2.2 Prokaryote Cells

Bacteria

Bacteria

Prokaryotic organisms that can be beneficial, harmful, or neutral to living organisms.

Cell wall

A structure present in all bacterial cells that prevents the cell from swelling and bursting, maintains the shape of the bacterium, and provides support and protection.

Capsule

A layer around the cell wall of some bacteria that protects the bacterium from phagocytosis by white blood cells and makes it harder to be identified by the immune system.

Pili (fimbriae)

Thread-like protein projections found on the surface of some bacteria that are used for attachment to a host cell and for sexual reproduction.

Flagella

Many-stranded helices of the protein flagellin that some bacteria use for movement.

Cell surface membrane

Similar in structure and function to the membranes of eukaryotic cells, it is the site of some respiratory enzymes in bacterial cells.

Mesosomes

Infoldings of the cell surface membrane of bacteria that may be associated with enzyme activity or used for photosynthesis.

Plasmid

Smaller circles of DNA found in some bacterial cells that code for specific aspects of the bacterial phenotype and can reproduce independently of the nucleoid.

Nucleoid

The area in a bacterial cell where the single length of coiled DNA is found.

70S ribosomes

Ribosomes in bacterial cells that are smaller than the ribosomes in eukaryotic cells and are involved in protein synthesis.

Gram staining

A staining technique used to distinguish between Gram-positive and Gram-negative bacteria based on their cell wall composition.

Gram-positive bacteria

Bacteria that have a thick layer of peptidoglycan in their cell walls and stain purple/blue with Gram staining.

Gram-negative bacteria

Bacteria that have a thin layer of peptidoglycan in their cell walls and stain red with Gram staining.

Antibiotics

Drugs used against bacterial pathogens that target features of bacterial cells such as cell walls and ribosomes.

Hypertonic solution

A solution with a higher concentration of solutes and lower concentration of water than the surrounding solution.

Peptidoglycan

A large, net-like molecule found in all bacterial cell walls, made up of polysaccharide chains with peptide cross-linkages.

Bacteriophages

Viruses that attack bacteria.

Cocci

Spherical bacteria.

Bacilli

Rod-shaped bacteria.

Spirilla

Bacteria with a twisted or spiral shape.

Vibrios

Comma-shaped bacteria.

Obligate aerobes

Organisms that require oxygen for respiration.

Facultative anaerobes

Organisms that can use oxygen if it is available but can also respire and survive without it.

Obligate anaerobes

Organisms that can only respire in the absence of oxygen and are killed by oxygen.

Viruses

Smallest microorganisms that invade living cells to reproduce and cause damage and disease.

Obligate intracellular parasites

Viruses that can only exist and reproduce as parasites in the cells of other living organisms.

Protein coat or capsid

Structure of viruses made up of repeating protein units that protect the genetic material.

Envelope

Lipid membrane covering some viruses, making them easier to pass from cell to cell but vulnerable to substances like ether.

Virus attachment particles (VAPs)

Specific proteins that viruses use to attach to host cells and target proteins in the cell surface membrane.

DNA viruses

Viruses with genetic material made of DNA that acts as a template for viral DNA and mRNA synthesis.

RNA viruses

Viruses with genetic material made of RNA that can mutate more easily than DNA viruses.

Positive ssRNA viruses

RNA viruses with RNA that acts directly as mRNA and can be translated at the ribosomes.

Negative ssRNA viruses

RNA viruses that cannot be directly translated and require transcription before translation at the ribosomes.

RNA retroviruses

Special type of RNA virus that uses reverse transcriptase to make DNA corresponding to the viral genome, which is then incorporated into the host cell DNA.

Lytic pathway

Viral replication pathway where the viral genetic material is replicated independently of the host DNA, leading to the production of new viruses and cell lysis.

Latency

Viral replication pathway where the viral DNA is inserted into the host DNA and replicated every time the host cell divides, remaining non-virulent.

Viral infections

Viruses cause disease by lysing host cells, releasing lysosomes, or producing toxins that inhibit cell metabolism.

Specificity of viral infections

Viruses are specific to particular tissues due to the presence or absence of recognition markers on host cells.

Spread of viral diseases

Viral diseases are spread through contact with infected material such as mucus, saliva, blood, feces, or direct contact between infected organisms.

Ebola

Definition:A severe viral illness caused by the Ebola virus that is often fatal if left untreated. It spreads from infected animals to humans through bodily fluids and can easily spread from person to person through direct contact.

Antiviral treatments

Definition:Treatments that target virus replication rather than the virus particles themselves. They can work by targeting virus receptors, enzymes involved in viral DNA or RNA replication, or protease enzymes that enable new virus particles to bud from host membranes.

Mortality rate

Definition:The percentage of people infected with a disease who die from it. The mortality rate of Ebola varies but can be very high, ranging from 25-90% depending on factors such as the strain of the virus and the health care received.

Vaccination

Definition:The process of administering a vaccine to stimulate the immune system and provide immunity against a specific disease. Vaccination plays a major role in preventing disease outbreaks and reducing the spread of viruses.

Disease control

Definition:The measures taken to understand the cause of a disease, prevent its spread, and minimize its impact. Disease control is particularly important during epidemics, and it involves rapid identification of the disease, isolation of infected individuals, prevention of transmission, and identification and monitoring of contacts.

Pathogen identification

Definition:The process of identifying the specific pathogen causing a disease, such as bacteria or viruses. Rapid identification of the pathogen is crucial for implementing control measures and administering appropriate treatment.

Isolation

Definition:Isolating individuals infected with serious infections, such as Ebola, to prevent the spread of the disease. Isolation units are used in developed countries, but in developing countries, infected individuals may be cared for within their families, increasing the risk of transmission.

Protective clothing

Definition:Clothing worn by health workers when dealing with dangerous and highly infectious viruses, such as Ebola. It includes facemasks, gowns, gloves, and goggles to protect against contact with infected material and prevent infection.

Development of new medicines

Definition:The process of developing new drugs or vaccines, which involves extensive research, testing, and regulatory procedures. It can take up to 10 years and involves collaboration among scientists and doctors.

Fast-tracking

Definition:Expediting the testing and approval process for new medicines or vaccines in order to save lives and prevent the spread of a deadly disease during an epidemic. This may involve speeding up clinical trials or using drugs that have not completed full human trials.

Ethical implications

Definition:The ethical considerations involved in using drugs or vaccines that have not completed full testing and approval in severe epidemics or pandemics. Factors to consider include the severity of the disease, availability of other treatments, transparency, informed consent, community involvement, and ongoing assessment of safety and efficacy.

Unexpected side effects

Unforeseen negative consequences that may arise from the use of an untested drug.

Ethical implications

Moral considerations and consequences associated with the use of a fast-tracked and relatively untested drug in an epidemic situation.

Informed consent

The process of obtaining permission from individuals after providing them with comprehensive information about a drug, including its potential benefits, risks, and side effects.

Trust issues

Challenges related to establishing and maintaining trust between individuals or communities and health workers, particularly when supplies of a new drug are limited.

Fast-tracked

The expedited process of approving and using a drug without completing the typical testing and evaluation procedures.

Guinea pigs

The perception that local people in an epidemic situation might feel used as experimental subjects for Western medicine if they are given a new drug without extensive testing.

Blame for treatment

The tendency of relatives of dying individuals to attribute the inevitable death to the treatment, even if it was not the cause.

Evaluation

The assessment and analysis of the effectiveness and outcomes of using a fast-tracked and relatively untested drug in order to make informed decisions about its future use.