MICR 2123 Exam 4Questions and
Answers
What is a pathogen? - Answer-A microbial organism that causes disease.
What is a commensal organism? - Answer-Harmless bacteria that are on our body and can only cause
disease if they are accidentally introduced into deeper tissues.
Describe the human microbiome. - Answer-All the microbes in or on our body.
Name the body sites that are most hospitable to bacteria and have their own microbiomes. - Answer-
Mouth, Respiratory tract, Stomach, Intestines (most hospitable), Skin (not very hospitable), eye (not
very hospitable), genitourinary
Why is skin difficult for microbes to colonize? - Answer-Because it's dry, salty, acidic, and has protective
oils.
Associate Propionibacterium acnes with acne. - Answer-It breaks down skin oil which causes
inflammation, also known as, acne.
What are factors that make the mouth hospitable to bacteria? - Answer-Nutrients/Food, Epithelial
debris, secretions, and it is warm and moist.
,How is Helicobacter Pylori associated with stomach ulcers? - Answer-It causes stomach ulcers.
What are the mucociliary escalator components and what is it's function? - Answer-Along the lining of
the lungs and parts of the lungs are cells with cilia lining them. The cilia containing cells have mucus on
them and as the cilia constantly beat up they propel the mucus up and out of the lungs slowly. If we
inhale anything it sticks to the mucus and is pushed up which keeps our lungs clear of bacteria and
allows for proper function.
What bodily location contains the most resident bacteria? - Answer-The intestine (gut microbiome)
What factors influence the composition of the gut microbiota? - Answer-Food (biggest One), Sleep,
Stress, Other diseases, and medication
What is dysbiosis? - Answer-An imbalance in the proportions of different commensal microbes in the
gut.
What is a probiotic? - Answer-Living bacteria that are ingested and help to restore a healthy microbial
population.
What is fecal microbial transplants? - Answer-Microbiotal species taken from a healthy individual
usually from a fecal sample, then purified, then transplanted to a person or host with dysbiosis to try to
correct it.
How do scientists assess the composition of a microbial community? What is the most commonly used
method? - Answer-sequencing of the 16s rDNA that encodes the small ribosomal subunits of rna. By
looking at the sequence of the DNA you are able to identify the species present.
What is an opportunistic pathogen? - Answer-A pathogen that typically only infects individuals who are
already ill or immunocompromised.
, What are 3 physical barriers to microbes entering the body? - Answer-Skin and Mucous membrane
physical and chemical barriers vs. innate immune functions vs. adaptive immune functions - Answer-
chemicals involve chemicals. physical are like fences. innate are like a police force always checking for
suspicious activity. adaptive always targeted.
What are the chemical barriers ? - Answer-Lysozyme, Peroxidase, Iron-binding proteins, Defensins
What is the function of the chemical barriers? - Answer-Lysozyme: enzyme that cuts peptidoglycan.
Peroxidase: creates reactive oxygen species that damage microbial cells. Iron-binding proteins: deprive
pathogens of iron. Defensins: small peptides made from mucous membranes that poke holes in bacterial
membranes and let them leak out.
Describe pathogen associated molecular patterns. - Answer-Patterns of molecules that are associated
with pathogens.
What phagocytic cells recognize and engulf pathogens to destroy them? - Answer-Neutrophils (white
blood cells), Macrophages, and dendritic cells.
Describe the process of phagocytosis. How does it kill microbes? - Answer-A bacterium is taken into a
phagosome and then the phagosome is fused with a lysosome and the lysosome contains chemicals and
enzymes to kill or degrade the bacterium.
What is in the lysosome? - Answer-enzymes mostly.
Describe pattern recognition receptors in terms of their function. - Answer-molecules that detects
PAMPS. Look for suspicious activity.
Answers
What is a pathogen? - Answer-A microbial organism that causes disease.
What is a commensal organism? - Answer-Harmless bacteria that are on our body and can only cause
disease if they are accidentally introduced into deeper tissues.
Describe the human microbiome. - Answer-All the microbes in or on our body.
Name the body sites that are most hospitable to bacteria and have their own microbiomes. - Answer-
Mouth, Respiratory tract, Stomach, Intestines (most hospitable), Skin (not very hospitable), eye (not
very hospitable), genitourinary
Why is skin difficult for microbes to colonize? - Answer-Because it's dry, salty, acidic, and has protective
oils.
Associate Propionibacterium acnes with acne. - Answer-It breaks down skin oil which causes
inflammation, also known as, acne.
What are factors that make the mouth hospitable to bacteria? - Answer-Nutrients/Food, Epithelial
debris, secretions, and it is warm and moist.
,How is Helicobacter Pylori associated with stomach ulcers? - Answer-It causes stomach ulcers.
What are the mucociliary escalator components and what is it's function? - Answer-Along the lining of
the lungs and parts of the lungs are cells with cilia lining them. The cilia containing cells have mucus on
them and as the cilia constantly beat up they propel the mucus up and out of the lungs slowly. If we
inhale anything it sticks to the mucus and is pushed up which keeps our lungs clear of bacteria and
allows for proper function.
What bodily location contains the most resident bacteria? - Answer-The intestine (gut microbiome)
What factors influence the composition of the gut microbiota? - Answer-Food (biggest One), Sleep,
Stress, Other diseases, and medication
What is dysbiosis? - Answer-An imbalance in the proportions of different commensal microbes in the
gut.
What is a probiotic? - Answer-Living bacteria that are ingested and help to restore a healthy microbial
population.
What is fecal microbial transplants? - Answer-Microbiotal species taken from a healthy individual
usually from a fecal sample, then purified, then transplanted to a person or host with dysbiosis to try to
correct it.
How do scientists assess the composition of a microbial community? What is the most commonly used
method? - Answer-sequencing of the 16s rDNA that encodes the small ribosomal subunits of rna. By
looking at the sequence of the DNA you are able to identify the species present.
What is an opportunistic pathogen? - Answer-A pathogen that typically only infects individuals who are
already ill or immunocompromised.
, What are 3 physical barriers to microbes entering the body? - Answer-Skin and Mucous membrane
physical and chemical barriers vs. innate immune functions vs. adaptive immune functions - Answer-
chemicals involve chemicals. physical are like fences. innate are like a police force always checking for
suspicious activity. adaptive always targeted.
What are the chemical barriers ? - Answer-Lysozyme, Peroxidase, Iron-binding proteins, Defensins
What is the function of the chemical barriers? - Answer-Lysozyme: enzyme that cuts peptidoglycan.
Peroxidase: creates reactive oxygen species that damage microbial cells. Iron-binding proteins: deprive
pathogens of iron. Defensins: small peptides made from mucous membranes that poke holes in bacterial
membranes and let them leak out.
Describe pathogen associated molecular patterns. - Answer-Patterns of molecules that are associated
with pathogens.
What phagocytic cells recognize and engulf pathogens to destroy them? - Answer-Neutrophils (white
blood cells), Macrophages, and dendritic cells.
Describe the process of phagocytosis. How does it kill microbes? - Answer-A bacterium is taken into a
phagosome and then the phagosome is fused with a lysosome and the lysosome contains chemicals and
enzymes to kill or degrade the bacterium.
What is in the lysosome? - Answer-enzymes mostly.
Describe pattern recognition receptors in terms of their function. - Answer-molecules that detects
PAMPS. Look for suspicious activity.
