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Developmental Biology > Post Embryonic Development > Flashcards

Post Embryonic Development Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q
  1. on what size scale does patterning of the embryo occur?
  2. what is growth a key factor in determining?
  3. name 3 methods of growth, what the method entails, and examples of tissues it is seen in.
A
  1. small scale (morphogens only act over small distances)
  2. final shape of the organism
  3. proliferation - cell division. seen in most tissuescell enlargement - cardiac hypertrophy and skeletal muscle enlargementaccretion - deposition of ECM; bone growth
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2
Q
  1. how do drosophila embryos initially develop?
  2. Describe the type of division that occurs during this initial phase
  3. what occurs at the 14th cycle?
  4. What are mitotic domains?
  5. what controls cell division within domains? What is this protein? What influences its expresion?
  6. Which germ layer is an exception to the above and why? Why is it important that it is an exception?
A
  1. as a syncitium
  2. rapid, synchronous nuclear divisions (S and M phase)
  3. introduction of G phases, and slowing of division. Nuclei migrate to periphery and undergo cellularisation.
  4. groups of cells that have similar division rate. A cells division rate is dependent upon its position within the axis.
  5. String. it is a phosphatase that activates Cdks. Maternal string is uniformly distributed contributing to the first 13 synchronous divisions. After this, string is produced under the control of patterning genes
  6. mesoderm. it is the first domain to express string, but the 10th to divide. This is because it expresses tribble, which inhibits string. This is important as mesoderm needs to invaginate. Division can inhibit invagination.
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3
Q
  1. Give an example of an organ in which growth is under the influence of intrinsic control
  2. give an example of an organ in which growth is under the influence of extrinsic control
  3. what is organ size dictated by? How can this be illustrated?
A
  1. thymus; if additional thymus glands are transplanted into an embryo, all will maintain their size
  2. spleen; if an additional spleen is added, both will grow to half the size so that the total amount of tissue will be the same.
  3. exact dimensions of the organ and not the number of cells. Making triploid organisms that have larger than normal cells have unaffected organ sizes, but organs have fewer cells.
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4
Q
  1. Describe the growth rate of humans
  2. Why do pygmies have a short stature?
  3. In drosophila, what is the size of the adult determined by?
  4. what signals is drosophila size indirectly influenced by?
A
  1. They initally grow rapidly, before growth rate drops over time. This is until puberty sets in when another growth spurt occurs
  2. they do not undergo the second growth spurt.
  3. larval size
  4. insulin signalling determines larval size.
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5
Q
  1. what is post embryoinic mammalian growth controlled by? What are the effects of this mediated by?
  2. how is the production of this hormone regulated?
  3. which parent influences growth
A
  1. Growth hormone, which mediates it effects via IGFs
  2. GHRH stimulates GH release. Somatostatin inhibits GH release. GH negatively regulates its release by inhibiting GHRH and stimulating somatostatin.

GH promotes the production of IGF1 and 2

  1. mother.
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6
Q
  1. why are tissues that are constantly replaced/continue to divide throughout life most commonly connected to cancer? (2)
  2. a failure in which process is often linked to cancer
  3. cancer is connected to acquired mutations in the tumour cells. Give an exception.
A
  1. because they are already proliferating; division can lead to copying errors.
  2. differentiation
  3. teratoma; may result of epigentic changes which disrupt the normal differentiation process
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7
Q
  1. give 4 examples of proto-oncogenes
  2. give 4 examples of tumour supressor genes
A
  1. Ras, Myc, Raf, EGFR
  2. APC, retinoblastoma, p53 and patched
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8
Q

give the cancers that can arise from inappropriate activation of the following:

  1. Wnt
  2. Hh
  3. Nodal
  4. Notch
  5. EGF
A
  1. colon cancer
  2. basal cell carcinoma
  3. melanoma
  4. Leukaemia
  5. Breast Cancer
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9
Q
  1. mutations in which type of genes form the basis of inherited cancer syndromes
  2. give 2 examples of inherited cancer syndromes
A
  1. tumour supressor genes
  2. Retinoblastoma, familial adenomatous polyposis
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10
Q

what is molting and metamorphosis co-ordinated by?

A

influences from the environment that act on the CNS. The CNS in turn produces hormones that act on an organismal level

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11
Q
  1. why do arthropods need to molt?
  2. what is the molting process called?
  3. what are the intermold stages called?
  4. what is molting initiated by? Name the 2 subsequent stages
  5. Describe the process of molting
A
  1. because their cuticle is rigid therefore does not allow for growth to occur
  2. ecdysis
  3. instar
  4. activation of stretch receptors in the cuticle, leading to the release of protothoracicotropic hormone and in turn the release of ecdyson
  5. the cuticle separates from epidermis. free epidermal cells proliferate and secrete a fluid that forms a barrier and the new cuticle. the old cuticle is then shed.
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12
Q
  1. Under the influence of what does metamorphosis occur?
  2. Which hormones control metamorphosis
  3. changes in the balance of what (2) induces metamorphosis?
  4. how are the levels of one of these factors regulated?
  5. One of the Q1 factors causes what of the limbs and what of the tail?
A
  1. a variety of cues which are integrated in the brain and affect the relative levels of certain hormones
  2. juvenile hormone prevents metamorphosisecdysone promotes it
  3. prolactin and thyroxine
  4. environmental cues act on the hypothalamus to regulate the release of CRH and consequently TSH
  5. thyroxine causes growth of limbs and degeneration of tail.
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13
Q
  1. name 2 types of cells which live as long as the organism
  2. name 2 types of cells which are replaced continuously from stem cells pools
  3. name a type of cell which is constant but replaced upon injury
A
  1. heart muscle; neurons
  2. blood; epithelia
  3. skeletal muscle
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14
Q
  1. what is morphallaxis?
  2. What is epimorphosis?
A
  1. regeneration involving repatterning of existing cells without growth
  2. regeneration by regrowth.
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15
Q

urodele amphibians

  1. what type of regeneration?
  2. regeneration occurs at which level?
  3. what is essential for limb regeneration?
  4. what is a blastema?
  5. what does dedifferentiation of muscle cells involve? (2)
  6. under the influence of what do muscle cells dedifferentiate? What is this produced as?
  7. why is it unusual that muscle cells dedifferentiate?
  8. do cells truely de-differentiate and become pluripotent?
A
  1. epimorphic
  2. at the level that is appropriate to where the cut was made
  3. the migration of epidermal cells over the wound surface
  4. dedifferentiated cells of the epithelium, muscle and cartilage
  5. msx1 expression and phosphorylation/inactivation of Rb gene (which under normal circumstances prevents proliferation
  6. thrombin, which is produced as a general wound response
  7. because they are multinucleate, therefore dedifferentiation involves them becoming mononucleate agane
  8. no. muscle cells will become muscle cells again etc.
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16
Q
  1. what occurs if the distal limb of a newt is removed and the stump is inserted into the flank of the body before being cut again?
  2. what occurs if a distal blastema is transplanted onto a proximal wound?
A
  1. both stumps will regenerate distal limbs, because this is the level of the cut.
  2. an entire limb will form anyway, because the blastema can sense the discontinuity in the positional values
17
Q
  1. what is regeneration dependent upon?
  2. give an example when this is not the case
  3. describe why Q1 is the case, and how nAG can rescue regeneration when this factor is absent.
A
  1. innervation
  2. if the limb has been void of innervation from early in development
  3. nAG is expressed in the nerve sheath and epidermis. Innervation leads to the down regulation of epidermal nAG; Innervation is required as it is the only source of nAG. If a limb is innervated, nAG addition can rescue regeneration (alt source)
18
Q
  1. what is important in determining positional values
  2. What molecule is proximalising. The effects of this molecule are what?
  3. How might this proximalisation occur?
A
  1. differential adhesion: distal cells adhere tightly to one another; proximal cells adhere tightly to distal cells
  2. RA. dose dependent (higher the [RA], the more proximal structure will be regenerated)
  3. upregulation of meis homeobox genes or prod 1 (prod1 expressed at highest level in proximal blastemas)
19
Q
  1. what does cockroach regeneration also involve?
  2. what occurs if positional values 1 and 5 from the same leg segment are opposed?
  3. what occurs if positional value 2 is grafted onto positional value 4?
A
  1. detecting differences in positional values
  2. intermediate values are regenerated and the normal leg is restored
  3. the intermediate values are generated but are intercalated, this a segment of the leg is formed in reverse orientation.
20
Q
  1. what occurs when heart tissue is damaged?
  2. name a vertebrate which can undergo heart regeneration
  3. what is this regeneration dependent upon?
  4. name 2 factors expressed during regeneration?
  5. how is the stopping of circulation initially prevented?
  6. what do differentiating muscle cells express? How do epicardial cells respond to this factor?
A
  1. necrotic tissue is replaced by scar tissue. Remaining muscle cells undergo hypotrophy
  2. zebrafish
  3. dedifferentiating muscle cells
  4. msxB and msxC
  5. formation of a blood clot
  6. FGF. Epicardial cells invade the regenerate to establish coronary vasculature
21
Q
  1. name 4 examples of mammalian regeneration
  2. why does very little regeneration occur in the CNS?
A
  1. young children and mice are capable of regenerating their finger tips

PNS axons can regenerate (stimulated by schwann cells)

liver

ribs (if periosteum is present)

  1. oligodendrocytes and astrocytes provide non-permissive environment
22
Q
  1. give the structture of the hydra
  2. how do hydra grow? Why do they maintain size?
  3. how do hydra regenerate?
  4. name the 2 gradients that act in regeneration.
A
  1. mouth region surrounded by tentacles, elongated body region and a basal disc
  2. continuously. they lose cells by budding of tentacles, basal disc and by asexual budding. Because cells are constantly moving within the body, they continuously change positional values
  3. morphallaxis
  4. a gradient in positional value. PV determines head inducing ability anf the level of resistance to a head inhibitor | head inhibitor produced by the head
23
Q
  1. what happens if a piece of region 1 (high head inducing capacity) is transplanted near the head of an intact hydra?
  2. What occurs if the head of the recipient is removed following the above transplantation?
  3. what happens if a piece of region 1 is transplanted onto region 6?
  4. What occurs if the head of the hydra is removed
  5. what type of signalling is involved in head formation?
  6. Inhibition of what leads to activation of this pathway. If this is performed in all hydra regions, what does this result in?
A
  1. no head is produced as the level of head inhibitor here is high
  2. the source of the head inhibitor is lost thus the graft can form a head
  3. the level of head inhibitor here is insufficient to prevent the formation of a head
  4. the leftover tissue with the highest positional value will reach the head value first thus will start producing inhibitor and restore original patterning.
  5. wnt signalling
  6. GSK3beta; all regions acquire head organiser characteristics.
24
Q
  1. what is senescence?
  2. give 2 examples of organisms where senescence is due to wear and tear.
  3. give an example of an organism where senscence is due to genetic programming?
  4. what is the disposable soma theory?
A
  1. age related decline in vital physiological function
  2. c elegans - feeding muscles degenerate over time

elephants - die of starvation as their teeth are worn off

  1. salmon - die soon after laying eggs
  2. natural selection tunes life history of an organism so that sufficient resources are invested in maintaining the repair mechanisms that prevent aging at least until the organism has reproduced and cared for its young
25
Q
  1. give 3 examples that show that metabolism is linked to senescence
  2. what is key to the theory of reactive oxygen species in aging?
  3. how has manipulation of ROS produced contradictory results?
  4. what induces resistance to oxidative stress?
A
  1. organisms with a high metabolism have a shorter lifespan | larger organisms with a lower metabolism live longer; cold blooded animals live longer at lower temperatures
  2. super-oxide anion
  3. juglone treatment which produces ROS increases lifespan; glucose restriction extends lifespan by increasing oxidative stress
  4. longevity genes
26
Q
  1. which syndromes show that mutated genes are involved in the proper maintenance of the genome, leading to aging
  2. what does the DNA damage theory of aging suggest?
  3. the induction of which enzyme may be responsible for aging? What is the role of this enzyme? How is this enzyme induced?
A
  1. progeria
  2. It is unrepaired damage in non-replicating cells that causes aging
  3. PARP. PARP is an enzyme that is essential for signalling to DNA repair machinery to a single stranded DNA break. PARP is normally activated by NAD. NAD depletion may be responsible for aging as DNA can’t be repaired.
27
Q

Describe 3 factors that have been involved to increase lifespan

A
  1. Dietary Restriction
  2. Environmental Stresses (hormostasis - low level stressors may activate protective mechanisms)
  3. Removal of germ cells (somatic gonad extend lifespan by producing longevity signal which is inhibited by germ cells; Daf12 acting on FOXO)
28
Q
  1. what does the modification of development drive?
  2. what is the most primitive group of organisms?
  3. What is the most complex group and what does it consist of?
  4. What are the drosophila and c. elegans?
  5. What 2 groups do the deutrosomes contain?
  6. What do the chordates give rise to?
A
  1. diversity of body plans
  2. parazoa
  3. bilaterians. protostomes and deutrosomes
  4. protostomes
  5. echinoderms and chordates
  6. 2 smaller groups and the vertebrates
29
Q
  1. changes in which regions of genes gives rise to diversity?
  2. what do these changes lead to?
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3. how does the way of life of an animal influence its development?
  4. why is it beneficial for drosophila to develop rapidly?
  5. why is it beneficial for some organisms to produce large number of eggs?
  6. give another example of environmental influence on development
A
  1. changes in control regions of genes, not in the protein coding region
  2. differences in where and how much of a particular existing protein is expressed.
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3. it creates evolutionary pressue for an animal to develop in a way that promotes its survival
  4. because they lay there eggs in rotting fruit therefore it will benefit from hatching before all fruit has disintegrated
  5. to increase the chance that at least a few will survive
  6. eyeless fish that live in caves - sight confers no selective advantage
30
Q
  1. when do general characteristics of a group develop? when do more species specific characteristics occur?
  2. Which group is this not true for and how?
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3. how have the branchial arches evolved?
  4. how have limbs evolved from fins?
  5. In darwin’s finches, what does the difference in beak shape/size correlate with?
A
  1. early; afterwards
  2. vertebrates; they have a phylotopic stage that is not at the start of development. The stages before are changed by reproductive adaptation, and the changes afterwards show more species specific adaptations.
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3. they were once structures that supported the gill slits in jawless animals. Their role became redundant as jaw containing animals evolved. Therefore they have evolved to give rise to other strucures such as facial ligaments, inner ear and thyroid
  4. fins contain humerus, radius and ulna, but no digits. They also have a cartilaginous sheet that is subdivided into single elements. Extension of this same mechanisms to form cartilage more distally may be responsible for finger like structures.
  5. onset and level of BMP4 expression
31
Q
  1. how do Hox genes INDIRECTLY determine how cells in a region will develop?
  2. by what mechanism have hox genes evolved? What does this entail?
  3. How many hox gene clusters do drosophila have? Mammals? Fish?
  4. What is the presence of extra clusters thought to provide?
  5. At which hox gene boundary do limbs arise?
  6. How have snakes evolved to have no limbs?
A
  1. influence other genes that create a pattern?
  2. duplication (which creates many genes) and divergence (changes in regulatory and protein coding sequences)
  3. 1 | 4 | 7
  4. the raw gene material for rapid evolution of species rich groups. Fish have the most clusters and are also the most species rich group.
  5. hoxc8
  6. anterior expansion of the hoxc8 expanding the non-limb bearing flank.
32
Q
  1. how has changes in the duration/rate of growth lead to the formation of the horse hoof?
  2. what is heterochrony?
  3. how has heterochrony aided marsupial evolution?
  4. What is neoteny? How is it shown in the Axolotl?
A
  1. the central digit grows at a faster rate/for longer, eventually leading to the loss of contact of the lateral digits. The loss of functionality of the lateral digit will favour their further reduction.
  2. changes in the relative timing of various developmental processes
  3. marsupial limbs are born prematurely and crawl into their mother’s pouch to continue to develop. Anterior limbs need to be functional in order to crawl into pouch. Compared to its hindlimb and the forelimb of a mouse at a similar developmental stage, the forelimb is well developed
  4. reaching sexual maturity in a larval stage

axolotl reproduces in larval form, leading to the loss of the adult form. Metamorphosis can be induced by the thyroxin of injection.

Developmental Biology (10 decks)

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