A tiny quantity of DNA can also be found in the mitochondria, although the majority of DNA is found in the cell nucleus, where it is referred to as nuclear DNA. The DNA consists of 2 twisted strands (double helix) of constant units called nucleotides

(The chemical bases that make up the code are paired up Adenine (A) goes with Thymine (T) and Guanine (G) with the Cytosine (C)).

WHEN DOES DNA NEED TO REPLICATE?

• Before cell division

• During Interphase of Mitosis and Meiosis

Both strands of DNA have directed ends, denoted by a 5' and 3'. Which side group is connected to the DNA backbone is indicated by this notation. A phosphate (P) group is connected to the 5' end, and a hydroxyl (OH) group is bonded to the 3' end. Replication relies on this directionality because it only moves in the 5' to 3' direction. The replication fork, however, is bidirectional; the leading strand is orientated 3' to 5', while the lagging strand is directed 5' to 3'. In order to account for the directional difference, the two sides are then reproduced using two distinct procedures.

2- Priming: Replicating the leading strand is the easiest. A brief segment of RNA known as a primer attaches to the 3' end of the DNA strand after the strands have been split. Replication always begins with the primer binding. The enzyme DNA primase produces primers.

3- Elongation: During elongation in DNA replication, DNA polymerase adds complementary nucleotides to the growing DNA strand in the 5' to 3' direction. On the leading strand, synthesis is continuous, while on the lagging strand, synthesis is discontinuous, resulting in the formation of Okazaki fragments.

4- Termination:In the termination phase of DNA replication, the process concludes when replication forks from adjacent origins meet and fuse, completing the replication of the entire DNA molecule. This ensures that the entire length of the DNA is replicated accurately and completely.

2- Elongation: RNA polymerase uses one of the DNA strands as a template to start synthesising a complementary RNA strand after unwinding the DNA double helix at the transcription start site. The base-pairing rules dictate that RNA polymerase adds nucleotides to the developing RNA molecule as it travels down the DNA strand (A pairs with U, G pairs with C).

3-Termination: A termination sequence in the DNA indicates the conclusion of a gene, and transcription proceeds until RNA polymerase reaches it. At this stage, the freshly created RNA molecule and RNA polymerase separate from the DNA.

2- Elongation: The ribosome reads the codons in successive order as it travels along the mRNA molecule. A particular tRNA molecule with the corresponding amino acid recognizes each codon. The elongation of the polypeptide chain is caused by the ribosome's catalytic action in creating peptide bonds between neighboring amino acids.

3- Termination: The process keeps on until the mRNA molecule comes across a stop codon (UAA, UAG, or UGA). Stop codons indicate the completion of protein synthesis but do not code for any amino acids. Protein synthesis stops when a stop codon is reached, and the finished polypeptide chain is released from the ribosome.

• Physical mutagens: This can be radiation, x-rays, gama rays or UV light, and radiative particles, like beta and alpha.

• Chemical mutagens: Substances can also cause these changes in the genes, like pollutants and tobacco substances.

• Biological mutagens: Such as viruses...

• Missense mutations: The change causes a change in the amino acid

• Nonesense mutations: The change causes the protein's termination

• Silent mutations: The change does not affect at all

2- Insertion mutation

• This can happen when a nucleotide is added during replication. The extra nucleotide is added when the replicating stand fails in the process. These slippages can lead to deletion mutations

3- Deletion mutations

• Occurs when a DNA strand messes up and causes a nucleotide to be omitted

Electrophoresis: This technique separates fragments of DNA according to size. The bigger they are, the slower they are going to pass through the pores. It moves towards the + pole, relled by a - charge. DNA profiling can also be used to detect suspects and blood, this can even be used as a paternity test.

Promoters: to activate the transcription of DNA

Restriction site: where enzymes cut to insert the gene

Selectable marker and antibiotic resistance gene: to look for the cells that express the plasmids

To know which ones worked or not you add the virus you wanted to prevent and the ones that work wont die because they have antibiotics

2. Use:

   • DNA: DNA is the blueprint for the production of proteins and contains an organism's genetic information. It is found in the cell nucleus and is duplicated to transfer genetic information to daughter cells when cells divide.

   • RNA: RNA is involved in the production of proteins, the regulation of gene expression, and the expression of genes. A variety of RNA molecules, including ribosomal RNA (rRNA), transfer RNA (tRNA), and messenger RNA (mRNA), are involved in various stages in the synthesis of proteins.

3. Stability:

   • DNA: DNA is resistant to deterioration and is comparatively stable. It is protected from harm by its double-stranded structure and location in the cell nucleus.

   • RNA: Ribonuclease enzymes have a greater tendency to degrade RNA than they do DNA. RNA molecules are constantly being created and broken down in cells, and they usually have a brief lifespan.

4. Location:

   • DNA: DNA forms chromosomes in the cell nucleus, which is where it is mainly found. Additionally, organelles known as mitochondria and chloroplasts contain some DNA.

   • RNA: RNA is present in every part of the cell, including the cytoplasm, nucleus, and organelles like mitochondria and ribosomes. Depending on their purpose, different forms of RNA can be found in different parts of the cell.