Week 3 - Fungi, Parasites, Viruses, Prions, Human Microbiome Flashcards
What are viruses
Viruses are neither procaryotes or eucaryotes as they do not possess all the cellular requirements for self replication. They are defined as obligate intracellular parasites and infect host cells, requiring living host cell components to replicate.
What is the structure of a virus
Outside a host cell, viruses exist as particles called virions which consist of genetic material (either DNA or RNA) surrounded by a protein coat called a capsid. Some viruses also have an outer envelope derived from the host cell membrane.
What is the classification system for viruses
Different types of viruses are grouped by the Baltimore Classification which divides viruses based on weather it has RNA or DNA and if this genetic material is single stranded or double stranded.
What are viruses in dentistry
- Herpes (directly impacts dentistry)
- HIV/AIDS (indirectly impacts dentistry)
Explain the steps of viral replication
- The virus attaches to specific receptors on the surface of the host sell, the virus then enters into the host cell through several different ways
- Once inside the host cell the capsid or envelope of the virus is removed, exposing the viral genetic material into the cell
- The viral genome is then replicated using the host cell’s machinery. This involves the synthesis of viral RNA or DNA
- The viral genetic material is then put together to produce new viral particles
- The newly assembled virus undergoes maturation where modifications of structure occurs e.g. adding an envelipe by taking some of the host cell membrane
- The virus is then released from the host cell
What are the different mechanicians where viruses enter the cell wall and membrane
- Translocation
- Endocytosis
- Cell surface fusion
Explain the process of translocation
- The virus directly passes through the host cell membrane without the involvement of vesicles or endocytosis
- This process is often utilised by non enveloped viruses that can cross the cell membrane by disrupting it or utilising host membrane transport proteins
Explain the process of endocytosis
- Involves the virus binds to specific receptors on the cell surface, triggering the formation of a vesicle that internalises the virus
What is the process of cell surface fusion
- Involves the direct fusion of the viral envelope with the host cell membrane, allowing the viral genetic material to enter the host cell’s cytoplasm
- Mostly used by viruses which have a lipid bilayer envelope derived from the host cell membrane
What is a Prion
Unlike traditional microorganisms, prions consist of misfolded or abnormal forms of a regular protein that have the ability to induce the misfolding of normal proteins with the same sequence.
Examples of diseases which prions cause
- Kuru, Scrapie and mad cow disease which are all diseases where the tissue of the brain is affected, and the neuro electrical impulses are negatively impacted.
What are parasites (protozoans)
- Parasites are complex single celled microscopic organisms.
- Protozoans are single celled organisms that also have a eukaryotic cell structure, they are considered animals as they lack a cell wall or the ability to photosynthesize
- Parasites are eukaryotes however they live in or on another host organism and derive nutrients and resources at the expense of the host.
- The relationship between the parasite and the host is typically harmful to the host
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What are diseases caused by protozoan
- Malaria
- Amoebic dysentery
- Leishmaniasis
- Giardiasis
What is the Human Microbiome
refers to the diverse community of microorganisms that inhabit various parts of the human body which includes every surface exposed to the environment. The microbiome plays a crucial role in maintaining health and influencing various physiological processes.
What is the human microbiome influenced by
- genetics
- age
- stress
- nutritional status
- Exposure to antibiotic therapy
