Advice 1: How to solve genetic tasks in biology

In the school course of biology in high school you must have met, or will meet genetic goals. Genetics is a very interesting science. It studies the laws of variation and heredity. Representatives of any of the species reproduce like themselves. However, there is no identical individuals, all descendants to a greater or lesser extent differ from their parents. Genetics, as a science, makes it possible to predict and analyze the transmission of hereditary characteristics.
Instruction
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To solve genetic problems using certain types of research. The method of hybridological analysis was developed by G. Mendel. It allows you to identify patterns of inheritance of individual traits in sexual reproduction of organisms. The essence of this method is simple: in the analysis of certain alternative characteristics traced their transmission to the offspring. Also be an accurate account of the occurrence of each alternative basis and the nature of each individual offspring.
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Basic patterns of inheritance have also been developed by Mendel. The scientist gave the three laws. In consequence of their so called Mendel's laws. The first is the law of uniformity of hybrids of the first generation. Take two heterozygous individuals. When crossing they will give two types of gametes. The offspring of such parents appear in the ratio 1:2:1.
P - parents, G - gametes; F1 - offspring.
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The second law of Mendel is the law of segregation. based on his assertion that the dominant gene suppresses the recessive is not always. In this case, not all individuals are among the first generation reproduce the characteristics of the parents - there is a so-called intermediate inheritance. For example, when crossed homozygous plants with red flowers (AA) and white flowers (AA) is obtained offspring with pink. Incomplete dominance is quite common. It is also found in some biochemical characteristics of a person.
How to solve genetic tasks in biology
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The third and last law - the law of the independent combination of traits. For the manifestation of this law is necessary to observe several conditions: there should be a lethal gene, dominance should be complete genes reside on different chromosomes.
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Stand out tasks on the genetics of sex. There are two types of sex chromosomes: X chromosome (female) and Y chromosome (male). Floor having two identical sex chromosomes, called homogametic. Gender, determined by different chromosomes, called heterogametes. Gender of future individuals is determined at the moment of fertilization. In sex chromosomes, in addition to genes that carry information about a field contained other not having anything to do with it. For example, the gene responsible for blood clotting, carries the female X chromosome. Sex-linked traits are passed from mother to sons and daughters of the father only to daughters.

Advice 2: How to solve problems in biology

All tasks in biology are divided into tasks in molecular biology and challenges in genetics. In molecular biology there are several themes that have tasks: proteins, nucleic acids, DNA and energy metabolism.
Instruction
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Solve tasks on "Proteins" using the following formula: m(min) = a/b*100%, where m(min) is the minimum molecular weight, a is the atomic or molecular weight of the component b – percentage component. The average molecular weight of one acid residue is 120.
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Calculate the required value for the topic "Nucleic acids", adhering to the rules Chargaff:1.The amount of adenine equals the amount of thymine, and guanine – cytosine;
2.The number of purine bases equals the number of pyrimidine bases, i.e., A+G = T+C. In the chain of the DNA molecule the distance between the nucleotides is equal to 0.34 nm. Relative molecular mass of one nucleotide is equal to 345.
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Tasks on the theme of "DNA Code" to solve it with the help of a special table of genetic codes. Thanks to it you will learn what acid encodes a particular genetic code.
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Calculate the desired response for tasks on the theme "Energy exchange" reaction equation. One of the most frequent is: is c6h12o6 + 6О2 → 6СО2 + 6Н2О.
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Find the solution of problems on genetics based on a special algorithm. First, define which genes are dominant(A, b) and which recessive(a,b). Is called a dominant gene, the symptom of which is shown in homozygous (AA, AA) and heterozygous state(AA, Bb). Is called a recessive gene, the characteristic which occurs only at the meeting of their genes, ie, in a homozygous state. For example, pea plants with yellow seeds crossed with a pea plant with green seeds. Received of pea plants all had yellow seeds. It is obvious that yellow seed is the dominant trait. Write down the solution of this task : A – the gene responsible for yellow seeds and the gene responsible for green seeds.P: AA x aa
G: A, A
F1: Assistaut tasks of this type with several characteristics, then one sign of label A or A, and second B or B.
Note
Tasks are an integral part of the whole biology course and it is very important to be able to solve them.
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