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DeoxyriboNucleic Acid

One molecule of DNA, consits of:

1. 2 strands of repeating units called nucleotides.

2. The 2 strands are twisted into a double helix structure.

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Deoxyribonucleic acid is made up of lots f nucleotides joined together.

What is DNA?

DNA is a polymer of mononucleotides, this ones join together between the phosphate of one nucleotide and the phosphate group of the adjoining nucleotide.(the sugar and phosphate units make up the "backbone" of the nucleic acid).

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· Guanine (G)

· Cytosine (C)

· Adenine (A)

· Thymine (T)

A and G are Purine bases and C, T and Uracil are Pyrimidine bases.

A pairs with T and G pairs with C

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Transcription is the process of copying a segment of DNA to RNA

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The RNA polymerase enters the DNA and attaches to a promoters (this part of the strand says where the gene starts)

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The RNA polymerase (builds from five prime to three prime) and starts doing the complementary of the template strand

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After the gene is transcribed at its fullest and the RNA polymerase reaches the termination signal. It leaves the DNA with the new RNA

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pre-mRNA,(this hanges only happen on Eukaryotes).

it is divaded into two parts:

Exons: the one with important information

Introns:the one with no important fuction

the proces that separates this two is called splicing.

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In this event the exons can not be assemble in the same order they were before:

Before: E1, E2, E3, E4

after A.S.: E4, E1, E3, E2

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·> m RNA: messenger RNA. Product of transcription, contains instructions to "build" a protein.

·> t RNA: transfer RNA. Carrles 1 aminoacid.

·> Aminoacid (aa): Monomere of a protein. A chain of aa is a protein.

·> Ribosome: Where protein synthesis takes place. Organelle with 2 subunits.

·> Codon: Group of 3 nucleotides. Codifies for 1 aa.

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Initiation: when the translation complex is formed. The small subunit attaches first.

Elongation:

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A mutation is a change in your genetic code

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Mutagens: agent which produces or facilitates a mutation to occur.

Types:

+Physical mutagen: radiation (X-ray or UV)

+Chemical mutagens: some substances can cause changes in genes. Like for example pollutants, substances in tabacco.

+Biological mutagens: some viruses can increase the frequency of genetic mutations.

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+Base substitution:

1.Missense mutation: the change of the base causes a change in amino acid inserted in the protein.

2.Nonsense mutation: the change of the base causes the protein to be terminated

3.Silent mutation:the change of the base does not cause a change in amino acids introduced in the protein.

+Insertion mutation:occurs when an extra nucleotide is added to replicating strand "slips", or wrinkles, which allows the extra nucleotide to be incorporated. Strand slippage can also lead to deletion mutations.

+Deletion mutation:occurs when a wrinkle forms on the DNA template strand and subsequently causes a nucleotide to be omitted from the replicated strand.

1.Frameshift mutations.

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Replication is the process in which the DNA is copied.

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1. the DNA is untwisted by the topoisomerase.

2. the two strands are separated by the helicase.

3. binding proteins keep the strands stabilized while the DNA polimerase III goes from 5 prime to 3 prime creating nucleotids

4. after completing the copy process the polimerase III goes away and the two dna strands are copied making you have now two DNAs

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1. leading strand: is the one that can be done in one go. since it start copying 5 prime to 4 prime

2. lagging strand: is the one that has to be done slower since when the dna is separated it is the one that has the primers twisted which means that the polimerase has to do the copying slowly entering and going away a lot of times.

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Termintion: when an stop codon enters site A, no new TRNA is attached. Site A "closes".

The translation complex disassembles.

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Genetic engineering is the modification of an organism at a genetic level todo something it was not able to do before.

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PCR (Polymerase Chain Reaction): The basis of PCR is to make exponential copies of a sequence of DNA. Specific primers will be used to find specific sequences.

Electrophoresis: a technique used to separate DNA by sizes. They use electricity to see who goes further. The further it goes, the smaller the DNA is the closer they are the bigger they are. With this you can do DNA sequencing,.