CH. 15, 16, 21

Source:  CH. 15, 16, 21    Tag:  lytic process
1. Viruses multiply via a process called the Lysogenic Pathway. In this process, viruses cut into the chromosomal DNA of a host cell and integrate its viral genes with that of the host. If that cell were a prokaryote, once it divided through binary fission, when cell wall material is deposited at the middle section of the cell to sever the cytoplasm, the replicated DNA, which also contained the viral DNA, manifest themselves in the creation of new infectious viruses.

2. The plasmid is the bacterial unit of DNA that contains genes that enable the transfer of genetic material between two cells. This process, which is called conjugation, causes a recipient cell to integrate foreign genetic material with its own genetic material, and, as a result, replicate the foreign DNA. The incorporating of external and internal genetic material will result in the recipient bacteria cell expressing new or alternated traits, in all called Bacterial Transformation.

3. A plasmid is the circle of DNA that is self-replicating and present in bacteria cells. When this genetic material becomes corrupted when the incorporation of DNA of an infective virus occurs, its self-replicating nature will benefit the virus because it only helps its proliferation. If this was a RNA retrovirus, the organism infected could express deadly diseases such as AIDS, for HIV is a retrovirus that destroys certain white blood cells, and, as a result, the immune system as a whole.

4. The prokaryotic organism E. Coli,, which resides in the large intestines of various mammals, feeds off the nutrients consumed by the host organism, If it infects the digestive system of a human baby ,for example, glucose is not as readily provided as lactose sugar from milk. In order to digest this hydrolysis composed disaccharide, E. Coli utilizes operator to regulate the production of the enzymes that breack down lactose. Operators serve as binding sites for repressor proteins that disable the transcription of the gene coding for lactose enzymes.

5. Okazaki fragments are disconnected DNA segments complimentary to the 5'->3' DNA parent strand that result from the discontinuous replication process of DNA polymerase on the lagging strand. Similarly restriction enzymes create fragmented DNA strands by cutting specific sequences on strands so that the genetic material of another organism can be incorporated by occupying the gaps. Both the Okazaki segments and the segments of restriction enzymes rely on the protein Ligase to consolidate the nicks and little openings resulting from fragmentation.

III. Essentials
1. The first stage of gene regulation is before transcription, for in the nucleus, before a DNA molecule is transcribed it can become attached to acetyl groups that loosen the grip of histones for an activating function, or inhibitory methyl groups which block an allele's expression on a trait. The second stage is after transcription in which an mRNA needs to exit the nucleus, for before traveling to the ribosomes certain proteins termed Y-boxed proteins can be binded to the transcript to completely stop its translation, in other words leaving it inactivated.

The third stage of regulation takes place during translation, for due to the fact that the longer a transcript lasts in the cytoplasm the more times it can be translated, enzymes digest and remove transcripts at certain times. The last stage is after translation because various factors can inhibit or activate a new protein, as seen by Y-box proteins that are only activated when a phosphate group is bonded to them by enzymes.

2. *This will be included in the notecards that get turned in later*

3. Prior to gel electrophoresis, a single-stranded DNA template is placed in a mixture containing the necessary enzymes, nucleotides, etc. to produce new strands of DNA. The numerous new copies of DNA fragments that have been produced are then separated from each other through the gel electrophoresis process, in which fragments pass through a semisolid gel slab in response to an electric field. Because each fragment's end is fluorescent-tagged, as they move through the gel and become subject to a laser, a computer can subsequently record what specific color the fragments express, and since the colors correspond to specific nucleotides a DNA sequence can thus be concluded (DNA fingerprint).

4. The primary difference between eukaryotic and prokaryotic genomes is the DNA of eukaryotes is linear whereas in prokaryotes it is circular (plasmids). In addition, the method in which prokaryote cells divide is very different when compared to mitosis. Known as prokaryotic fission, this process begins with the replication of DNA. Following duplication, the genetic materials attach to the cell's plasma membrane. Using newly produced lipids and proteins, the cell adds the molecules to the membrane to separate the attached strands, thereby stretching the length of the cell and the DNA attached to its walls. The cell finally undergoes  cytokinesis by depositing cell membrane material in the midsection of the now elongated cell, soon resulting in a new membrane being formed.

5. The lytic pathway is a variation cycle of how viruses multiply from cells. In the lytic cycle, viruses inject their genetic material in a host cell so that new viral particles can be synthesized within the cell. These infectious agents are released from the host after it goes through the process lysis, when the cell dies. This pathway is different from the lysogenic cycle in that it is relatively quicker since the lysogenic cycle is essentially an extension of the lytic pathway. Instead of just killing the cell, the lytic cycle focuses on incorporating the viral DNA with the genetic material of the host cell, so that when that cell divides, the foreign DNA will successfully spread, resulting in proliferation of the viruses.