4. Genetic information
Where are the gens??
Genes are located on the chromosomes that are located in the nucleus of the cell.
All cells have 23 pairs of chromosomes, except for sex (gametes) that have 23 chromosomes
Genes are pieces of chromosomes and these are made from a macromolecule called DNA.
DNA is formed by two nucleotide chains, bound together by the bases by means of hydrogen bonds, forming a double helix.
http://www.biologia.edu.ar/adn/adntema0.htm
DUPLICATION ADN
REPLICATION
1st Phase:
Development of the chain (double helix) and separation of the two chains.
2nd Phase:
Each chain doubles independently, each one serves as a mold to make a new complementary chain by connecting the nucleotides. Those who carry Adenina with those who carry Timina and those who carry Guanina with those of Cytosine.
3rd Phase:
The final result is two new double helix, which are an exact copy of the initial molecule
We can see in the next link how the replication is given:
Gens have an special function:
They store the genetic information and they are made of DNA.
They allow this information to be available to make proteins, which in turn are responsible for the reactions (functions) of living beings to be carried out.
And, the special protagonists of transmition of the information are:
ADN: ARN:
Double hèlix Simple chain
Timina Uracil
Complementary: Complementary:
◦Adenina -->Timina ◦Adenina --> Uracil
◦Guanina -->Citosina ◦Guanina --> Citosina
ARN types:
◦ARNr, ARNt i ARNm
Amino Acids: they are organic molecules formed by an amino function and a carboxyl:
NH2-R-COOH
There are 20 different amino acids, which are the basic units that make up proteins.
Ex: Serine, proline, methionine, valine, ...
Proteins: they are strings formed by amino acid sequences, can reach 300-400 amino acids. A very important type is the enzymes that intervene in all the chemical reactions that take place in living things
2O Amino Acids Protein structure
Transmition of genetic information needs protein synthesis, and for this process it have 2 stages:
Transcription and Translation
TRANSCRIPTION
DNA information is transferred to the mRNA, which is constituted by the complementary bases of a fragment of DNA (gene) of one of the DNA chains that served as mold, with the difference that the nucleotide the complement of the adenine is uracil instead of thymine.
mRNA carries genetic information from DNA in the nucleus to direct protein synthesis in the cytoplasn in the next stage.
This occurs in the nucleus of the cell.
Stage 1 inside nucleus
TRANSLATION
The amino acid chain (protein) is formed according to the order that will determine the nucleotide sequence of the mRNA.
After transcription, the mRNA passes to the cytoplasm through the cell membrane, where it adheres to the ribosomes.
At the same time, the free ones (in the cytoplasm) that are selected, bind to the tRNA that transports them to the ribosome where it will be read by the mRNA. Each tRNA (ANTICODON) recognizes a sequence of three base pairs of the mRNA (CODON) and binds it to the corresponding one and it is forming the chain of amino acids --> protein is formed.
PROTEIN SYNTHESIS
GENETIC CODE
