biology

PRINCIPLES decline (heredity) MOLECULAR BIOLOGY GENES 

The molecule of heredity, replication, transcription, tranlasi1. DNA is the genetic material

• The discovery or research using viruses and bacteria prove that the instruction to produce a heritable trait is DNA.
• In other words, studies have shown that DNA is the genetic material.
• For example, Hershey-Chase experiment using T4 virus that has DNA just that the only DNA that breaks through the bacterial cell membrane proteins do not function results in DNA. Protein in solution (supernatant) DNA in pellets.

DNA and RNA are polymers of nucleotides

• Structure of nucleotide consists of :

1. five carbon beratom sugar (ribose, and the content of one atom of oxygen, called deoxyribose for DNA
2. a phosphate group
3. one of the nitrogen bases adenine or guanine purine or pyrimidine thymine or cytosine (cytosine). The three components are the nucleotide monomers of DNA and RNA monomers nukleotidanya to differ from DNA is a component of sugar and pyrimidine bases uracil, not thymine.

DNA Structure :

1. Double helix (see Figure in Chapter cells). Double helix structure of DNA was discovered Watson and Crick in 1953, was given the Nobel in 1962.
2. The structure of DNA in chromosomes: on one component, there is one strand of the DNA molecule
3. If the strands of the DNA molecule of all chromosomes are connected end to end, it can be very long
4. The fact that the DNA into a solid mass on chromosome because no protein. So in addition to chromosomal DNA is protein
5. Protein is an autosomal chromosomes in eukaryotic histones.
6. Because of the proteins (histones) that are strongly bound to DNA to form what is called a nucleosome.

DNA FUNCTION (DNA Replication and Repair).

1. DNA replication depends on the particular base pair
2. Bases Adenine always pairs with thymine bases (A_T).
3. Languages ​​guanine always pairs with cytosine (GC).
4. The process of DNA replication occurs before cell division phase
5. The replication process begins in a special section of the double helical structure called the origin of replication, which is where the starters replication protein attached to the DNA strand.
6. Then the DNA double helix to form the so-called bubbles, which double strands split, expands.
7. Parental DNA strand opening, but still united, that to facilitate described as a fork.
8. Then the enzyme polymerase nucleotide initiate replication by attaching a partner
9. One side of the DNA strand connecting nucleotide polymerase works point toward the fork and the other fork DNA polymerases work out the point of a fork.
10. Directions replication always keep the end of the carbon atom 5 'to the 3' end, because the direction of the DNA polymerase enzyme that causes the replication process only add nucleotides from the 3 'end of DNA strands.
11. After working polymerase, DNA ligase enzyme confront two short strands into longer strands panjangAda enzyme that provides correction, controls whether or not proper base pair.
12. Process control and DNA repair or repair involving the so-called DNA polymerase, and DNA ligase.
13. The start of replication in eukaryotic chromosomes can be few places and can simultaneously run replication, thus shortening the total time replication.

Gene Expression

DNA genotype is expressed as proteins that are the molecular basis for phenotypic traits diturunkanDNA to be proteins or RNA must be transcribed into single-stranded DNA.

So the DNA determines the nature of the resulting protein, indirectly is through the transfer of information to form RNA, which is then programmed protein synthesis or translation of RNA into protein

So in the process of gene expression are two important stages of the transcription, the process of transfer of genetic information into RNA molecules and translation, the process of information transfer from RNA to protein.

The process of transcription is the synthesis of RNA from a DNA template, the difference between RNA bases are Uracil (U) instead of thymine (T).

So if the A strand of DNA transcription is the result when the DNA U and T, then the RNA to A, then C when the DNA results on the RNA transcript is G and vice versa.

Examples of the DNA strand AAACCGGCAAAA strand RNA molecule is RNA transcription UUUGGCCGUUUURNA result is single-stranded, complementary DNA.

RNA is the messenger RNA is read DNAUrutan bases on three-three called codons, dictate the types of amino acids encoded in the phase of genetic information translasi.Jadi written as codons and translated into a series (sequence) amino acid.

The enzymes to transcribe DNA into RNA is called RNA transcription polimeraseProses starts when the enzyme RNA polymerase contact with the protein on the DNA called a promoter.

After starting the transcription stage of a process called initiation, when the enzyme RNA polymerase join promotor.Pada each gene, encodes only promoter to transcribe only a single strand of DNA

Different Part transcribed from one gene with subsequent gene transcription is lainnyaTahap RNA elongation, RNA isolation or away from the DNA template, so that the two strands of DNA can be joined again, followed by the third stage.

The third stage is the termination of transcription, ie when RNA polymerase reaches a certain base sequence called a terminator

The process produces three types of RNA transcription, the first is the RNA that encodes the amino acid sequence, called abbreviated Messenger RNA or mRNA carrier, and two types of RNA, transfer RNA is a molecule translator abbreviated tRNA and ribosomal rRNA abbreviated itself as a place that provides or protein manufacturer, all play a role in the process translasi.mRNA generated not only strand of genetic information from DNA, but each ends with an extended strand news besides genetic transcription processes necessary for the translation later.

Genetic news translated in the cytoplasm. In all prokaryotic transcription and translation occurs in the cytoplasm.

So RNA transcription in the nucleus result is transported out of the core into the genetic message translation sitoplasma.Proses brought mRNA to the amino acid sequence of language requires an interpreter by translating genetic tRNA.tRNA of three-letter words (codons) to amino acid one-letter word proteins.

The enzymes needed to attach the appropriate amino acid to the tRNA reading codons that tRNA concerned.

Just as transcription, translation also can be divided into three stages: initiation, elongation, and termination

The process of initiation involves combining together mRNA, the first amino acid attached to the tRNA and the two ribosomal subunits.

Stages of translation initiation of mRNA molecules are attached to the small ribosomal subunit. initiator tRNA located and attached to a particular codon on the mRNA translational beginning, called codons starters, the AUG codon where tRNAs carrying the amino acid Met.

Then the large ribosomal subunit joins the small subunit, generating functional ribosomes for protein synthesis takes place, in which the initiator tRNA occupies the right position.

Then the polypeptide chain elongation phase lasts until a termination codon is UAA translasiKodon termainasi or UAG or UGA do not code for amino acids, and it marks the termination of translation.

During and after translation, curled or folded polypeptide chains form a three-dimensional structure, tertiary structure.

There are several polypeptides that join together to form the structure of the protein kwartener.

So the flow of genetic information goes from DNA to RNA and then to protein

Mutations 

Mutation are changes in what happens to the nucleotide sequence of DNA. Mutations may include a number of long or large strand of chromosomes or only one base pairs only, such as for example sickell cell disease. So a mutation in just one or a few base pairs in DNA can affect gene translation or protein synthesis. There are two types of base substitution mutations and the removal or insertion of base Source cause mutations are called mutagens. The process of mutation formation called mutagenesis. The cause of mutation could result from errors during replication or recombination called spontaneous mutations, the other unknown cause. Mutagens commonly found in nature are X-rays and UV rays Both mutations occur in nature or intentional (experimental) mutations creating different alleles gen.DNA necessary to study the virus could become part of the host cell DNA. Some viruses cause disease in animals, plants, humans. AIDS virus from making DNA template that RNA. Research the virus is closely related to molecular genetics.