How does polygenic inheritance differ from Mendelian inheritance?
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There really is no essential difference in the way\nthe genes are inherited.  The difference is in how\nthey affect the offspring.  In polygenic inheritance\nthere are many gene pairs involved, each of which\nhas a small effect and the effects of each pair are\nadditive with the others.  Such genes control things\nlike height, weight, skin color, etc.  The genes in\nwhat is usually called Mendelian inheritance have a\nlarger and more noticeable effect.  Actually the\nexamples given in biology courses are usually\nover simplified.  The case of eye color is a good\nexample.  What is usually taught is that brown eyes\nare dominant and blue eyes recessive, but this is\ntrue only if all other things are equal, that is, there\nare no other genes affecting eye color to interfere.\nIn the fruit fly there are dozens of gene pairs that\naffect eye color, and probably as many in human\nbeings.  My father had blue eyes, my mother has\nbrown eyes.  I have never been able to decide\nwhat color my eyes are.  They are sort of blue\naround the edges, yellow more toward the center,\nwith a reddish brown spot in one of them.  Also\nwhat about eyes that are described as green, gray\nhazel, violet?
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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?
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There is no difference, dear, both mean the same thing.  It's a disease in your genetic code, which you inherited.
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Well there are so many technicalities revolving around this question. While biologically speaking you could call the children sibblings is erelevant to the question. Manly because they will have there own genetic codes.  That is where this becomes quite complicated because genetics deals with more than just genes it deals with traits, DNA, Chromosomes, Blood Types, etc...  As far as them being related, coming from not only the same father, but an identical twin they are going to have very similar genes.  In fact when it comes to there family traits it will be identical.  However no individual, no matter if they are identical will ever have the exact same genetics (in the broad since) as another because that would go against the natural law of diversity.  So sumary exact same family traits, but overall two different people (genetics).
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Heredity is the genetic transmission of characteristics (bone structure, skin color, and mentality)\nVariation is the acts, processes, or deviations (education, wealth, and sense of reality)
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In genetics, the term "recessive gene" refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). Every person has two copies of every gene, one from mother and one from father. If a genetic trait is recessive, a person needs to inherit two copies of the gene for the trait to be expressed. Thus, both parents have to be carriers of a recessive trait in order for a child to express that trait. If both parents are carriers, there is a 25% chance with each child to show the recessive trait.\n\nThe term "recessive gene" is part of the laws of Mendelian inheritance created by Gregor Mendel. Examples of recessive genes in Mendel's famous pea plant experiments include those that determine the color and shape of seed pods, and plant height.
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what Mendel gave us was the "Law of Independent Assortment" and the "Law of Random Segregation".  Basically, that chromosomes behave in an independent manner when segregating from each other. (ie-when chromosomes are segregated to your gametes, the chromosomes your father gave you will not all go together, they will act independently of each other.)\nIn short, he gave us a way to predict what ratios of progeny to expect from parental generations. \n\nFor example, a dihybrid cross between PPSS and ppss will result in all F1 progeny PpSs, and if intercrossed, those F1 progeny will produce F2 progeny in a 9:3:3:1 ratio....\nso on and so forth.\n\nOf course these principles don't really apply with more complex human genetics...
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Down syndrome is not inherited. It happens when something goes wrong in the formation of either the egg or the sperm. Normal people recieve a copy of each chromosome from both parents. People with down syndrome have an extra copy of chromosome 21.  When one of the sex cells was developed, the two copies didn't get pulled apart when they should have during meiosis.
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recessive features are passed through family trees as "traits"; people who are heterogenous for the feature and their phenotype shows the dominant feature but they carry the recessive feature into their offsprings.
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1. at a basic level, genetic traits are determined ultimately by the DNA sequence. Differences in the DNA sequence between individuals may result in differences in traits. Differences in the DNA sequence of a gene are known as alleles. \n\n2. The traits determine the characteristics of an organism because the DNA sequence manifests itself as a protein. DNA is transcribed into RNA which is then processed (spliced) into mRNA. mRNA is translated at the ribosome (through the use of tRNA which brings in amino acids) into a polypeptide or protein. Differences in protein sequence may alter protein function thus resulting in an altered trait, also known as a phenotype.
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Husband- Heterozygous since there are albino children.\nWife- Homozygous Recessive because it's the only way the recessive can show up.\nPigmented Children- Heterzygous since the dominant trait showed up but the other parent was homozygous recessive.\nAlbino Children- Homozygous Recessive for the same reasons as the mother.
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Mendel's law of dominance\nIn a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. Offspring that are hybrid for a trait will have only the dominant trait in the phenotype. \n[edit]\nMendel's law of segregation\n \nFigure 3 : The color alleles of Mirabilis jalapa are not dominant or recessive.\n(1) Parental generation. (2) F1 generation. (3) F2 generation. The "red" and "white" allele together make a "pink" phenotype, resulting in a 1:2:1 ratio of red:pink:white in the F2 generation. \nFigure 1 : Dominant and recessive phenotypes.\n(1) Parental generation. (2) F1 generation. (3) F2 generation. Dominant (red) and recessive (white) phenotype look alike in the F1 (first) generation and show a 3:1 ratio in the F2 (second) generationMendel's law of segregation, also known as Mendel's first law, essentially has four parts.\n\nAlternative versions of genes account for variations in inherited characters. This is the concept of alleles. Alleles are different versions of genes that impart the same characteristic. Each human has a gene that controls eye color, but there are variations among these genes in accordance with the specific color the gene "codes" for. \nFor each characteristic, an organism inherits two genes, one from each parent. This means that when somatic cells are produced from two gametes, one allele comes from the mother, one from the father. These alleles may be the same (true-breeding organisms, e.g. ww and rr in Fig. 3), or different (hybrids, e.g. wr in Fig. 3). \nIf the two alleles differ, then one, the dominant allele, is fully expressed in the organism's appearance; the other, the recessive allele, has no noticeable effect on the organism's appearance. In other words, the dominant allele is expressed in the phenotype of the organism. However this does not always hold true: Today, we know several examples that disprove this "law", e.g. Mirabilis jalapa, the "Japanese wonder flower" (Fig. 3). This is called incomplete dominance. There is also codominance on a molecular level, e.g. people with sickle cell anemia, when normal and sickle-shaped red blood cells mix and prevent malaria. \nThe two genes for each character segregate during gamete production. This is the last part of Mendel's generalization. The two alleles of the organism are separated into different gametes, ensuring variation. \nDuring his experiments, Mendel encountered some traits that did not follow the laws he had encountered. These traits did not appear independently, but always together with at least one other trait. Mendel could not explain what happened and chose not to mention it in his work. Today, we know that these traits are linked on the same chromosome.\n\n[edit]\nMendel's law of independent assortment\nAlso known as Mendel's Second Law \nThe most important principle of Mendel's law of independent assortment is that the emergence of one trait will not affect the emergence of another. While his experiments with mixing one trait always resulted in a 3:1 ratio (Fig. 1) between dominant and recessive phenotypes, his experiments with mixing two traits showed 9:3:3:1 ratios (Fig. 2). Mendel concluded that each organism carries two sets of information about its phenotype. If the two sets differ on the same phenotype, one of them dominates the other. That way, information can be passed on through the generations, even if the phenotype is not expressed (F1 generations, figures 1 and 2).\n\nMendel's findings allowed other scientists to simplify the emergence of traits to mathematical probability. A large portion of Mendel's findings can be traced to his choice to start his experiments only with true breeding plants. He also only measured absolute characteristics such as color, shape, and position of the offspring. His data was expressed numerically and subjected to statistical
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Short answer:\n\nYour genes are a combination of both of your parents genes, and they constitute a full set.  Through meiosis however, a process which creates sperm and egg cells, the cells divide in such a way as to halve their genetic "info".  These halves are carried by the sperm and egg cells, and recombined into a single, new whole through fertilization.
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Such characteristics are shaped by the chromosomes you receive from your parents. There's a gene for every color of eye, color of hair, thickness of hair, color of skin, thickness of skin, shape of eyes, weight, height, life span, character, etc.\n\nEvery person receives information for every part from 2 people, so it will have 2 probably eye color, hair color, etc. Even when only one will appear, that person still can give the other gene to a child.
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In organisms that reproduce only sexually, the mutations in somatic cells normally don't go beyond the individual. But in the case of organisms that can reproduce asexually, by means of divisions of those somatic cells, a mutation in those cells could be passed to the descendants and thus be under the influence of evolutionary forces. \nThat's a common event in plants, especially a type of mutation called polyploidy (multiplication of the entire chromosome set). These types of mutations are also induced by man to obtain new varieties.
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chromosomes from different parents determine the genetic structure of the child - with recessive genes only becoming apaprent if they are present from both parents
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The laws of inheritance were derived by Gregor Mendel, a 19th century Austrian monk, who was conducting plant hybridity experiments. Between 1856 and 1863, he cultivated and tested some 28,000 pea plants. His experiments brought forth two generalizations which later became known as Mendel's Laws of Heredity or Mendelian inheritance. These are described in his paper "Experiments on Plant Hybridization" that was read to the Natural History Society of Brno on February 8 and March 8, 1865, and was published in 1866.