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48 Cards in this Set

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  • Back
what are the three multicellular kingdoms?
fungi, plant, & animal
Describe the four developmental systems studied.
1.)mammals-complex bodies-many specialized cells, less sensitive to environm.
2.)insects-intricate develop. cycle
3.)flowering plants-flexibilty-array of tissues influenced by environm.
4.)nematodes-very simple design
what are the six stages, in order, of vertebrate development?
cleavage, blastula formation, gastrulation, neurulation, cell migration, & organogenesis
what happens during cleavage?
zygote divides rapidly into large # of blastomeres w/in one hour; no increase in overall size; larger # of smaller cells; two ends referred to as animal pole (becomes external tissues) and vegetal pole (becomes internal tissues); slow after 12 divisions
how does a blastula form?
water is drawn into the cell mass forming a hollow ball of cells
what happens during gastrulation?
-some cells of blastula push inward, forming an invaginated gastrula
-cells move using lamellipodia
-creates main axis of verteb. body
-3 germ layers: ectoderm, mesoderm, & endoderm
what happens during neurulation?
-zone of ectoderm thickens on dorsal surface of embryo
-neural tissue rolls & forms neural tube- gives rise ro brain and spinal cord
what happens during cell migration?
-variety of cells migrate to form distant tissues
-neural crest-form sense organs
-somites-blocks of muscle tissue that form sketal muscle
what happens during organogenesis & growth?
-basic body plan established
-tissues develop into organs
-embryo will grow to be 100x larger
what are the two types of insect body types?
-larvae-gather food, metamorph into...
-adult-capable of flight and reproduction
what are the six stages of insect development?
egg, syncytial blastoderm, larval instars, imaginal discs, metamorphosis, adult
what happens in the egg?
-maternal genes produce mRNA before fertilization
-nurse cells help move mRNA to diff, parts of egg
-determines initial course of development
what happens in syncytial blastoderm?
-after fertilization, 12 rounds of nuclear division w/out cytokinesis produces about 6000 nuclei in a single cytoplasm
what is a syncytium?
a single cell containing many nuclei
what happens during larval instars?
-feeds and grows
-sheds exoskeleton as it grows-exoskeletons do not grow and have to be shed for the insect to grow; 3 larval stages over four days
what are imaginal disks?
-groups of cells that play no role in life of larvae
-committed to form key parts of adult fly
what is imago?
final state of insect when it appears in proper shape and colors
what happens in metamorphosis?
-larvae transformed into pupa
-larval cells break down & nutrients used by imaginal discs to form all parts of adult
-pupa transformed into adult
what are halteres?
counterweights during flight
how do plants develop?
plants build their bodies outward, creating new parts from renewing cells (meristems); plants are anchored and must endure environm. conditions
what are the five stages of plant development?
early cell division, tissue formation, seed formation, germination, and meristematic development & morphogenesis
what happens in early cell division?
embryo (eventually forms shoot) and suspensor (eventually forms roots) are linked
what happens in tissue formation?
3 basic tissues differentiate
1.) epidermal-outermost cell layer
2.) ground-bulk of interior, food, & water storage
3.) vascular-core, food, & water transport
what happens in seed formation?
-flowering plant embryo develops cotyledons & development is arrested
-cotyledons-seed leaves, stores food
-resultant package is known as a seed & is relatively resistant to environm. conditions
what happens in germination?
-embryo w/in seed resumes development in response to changes in the environm. (water, temp., light)
what happens in meristemic development?
-generate cells that form the plant
-hormones influence activity
what happens in morphogenesis?
-form of plant body largely determined by changes in cell shape
describe nematode development.
-nematode C. elegans develops 959 somatic cells from a single fertilized egg
-developmental fate of every cell has been mapped
what are the six basic mechanisms of multicellular development?
cell movement, induction, determination, pattern formation, homeotic genes,and programmed cell death (apoptosis)
describe cell movement.
-cells move by pulling themselves along w/adhesion molecules
-tissues have most volume taken up by extracellular spaces filled w/matrix of polysacch. chains
-migrating cells travers by binding to matrix w/cell surface proteins
what happens in induction?
-occurs when a cell switches from 1 path to another as a result of interactio w/an adjacent cell
-secrete proteins that act as intercellular signals
what are morphogens?
signal molecules that convey positional info to toher cells and are produced by organizer cells
what is determination?
the committment of a cell to a specialized developmental path
what does totipotent mean?
mammalian cells are totipotent which means they are potentially capable of expressing all their genes
when do mammlian cells begin to differentiate?
after 8-cell cycle
what is differentiation?
the cell specializtion that occurs at the end of the developmental path
is determination reversible?
what is pattern formation?
positional info determines the basic pattern of body compartments
what are homeotic genes?
-they are master switch genes
-they code for proteins that function as transcription factors
what happens when mutations occur in homeotic genes?
normal body parts are found in unusual
what is a homeobox?
a sequence of 180 nucleiotides that codes for a 60-amino acid, dna-binding peptide domain called the homeodomain
what is a homeodomain?
a protein that regulates the expression of specific genes; ensures that related genes are transcribed at the proper time.
what is apoptosis?
-process of cells shriveling, shrinking, & dying in a preprogramming timeframe
-program regulated by gene activation
what is necrosis?
-injured cells swell and burst, & release contents into extracellular fluid
what is the accumulated mutation hypothesis?
-as they age, cells accumulate mutations
what is the telomere depletion hypothesis?
-telomeric regions (extra dna at ends of chromo.) shortened by repeated replications
what is the "wear & tear" hypothesis?
-over time,disruption, wear, & damage, eventually erode cell's ability to funct. properly
-no inherent limit to aging
what is gene clock hypothesis?
-genes regulate rate of aging