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48 Cards in this Set
- Front
- Back
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what are the three multicellular kingdoms?
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fungi, plant, & animal
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Describe the four developmental systems studied.
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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 |
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what are the six stages, in order, of vertebrate development?
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cleavage, blastula formation, gastrulation, neurulation, cell migration, & organogenesis
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what happens during cleavage?
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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
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how does a blastula form?
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water is drawn into the cell mass forming a hollow ball of cells
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what happens during gastrulation?
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-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 |
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what happens during neurulation?
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-zone of ectoderm thickens on dorsal surface of embryo
-neural tissue rolls & forms neural tube- gives rise ro brain and spinal cord |
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what happens during cell migration?
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-variety of cells migrate to form distant tissues
-neural crest-form sense organs -somites-blocks of muscle tissue that form sketal muscle |
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what happens during organogenesis & growth?
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-basic body plan established
-tissues develop into organs -embryo will grow to be 100x larger |
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what are the two types of insect body types?
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-larvae-gather food, metamorph into...
-adult-capable of flight and reproduction |
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what are the six stages of insect development?
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egg, syncytial blastoderm, larval instars, imaginal discs, metamorphosis, adult
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what happens in the egg?
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-maternal genes produce mRNA before fertilization
-nurse cells help move mRNA to diff, parts of egg -determines initial course of development |
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what happens in syncytial blastoderm?
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-after fertilization, 12 rounds of nuclear division w/out cytokinesis produces about 6000 nuclei in a single cytoplasm
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what is a syncytium?
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a single cell containing many nuclei
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what happens during larval instars?
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-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 |
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what are imaginal disks?
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-groups of cells that play no role in life of larvae
-committed to form key parts of adult fly |
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what is imago?
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final state of insect when it appears in proper shape and colors
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what happens in metamorphosis?
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-larvae transformed into pupa
-larval cells break down & nutrients used by imaginal discs to form all parts of adult -pupa transformed into adult |
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what are halteres?
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counterweights during flight
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how do plants develop?
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plants build their bodies outward, creating new parts from renewing cells (meristems); plants are anchored and must endure environm. conditions
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what are the five stages of plant development?
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early cell division, tissue formation, seed formation, germination, and meristematic development & morphogenesis
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what happens in early cell division?
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embryo (eventually forms shoot) and suspensor (eventually forms roots) are linked
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what happens in tissue formation?
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3 basic tissues differentiate
1.) epidermal-outermost cell layer 2.) ground-bulk of interior, food, & water storage 3.) vascular-core, food, & water transport |
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what happens in seed formation?
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-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 |
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what happens in germination?
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-embryo w/in seed resumes development in response to changes in the environm. (water, temp., light)
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what happens in meristemic development?
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-generate cells that form the plant
-hormones influence activity |
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what happens in morphogenesis?
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-form of plant body largely determined by changes in cell shape
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describe nematode development.
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-nematode C. elegans develops 959 somatic cells from a single fertilized egg
-developmental fate of every cell has been mapped |
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what are the six basic mechanisms of multicellular development?
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cell movement, induction, determination, pattern formation, homeotic genes,and programmed cell death (apoptosis)
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describe cell movement.
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-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 |
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what happens in induction?
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-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 |
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what are morphogens?
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signal molecules that convey positional info to toher cells and are produced by organizer cells
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what is determination?
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the committment of a cell to a specialized developmental path
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what does totipotent mean?
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mammalian cells are totipotent which means they are potentially capable of expressing all their genes
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when do mammlian cells begin to differentiate?
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after 8-cell cycle
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what is differentiation?
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the cell specializtion that occurs at the end of the developmental path
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is determination reversible?
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yes
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what is pattern formation?
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positional info determines the basic pattern of body compartments
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what are homeotic genes?
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-they are master switch genes
-they code for proteins that function as transcription factors |
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what happens when mutations occur in homeotic genes?
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normal body parts are found in unusual
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what is a homeobox?
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a sequence of 180 nucleiotides that codes for a 60-amino acid, dna-binding peptide domain called the homeodomain
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what is a homeodomain?
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a protein that regulates the expression of specific genes; ensures that related genes are transcribed at the proper time.
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what is apoptosis?
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-process of cells shriveling, shrinking, & dying in a preprogramming timeframe
-program regulated by gene activation |
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what is necrosis?
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-injured cells swell and burst, & release contents into extracellular fluid
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what is the accumulated mutation hypothesis?
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-as they age, cells accumulate mutations
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what is the telomere depletion hypothesis?
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-telomeric regions (extra dna at ends of chromo.) shortened by repeated replications
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what is the "wear & tear" hypothesis?
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-over time,disruption, wear, & damage, eventually erode cell's ability to funct. properly
-no inherent limit to aging |
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what is gene clock hypothesis?
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-genes regulate rate of aging
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