Term
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Definition
| The process where two cells (gametes) fuse to form one fertilized cell or zygote. |
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Term
| Cost of Sexual Reproduction |
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Definition
1. gamete timing
2. selecting a male/female (sexual selection)
3. seperate sexes
4. nourishment and care of young. |
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Term
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Definition
| built-in controls that synchronize the timing of gamete formation and sexual readiness in two individuals. |
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Term
| Reproductive timing depends on... |
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Definition
| enery outlays for constructing, maintaining, and operating neutral as well as hormonal control mechanisms in each parent. |
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Term
| What must line up between the two parents? |
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Definition
| Parents must produce mature gametes in reponse to the same cues, such as seasonal change in daylight, that mark the onset of appropriate time of reproduction for their species. |
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Term
| Whats involved in locating and recognizing a likely mate? |
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Definition
| Production of pheromones, visual signals, courtship and keeping mates. |
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Term
| Costs of internal fertilization: |
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Definition
| They invest metabolic ebergy to construct elaborate reproductive organs. |
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Term
| Cost of external fertilization: |
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Definition
| invest energy into making numerous (often thousands) of gametes. |
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Term
| Nearly all animal eggs contain.. |
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Definition
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Term
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Definition
| Rich in proteins and lipids, it nourishes embryotic stages. |
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Term
| Do human eggs contain yolk? |
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Definition
| Yes, but very little. Fetus is sustained through pregnancy by physical exchanges with the mothers tissue. |
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Term
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Definition
| a class of transitional forms between the fertilized egg and the adult. |
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Term
| Stages of animal development: |
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Definition
gamete formation
fertilization
cleavage |
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Term
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Definition
first stage
eggs or sperm develop inside the reproductive organs of the parent body. |
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Term
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Definition
second stage
starts when a sperms plasma membrane fuses with the eggs plasma membrane. |
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Term
| When does fertilization end? |
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Definition
| when the sperm nucleus and egg nucleus fuse and form a zygote. |
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Term
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Definition
third stage
a program of mitotic cell divisions that divide the volume of egg cytoplasm into a number of blastomeres. |
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Term
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Definition
| smaller cells, each with its own nucleus. |
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Term
| During cleavage, what increases and what stays the same? |
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Definition
| The number of cells increase, but there is no overall growth. |
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Term
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Definition
Pace of mitotic division slackens.
A time of cellular reorganization.
Germ layers develop. |
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Term
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Definition
| The new cells become arranged into a gastrula with 2 or 3 primary tissues, called germ layers. |
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Term
| Why is the germ layer important? |
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Definition
| The cells that make up the germ layer give rise to all tissue and organs in the adult. |
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Term
| The three types of tissue: |
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Definition
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Term
| What type of tissue forms first? |
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Definition
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Term
| What does the ectoderm give rise to? |
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Definition
nervous system
integumentary system |
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Term
| Where is the endoderm located? |
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Definition
| It is the inner most layer. |
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Term
| What does endoderm give rise to? |
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Definition
| guts inner lining and organs derived from the gut. |
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Term
| What does the mesoderm give rise to? |
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Definition
muscle
skeletal
circulatory
reproductive
excretory
connective tissue |
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Term
| Which layer evolved hundreds of millions of years ago and was a pivotal step in the evolution of nearly all large, complex animals? |
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Definition
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Term
| What happens after the primary tissue layers form? |
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Definition
| they give rise to subpopulations of cells. Diverse tissues and organs start to form from their cellular descendants. |
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Term
| Last stage of animal development? |
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Definition
| growth and tissue specialization |
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Term
| What happens during growth and tissue specialization? |
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Definition
tissues and organs gradually assume their final shape, size, proportions, and functions.
This stage goes on into adulthood. |
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Term
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Definition
| Appears on the surface of the embryo and establishes the bodies anterior, posterior axis. |
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Term
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Definition
| A ball of cells with fluid-filled cavity called a blastocoel. |
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Term
Frog Egg
Stages of animal formation |
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Definition
1. a jelly-like layer that surrounds the frog egg has been removed.
2. about an hour after fertilization, the gray cresent forms. Gastrulation starts here.
3. Cleavage produces a blastula.
4. cells actively migrate to new locations and are rearranged during gastrulation.
5. primary tissue layers form, then a primitive gut cavity i which internal organs will become suspended.
Cell differentiation proceeds, moving the embryo on its way to becoming a tadpole. |
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Term
| What happens to an oocyte when it is maturing? |
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Definition
| Its volume increases, enzymes, RNA transcripts and other factors become stockpiled in different parts of the cytoplasm. |
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Term
| What is the function of tubulin molecules in the oocyte? |
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Definition
| Will help control the angle and timing of tubulin assembly into microtubules for mitotic spindles. |
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Term
| What influences how large the blastomeres are? |
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Definition
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Term
| What action in the frogs egg proves the effect of "maternal messages?" |
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Definition
| At fertilization, part of the granule-containing cortex shifts toward the point of sperm entry. This exposes lighter-colored, yolky cytoplasm in a crescent shaped gray area. The first cleavage normally puts part of the gray cresent in both of the resulting blastomeres. |
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Term
| Describe the experiment that proved the importance of the gray cresent (and therefore, maternal messages): |
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Definition
| In one experiment, the blastomeres that formed were physically seperated from each other. Each still gave rise to a tadpole. In the next experiment, a fertilized egg was manipulated so the cut through the first cleavage plane missed the gray cresent. The blastomere with the gray cresent developed into a tadpole, and the one without turned into a ball of undifferenciated cell forms. |
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Term
| How are the blastomere seperated? |
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Definition
| Cleavage Furrow- Underneath the plasma membrane, its midsection has a ring of microfilaments made of the contractile protein actin. |
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Term
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Definition
| Simply by virtue of where they form, blastomeres end up with different maternal messages. |
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Term
| What is the point of cytoplasmic localization? |
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Definition
| It helps seal the developmental fate of each cells descendants. |
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Term
| What controls how fast the cuts proceed and what arrangement the blastomeres will be in in most animals? |
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Definition
| Proteins and mRNA's stockpiled in the cytoplasm. |
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Term
| What controls cleavage patterns in mammals? |
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Definition
| Certain genes must be activated first. Cleavage cannot be completed without the protein products of those genes. |
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Term
| What effect does the amount of yolk have on the cleavage pattern? |
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Definition
| Cuts can go right through a nearly yolkless egg. Early cuts only go through partially in an egg stockpiled with yolk. The egg therefore has polarity. |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| cleavage furrows run horizontal and vertical to animal-vegetal axis. |
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Term
| What do cuts in the oocyte produce? |
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Definition
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Term
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Definition
| an embryonic stage in which the blastomeres surround a fluid filled cavity (a blastocoel) |
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Term
| Why is a frog egg shaped like a mulberry? |
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Definition
| Because of the yolk, more, smaller blastomeres form near its animal pole, and the blastoceol is offset. |
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Term
| What is another name for an amphibian blastula? |
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Definition
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Term
| What kind of cleavage do eggs of reptile, birds and most fishes undergo? |
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Definition
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Term
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Definition
| The large volume of yolk restricts the early cuts to a small, caplike region near the animal pole. |
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Term
| What is the shape of the oocyte after incomplete cleavage? |
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Definition
| Two flattened layers of cells with a narrow cavity inbetween. |
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Term
| what type of cleavage do mammalian eggs undergo? |
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Definition
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Term
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Definition
| blasomeres divide slowly at different times |
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Term
| Explain what types of cuts are made and when during rotational cleavage: |
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Definition
| 1-vertical through both poles. 2- one blastomere is cut horizontally, the other vertically. 3-yields a loose arrangement with space between eight cells. Cells undergo compaction. |
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Term
| How to tight and gap juctions come into play when talking about rotational cleavage? |
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Definition
| Tight juctions stabilize the blastomeres outside and seal off the ones inside. Gap Junctions form between the inner cells and facilitate chemical communication among them. |
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Term
| What is the purpose of the descendents of the cells on the outer layer during rotational cleavage? |
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Definition
| They Form a thin surface layer. |
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Term
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Definition
| A type of blastula. Secretions from the cell descendence of the outer layer form a fluid filled cavity in the ball,and the inner cells mass together against one side of it. |
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Term
| How are identical twins formed? |
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Definition
| When the first two blastomeres, the inner cell mass, and even a later stage splits. |
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Term
| How are fraternal twins formed? |
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Definition
| Arise from two oocytes that matured and then became fertilized during the same menstral cycle. |
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Term
| How are identical twins different than fraternal twins? |
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Definition
| Identical twins have identical genetic makeups, and share a placenta. Fraternal twins have unique DNA and are serviced by different plancentas. |
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Term
| The three layer body plan shared by nearly all animals: |
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Definition
| gut, surface parts, organs. |
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Term
| When does the three part body plan emerge? |
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Definition
| as cleavage ends and gastrulation begins. |
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Term
| What determines where the neural tube will form? |
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Definition
| The anterior-posterior axis |
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Term
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Definition
| The forerunner of a brain and spinal cord. |
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Term
| All cells of an embryo have the same... |
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Definition
| number and kinds of genes. |
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Term
| What happens to the genes in the cells from gastrulation onwards? |
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Definition
| Certain groups of genes are used in some cell but not in others. |
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Term
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Definition
| When a cell selectively activates genes and synthesizes proteins not found in other cells types. |
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Term
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Definition
| a family of proteins that are assembled into transparent fibers for each lens. |
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Term
| Who did the experiment that proved that nearly all cells differentiate without losing any genetic information? |
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Definition
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Term
| Describe the experiment done by John Gurdon: |
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Definition
| Gurdon stripped unfertilized eggs of an African Clawed frog of their nucleus. He then inserted full differentiated intestinal cells from a tadpole of the same species. |
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Term
| What was the outcome of Gurdons experiment? |
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Definition
| Some of the eggs still gave rise to a complete frog. |
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Term
| Why did Gurdons experiment turn out the way it did? |
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Definition
| The intestinal cells still had the same number and kinds of genes as a zygote, its nucleus still had all the genes required to make all cell types that made up the frog. |
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Term
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Definition
| refers to the program of orderly changes in an embryo's size, shape, and proportions. |
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Term
| What is the result of morphogenesis? |
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Definition
| specialized tissues and early organs |
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Term
| How do cells move around? |
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Definition
| They use pseudopods that move them along prescribed routes. |
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Term
| What do cells do when they reach their prescribed location? |
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Definition
| they establish contact with the cells already there. |
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Term
| How do cells know where to go? |
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Definition
| They respond to chemical gradients and adhesive cues. |
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Term
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Definition
| When migrating nerve cells stick to adhesion proteins on glial cells but not blood vessels. |
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Term
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Definition
| Coordinated by the synthesis, release, deposition, and removal of specific chemicals in the extracellular matrix. |
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Term
| How do adhesive cues tell the cell when to stop? |
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Definition
| Cells will migrate to regions of strongest adhesion, but once there, further migration is impeded. |
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Term
| what happens after the three primary tissues form in embryos? |
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Definition
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Term
| How does the neural tube form? |
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Definition
| At the embryo midline, ectodermal cells elongate and form a neural plate. Specific cells lengthen, or some become wedge shaped. The changes in shape cause tissue flaps to fold over and meet at the midline, thus forming the neural tube. |
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Term
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Definition
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Term
| How does apotosis help form the fetus's hand? |
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Definition
| Cartilage models of finger form inside the "paddle." Cells in thin tissue zones between the digits have receptors for proteins (a product of selective gene expression). When proteins bind to those receptors, the cells die and the fingers seperate. |
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Term
| What causes changes in cell shape? |
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Definition
| Microtubules lengthen and microfilament rings constrict inside cells. |
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