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Biology 189 > L22: Bacteria, Disease, Treatment, & Resistance > Flashcards

L22: Bacteria, Disease, Treatment, & Resistance Flashcards

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1
Q

Bacteria are prokaryotes. Which characters are used to discern among prokaryotes and eukaryotes?

A

they lack a nucleus, membrane-bound organelles, and internal membranes/compartmentalization

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2
Q

What are the three general shapes/morphologies expressed by bacteria?

A

They tend to possess one of three morphologies: coccus (spherical), bacillus (elongated rod), or spiral-shaped

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3
Q

What role does a bacterium’s cell wall play?

A

• protects cell
• prevents lysis in hypotonic environments (aka hosts)

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4
Q

Which compound is used extensively to make bacterial cell walls?

A

peptidoglycan

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5
Q

How do Gram+ and Gram– bacteria differ in their cell wall?

A
  • Gram+ bacteria: thick cell wall
  • Gram- bacteria: thin cell wall with an additional membrane = perimembrane
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6
Q

Which three factors influence bacterial pathogenicity?

A

Cell wall, perimembrane, and virulence factors (e.g., capsule, flagella, surface proteins) influence pathogenicity

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7
Q

Which four virulence factors did we explore? What role does each serve?

A

capsule - protection and ability to adhere
flagella - movement
surface proteins - cell communication to external environment

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8
Q

Did you know that virulence factors can cause host inflammation?

A

yea

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9
Q

How is the genome of a bacterium organized?

A

single, circular chromosome (generally lacking histone scaffolding) has most genes

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10
Q

What is a plasmid?

A

small extra pieces of DNA that carry few 10s of genes

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11
Q

Do bacteria transcribe and translate genetic material?

A

yes

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12
Q

Do they undergo the extensive RNA processing as observed in eukaryotes?

A

no

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13
Q

How do bacteria reproduce?

A

Bacteria reproduce asexually
typically via binary fission (vertical)
• chromsome undergoes
DNA replication
• origins (DNA replication
was initiated) attach to
opposite ends of cell
• cell elongates separating
replicated chromosomes
• proteins induce septum
formation between
chromosomes
• new membrane/cell wall
assembled along septum

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14
Q

What is an endospore?

A

a multilayered shell that protects the bacterial genome during stress conditions and is composed of dozens of proteins

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15
Q

Bacteria are haploid. What does this mean?

A

they have only one chromosome and only reproduce asexually

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16
Q

What is horizontal gene transfer?

A

Transferrin genetic information from one individual to another

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17
Q

Are humans capable of horizontal gene transfer? Why or why not?

A

no because human cells divide through meiosis and mitosis

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18
Q

What are the three mechanisms for horizontal gene transfer and how does each work?

A

a) transformation = a dead bacterium releases DNA into environment where it is taken in by living bacteria

• b) conjugation = a donor bacterium grows a hollow conjugation pilus to transfer plasmid(s) or fragments of main chromosome

• c) transduction = bacteriophage transfers DNA between bacteria

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19
Q

Why is horizontal gene transfer important to bacteria that can undergo this process?

A

a way to acquire new genes to help survive in nature and survive antibiotic exposure

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20
Q

How is horizontal gene transfer important in a medicine?

A

It can turn otherwise harmless bacteria into drug-resistant ‘superbugs’

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21
Q

We examined four examples of pathogenic bacteria. Do you recall that each entered its host by a different mechanism?

A

E. Coli - ingestion
Borrelia burgdorferi cause lyme disease - tick vector
Chlamydia - genital, oral, and anal sex

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22
Q

What were the four routes of entry we discussed?

A
  • infection usually via ingestion
  • infection via tick vector
  • sexual acts
23
Q

Where does E. coli typically live in human hosts?

A

colon (large intestine)

24
Q

Which strain has become a human health concern and why (what does it do to its hosts)? (e coli)

A

(Gram- bacillus)

Serotype O157:H7 evolved an exotoxin (Shiga toxin) that causes hemorrhagic diarrhea

25
Q

How are people infected by this bacterium? (e coli)

A

infected ground meat
contaminated produce

26
Q

Which bacterium causes Lyme disease?

A

Borrelia burgdorferi (Gram-indeterminate spirochete)

27
Q

How is this bacterium transmitted to human hosts? (lyme)

A

bite from black legged ticks

28
Q

What is a vector?

A

a vector transmits pathogen to human via bite

29
Q

What is the vector for the bacterium that causes Lyme disease?

A

ticks

30
Q

Which signs/symptoms characterize Lyme disease?

A
  • acute symptoms: fever, fatigue, headache
  • chronic symptoms may include: joint pain, heart arrhythmia, and neuropathy
  • signs: erythema migrans (reddening of skin migrating in rings from
    bite -bullseye rash); a tick
31
Q

What is the difference between a sign and a symptom anyways?

A

Symptoms are subjective and can be perceived only by the person affected. Signs are objective findings that can be seen or measured

32
Q

Chlamydia is caused by which bacterium?

A

Chlamydia trachomatis

33
Q

What is its morphology and gram staining status? (chlamydia)

A

Gram- coccus

34
Q

Which tissue(s) does it infect? (chlamydia)

A

it lives in your epithelial cells that line your urogenital tracts and your anus

35
Q

It is described as an intracellular bacterium, what does this mean? (chlamydia)

A

it is capable of growing/reproducing inside the cells of a host

36
Q

How is this bacterium transferred from host to host? Which persons are most susceptible to infection? Are there always signs/symptoms? When they do occur what are they? (chlamydia)

A

Infection gia genital, oral, and anal sex

• initially asymptomatic but painful urination and mucous
discharge often ensue

most common in teens

37
Q

Which more serious conditions can undiagnosed males and females develop due to chronic infection? (chlamydia)

A

• chronic infection may lead to epididymitis (inflammation of tube that transport form from testes to the urethra) in males and
pelvic inflammatory disease (PID) (inflammation of oviducts) and sterility in females (can b severe in woman)

38
Q

What is the morphology and gram staining status of Streptococcus pneumoniae? Which tissue(s) does it infect?

A

Streptococcus pneumoniae (Gram+ coccus) that grows in short chains
• infects respiratory tract and meninges (tissue layers around spinal cord and brain)

39
Q

How is this bacterium transferred from host to host? Which medical conditions does it cause? (morphology and gram)

A

Infection via inhalation of aerosolized body fluids (most common in elderly)

causes sinusitis, pneumococcal disease (e.g., pneumonia), and, sometimes, meningitis (inflammation of meninges)

40
Q

What is the difference between a community-acquired and a hospital-acquired infection?

A

community - infected in the community at large
hospital - infected in the hospital

41
Q

What are antibiotics used for?

A

Antibiotics are drugs used to kill bacteria (and some protists)

42
Q

What are the four general mechanisms of antibiotics action?

A

Antibiotics disrupt:
• cell wall construction (penicillin)
• metabolism (sulfonamides)
• protein synthesis (tetracycline)
• DNA replication (fluoroquinolones)

43
Q

What is antibiotic resistance?

A

resistance to an antibiotic

44
Q

How does resistance evolve in bacteria (consider how resistance evolves in viruses to help you form your answer)?

A

mutation and selection

45
Q

What is a multi-resistant strain (aka superbugs)?

A

Many pathogenic bacteria have evolved resistance to an antibiotic(s)

46
Q

Why do superbugs pose a serious problem to medical community?

A

can be acquired in healthcare settings so follow all protocols as if your life depends on it

47
Q

Which two superbugs did we examine as examples of multi-drug resistant bacteria?

A

Methicillin-resistant Staphylcoccus aureus (MRSA)
- a skin infection that can kill

Multidrug-resistant Mycobacterium tuberculosis (MDR TB)
- causes TB (consumption)

48
Q

For which pathogens have we developed vaccines for: viruses, bacteria, or both?

A

both but fewer for bacteria

Bacterial vaccines include:
Streptococcus pneumoniae (one cause of pneumonia) Neisseria meningitidis (one cause of spinal meningitis)

49
Q

What is a protist?

A

eukaryotic organism that many act as pathogens to humans

50
Q

Which two diseases caused by protists are leading causes of death in the developing world?

A

malaria

51
Q

Which protist commonly infects the mucous linings of human urogenital tracts?

A

Trichomonas vaginalis

52
Q

How is this protist transmitted from host to host?

A

mosquito vector

53
Q

What is a STD?

A

sexually transmitted disease

Biology 189 (17 decks)

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