Option FKeegan Murphy

Statement 1.3- Distinguish Between the Characteristics of the Three Domains Domain Eukarya contains all Eukaryotic cells while Domains

Archaea and Bacteria are prokaryotic. This means that organisms of domain Eukarya have membrane bound proteins and DNA that is wrapped about histone proteins.

Archaea and Bacteria are defined as separate because Archaea have some genes common to prokaryotes and some of eukaryotes

For example, Archaea has an rRNA sequence that is different than that of Bacteria.

Archaea also have 3 types of polymerase like eukaryotes as opposed to the 1 that is typical of Bacteria.

Finally, Archaea are known to have intron segments in their DNA, like eukaryotes, while prokaryotes do not have intron segments.

Statement 1.7- Compare the Structure of the Cell Walls of Gram-positive and Gram-negative Eubacteria Gram-positive and Gram-negative refer to a

positive or negative result in a Gram Staining test.

In this test bacterial colonies are separated from one another using a chemical that stains any bacteria with a significant quantity of peptidoglycan in their cell wall a violet color.

Bacteria that have peptidoglycan in their cell walls (Gram-positive) have an extra mesh-like layer of peptidoglycan, amino acids, and sugars around their plasma membrane

Statement 1.8- Outline the Diversity of Structure of Viruses A caspid is the protein shell of a virus. Some viruses

have enveloped caspids, protein shells that are covered in a lipid membrane known as the viral envelope, while others have naked caspids which do not have the envelope.

Some viruses (DNA Viruses) replicate by inserting their own genetic sequence into the DNA of the host cell while others (RNA Viruses) instead inject their genetic code into sequences of RNA.

Viruses will insert sections of RNA and DNA that differ in the amount of strands that they have. Some will have only one strand and some will have two strands.

Statement 2.5- Explain the Consequences of Releasing Raw Sewage and Nitrate Fertilizer into Rivers Sewage contains many different pathogens which are

dangerous if they come into contact with an individual. This also draws a number of saprotrophs to break down the organic waste which, in turn, consumes the water’s dissolved oxygen and creates BOD (Biochemical oxygen demand)which kills aquatic oxygen dependent organisms.

Releasing nitrate fertilizers into rivers can cause eutrophication (excessive algal growth) which can lead to algal blooming which also consumes all of the dissolved oxygen in the water and creates BOD which, again, causes the death or emigration of oxygen dependent aquatic organisms.

Statement 2.8- Explain the Principles Involved in the Generation of Methane from Biomass In order to produce methane a number of bacteria are

needed. First, bacteria are needed to convert organic matter into organic acids and alcohol.

Then, a second group of bacteria is needed to convert the acids and alcohols into acetate, carbon dioxide and hydrogen.

Finally, a third group of what is called Methanogenic bacteria is needed to create methane in the following chemical reactions:

Carbon Dioxide + Hydrogen -> Methane + Water Acetate -> Methane + Carbon Dioxide The conditions that are needed include the absence of

oxygen, a temperature of about 35˚C and a non-acidic pH

Statement 3.2- Explain How Reverse Transcriptase is Used in Molecular Biology Reverse transcriptase is used by reverse

transcribing RNA viruses like retroviruses

Reverse transcriptase takes the RNA of the virus and performs the process of transcription in reverse to form viral DNA

The viral DNA is then integrated into the host’s DNA and is used to code for the replication of the virus.

Statement 3.4- Outline the Use of Viral Vectors in Gene Therapy In the process of viral vector gene

therapy, specific viruses are used to remove harmful sections of DNA and replace them with healthy DNA.

One example is in the case of an immune deficiency condition called SCID where gene therapy can be used to insert genes that code for the production of an enzyme Adenosine Diamenase

Statement 3.5- Discuss the Risks of Gene Therapy The use of viral vectors can trigger cancer

causing genes If something goes wrong then a gene can be

over expressed and too much of a certain protein will be made

There is always a potential that the new gene will be misplaced causing major problems

Gene therapy may stimulate an immune reaction Viral vectors can be transferred from person to

person

Statement 4.4- Outline the Symptoms, Method of Transmission and Treatment of One Named Example of Food Poisoning

Salmonella Symptoms: Nausea, Diarrhea, Vomiting, Abdominal Pain, Fever, Chills, Headache, Muscle Pains and Blood in the Stool.

Transmission: Salmonella is first contracted through the consumption of undercooked meat and eggs but then can be transferred through improper hand washing/other sanitary procedures.

Treatment: Drinking lots of water to combat dehydration. If dehydration is severe then fluids are given intravenously. If the infection spreads beyond the intestines to the blood then antibiotics should be administered.

Statement 6.5- Outline the Mechanism of the Action of Antibiotics, Including the Inhibition of Synthesis of Cell Walls, Proteins and Nucleic Acids.

Cell Walls: Penicillin is a common example. To perform its task, penicillin breaks apart at the beta lactam ring in its structure and binds to the enzymes that synthesize cell walls in bacteria, causing the cell to explode from osmotic pressure.

Protein Synthesis: Inhibition is carried out by attacking the bacterial ribosomes which the drug differentiates from human ribosomes.

Nucleic Acids: Nucleic acid inhibiting antibiotics bind to the bacterial cell’s DNA or RNA to make it unreadable which stems the cell’s growth.

Statement 6.6- Outline the Lytic Life Cycle of the Influenza Virus Influenza binds to a cell through the use of specific receptors Influenza is taken in through endocytosis Viral RNA is released into the cytoplasm RNA is transported to the nucleus where it is copied and

replicated into RNA using a viral enzyme Some RNA is transported to the cytoplasm where it is

translated to make viral proteins which return to the nucleus to assemble the caspid

Influenza’s envelope proteins assemble in the cell membrane. Influenza buds off of these points and uses the cell membrane as its envelope

Lysis of the cell occurs to release many new influenza units to attack the other cells in the body.

Statement 6.10- Discuss the Prion Hypothesis for the Cause of Spongiform Encephalopathies The Prion Hypothesis states that the transmitting agent of

spongiform encephalopathies contains no nucleic acids and instead is an entity composed of of misfolded proteins called a prion.

The abnormal protein in the prion causes the disease Prions can change the shape of other proteins to cause

cell death The action of these prions causes spongiform

encephalopathies because it causes brain tissue to decay, leading to memory loss, personality changes, speech lapses and eventually death.

One example is the disease CJD (Creutzfeldt-Jakob's Disease) in humans