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73 Cards in this Set
- Front
- Back
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chromosomes
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contain a long double helix of dna, wrapped around proteins. DNA carries the cells genetic information.The process of mitosis is to distribute this information evenly among daughter cells.
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unreplicated chromosome
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consists of a single long strand of dna wrapped around proteins.
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chromosome replication
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allows 2 dna strands to be perfectly duplicated. resulting in two copies of the same chromosome.
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Chromosome condensation
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Chromosomes compact and shorten for ease of transportation within the cell.
10,000 times more shorter than original length. |
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How long does S phase last?
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6-8 hours.
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Are there gaps between m and s phase.
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Yes within interphase there are G1 and G2 gaps. G1 is twice as long as G2. Allow time to replicate organelles and produce cytoplasm.
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How do microtubules shorten to pull sister chromatids apart at anaphase.
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Kinetochore microtubules pull apart and shorten at the kinetochore. Proteins in the kinetochore catalyze the loss of tubulin subunits at the plus end of the spindle fiber, while dyneins and other kinetochore motor proteins walk toward the minus end. As the microtubule shortens and the detach-move-reattach cycle of the motor proteins repeats, the chromosome is pulled to one end of the mitotic spindle.
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MPF's role
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Mitosis promoting factor. Signals the start of mitosis. It induces mitosis in all Eukaryotes and is found in m phase cytoplasm and not interphase cytoplasm. Causes chromosomes to condense also involved with the assemblage of the mitotic spindle. Negative feedback, it activates an enzyme that attacks cyclin, this causes the cyclin concentration fluctuations.
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MPF components
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Made up of two polypeptide subunits. Protein Kinase (enzyme that catalyzes the transfer of a phosphate group from ATP to a target protein, is always present throughout the cell cycle. The second MPF subunit is cyclins, (fluctuates concentrations throughout cycle, builds up during interphase and peaks at m phase. Protein kinase is dependent on cyclin, cyclin dependent kinase-Cdk
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What does it mean when a tumor is metastatic?
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It's cells can spread to distant parts of the body and initiate new tumors. Malignant tumors cause cancer.
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G1 checkpoint pathway.
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1. Growth factors arrive from other cells. 2. Regulatory protein E2F which is comparable to MPF, MPF activates genes required for m phase, E2F activates genes necessary for s phase. Growth factors cause Cyclin and E2F concentrations increase. 3. Cyclin bind to CdK, CdK is phosphorylated. Rb protein inactivates E2F by binding to it. Rb enforces G1 checkpoint. 4. Cdk is activated by dephosphorylation. Catalyses phosphorylation of Rb. 5.) Rb releases E2F. 6.) E2F enters nucleus and triggers production of s-phase proteins.
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blastula vs. gastrula
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Blastomeres make up the blastula, which becomes the gastrula after the blastocoel undergoes invagination to create the digestive tract.
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What is a blastocyst?
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is a structure formed in the early embryogenesis of mammals, after the formation of the morula, but before implantation. It possesses an inner cell mass (ICM), or embryoblast, which subsequently forms the embryo, and an outer layer of cells, or trophoblast, which later forms the placenta. The trophoblast surrounds the inner cell mass and a fluid-filled blastocyst cavity known as the blastocoele
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Early cleavage patterns influence?
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The establishment of polarity in the developing embryo.
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cortical granules?
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In eggs these are small vesicles filled with enzymes that are activated during fertilization.
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Can yolk exist as a large mass as well as in granule form?
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yes.
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centriole?
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In sperm the neck encloses the centriole, play a key role in the formation of the spindle apparatus, which transports chromosomes to daughter cells. The fertilized egg contains one centriole from the female and one from the male.
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Flagellum?
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In sperm the flagellum is a long structure composed of microtubules and surrounded by the plasma membrane. This is the propeller.
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Radial division.
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90 degree angle column division.
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Discoidal division.
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the bubbling up of dividing cells so that they create a mound on top of the cell or above the yolk.
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Spiral division.
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The oblique splitting of cells so that they pile up.
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Superficial cleavage.
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The nuclei build inside the cell, no cytokinesis takes place, eventually the nuclei will migrate to the edges of the cell.
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Sperms head contains...
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A haploid nucleus, and is tipped with an sac (acrosome), located just inside the plasma membrane.
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Sperm structure
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Acrosome contains enzymes that help penetrate the eggs coat. Neck and midpiece contain a long spiral mitochondrion. Sperm absorbs high energy nutrients, such as fructose from seminal fluid (ejaculation fluid)
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Spermatogenesis details
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65-75 days in humans. Sperm formation occurs in coiled tubes in testes, called seminiferous tubules. Primary spermatocytes are continuousely generated by meiosis in the outer portion of the seminiferous tubules.
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Spermatogenesis pathway.
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Diploid parent cells>mitosis>primary spermatocytes>meiosis I>secondary spermatocytes>meiosisII>sperm cells(haploid).
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Oogenesis details
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Takes place in follicles. Each follicle contains a dormant primary oocyte (a diploid cell resting in prophase of meiosis I). After puberty every 28 days follicle stimulating hormone triggers the development of a single follicle. The follicle enlarges and the primary oocyte undergoes meiosis I.
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Oogenesis Meiosis I
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involves an unequal cell division, producing 1. a secondary oocyte (contains most of the cytoplasm from the primary oocyte) and 2. a small haploid cell known as the polar body.
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Follicular phase
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oocyte is surrounded by folical cells prior to ovulation.
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Luteal phase
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oocyte has ovulated, burst free of follicle, follicle cells persist as yellow body called the corpus luteum.
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Spermatogenesis vs. oogenesis
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1 ovum egg produced per diploid nucleus undergoing oogenesis. 4 sperm produced per spermatogonium.
At birth the ovary contains all the oocytes it will ever have. Males during their reproductive years continuously produce sperm. Oogensis is not completed without the stimulation of a sperm cell. Spermatogenesis produces mature sperm in an uninterrupted sequence. |
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Polyspermy is blocked by...
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electrical depolarization of the cell membrane.
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When cloning a sheep where does the nucleus come from that will fertilze the egg?
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The nucleus from a cell from the sheep attempting to be cloned.
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A sexual reproduction
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Ofspring whose genes are derived entirely from one parent.
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Variations of a sexual reproduction
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budding (offspring begin to form in or on a parent, (hydra branch), fission (an individual splits into two or more descendants (flatworm tips dividing), fragmentation and regeneration
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Do some animals aternate between sexual and asexual reproduction.
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yes. asexual reproduction is more favorable energy wise, but does not create diversity within a population. Sexual reproduction requires the creation of haploid gametes by males and females.
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Sexual reproduction.
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The creation of a diploid offspring via the union/fusion of haploid gametes.
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hermaphroditism
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Bi-sexual individuals, sometimes capable of self fertilization (earthworms).
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Gametogenesis
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The meiotic, mitotic cell divisions, and developmental events that produce haploid gametes.
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Spermatogenesis occurs in the males...
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testes
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Oogenesis occurs in the females
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ovaries
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Male Gametogenesis
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Spermatocytes that are produced after a spermatogonium divides mitotically, undergo meiosis I and produce two secodary spermatocytes which then undergo meiosis II. The result is four haploid spermatids which will mature into sperm.
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Female Oogenesis
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Oogonium divides by mitosis to form a ocyte, which then undergoes meiosis. Of the four haploid cells only one matures into an ovum. The others have very little cytoplasm in comparison to the ovum, these are polar bodies, they do not mature into eggs.
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Internal fertilization
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sperm are deposited in or close by the female reproductive tract. The gametes unite within the female body.
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Oviparous egg development.
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Egg laid outside the mothers body, it may or may not recieve parental care.
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Vivaprous egg development
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Egg kept inside the mothers body for heat. Nutrition recieved directly from mother via digestive tract.
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Infertility
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Men impotent/invigorous sperm, not producing enough sperm, women scaring of the oviduct via STDs.
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Extraembryonic tissues
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yolk sac (derived from inner cell mass), amnion (derived from inner cell mass), allantois(derived from innner cell mass), Chorion (derived from inner and outer cell mass) secretes hcg if embryo implants in uterine lining.
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Hcg
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secreted by the chorion, it is a chemical messenger that prevents the corpus luteum from degenerating. When it is present the ovary secretes progesterone and the mentrual cycle is arrested.
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Teratogens
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chemical agents that induce developmental defects. Ethanol causes fetal alchohol syndrome. Retinoic acid causes supernumerary limbs in developing tadpole tails, it's found in acne creams.
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chorion
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Outermost membrane that secrets hcg.
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amnion
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A membrane that encloses the embryo, it is a water filled sac that provides cushion.
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allantois
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forms part of the embryos urinary bladder. In reptiles and birds it wraps around the embryo and involved in respiration and waste disposal.
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yolk sac
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evolutionary remnant of the yolk sac in birds and reptiles, it produces germ cells and the first red blood cells.
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Pregnancy, gestation, carrying developing young.
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266 days in humans. First 6-7 days the human embro is a blastocyst comprised entirely of cells.
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Ectoderm derived
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Nervous system, cornea and lens of the eye, epidermis of skin, epithelial lining of mouth and rectum.
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Mesoderm derived
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Skeletal system, circulatory system, lymphatic system, muscular system, excretory system, reproductive system, dermis of skin, lining of the body cavity.
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Endoderm derived
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epithelial lining of the -digestive tract, respiratory tract, reproductive tract, urinary tract. Also the liver, pancreas, thyroid, parathyroids, thymus.
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slow block
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After the calcium ions release, cortical granules fuse with the plasma membrane and release their contents. This causes water to enter into the space between the plasma membrane and the vitelline envelope via osmotic pressure made possible by the contents of the cortical granules. This creates the fertilization envelope.
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fast block
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Changes the eggs charge from negative to postive, via propagation of calcium ions that just release when one sperm enters the egg. Sperm cannot come into a positive egg. Electrical polyspermy block, electrical depolarization (makes the membrane more positive). In sea urchins the sperm head is slightly positive, which is repelled by the newly positive egg.
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Zona Pellucida
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We have an unusually large vitelline envelope that is called the zona pellucida. This is a mat like sheet of glycoproteins. Some species like sea urchins have an additional structure called a jelly layer.
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Histogenesis
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tissue formation.
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Organogenesis
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The process in mammals where the ectoderm, mesoderm, and endoderm, develop into internal and external organs of the body.
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Notochord
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During organogenesis a rod like structure forms in the dorsal mesodermal region of the embryo. It runs the length of the anterior posterior axis of the embryo. In humans as organogenesis proceeds apoptosis occurs and programmed cell death happens. This notochord produces signaling molecules the that cause the dorsal ectoderm to fold.
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Neural tube formation
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Ectoderm cells expand on the ventral side and constrict on the dorsal side. This forms the neural tube which will develop into the brain and spinal cord.
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Somite
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Somites form on both sides of the neural tube down the length of the body. It does not undergo apoptosis like the notochord on which it is attached. They become the vertebrae and ribs, the deeper layers of skin that cover the back, the muscles of the back, body wall, and limbs.
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Plant mutants that portray abnormal development of the root to shoot axis fall into three groups
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apical mutants, central mutants, basal mutants.
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apical mutants
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lacking cotyledons (significant part of the embryo of a seed).
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central mutants
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lacking hypocotyl structures.
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basal mutants
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lacking hypocotyl and root structures.
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The floral meristem produces...
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four organs, sepals are leaflike protective structures, petals are modified leaves that enclose the reproductive organs, the male and female reproductive organs, stamen and pistel respectively.
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How do floral identity genes work?
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Each of the three genes contains a segment that encodes a 58-amino acid DNA-binding domain known as MADS box.
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Hoeotic flower structure mutations can be sorted into three classes according to the type of homeotic transformation:
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pistel/stamen only, sepal/pistel only and sepal/petal only.
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