Homologous recombination (HR) can be explained as a process where DNA is exchanged or copied between two chromosomes or different regions of the same chromosome. The process requires homology between the exchanging DNA regions. Homologous recombination repairs DNA breaks, especially double stranded breaks (DSBs), stabilizes and repairs stalled forks. HR consists of a series of inter related pathways that function in repair of DNA breaks (Figure 4). Initially, stretches of single stranded DNA (ssDNA) are resected at the stalled forks or DSB ends which are quickly bound by replication protein A (RPA).
Ribosomes are found in both types of cells. Ribosomes make proteins by connecting chains of amino acids together for the cell to use. D. The Golgi apparatus turns simple molecules into larger, more complex ones and packages them in vesicles for storage and transport. This is only found in eukaryotic cells. E. Vacuoles are storage facilities for either nutrients for or waste from the cell.
DNA consist of macromolecules which are; nitrogenous base, a phosphate sugar backbone and a pentose sugar. DNA has a double helical structure due to the coiling of two biopolymer strands. This double helix structure is made of nucleotides composed of either, thymine, guanine, cytosine or adenine, a monosaccharide(deoxyribose) and a phosphate group. Covalent bonds join the nucleotides together in a chain form. This is between the deoxyribose sugar of one nucleotide and the phosphate component of the other nucleotide, which brings about the alternating sugar phosphate backbone.All biological information is stored in DNA which makes every organism unique.
Abstract The transformation principle suggests that bacteria use DNA as their genetic material and are able to exchange their genetic material via a process of transformation. Griffith had theorised the concept of the transformation principle using two strains of bacteria and studied their ability to recombine. Avery and MacLeod followed his studies and suggested DNA was sensitive to DNase, and that the enzyme would destroy the bacteria's ability to exchange genetic material and transform into a new strain. This was then tested in the labs at Wits by second year students where they studied the transformation of ampicillin sensitive E. coli to ampicillin resistant E. coli. The results obtained there were similar to those of Avery and MacLeod,
Other genes with adjacent methylated CpG islands are transcriptionally silenced. The methyl groups in CpG islands occupy the major groove of DNA, and block the binding of transcription factors necessary to form transcription complexes. CpG islands are usually located upstream of promoter regions The bulk of methylated CpG dinucleotides are not adjacent to genes, and are found in repetitive DNA sequences located in heterochromatic regions of the genome, including the centromere. Methylation of these sequences contributes to silencing the transcription and replication of transposable elements such as LINE (long interspersed nuclear element) and SINE (short interspersed nuclear elements) sequences, which form a major part of the human genome. Heterochromatic methylation also maintains chromosome stability by preventing translocation and other chromosomal abnormalities.
DNA synthesis. When primers detect and limit the amplification DNA sequence on two sides, the thermostable DNA polymerase synthesizes a complementary fragment from the 3 'end of the primers from both DNA single chain fragments using the nucleotides added to the mixture. The procedure is carried out at 72 ° C, using a thermostable Taq polymerase. APPLICATIONS: The ability of the PCR to analyze a very small amount of DNA plays an important role in disease diagnostics. One of the important uses of PCR is the diagnosis of possible AIDS infection at a very early stage even before antibodies have developed .
It is a continuous process in which replication of genetic material took place in parent cells which is equally distributed into two daughter cells. The genetic material is composed of chromosomes. The process of mitosis begins when the chromosomes condense. The chromosomes align themselves. .
Eg. Ferritin. Nucleic Acids  Nucleic acids are known as genetic materials. They are macromolecules meaning that they are polymers of nucleotides (phosphate group, pentose sugar, and a nitrogenous base). Living matter is composed of nucleic acids in the form of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA).
The method involves a matrix of two values: propensity values, a given amino acid will appear within the structure and frequency values, found in a hairpin turn for a provided amino acid. Taking these values into account the method then predicts regions of α-helices, regions of β-sheets, and positions where β-turns may appear. Chou P.Y. and Fasman G.D (1974)., is used to predict the Alpha-helices and beta-strands predicted by setting a cut for the total propensity for a slice of four residues. The residues values were classified into helix or strand breakers and formers.
These glycoproteins are enable the virus to enter the host cell by serving as receptors for binding. The tegument is the next inner layer after the envelope, composed of another layer of viral proteins. Next is the nucleocapsid, a protein shell. The nucleocapsid contains the DNA of the virus. This capsule is a unique shape, it is a twenty-faced icosahedron.
Next step is translation, in which the RNA becomes a protein, which then can act as structural units or enzymes. 2. How does DNA replicate itself? In order to replicate itself, DNA undergoes DNA replication, a process in which the DNA unwinds and splits in two. From that point on, new nucleotides are added to each of the original strands (A to T, C to G) until the result is two identical sequence copies of DNA.
What role does the Polymerase Chain Reaction (PCR) play in producing a DNA Profile? PCR amplifies the regions of DNA with short tandem repeats and uses primers with fluorescent labels. This works by replicating the region of DNA several times. The same region is also amplified on both chromosomes, however they are different sizes, which are then put into gel
Meiosis goes through the same process I just went through, but instead of being done after cytokinesis the cell goes to another cycle of replication. During the first cycle of replication in meiosis, Prophase is the same but crossing over occurs along side of the nuclear membrane dissolving, chromosomes developing, and the spindle fibers forming. Crossing over is the process in which homologous chromosomes from both parents pair up and exchange DNA. Also during metaphase and anaphase homologous chromosomes are separated and pulled to opposite sides. During this second cycle of replication the cells grows through Prophase II, Metaphase II, Anaphase II, Telophase II, and its final cycle of cytokinesis which is the exact same as during mitosis.
The Solid sequencing platform, produced by Technologies/Applied Biosystems (ABI), performs sequencing by ligation method. Similar like the Roche 454 library preparation, genomic double strand DNA were sheared into small pieces and ligated with two types of adatptors P1 and P2 on two ends. One end with P1 adaptor binds onto the surface of the magnetic bead and emulsion PCR takes place to amplify single nucleotide fragment. Then the oil was washed out and four fluorescent labeled di-bases probes were added into the beads mixture. By matching the 1st and 2nd position of the template by di-base probes, fluorescence was detected and the extra tail with fluorescent probe is cleaved out.
An operon is a part of DNA found in bacteria that controls gene regulation. Operons are controlled by an on switch known as the promoter. The Promoter is a place where the protein RNA polymerase binds. RNA polymerase is an enzyme that binds to DNA during transcription and unravels the DNA strands. RNA polymerase also transcribes the sequence of a messenger RNA (mRNA) molecule.