Week 7: Microbes & Infection Flashcards
T/F: The coat of a virus consists of protein.
True
T/F: A “bacillus” is a spiral-shaped bacterium.
False
T/F: A bacterial cell wall contains chitin.
False
T/F: A prokaryotic cell is identified by the presence of ribosomes.
False - Ribosomes are found in both prokaryotic and eukaryotic cells.
T/F: Viruses can transform host cells into tumor cells.
True
T/F: Fungi are eukaryotic cells whose cell wall contains peptidoglycan.
False - The cell wall of fungi contains chitin. Peptidoglycan is found in bacterial cell walls.
T/F: Bacteria feed off living matter only.
False
T/F: The most common type of viral infection is lytic.
True
T/F: Prokaryotic cells contain a nucleus but no membrane-bound organelles.
False - The nucleus is a membrane-bound organelle and thus is not present in prokaryotes.
T/F: Fungi generally only cause mild, superficial infections in healthy hosts.
True
In which symbiotic relationship does one partner benefit while the other is unaffected?
a Infection
b Parasitic
c Commensal
d Mutualistic
c Commensal
What benefits do the normal flora receive from the host?
Nutrition
Prevent colonisation and infection of the host by pathogens
Provide nutrients such as vitamins B and K
Living space
Nutrition
Living space
The normal flora can be found in/on which of the following:
upper respiratory tract (i.e. nose, pharynx)
lungs and uterus
urinary bladder
warmer, more damp areas of the skin
mouth and stomach
the upper reprodcutive tract
large, but not the small, intestine
upper respiratory tract (i.e. nose, pharynx)
warmer, more damp areas of the skin
mouth and stomach
T/F: Transient microbes are unable to colonise body surfaces.
True
A pathogen has a _____ relationship with the host.
a mutualistic
b transient
c commensal
d parasitic
d parasitic
T/F: Infectious disease is transmissible disease.
False - “Infectious” refers to tissue damage caused by a pathogen, not an ability to be transmitted.
Which terms have been correctly identified?
Infection = invasion of a body surface by a pathogen
Infectious disease = invasion of a body surface by a pathogen involving tissue damage
Colonisation = establishment and growth of a microbe on a body surface involving tissue damage
Infection = establishment and growth of a microbe on a body surface
Colonisation = establishment and growth of a microbe on a body surface
Infection = invasion of a body surface by a pathogen
Infectious disease = invasion of a body surface by a pathogen involving tissue damage
Colonisation = establishment and growth of a microbe on a body surface
The normal flora can cause an opportunistic infection when:
their own defences are compromised
their ecological balance is upset and a specific population multiplies to high numbers
host defences are compromised
they penetrate a body surface and colonise deeper tissues
they are relocated to body areas they are normally excluded from
they colonise a body surface different to their usual location
they turn to the dark side
their ecological balance is upset and a specific population multiplies to high numbers
host defences are compromised
they penetrate a body surface and colonise deeper tissues
they are relocated to body areas they are normally excluded from
T/F: Compromised surface barriers increase host susceptibility to infection.
True
Opportunistic pathogens, that do not usually cause disease in otherwise healthy hosts, include:
transient microbes
conventional pathogens
environmental microbes
normal flora
transient microbes
environmental microbes
normal flora
T/F: A more virulent microbe has a high infectious dose.
False - A more virulent microbe can establish an infection with a low number of organisms.
T/F: A symptom is an objective change in a patient that can be observed and measured.
False - A symptom is the subjective patient experience.
T/F: If a host has memory lymphocytes that recognise a particular pathogen they are likely to experience an asymptomatic or subclinical infection the next time they encounter that pathogen.
True - Memory lymphocytes will mediate a secondary immune response that prevents, or reduces the severity of, an infection.
T/F: Whether an infection occurs depends on host susceptibility, pathogen virulence and environmental conditions.
True
T/F: A major cause of tissue damage by the host can be the process of inflammation.
True
T/F: Viruses generally kill a host cells upon exit, causing tissue damage and promoting inflammation.
True
T/F: Most pathogens can use multiple portals of entry into the body.
False - Most pathogens have a preferred portal of entry.
The most common portal of entry is the:
a respiratory tract
b urinary tract
c gastrointestinal tract
d skin
a respiratory tract
In order to establish an infection, a pathogen must first
a be able to use the host as a food resource
b avoid host defences
c attach to a body surface
d multiply to a critical population size
c attach to a body surface
Pathogens can overcome host INNATE defences by:
- using enzymes to break though surface barriers
- using enzymes to destroy host anitbodies
- killing phagocytes with toxins
- changing their surface proteins
- degrading phagocyte digestive enzymes with their own enzymes
- using enzymes to break though surface barriers
- killing phagocytes with toxins
- degrading phagocyte digestive enzymes with their own enzymes`
Damage to the host can be caused:
- indirectly by the activity of the pathogen
- directly by the activity of the host defences
- by perforins and granzymes from cytotoxic T cells or NK cells
- through the lytic activity of viruses
- by enzymes dervied from the pathogen or from host phagocytes
- by toxins that kill host cells
- by perforins and granzymes from cytotoxic T cells or NK cells
- through the lytic activity of viruses
- by enzymes dervied from the pathogen or from host phagocytes
- by toxins that kill host cells
Pathogens most commonly exit the host via the:
a respiratory or gastrointestinal tracts
b secretions from the eyes and nose
c urine and faeces
d skin
a respiratory or gastrointestinal tracts
T/F: Viruses, but not bacteria, can overcome host defences by changing their surface antigens.
False- Both viruses and bacteria can undergo antigenic variation.
T/F: Bacteria release enzymes that can kill phagocytes.
True
T/F: In an acute infection, host defences are never able to clear the pathogen.
False
T/F: Pathogens cannot be transmitted during the incubation period of an infection.
False - Pathogens can be transmitted during any period, as long as the pathogen is multiplying.
T/F: During the latent period of a chronic infection, the pathogen does not multiply and cannot be transmitted and the host is asymptomatic.
False - A chronic infection does not have a latent period.
The phases of an acute infection occur in the following order:
a disease, incubation, prodromal, recovery
b recovery, prodromal, disease, incubation
c prodromal, recovery, incubation, disease
d incubation, prodromal, disease, recovery
d incubation, prodromal, disease, recovery
A chronic infection generally results in:
a no tissue damage after a chronic period of time
b a dormant period when the pathogen does not multiply or cause tissue damage
c ongoing, long-term tissue damage
d recurrent periods of acute, symptomatic disease
c ongoing, long-term tissue damage
T/F: Herpes viruses cause latent infections and cannot be transmitted in the latent period becasue the virus is not multiplying.
True
Define:
Microbes
Microorganisms, including bacteria, viruses, fungi, and protozoa, that can live in and on the human body, influencing health in both positive and negative ways.
Define:
Microbes
Microscopic organisms, including bacteria, fungi, viruses, protozoa, and algae, that can only be seen with a microscope. They make up a significant portion of Earth’s biomass.
Define:
Bacteria
Single-celled prokaryotic organisms that lack membrane-bound organelles. They are found in various environments, including the human body.
Define:
Fungi
Eukaryotic organisms that can exist as single cells or multicellular forms, such as molds and yeasts. They can produce toxins and antibiotics, like penicillin.
Define:
Viruses
Acellular microbes that do not have all the components necessary for independent cell function and metabolism. They are not considered living organisms outside of a host.
Define:
Protozoa
Single-celled eukaryotic organisms that can live alone or in colonies, typically found in water. Examples include amoebas.
Define:
Algae
Photosynthetic eukaryotic organisms that can be single-celled or multicellular, found mainly in aquatic environments.
Define:
Eukaryotic cells
Cells with membrane-bound organelles, including a nucleus, Golgi apparatus, lysosomes, and mitochondria. Found in animals, plants, fungi, protozoa, and algae.
Define:
Prokaryotic cells
Simpler cells that lack membrane-bound organelles and a nucleus. All bacteria are prokaryotes.
Define:
Bacilli
Rod-shaped bacteria. The term is used in the names of rod-shaped bacterial species.
Define:
Cocci
Spherical-shaped bacteria. The term is used in the names of spherical bacterial species.
Define:
Spirilla
Spiral-shaped bacteria. This term is used for bacteria with a spiral shape.
Define:
Spirochete
A specific type of spiral-shaped bacteria with a unique corkscrew motion.
Define:
Vibrio
A comma-shaped or curved rod-shaped bacteria.
Define:
Cell envelope
The outer layers surrounding a bacterial cell, including the cell membrane and cell wall.
Define:
Peptidoglycan
A glycoprotein consisting of protein and carbohydrate groups that forms a mesh-like layer in the bacterial cell wall, targeted by certain antibiotics.
Define:
Capsule
An additional outer layer found in some bacteria, which can be sticky or slippery and aids in host colonization.
Define:
Pili
Hair-like structures on the surface of bacteria used for genetic material exchange and adherence to surfaces.
Define:
Flagellum (Plural: Flagella)
A whip-like structure used by bacteria for locomotion and sometimes as a receptor for environmental changes.
Define:
Nucleoid
A region within a bacterial cell where the genetic material, a single circular DNA chromosome, is located.
Define:
Binary fission
The process of bacterial reproduction where a single bacterium divides into two identical daughter cells after DNA replication.
Define:
Obligate parasites
Organisms that can only reproduce inside a host cell, relying on the host’s cellular machinery for replication.
Define:
Naked viruses
Viruses that have a protein coat called a capsid surrounding their genetic material but lack an outer lipid envelope.
Define:
Enveloped viruses
Viruses that have a phospholipid bilayer derived from the host cell’s plasma membrane surrounding their capsid, which may contain embedded proteins for host cell attachment.
Define:
Capsid
A protein coat surrounding the genetic material of a virus. It helps protect the viral genome and facilitates attachment to host cells.
Define:
Envelope
An outer lipid bilayer surrounding some viruses, derived from the host cell’s membrane, which may contain viral proteins that assist in infection.
Define:
Lytic infection
A type of viral infection that results in the destruction (lysis) of the host cell, releasing new viral particles.
Define:
Endocytosis
A process by which cells take in external substances, such as viruses, by engulfing them in a vesicle.
Define:
Fusion
The process by which an enveloped virus merges its lipid envelope with the host cell membrane to gain entry into the cell.
Define:
Exocytosis
The process by which viruses exit the host cell, often involving the budding off of new viral particles from the cell membrane.
Define:
SARS-CoV-2
The virus responsible for COVID-19, characterized as an enveloped virus with spike proteins that facilitate attachment and entry into host cells.
Define:
Spike proteins
Surface proteins on some viruses, such as SARS-CoV-2, that enable the virus to bind to specific receptors on the host cell, facilitating infection.
Define:
Chronic or persistent infection
A type of viral infection where the virus is released slowly from the host cell without killing it, leading to a prolonged presence in the host.
Define:
Latent state
A condition in which a virus remains dormant inside a host cell without replicating, potentially becoming reactivated later.
Define:
Chitin
A carbohydrate derivative of glucose that forms a tough, protective shell around fungal cells, similar to the exoskeletons of insects and crustaceans.
Define:
Yeast
Single-celled fungi that reproduce by budding. They are oval-shaped and can be found in various environments.
Define:
Budding
A form of asexual reproduction in yeast where a new cell develops from an outgrowth or bud on the parent cell.
Define:
Molds
Multicellular fungi that form a network of cells known as mycelium. They often appear as fuzzy or thread-like structures and are commonly seen on spoiled food.
Define:
Mycelium
A network of fungal cells that forms the vegetative part of a fungus, such as mold. It helps in nutrient absorption and growth.
Define:
Tinea
A type of fungal infection commonly known as athlete’s foot, which affects the skin between the toes.
Define:
Candidiasis
A fungal infection caused by Candida species, which can occur in areas such as the mouth (thrush) or other mucosal surfaces.
Define:
Immunocompromised
Individuals with weakened immune systems, such as those with HIV/AIDS, undergoing immunosuppressive treatments, or having chronic conditions like cancer or diabetes, who are more susceptible to severe fungal infections.
Define:
Symbiosis
A relationship between two organisms living together in close association. In the context of microbes and humans, it refers to how microbes interact with humans, either beneficially, neutrally, or harmfully.
Define:
Normal flora
Also known as resident flora, microbiota, or the microbiome. These are the microorganisms that regularly inhabit various parts of the human body and usually benefit the host by outcompeting harmful pathogens and assisting in various bodily functions.
Define:
Transient microbes
Microorganisms that temporarily inhabit the body but do not establish a permanent presence. They may be picked up from the environment and do not necessarily contribute to the body’s normal flora.
Define:
Commensalism
A type of symbiotic relationship where the microbe benefits from the interaction, while the host is unaffected (neither helped nor harmed).
Define:
Mutualism
A symbiotic relationship where both the microbe and the host benefit from the interaction.
Define:
Parasitism
A symbiotic relationship where the microbe benefits at the expense of the host, potentially causing harm or disease to the host.
Define:
Communicable
Refers to diseases that can be transmitted from one person to another. Infectious diseases are not always communicable, as some, like tooth decay, do not spread between individuals.
Define:
Lactobacillus
A type of bacteria found in the gastrointestinal tract and vagina. They metabolize glycogen to produce lactic acid, which maintains an acidic environment that inhibits the growth of harmful microbes.
Define:
Escherichia coli (E. coli)
A bacterium commonly found in the large intestine. It helps with the metabolism of waste products and the production of essential vitamins, such as B-group vitamins and vitamin K, which are crucial for various bodily functions.
Define:
Vitamin K
A vitamin produced by intestinal bacteria, essential for normal blood clotting. Infants are often given a injection at birth to ensure proper clotting until their gut flora is established.
Define:
Butyrate
A fatty acid produced by intestinal microbes that serves as an energy source for epithelial cells in the large intestine. It supports cell health and reduces the risk of colon cancer by enhancing blood flow and immune function.
Define:
Innate immune defenses
The body’s initial, non-specific defense mechanisms that respond quickly to pathogens. It includes physical barriers like skin and mucous membranes, as well as various immune cells and proteins.
Define:
Adaptive immune defenses
The part of the immune system that develops a specific response to pathogens and improves its response with each exposure. It involves specialized cells and antibodies.
Define:
Sign
An objective change in the body that can be observed or measured by a healthcare provider, such as a fever.
Define:
Symptom
A subjective experience reported by the patient, such as pain or fatigue, which cannot be directly measured but indicates an underlying condition.
Define:
Subclinical disease
An infection or disease that does not produce noticeable symptoms, often because the immune system has successfully contained the pathogen.
Define:
Virulence
The capacity of a microbe to cause disease. It measures how harmful the microbe is and affects the severity of the disease it can cause.
Define:
Infectious dose
The minimum number of pathogens required to cause an infection. A lower infectious dose indicates higher virulence.
Define:
Conventional pathogens
Microbes that cause disease in individuals with normal immune defenses. Examples include viruses like the measles virus and bacteria like Neisseria gonorrhoeae.
Define:
Opportunistic pathogens
Microbes that usually do not cause disease in healthy individuals but can lead to infections when the host’s immune defenses are compromised or when they colonize an unusual body site.
Define:
Ecological imbalance
A disruption in the normal balance of microbes, allowing opportunistic pathogens to overgrow. For instance, the reduction of Lactobacillus bacteria can lead to the overgrowth of Candida albicans.
Define:
Relocation
When normal flora microbes move to a part of the body where they are not typically found, potentially causing infections. For example, E. coli from the large intestine causing a urinary tract infection.
Define:
Compromised host defenses
When the immune system or physical barriers are weakened, making the host more susceptible to infections. Factors include preexisting conditions, age, and compromised immune systems.
Define:
Aspergillus
A genus of fungus found in various environments, such as damp hay, which can cause respiratory infections in immunocompromised individuals.
Define:
Primary immune response
The initial reaction of the immune system to a pathogen, aimed at eliminating it and leading to recovery.
Define:
Secondary immune response
A faster and more effective immune response that occurs upon subsequent exposure to a pathogen, often preventing disease or reducing its severity.
Define:
Portal of Entry
The site through which a pathogen enters the body. Different pathogens may have preferred entry points for effective infection.
Define:
Skin and Mucous Membranes
Physical barriers of the body that act as the first line of defense against pathogens. Pathogens may enter through openings in the skin or mucous membranes.
Define:
Glycocalyx
A sticky substance secreted by some bacteria that helps them adhere to body surfaces and can contribute to the formation of biofilms, such as dental plaque.
Define:
Viral Attachment
The process by which viruses bind to specific molecules on the surface of target cells to facilitate infection.
Define:
Extracellular pathogens
Microbes that obtain nutrients from extracellular fluids and do not need to enter host cells to cause disease.
Define:
Intracellular pathogens
Microbes that obtain nutrients from within host cells, causing disease by infecting and replicating inside these cells.
Define:
Virulence factors
Traits or abilities of a pathogen that enable it to evade host defenses, cause damage, or persist within the host.
Define:
Surface Barriers
Physical and chemical defenses of the body, such as the skin and mucous membranes, that prevent microbial entry and infection.
Define:
Antigenic Variation
A mechanism by which pathogens alter their surface proteins to evade recognition by the immune system, leading to ongoing or repeated infections.
Define:
Cytopathic Effects
Direct damage caused by pathogens, particularly viruses, which leads to the death of host cells.
Define:
Fibrosis
Formation of excess fibrous connective tissue in response to chronic inflammation, leading to scarring and loss of function.
Define:
Portal of Exit
The route through which a pathogen exits the host’s body to spread to new hosts, commonly through respiratory or digestive tracts.
Define:
Acute Infection
An infection characterized by a rapid onset of symptoms and a relatively short duration, typically resolved once the pathogen is eliminated.
Define:
Chronic Infection
An infection that begins acutely but persists over a long period, often with slow multiplication of the pathogen and progressive tissue damage.
Define:
Latent Infection
An infection where the pathogen remains dormant within the host after an initial acute phase, not causing symptoms or being transmissible until reactivation.
Define:
Prodromal Period
The phase of an infection characterized by mild or nonspecific symptoms that precede the onset of more severe symptoms.
Define:
Disease Period
The phase of an infection marked by the peak of symptoms and tissue damage, defining the disease’s impact on the host.
Define:
Recovery Period
The phase following the peak of an infection where symptoms decrease as the host’s defenses overcome the pathogen.
Define:
Immune Complex
A combination of antigens and antibodies that can deposit in tissues, activating complement proteins and attracting phagocytes.
Define:
Complement Proteins
Proteins in the blood that assist in the immune response by marking pathogens for destruction and attracting phagocytes.
Define:
Flaccid Paralysis
A condition where muscles become weak and limp due to the inability to contract, often caused by toxins affecting neuromuscular junctions.
Define:
Tetany
Sustained muscle contractions due to a disruption in normal nervous system function, often caused by certain toxins.
Define:
Shingles
A reactivation of the varicella-zoster virus that causes a painful rash, usually along the path of a spinal nerve.
Define:
Herpes Viruses
A group of viruses that can cause latent infections and reactivate later, such as varicella-zoster virus which causes both chickenpox and shingles.
What is…
Microorganisms, including bacteria, viruses, fungi, and protozoa, that can live in and on the human body, influencing health in both positive and negative ways.
Microbes
What is…
Microscopic organisms, including bacteria, fungi, viruses, protozoa, and algae, that can only be seen with a microscope. They make up a significant portion of Earth’s biomass.
Microbes
What is…
Single-celled prokaryotic organisms that lack membrane-bound organelles. They are found in various environments, including the human body.
Bacteria
What is…
Eukaryotic organisms that can exist as single cells or multicellular forms, such as molds and yeasts. They can produce toxins and antibiotics, like penicillin.
Fungi
What is…
Acellular microbes that do not have all the components necessary for independent cell function and metabolism. They are not considered living organisms outside of a host.
Viruses
What is…
Single-celled eukaryotic organisms that can live alone or in colonies, typically found in water. Examples include amoebas.
Protozoa
What is…
Photosynthetic eukaryotic organisms that can be single-celled or multicellular, found mainly in aquatic environments.
Algae
What is…
Cells with membrane-bound organelles, including a nucleus, Golgi apparatus, lysosomes, and mitochondria. Found in animals, plants, fungi, protozoa, and algae.
Eukaryotic cells
What is…
Simpler cells that lack membrane-bound organelles and a nucleus. All bacteria are prokaryotes.
Prokaryotic cells
What is…
Rod-shaped bacteria. The term is used in the names of rod-shaped bacterial species.
Bacilli
What is…
Spherical-shaped bacteria. The term is used in the names of spherical bacterial species.
Cocci
What is…
Spiral-shaped bacteria. This term is used for bacteria with a spiral shape.
Spirilla
What is…
A specific type of spiral-shaped bacteria with a unique corkscrew motion.
Spirochete
What is…
A comma-shaped or curved rod-shaped bacteria.
Vibrio
What is…
The outer layers surrounding a bacterial cell, including the cell membrane and cell wall.
Cell envelope
What is…
A glycoprotein consisting of protein and carbohydrate groups that forms a mesh-like layer in the bacterial cell wall, targeted by certain antibiotics.
Peptidoglycan
What is…
An additional outer layer found in some bacteria, which can be sticky or slippery and aids in host colonization.
Capsule
What is…
Hair-like structures on the surface of bacteria used for genetic material exchange and adherence to surfaces.
Pili
What is…
A whip-like structure used by bacteria for locomotion and sometimes as a receptor for environmental changes.
Flagellum (Plural: Flagella)
What is…
A region within a bacterial cell where the genetic material, a single circular DNA chromosome, is located.
Nucleoid
What is…
The process of bacterial reproduction where a single bacterium divides into two identical daughter cells after DNA replication.
Binary fission
