The legacy is that the offspring tend to resemble their parents, based on the fact that our appearance and function, ie our phenotype, is largely determined by our genetic makeup, that is our genotype.

However, we must bear in mind that the expression of many genes, and therefore the expression of the corresponding phenotypes, is influenced by environmental factors.

This discipline involves the study of cells, individuals, their descendants, and people who live in the agencies. Investigate the genetic variation of all forms of hereditary and the underlying molecular basis of such characteristics. Thus Genetics has been divided into three main branches: classical genetics (also known as Mendelian genetics or transmission), molecular genetics and population genetics.

What is the heart of heredity in the cell?

Eukaryotic organisms are characterized by the presence of a nucleus in which the genetic material. In prokaryotes, such as bacteria, the genetic material is in an area not limited, but recognizable, the cell called nucleoide. In viruses, the genetic material is sheathed in a head cover or a protein called viral capsule.

What is the genetic material?

Both in eukaryotes as in prokaryotes DNA (deoxyribonucleic acid) is the molecule that stores genetic information. RNA (ribonucleic acid) is the genetic material of some viruses. These are the two types of nucleic acids that are found in organisms. Nucleic acids, along with carbohydrates, lipids and proteins, are the four main classes of organic molecules that characterizes life on our planet.

What is a gene?

In simple terms, the gene is the functional unit of heredity. In chemical terms is a linear chain of nucleotides (chemical blocks that make up DNA and RNA). A conceptual definition is regarded as a data storage unit capable of suffering replication, mutation and expression.

What is a chromosome?

The genetic material is packaged in discrete units called chromosomes. While some viruses have several chromosomes, most have only one, consisting of a single molecule of DNA or RNA. Depending on the type of virus, the molecule can be unicatenaria or bicatenaria, linear or circular. The bacterial chromosome is a molecule composed of a circular DNA bicatenaria associated proteins and RNA. Some bacteria have additional genetic elements called plasmids, small size and circular DNA bicatenario.

In eukaryotic cells, each chromosome is a DNA molecule bicatenario associated with basic proteins called histones and other proteins histónicas. The role of histones is to provide the structural support of DNA in a complex fiber structure, the chromatin, which is the basic subunit nucleosoma.

When and how you can display a chromosome?

In eukaryotic chromosomes are easily viewable with the microscope when they are in mitosis and meiosis. After the division, this material, called chromatin, is desespiraliza at the interface and can be more easily studied by electron microscopy.

How many chromosomes have a body?

Although there are many exceptions, members of many species have a specific number of chromosomes, called the diploid number (2n), present in every somatic cell. Through careful analysis, is that these chromosomes are in pairs, and each member of the pair when they are visible in cell division, share almost the same look. The members of each pair, called homologous chromosomes are identical in the length and location of Centromere, the point at which the fibers connecting the spindle in the division. They also have the same sequence of locations or loci gene and are paired in meiosis.

The number of different types of diploid chromosome of any species is equal to half the diploid number, which is called the haploid number (n). Other agencies, especially many plants, are characterized by polyploids, in this case, the number of different types of chromosomes is called monoploide number (n).

What is achieved during the process of mitosis and meiosis?

In eukaryotic cells a cell cycle, divided into two phases: interphase and mitosis. The interface is made up in turn three phases: G1, S, G2. DNA replication of chromosomes occurs during the S phase at the end of which each cell presents 2n chromosomes 4n chromatids. Mitosis (M phase) or cell division in turn consists of four phases: prof (during which the chromosomes become visible as structures with two chromatids), metaphase (during which the chromosomes are arranged in the equatorial plane cell attached to the spindle), anaphase (which occurs during the separation of chromatids); telophase (phase of reconstitution of the nucleus). At the end of mitosis each daughter cell chromosomes and 2n presented 2n chromatids.

Meiosis is a special process of cell division that leads to the emergence of four haploid gametes, which are one member of each of the homologous pairs of chromosomes, from a diploid cell. This process consists of two successive mitoses, called first and second meiotic division. During the first mating takes place profase chromosome counterparts and exchange of genetic material (crossing). During the first anaphase chromosome counterpart migrates toward each pole (n chromosomes, 2n chromatids) and during the second anaphase is the separation of chromatids (n chromosomes, chromatids n). At the end of meiosis each daughter cell chromosomes presents n yn chromatids.

What are the causes of genetic variation?

There are two causes of genetic variation: structural chromosomal abnormalities and numerical chromosomal abnormalities. Among the former, also called chromosomal aberrations are duplication, deletion and rearrangement of chromosome segments (investment, translocations, fusions and fissions or changes robertsonianos). Alternative forms of a gene, which occur as a result of the mutation, called alleles. Often, but not always, the genetic variation leads to change in any feature of the body. Once part of the body’s genetic code, this option can be extended throughout the population through various reproductive mechanisms.

Changes in the number of chromosomes that affect only one or more chromosomes are known as aneuploidies (nulisomía, monosomy, trisomy, tetrasomy …). These phenomena are due to the occurrence of meiotic non-disjunction anafásico or delayed during the first or second meiotic division. The monosomy and trisomy can affect both the autosomes and the sex chromosomes, and cause many different syndromes in humans, as well as abnormalities in meiotic segregation. However, plants are more tolerant to aneuploidies.

Variations by presenting a multiple number of chromosomes haploid normal complement of a species called euploidías. Depending on the number of chromosomal allocations of agencies that have, they are classified into monoploides, diploid, triploid, tetraploids, etc.. Depending on the origin of the chromosome that have multiple sets, individuals are called polyploids autopoliploides (homologous chromosomes of the same species) or alopoliploides (homologous chromosomes of two or more species that have hybridized with each other). Autotriploides plants and autotetraploides properties that confer greater commercial value (eg, larger).

How genetic information is stored in the DNA?

The nucleotide sequence of a DNA fragment of a gene which is present in the form of a genetic code. This code specifies the chemical nature of protein (the composition of amino acids) that are the end product of gene expression. Mutations occur when you change the sequence of nucleotides. In DNA, there are four different nucleotides, distinguished by one of its components, the nitrogenous base. The genetic code is a triplet, therefore, each combination of three nucleotides constitutes a code word. Almost all possible triplets specify one of the 20 amino acids (chemical units that make proteins).

How is the genetic code?

Information encoded in DNA is transferred first to the process of transcription in the molecule of messenger RNA (mRNA). Subsequently, the mRNA is associated with a cellular organelle, the ribosome, which translates into a protein molecule.

Are there exceptions where the proteins are not the final product of a gene?

Yes, for example, genes that encode ribosomal RNA (rRNA), which is part of the ribosome and RNA transfer (tRNA), active in the translation process, but not transcribed translated. Therefore, sometimes, RNA is the end product of genetic information stored.

Why are the proteins that constitute the final product of the vast majority of genes are so important to living things?

Many proteins are biological catalysts, highly specific (enzymes). The role of these proteins is to control cell metabolism, determining which carbohydrates, lipids, nucleic acids or proteins are found in the cell. Many other proteins carry out missions enzyme. For example, hemoglobin carries oxygen, collagen provides structural support and flexibility to many tissues, immunoglobulins are the basis of the immune response and insulin is a hormone.

Why enzymes are necessary for living things?

Enzymes as biological catalysts, decrease the activation energy necessary for many biochemical reactions and accelerate the achievement of balance. Otherwise, these reactions so slowly that they would have no effect on the living conditions of our planet.