What sex-linked trait(s) appear in fruit flies?
463347
I believe eye color is sex linked.  I think wing structure is too (like normal versus vestigial).
871407
1. The trait must be genetic.\n\n2. There needs to be variation within the gene between different individuals (e.g. two or more alleles for a single gene).\n\n3. There needs to be differing fitness between alleles (e.g. one allele gives a reproductive advantage over another).
409310
Assuming we're talking about humans ...\n\nIn the female gamete (the ovum, or egg cell) the DNA in the nucleus is contained in 23 chromosomes.  One of these is the sex chromosome, but this is always an X chromosome.  Outside the nucleus are additional pieces of DNA ... most notably, DNA in the mitochondria of the cell, which will get passed intact to the offspring.\n\nIn a male gamete (spermatozoan or sperm cell) the DNA in the nucleus is also contained in 23 chromosomes.  One of these is the sex chromosome and is either a Y or an X chromosome.  This will determine the gender of the offspring.  Sperm cells also have DNA in their mitochondria, but these are discarded upon fertilization (so the offspring gets mitochondrial DNA exclusively from the mother).\n\nUpon fertilization, the two gametes make a zygote.  The 23 chromosomes from each (haploid) gamete produces a complement of 46 total chromosomes in the (diploid) zygote.  The pair of sex chromosomes determines the gender of the developing offspring ... XY is a boy, XX is a girl.
295926
I think one is the division of chromosomes and that is just a guess as for the other I assume that it has something to do with two sexes becoming one.
930754
Mitosis is the reproduction of somatic (body) cells, while meiosis is the production of gametes (sex cells).\n\nThe normal cell has a chromosome number of "2n".  For example, a fruit fly has a chromose count of 8, so 8=2n.\n\nFollowing so far? Good.\n\nMitosis:\nMitotic division begins with a cell in Interphase, with a chromosome count of 2n.\nThe chromosomes are not visible right now under the microscope, they just look like a mass of tangled string called chromatin.\n\nIn Prophase, the chromosomes replicate, but remain attatched to their partner by a centromere (kinda look like an x).  Spindle fibres form and the centrioles migrate to the ends of the cell, opposite each other.  Nuclear membrane disappears.\n\nIn Metaphase, the chromosomes line up on the equatorial line (a bunch of x in a row along the middle of the cell), and spindle fibres attatch to each chromatid in the pair (right now, the two parts to the x are individually chromatids, but are together a chromosome).\n\nDuring Anaphase, the spindle fibres pull each daughter chromosome so that the pair of chromatids splits apart and half of them go to one end of the cell, and half to the other.\n\nDuring Telophase, the nucleolus forms and the nuclear membrane forms around the two sets of chromosomes.  A clevage furrow separates the cell into two daughter cells, each having a 2n number of chromosomes.\n\nPhew.  Still following?  Good- that was just Mitosis!\n\nNow for the fun one.  Meiosis.\nMeiosis takes the 2n cell and turns it into FOUR  (4) gametes.\nIn your body, each individual chromosome is part of a homologous pair.  That is, each has a match.  This is why we represent the chromosome number as 2n- There are two sets of n chromosomes.  In our fruit fly, the 2n number is 8, so there are 4 sets of homologous pairs.  Following? Good.\n\nMeiosis in the fruit fly begins with a single cell with 8 chromosomes, and ends with 4 cells with 4 chromosomes each.\n\nWhy does it end with "n" instead of "2n"?  Each gamete provides half the genetic information needed to create the new organism.  You get half your genes from your mother and half from your father.\n\nAnyway, meiosis takes place in two stages: aptly called meiosis 1 and meiosis 2.\n\nMeiosis 1:\nIn Interphase, the cell has roughly the same appearance as it did in Interphase of Mitosis.\n\nIn Prophase 1: The chromosomes duplicate and find their homologous pairs.  Now, the little groups istead of looking like an x, look like an x with four little lines joining, because there are 4 chromatids attached together, called a tetrad.  Understand?  I hope so!\nAt this point, the two chromatids nearest together in the tetrad may "cross over".  In other words, they swap genetic information.  Homologous pairs carry similar, but not identical coding (remember one was from your father, one from your mother).  In this way, you now have 4 chromatids that are each unique in their coding, which allows for genetic variation!  \nCentromers go to opposite ends, and spindle fibres begin to form.  Nuclear membrane disappears\n\nIn Metaphase 1: The tetrads line up on the equatorial line (remember this?)  The spindle fibres attatch to each side of the tetrad.\n\nIn Anaphase 1: The spindle fibres split the tetrads in half, so that 2 chromatids (1 chromosome now) go to one pole of the cell, and 2 chromatids (1 chromosome) go to the other.\n\nIn Telophase 1: The nuclear envelope/membrane reappears around each set of chromosomes, and a cleavage furrow splits the cell into two daughter cells.\n\nAt this point, we now have two daughter cells with "n" for the chromosome count, because there is half the amount of chromosomes we had when we started!\n\nOk, now each daughter cell undergoes meiosis 2, so that at the end we have 4 gametes.\n\nProphase 2:  Nuclear envelope dissappears.  Centroles migrate to the opposite sides of the cells, spindle fibres form.  Remember that the chromosomes are composed of
1154323
First off, the effects of the X and Y genes aren't "averaged out" but rather regulated.  A female does have two X chromosomes, but the genes on those chromosomes are being regulated by protein production which is regulated by hormones.  Basically what is happening is that the female cell is recognizing that there are two copies of a certain gene (like one on the X chromosome) and it down regulates this gene, essentially terminating its transcription.  A "normal" male however, only has one X chromosome and therefor the genes on this chromosome must be upreguated to produce enough gene product.  Earlier I said "normal" male meaning one with XY genotype, this is because you can have other genotypes such as XYY.  The sex of an individual on the genomic level is determined by the RATIO of sex chromosomes to autosomes, not neccesarily the number of chromosomes.  \nFurthermore, a males body is built with larger thicker bones that allow for more muscle mass.  The physiological composition of a female just doesn't allow for the gain of that much muscle.  For example you can use a toothpick to pick up a cocktail weenie, the same toothpick would surely break if you tried picking up a steak... It's just too much mass for the small structure.  \nHope this helps!
641246
Sex-linked inheritance is usually used for genes inherited on the X chromosome. Holandric is the term usually used for inheritance on the Y chromosome. Some textbooks will call sex-linked both though. Basically the mother has two X chromosomes and the father has an X and a Y. The son only inherits an X chromosome from the mother so if this chromosome has a disease allele on it, the son will have the disease. The daughter gets an X from the mother and an X from the father so needs an X allele with a disease from each parent to get a disease.\n\nThis is the way sex-linked inheritance is usually used in genetics problems.
850350
They're a mammalian characteristic.  Gender differentiation doesn't override the basic template for mammals.  Male/female is chromosomal.  Other physical differences are mainly hormonal.
352274
it depends if youre asking about a sex-linked trait or not.  if a sex-linked trait is in question, then the mother gives the son her x chromosome that has one copy of all the genes on her x chromosomes, the father will contribute the y chromosome.  however, if the trait is x-linked and the father expresses it then there's no way to pass it on to his son as he is only passing on his y chromosome.  if it't not sex linked then it's just a random luck of the draw on which genes that kid will get.
305803
Several modes of speciation have been suggested/observed, but they break down into two types: sympatric, in which the new species is in the same geographic location as the original species, and allopatric, in which the new species is formed in a geographically separated location. Allopatric is generally considered to be more common, but sympatric is common in some groups, for example, plants.\n\nThe rest of my answer: A sympatric example that has been observed occurred in apple maggot flies (Rhagoletes). These are host specific insects that lay their eggs on one species, which become adults, which then mate on the host tree. A mutation causes one or more flies to choose a different species of host tree (which might be right next door) and the adults mate near that tree, not encountering the non-mutant forms. Thus you have the conditions of an isolated population which will allow divergence through selection or drift, leading ultimately to a new species (this latter part has not been observed, but all the preconditions are there). There are several other modes of sympatric speciation possible.\n\nIn allopatric, the classic case would be an isolated founding population that diverges due to selection and/or drift to a point where - were the two populations brought back together - there are no viable offspring produced from intermating (=reproductive isolation). \n\nThere are many more details to both these modes which any text on evolution will outline and provide examples for.
826685
You might try posting this question in the general biology area, it seems to get a bit more traffic than over here. Good luck.
71183
Genetics, scientific study of how physical, biochemical, and behavioural traits are transmitted from parents to their offspring. The word itself was coined in 1906 by the British biologist William Bateson. Geneticists determine the mechanisms of inheritance whereby the offspring of sexually reproducing organisms do not exactly resemble their parents, and the differences and similarities between parents and offspring recur from generation to generation in repeated patterns. The investigation of these patterns has led to some of the most exciting discoveries in modern biology.\nSoon after Mendel's work was rediscovered, scientists realized that the patterns of inheritance he had described paralleled the action of chromosomes in dividing cells, and they proposed that the Mendelian units of inheritance, the genes, are carried by the chromosomes. This led to intensive studies of cell division.\n\nEvery cell comes from the division of a pre-existing cell. All the cells that make up a human being, for example, are derived from the successive divisions of a single cell, the zygote (see Fertilization), which is formed by the union of an egg and a sperm. The great majority of the cells produced by the division of the zygote are, in the composition of their hereditary material, identical to one another and to the zygote itself (assuming that no mutations occur; see below). Each cell of a higher organism is composed of a jellylike layer of material, the cytoplasm, which contains many small structures. This cytoplasmic material surrounds a prominent body called the nucleus. Every nucleus contains a number of minute, threadlike chromosomes. Some relatively simple organisms, such as cyanobacteria and bacteria, have no distinct nucleus but do have cytoplasm, which contains one or more chromosomes.\n\nChromosomes vary in size and shape and usually occur in pairs. The members of each pair, called homologues, closely resemble each other. Most cells in the human body contain 23 pairs of chromosomes, whereas most cells of the fruit fly Drosophila contain four pairs, and the bacterium Escherichia coli has a single chromosome in the form of a ring. Every chromosome in a cell is now known to contain many genes, and each gene is located at a particular site, or locus, on the chromosome.\n\nThe process of cell division by which a new cell comes to have an identical number of chromosomes as the parent cell is called mitosis (see Reproduction). In mitotic division each chromosome divides into two equal parts, and the two parts travel to opposite ends of the cell. After the cell divides, each of the two resulting cells has the same number of chromosomes and genes as the original cell (see Cell: Division, Reproduction, and Differentiation). Every cell formed in this process thus has the same genetic material. Simple one-celled organisms and some multicellular forms reproduce by mitosis; it is also the process by which complex organisms achieve growth and replace worn-out tissue.\n\nHigher organisms that reproduce sexually are formed from the union of two special sex cells known as gametes. Gametes are produced by meiosis, the process by which germ cells divide. It differs from mitosis in one important way: in meiosis a single chromosome from each pair of chromosomes is transmitted from the original cell to each of the new cells. Thus, each gamete contains half the number of chromosomes that are found in the other body cells. When two gametes unite in fertilization, the resulting cell, called the zygote, contains the full, double set of chromosomes. Half of these chromosomes normally come from one parent and half from the other.\n\nFor more than 50 years after the science of genetics was established and the patterns of inheritance through genes were clarified, the largest questions remained unanswered: how are the chromosomes and their genes copied from cell to cell, and how do they direct the structure and behaviour of living things? Two American genet
303496
Sex determination: sex is based on number of X chromosomes. grasshopper XO male, XX is female. \n\nTaxonomy of one species of grasshopper: http://www.cnr.vt.edu/fishex/nmex_main/species/082715.htm\n\nThis is an excellent source for the feeding behavior: http://www.colostate.edu/Depts/Entomology/courses/en507/papers_1999/nadeau.htm\n\nMovement of Grasshopper:\nJointed appendages move for locomotion\nThinner at joints to allow movement\nAppendages are weight bearing: allows for crawling and jumping\nMuscles are not associated with body wall\nMuscles bundles on inside, attached to exoskeleton\nAntagonistic pairs allow movement of appendage in both directions\nThird pair of legs are long with powerful muscles for jumping\nTwo pairs of wings for flight\nAnterior pair stiff like fixed wings of planes\nPosterior pair are membranous provide lift and propulsion\n(source: http://www.ucs.mun.ca/~iemerson/lectures1001/lecfram24.html)
239913
to be food for another kind of bug.  There isn't any real research that states "what" fruit flies do to help the ecosystem.  They might possibly eat microscopic organisms that we don't see.\n\nAnother possible job, to pester people at picnics!
879744
For the most part, males and females are genotypically the same until you reach Chromosome #23, the sex chromosomes.  For females, the 23rd chromosome is XX, while the males have XY.  They are labelled "X" and "Y" because they are shaped like the letters "X" and "Y" in their condensed forms.  \n\nThe embryo knows which sex to turn into based on the presence of the Y chromosome.  In all cases, all embryos will turn into a female UNLESS there is a Y chromosome.  The Y chromosome will trigger a series of biochemical pathways (which includes testosterone, the male hormone) that will activate some important items while inhibiting others.  The end-result is a male.\n\nIt has been argued that in evolution, the Y chromosome resulted from the cutting off of a portion of the X chromosome; it is up to you to decide whether or not you believe it.  \n\n\nPhenotypically, males and females differ in reproductive organs and breast development.  You might also be aware of the puberty onsets that take place in males and in females in their teens.  Males tend to have deeper voices than females, later growth spurts, and a more masculine physique.  Females begin their monthly cycles, and so on so forth.
182322
http://en.wikipedia.org/wiki/Drosophila_melanogaster
728283
The male and female reproductive "tracts" are homologous.  This means that they're similar in structure and evolutionary origin, but are different in function.