions but no cell division until later] - forms a yolk pore and a single layer of embryonic cells b/c the nuclei migrate to the periphery
Term
asynchronous
Definition
lots of nuclear divisions without any mitosis and sometimes it can lag behind the rapid rate of nuclear division - and maybe you can get only a few nuclei per mitotic round
Term
synchronous
Definition
every time you get a nuclear division, you also get a cellular division, and each resulting daughter cell ends up with one nucleus
Term
blastomere
Definition
early daughter cells of original zygote
Term
purpose of hollow hole in blastocele
Definition
ensures seperation between activities that are occurring up and down poles and this is one of the keys to differentiation in the embryo
Term
totipotential
Definition
developmental ability to produce viable organisms
Term
3 stages of cell differentiation
Definition
totipotent, pluripotent, committed cell lineages
Term
example of pluripotent cell
Definition
bone marrow - give rise to numerous different types of blood -- cannot go back and form other tissues
Term
cytoplasmic segregation
Definition
certiain cytoplasmic determinants exist in the egg -- equally distributed = totipotency; uneven = committed to different fates
Term
transcription factor
Definition
proteins that bind to DNA and control what genes get turned on during transcription [gene expression]
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