How come when you have recessive and recessive, there is a probability of a dominant gene coming out?
354197
All dominant means in genetics is the expression.  There are two types of dominant genes biochemically speaking.  The first is a 'dominant negative', where a gene becomes mutated and somehow blocks the good genes.  If this is the case only one mutation is enough to remove the function of both copies of the gene (the dominant negative copy and the wild-type copy).  This is teh case in p53, where the DNA binding domain is mutant, but the tetramerization domain is intact.  So this protein will bind to normal p53 protein, and inhibit DNA binding of teh complex. The second type of dominant gene is one that give a phenotype.  For example, a gene to give a flower red color may be dominant to white.  This can be a novel activating mutation or something else.  \n\nSo in your example if there is no dominant R allele, the 'r' allele would be expressing.  Maybe that is what your teacher meant; i would ask him/her to clarify the issue.
415287
Although this seems to be a problem about Gregor Mendel and his tall and dwarf pea plants, once it is realised that the probability of any child being short is 1/2, it simplifies to being the simpler and more familiar one of tossing a coin, heads or tails, n times\n\nIt would have produced more interesting results perhaps if the parents were Aa and Aa and three children out of four were therefore tall and we had looked at grandchildren (offspring of children who are one quarter AA, one half Aa and one quarter aa, eg if they intermarry with another such distribution among their partners.) However ...\n\n(i) is imprecisely worded. How big is the family?\n\nIf there is one child, the chance of that child being short is  1/2\n\nIf there are two children, the chance that both are tall is 1/4 and the chance that at least one child is short is 3/4. (Of one being short is 1/2 and of both being short is a quarter.)\n\nIf there are three children, the chance that all three are tall is 1/8 and the chance that at least one child is short is 7/8 (of one being short: 3/8, of two being short also 3/8, of all three being short: 1/8).\n\nWith 4 children, the chance of at least 1 being short is 15/16, of 1  being short is 4/16 or 1/4; of 2 being short is 6/16 or 3/8; of 3   being short is 4/16 or 1/4; of all 4 being short is 1/16;\n\nOne just reads across successive lines of Pascal's Triangle.\n\n(ii) the answer to this is buried in the above: 3/8ths\n\n(iii) again, imprecisely phrased. Does "such families" refer back to (i) or to (ii)? Taking it to mean families of four children, there is one chance in 16 of 4 tall children, 4 chances in 16 of 3 tall children, 6 chances in 16 of 2 tall children, 4 chances in 16 of 1 tall child and 1 chance in 16 of 0 tall children.\n\nIn 16 such families, there are 64 children and unsurprisingly 32 are tall\n(1 x 4) + (4 x 3) + (6 x 2) + (4 x 1) + 0\n\nwith an average number of 2 tall children per family, and as you would expect an average number of 2 short children per family, too.\n\n(iv) 256 = 16 squared and so the expectation is 16 families out of 256 will have 4 tall children, given 1 family in 16 has this particular expectation.
187575
Dominant traits are expressed in an offspring whether the individual has alleles Rr or RR while recessive is only expressed in rr individuals\n\nEven though an individual might have one r and one R, they will still exhibit dominant traits because it is a dominant allele
512854
genetics is the study of heredity and variation. most traits are inherited from the parents; sometimes it's the same as the father's, sometimes it's the same as the mother's, other times it's a combination of both and in some cases, the traits inherited can not be seen in any of the parents. \n\nlet's try to find out the probabilities or chances of inheriting the eye color trait... i think brown eye color is a dominant trait (B), and green eye color is probably recessive (b) so:\n\nif the father (or male/m) is heterozygous dominant for the trait (Bb) and the mother (or female/f) is most probably homozygous recessive (bb) then...\nm&#92;f b b\nB Bb Bb\nb bb bb\n-----------\n2 Bb : 2 bb\nor 50% chance of brown eyes and 50% chance of green eyes\n\nbut if the father (or male/m) is homoozygous dominant for the trait (BB) and the mother (or female/f) is most probably homozygous recessive (bb) then...\nm&#92;f b b\nB Bb Bb\nB Bb Bb\n------------\n4 Bb\nor 100% chance of brown eyes
374887
Very simply put, dominance and recessiveness are characteristics of genes.\n\nA dominant gene is expressed (shows up visibly in the offspring) when only one copy of the gene is present, on one chromosome from one parent. Let's say Tallness is a Dominant gene. If you have ONE tall parent, and get ONE copy of the Tall gene, you will probably be tall. If your tall parent was the son or daughter of a TALL and a SHORT person, they may only have ONE copy of that gene. If you get both SHORT chromosomes from Mom and DAD, you will NOT be tall. So you have 50 to 100 chance of being tall with a Dominant gene.\n\nNow, let's take the gene for BLUE eyes. It is recessive. You need TWO copies of this gene to get blue eyes. If Mom has blue eyes and Dad has blue eyes, and you get copies of both blue eye genes, you will have blue eyes. But if Mom has blue eyes, and Dad has brown eyes, you might end up with Brown eyes. Don't that make your blue eyes brown, so to speak.\n\nBUT..if Dad's mom had blue eyes and Dad's dad brown (your grandparents) and if Dad has one blue eye gene and one brown eye gene and has brown eyes AND if your Mom still has those blue peepers, you have a 1/4 chance of ending up with one blue eyed gene from AND a blue eyed gene from Dad and you will also have blue eyes like your Mum. Don't that make your brown eyes...blue?
956460
To start with, You need more information as to the Parental genotype for each question, \nFor example in question (a) since you have only mentioned full dominance, we can either assume both parents will be A/A x A/A. However this cross is useless because you know there will not be variation in the F1 progeny because both are dominant. thus the ratio is 100% all dominant A/A.\nThe second assumption is to cross a dominant parent A/A with a recessive parent a/a. If that's the case then you choose one gamete from each parent to form the F1 as follow\n\nParental Genotype        A/A    x    a/a\nGametes                          A     x    a\n\nF1                                         A/a\n\nfrom here, if you need to get genotype and phenotype ratio for your F2, you need information as to what kind of cross you want do. You can self the F1 or you can testcross with a recessive parent. In either case the ratio is different\n\nSelf-cross                  A/a    x      A/a\nGametes              1/2 A , 1/2 a    x   1/2 A , 1/2 a\n\nF2  punnet square\n..............1/2  A..........1/2 a\n\n1/2 A......1/4 A/A........1/4 A/a\n\n1/2 a.......1/4 A/a........1/4 a/a\n\nPhenotypic ratio of F2:  1/4 A/A; 2/4 A/a; 1/4 a/a = 1:2:1\nGenotypic ratio of F2:  (1/4 A/A + 2/4 A/a); 1/4 a/a = 3:1\n\n\n\nTest-cross                  A/a    x      a/a\nGametes              1/2 A , 1/2 a    x   1/2 a , 1/2 a\n\nF2  punnet square\n..............1/2  A..........1/2 a\n\n1/2 a......1/4 A/a........1/4 a/a\n\n1/2 a.......1/4 A/a.......1/4 a/a\n\nPhenotypic ratio of F2:  1/2 A/a; 1/2 a/a = 1:1\nGenotypic ratio of F2: same as genotypic ratio\n\nquestion (a) is not formulated in a clear way. for example. question (a) should have mentioned something like this:\n\na) The F2 of monohybrid cross with both parents full dominance, or 1 parent full dominance, 1 parent recessive.\n\nIs hard to work in genetics problems when the problem lacks crucial information. let me know if there is more information that you did not write down on your question.
612642
brown is dominant, green and blue are recessive, therefore both parents have two copies of the gene for their eye color therefore they don't have a brown gene to pass on.
615959
Because of the recessive and dominant genes that you inherit.\nWhen the sperm and the egg join together, they each carry half of the total genetic mixture that creates a person. Sometimes, the skin-color genes of one person "dominate" over that of the other, but other times the "recessive" genes outnumber the dominant ones and so the other skin color "wins".\n\nI'm not a genetics expert, but from my little knowledge I can tell you that it's all the result of a pretty much random combination process. Sometimes the recessive (or "weaker") genes outnumber the dominant ones, and "win", while sometimes the dominant ones do.\n\nhttp://en.wikipedia.org/genetics
821121
Because dominant mutations will be selected against.  Keep in mind for all dominant mutations, a phenotype will be expressed, and in a lot of these cases, the gene may not be passed on because the affected person may not be able to reproduce (or will be dead before he/she can reproduce). \n\nRecessive mutations can be carried without expressing a phenotype, so unless both alleles are mutated, no phenotype will be expressed.
61473
Well, being that blonde and red are submissive genes..one could say that in time, they will die out, or at least become rare, because even Asian people have a few blue/grey eyed children. \n Say B= brown (or black whatever).. and r=red. If a brown headed man(Br) has four children with a red headed woman(rr)..the odds or this:\nDad B  r\nMom r  r\n Meaning there is at least a 1 in four chance that the child will have red hair. As long as the submissive gene is there, the hair/eye color will be there. Even if both parents have Brown or Black hair. If both have the submissive gene for Red/ blonde. they have a 1 in 4 chance of having that color show in their children
594586
Well, I tend to agree with the other post on this...I wouldn't call a gene "superior" because it's dominant or recessive.  (Red hair, is, by the way, recessive!  I'm a redhead!)  A dominant allele need only be present for the trait to be apparent, that is, it can carry a recessive gene, but will show the traits of the dominant gene.  However, even though a trait is dominant, does not mean that it is the most common.  Take blood type, for example.  The O blood type is completely recessive, yet it is the most common, so I wouldn't really say that either of them are "superior".
579970
No that is not true.  Every baby gets half of their genetic coding from the father and half from the mother.  For things such as eye color we all have a dominate gene and a recessive gene.  Lets assume both parents have brown eyes, which means they have a dominate gene for brown eyes, but lets also assume that each of them have a recessive gene for blue eyes.  In this case there are 4 possible combinations of genes between the father and mother.  1. Father brown and Mother brown, 2. Father blue and Mother brown, 3. Father brown and Mother blue, and 4. Father blue and Mother blue.  In 1 through 3, the baby receives a dominate gene for brown eyes from at least one of the parents and the baby will have brown eyes.  In the final case the baby receives two recessive genes for blue eyes, resulting in a blue eyed baby.
265336
First generation was two dominants (LL) crossed with two reccisive genes (ll). Except for mutations the next generation would give 100% heterozygous (Ll). These plants would show only dominant charateristics. Upon crossing the heterozygous plants, appx. 25% of the next generation would be (ll) causing the expression of a short plant.
515090
dominant e.g. Aa, AA - Recessive -aa
692071
Homozygous genotype is when youre alleles are AA, Homozygous means the same-- and the capital letters represent dominant alleles.\nits dominant because only DOMINANT alleles are represented (AA)\n\nHeterozygous genotype's occur when you have one dominant allele and one recessive.. like Aa, because lower case is recessive.\n\nif the heterozygous genotype is recessive.. the genotype will not be seen in the phenotype. \nIf it is dominant .. the uppercase letter (the dominant allele) will be shown in the phenotype.\n\nUsually a heterozygous genotype is recessive- but it depends on the first filial generation\n\nthis is all easier to explain on a punnets sqaure..email me if you have more questions! emo4@uakron.edu
485911
because if its y linked then women can't have it because women don't have a Y chromosome while if its X linked it is usually recessive so males don't have a dominate allele to counteract it so the recessive shows through and to have two X recessive alleles in one cell is very rare because the male has to have the recessive phenotype and the female has to have a heterozygous genotype. Sorry for the in depth language.
324822
Segregation in cell division, when it goes correctly, results in each meiotic daughter cell having half of the genetic material of the parent.  The catch is, however, that there is no rhyme or reason a certain chromosome will go one way or the other.  So a child will share on average 50% of their geenetic material with each parent.\n\nIn terms of probability, I'm not certain what you mean, so I'll try to just give you my take on it.  If you're talking about the probability of the offspring having a certain allele when the parent is heterozygous, the probability is 50%.  There's a 50/50 chance that when the chromosomes segregate, the one with the allele in question will go to the offspring.  If you've ever done a Punnett square, you can see this: the allele in question will be present in 2 of the 4 boxes, or half of the total.\n\nDoes that help?