FINAL EXAM LECTURE 2

What did Watson and Crick contribute to DNA research?

Created a 3D model of DNA's double helix structure.

What did Rosalind Franklin discover about DNA?

Used X-ray diffraction to show DNA is a double helix.

Describe the structure of DNA.

Double-stranded helix held by hydrogen bonds.

Starting and ending molecules of DNA replication?

DNA → DNA.

Base pairing in DNA replication?

A→T, G→C.

Function of mRNA?

Brings DNA's message to ribosome to make proteins.

Function of tRNA?

Brings amino acids to ribosome.

Function of rRNA?

Forms part of the ribosome with proteins.

Transcription: starting molecule → final product?

DNA → mRNA.

Translation: starting molecule → final product?

mRNA → protein.

Transcribe DNA to mRNA: G→?, T→?, A→?

G→C, T→A, A→U.

What is a DNA mutation?

A change in DNA; may change protein and traits.

What is horizontal gene transfer in bacteria?

Bacteria gain new DNA and new traits.

What are resident microbes (normal flora)?

Microbes that live on skin or body openings.

When does initial colonization of normal flora occur?

At birth.

What does STORCH stand for?

Pathogens passed to fetus causing serious infections.

Body sites with resident microbes?

Skin, oral cavity, pharynx, vagina, colon, etc.

Sterile body areas?

Lungs, blood, CSF, heart, kidneys.

Define pathogen.

Microbe that causes disease.

Define infectious disease.

Damage caused by a pathogen.

Immunocompetent vs. immunocompromised?

Healthy vs. weak immune system.

Who is immunocompromised?

AIDS, elderly, cancer patients.

What is a virulence factor?

Microbe trait that helps cause infection.

4 stages of clinical infection?

Incubation, prodromal, invasion, convalescence.

Patterns of infection?

Systemic, acute, chronic, latent.

Sign vs. symptom of infection?

Sign = observed. Symptom = felt.

Define reservoir.

Long-term habitat of a pathogen.

Define carrier.

Person who harbors and transmits a pathogen.

What is an asymptomatic carrier?

Infected person with no symptoms.

What is a fomite?

Object that transmits pathogens.

Define endemic, epidemic, and pandemic.

Endemic = low, local. Epidemic = above expected. Pandemic = global outbreak.

Who is likely to get a zoonotic infection?

People exposed to infected animals.

What are HAIs?

Healthcare-associated infections.

What are SPs?

Standard precautions to prevent HAIs

What is mortality rate?

deaths.

What is morbidity rate?

Morbidity = illness cases.

What is endemic?

A disease that occurs at a low rate in a specific geographic area.

What is an epidemic?

A disease where the number of cases is greater than what is expected in a specific area.

What is a pandemic?

A disease that occurs worldwide at a higher rate than expected.

What is the shape and Gram stain of Neisseria?

Gram negative− cocci.

Where is Staphylococcus aureus part of the normal flora?

Skin and anterior nares.

Where does Staphylococcus aureus cause localized infections?

Skin.

What are the other infection sites for Staphylococcus aureus?

Blood, lungs, bones, heart.

What toxins does Staphylococcus aureus produce?

Enterotoxin, exfoliative toxin, TSS toxin.

What is MRSA?

Methicillin-resistant Staphylococcus aureus.

How are Streptococcal species differentiated on Blood Agar Plate (BAP)?

Hemolytic patterns.

What is another name for Streptococcus pyogenes?

Group A Strep (GAS).

What infections are caused by Streptococcus pyogenes?

Skin infections and strep throat.

What is a virulence factor of Streptococcus pyogenes?

Erythrogenic toxin.

What systemic infection is caused by Streptococcus pyogenes?

Scarlet fever.

What organs are affected by sequelae of strep throat?

Heart and kidneys.

What is VRE?

Vancomycin-resistant Enterococcus.

What is the genus of the Viridians group?

Streptococcus.

Where is the Viridians group commonly found and what disease do they cause?

Oral cavity; causes dental caries.

What infections are caused by Streptococcus pneumoniae?

Meningitis, Otitis media, Pneumonia, Sinusitis (MOPS).

What diseases are caused by Neisseria?

Gonorrhea and meningitis.

What is a symptom of gonorrhea?

Whitish, milky discharge from urethra.

What is the Gram stain classification of Bacillus and Clostridium?

Gram positive.

What protective structure do Bacillus and Clostridium form?

Endospores.

What is the acid-fast positive Gram+ bacilli genus?

Mycobacterium.

What are the forms of anthrax?

Cutaneous, pulmonary, GI.

What disease is caused by Clostridium perfringens?

Gas gangrene (myonecrosis).

What is the treatment for gas gangrene?

Antibiotics, debridement, hyperbaric O₂.

What is the effect of Clostridium tetani?

Tetanus → rigid paralysis.

What is the effect of Clostridium botulinum?

Botulism → flaccid paralysis.

What condition does C. difficile cause and what is its trigger?

Diarrhea; from long-term antibiotic use.

What is a virulence factor of Listeria monocytogenes?

Induces phagocytosis to evade immune system.

Who is at risk for Listeria infection?

Pregnant women (fetal infection).

What disease does Corynebacterium diphtheriae cause and what is its virulence factor?

Diphtheria; toxin.

What is the acid-fast virulence factor found in Mycobacterium?

Mycolic acid in cell wall.

What disease is caused by Mycobacterium tuberculosis?

Tuberculosis.

What is the first organ infected by TB?

Lungs.

What are the stages and symptoms of tuberculosis?

Primary: fever/cough, Latent: no symptoms, Secondary: bloody sputum, Disseminated: body-wide.

What disease is caused by Mycobacterium leprae?

Hansen’s disease (leprosy).

Which two body parts are damaged by M. leprae?

Skin and nerves.

What diseases are covered by the DTP vaccine?

Diphtheria, Tetanus, Pertussis.