ASCORERS STUVIA
BIOL211: MICROBIOLOGY - EXAM 3 WITH 215 HIGHLY TESTED QUESTIONS
WITH CORRECT ANSWERS ALREADY GRADED A+ ***ANSWERS IN NON - BOLD*** 1.What is a holobiont?: Human + all of its resident microbiota
All of the naturally-occurring microbes that reside in a given person is that person's microbiome/microbiota
2.What does colonize mean?: The ability of microbes to become resident on a particular host such as the human body (along for the ride until further notice)
3.What is an infection?: Occurs when microbes get past host defenses, enter the tissues, and multiply (making babies)
4.What is a disease?: Occurs when the cumulative effects of the infection dam- age/disrupt tissues and organs
5.What is the difference between infection and disease?: Infection: multiplying microbes
Disease: when microbe causes harm
6.What is the Human Microbiome Project (HMP)?: A project done by the National Institutes of Health (NIH)
Goal: identify microbial inhabitants of the human body and their role in health and
disease
Done using metagenomic techniques instead of culturing
7.What have been the results so far of the Human Microbiome Project?: Mi- crobes
are found in previously-thought "sterile" areas of the human body (like the lungs)
Viruses are actually present in healthy humans, in vast quantities
The gut microbiome can influence many aspects of health (gut-brain access) ASCORERS STUVIA
8.What is a microbial antagonism?: Exist in either a commensal (one benefits, one
neutral) or mutualistic (both benefit) association
Microbiota participates in microbial antagonism
"Good" microbes compete for survival against pathogenic microbes (usually "win- ning") - they fight for their home
Note that members of the "normal" biota can become pathogenic if allowed to multiply to large numbers
9.What are endogenous infections?: Endogenous infections can occur in im- munocompromised individuals
Infections caused by biota already present in the body
10.Where does the microbiota come from?: In utero: The womb has its own micrbiota
Birth: Vaginal/birth canal and C-section/skin give baby exposure to difference micro- biomes
Milk: Breast milk and formula have different microbes Caregivers: Hugs, kisses, cradling, etc.
Environment: Baby can get microbes from anywhere (A little dirt won't hurt, microbe moderation is good for them)
11.What is a true pathogen?: Capable of causing disease in most healthy persons with normal immune systems
Examples: influenza virus, malarial protozoan
12.What are pathogens that aren't "true"?: Cause disease in people with some deficit in their immunity
Example: People with cystic fibrosis are prone to Pseudomonas lung infections
13.What are opportunistic pathogens?: Normal microbiota that exploit a new opportunity in the host to become pathogenic ASCORERS STUVIA
**Tries to take over if the person is immunocompromised
Example: E. coli are part of the normal biota in the digestive tract but can cause UTIs if they become displaced into the urinary system
14.What determines if a microbe will cause disease?: Most microbes can cause disease
under the proper conditions, but can also coexist peaceably with their human hosts under other conditions
Based on both microbe factors (Virulence Factors) and host factors
General level of health
Prior exposure to the microbe Genetic profile
15.What are virulence factors?: Any characteristic or structure of the microbe that contributes towards causing disease in the host
Ex: Antibiotic resistance, tissue grip, ability to hide from immune system
16.What is an Infectious Dose (ID)?: The minimum quantity of a given microbe needed to cause infection
In general, smaller infectious doses = higher virulence
Numbers below an infectious dose will generally not result in an infection
Examples of IDs
10 cells for tuberculosis and giardiasis
1,000 bacteria for gonorrhea (common STD) 1,000,000,000 bacteria for cholera (contaminated water)
**If number is smaller than ID, the body takes care of it just fine ASCORERS STUVIA
.What is a portal of entry?: Route of entry for an infectious agent
Microbe wants to enter the host at a location that enables it to survive and thrive
18.What are 2 host factors?: Human Genetics
Why the same infectious agent can cause severe disease in one person and mild in another
Human Health (psychological stress, multiple infections, etc.)
19.What happens in step 1 of the steps that cause disease? (Find a portal of entry): Majority of pathogens have adapted to a specific portal of entry
Usually occurs through the skin or a mucous membrane
Sometimes can enter through more than one portal
Example: Staphylococcus can enter through the (broken) skin, urogenital tract, or respiratory tract
Too restrictive can prevent infection
Example: influenza virus enters nasal mucosa = flu, but virus only contacts skin = no infection
20.How is skin a portal for disease?: Usually occurs via broken skin vs intact skin (very
tough barrier)
Helminth worms use digestive enzymes to create passageways into the skin Bites of
insects can creates holes for microbes to enter
Intravenous drug abusers breach the skin with contaminated needles
21.How is the GI tract a portal for disease?: Entry point for pathogens contained in food and drinks
Microbes have adapted themselves to survive digestive enzymes and abrupt pH changes
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