UC Berkeley PH 162A Midterm 1

Characteristics of Prokaryotes

no nucleus, no membrane bound organelles

examples of prokaryotes

bacteria and archaea

Characteristics of Eukaryotes

nucleus and membrane bound organelles

examples of eukaryotes

plants, animals, fungi, protists

Purpose of Koch's Postulates

series of guidelines used to identify the microorganism that causes a specific disease

What are Koch's Postulates?

1. The same pathogen must be present in every case of the disease.

2. The pathogen must be isolated from the diseased host and grown in pure culture.

3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.

4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

What are the three kinds of horizontal gene transfer?

transduction, conjugation, transformation

How does specialized transduction work?

Phage DNA is integrated into plasmid of bacteria; bacteria reproduces, allowing phage DNA to replicate

How does generalized transduction work?

Any section of bacterial DNA is transferred; random bacterial DNA is included in new virions and introduced to new bacteria upon infection

What is conjugation?

transfer of DNA between bacteria using a pilus; involves plasmids

What's a plasmid?

Tiny circles of DNA found in bacteria, non-chromosomal

What is transformation in horizontal gene transfer?

uptake of new, random genes from environment; "competence" is required

What is competence in transformation?

bacteria needs to be in a state where it can be transformed; sometimes in lab they are electrocuted

What is the importance of ribosomes in taxonomy?

bacterial ribosomes remain consistent among all living things; slight differences allows us to determine common ancestors

What size ribosome do we sequence for taxonomy?

16S

How much similarity do the ribosomes in bacteria need to have to be the same species?

97% or greater

What's a silent mutation?

a base change mutation where it doesn't effect the amino acid produced

What's a missense mutation?

a base change mutation changes the amino acid produced

What's a nonsense mutation?

a base change mutation prematurely introduces stop codon, shortening the protein

What's a frameshift mutation?

insertion/deletion of a base which shifts the ribosome's reading frame; can result in premature stop codons or affect the folding of protein entirely

What are characteristics of gram-positive bacteria?

thick peptidoglycan layer, one membrane, techoic acid, stains purple

A bacteria is stained purple. Is it gram-positive or gram-negative?

gram-positive

What are characteristics of gram-negative bacteria?

thinner peptidoglycan layer, two membranes, outer membrane has lipopolysaccharides (LPS)

What kind of cell shape is this?

What kind of cell shape is this?

What kind of cell shape is this?

What does a Zeihl-Neelsen acid fast stain do?

detects high lipid content in cell walls for non- gram-pos or gram-neg bacteria

What are exotoxins?

proteins secreted by certain bacteria and other organisms into host cell

What kind of toxin is an A-B toxin?

exotoxin

What are some endotoxins?

lipopolysaccharides from the cell wall of gram-negative cells; contains lipid A;

What are endotoxins?

Lipid A released, can cause systemic shock and other fatal effects.

How do A-B toxins work?

work by binding to host cell receptor (B part) and transferring damaging agent (A part) cross the membrane

What's a Type III secretion system?

in gram-negative bacteria; shoot "conjugation pilus" into host cell to secrete virulence factors

Name the steps for diagnosis and identification of bacteria.

1. culture

2. gram stain

3.. selective media (blood agar, for example, to see hemolysis)

4. serological and biochemical (like the COVID rapid test)

5. antibiotic test

6. MALDI-TOF mass spectrometry (ionizes sample)

7. sequencing

What are membrane-disrupting toxins?

exotoxins that lyse host cells by disrupting plasma membranes

Antibiotic type that does inhibition of cell wall synthesis

beta-lactams

Name a beta-lactam

penicillin

Antibiotic that inhibits protein synthesis

tetracycline

Antibiotic type that inhibits nucleic acid synthesis

quinolones

Name a quinolone

ciprofloxacin

Antibiotic type that acts as antimetabolites, inhibits folic acid synthesis pathway

sulfonamides

What are some kinds of antibiotic resistance?

efflux pumps, inactivating enzymes, decreased uptake, target alterations

Name two antivirals.

acyclovir, AZT

What is acyclovir an analog for?

nucleotide base guanine

What antiviral treats herpesvirus?

acyclovir

What is AZT an analog for?

nucleotide base thymine

What antiviral treats HIV? How?

AZT; blocks reverse transcriptase which HIV creates

What fungal cell component does antifungals target?

Ergosterole

What are prions?

misfolded proteins

Name four diseases related to prions.

scrapie, mad-cow, kuru, creuzfeldt-jacob

What kind of cancer can HPV cause?

cervical cancer

What kind of cancer can Hep B and C cause?

liver cancer

What kind of cancer does Epstein Barr cause?

Burkitt's lymphoma, nasopharyngeal carcinoma

Baltimore

Anopheles mosquito causes what disease?

malaria

Malaria affects which parts of the body?

blood and liver, in a cycle

What are the two types of trypanosoma spp.?

African and American trypanosomiasis

What's another name for African trypanosomiasis?

sleeping sickness

What's another name for American trypanosomiasis?

Chaga's disease

African trypanosomiasis is caused by what? Where in the body does it affect?

Tsete fly, from cattle reservoir; extracellular in blood, lymph, cerebrospinal fluid

American trypanosomiasis is caused by what? Where in the body does it affect?

can be eaten or given by Triatome bug ("kissing bug") from a mammalian reservoir; infects smooth muscle (heart)

Why is it hard to diagnose Chaga's disease?

mostly flu-like symptoms early on

Leishmaniasis is cause by what? Where in the body does it affect?

Sandflies, varying based on subspecies; affects skin, nose, mouth, and internal organs

What's another name for cestodes?

tapeworms

How do you get tapeworms?

Red meat, fish, water

Are humans definitive or intermediate hosts for cestodes?

both

How does the life cycle of a tapeworm work?

Animal eats egg; larvae form cysts; human eats animal; larvae matures into adulthood

What are the two kinds of African trypanosomiasis?

T. brucei gambiense and T. brucei rhodesiense

Name an American trypanosomiasis strain?

T. cruzi

What disease do trematodes cause?

Schistosoma spp.

What's an intermediate host for trematodes?

freshwater snails, fish

How do trematodes get to their definitive host?

They're attracted to lipids in skin; humans swimming have a chance of being penetrated through the skin by trematodes

Schistosoma haematobium affects what?

urinary tract, bladder

Schistosoma japonicum affects what?

intestinal wall, liver

Schistosoma mansomi affects what?

colon, rectum, liver

What are some of the symptoms of schistosoma spp.?

bloody urine, dermatitis, hypertension, granuloma formation creating swelling

What's another name for onchocerciasis?

river blindness

What causes the blindness in river blindness?

adult worm makes microfilariae, which can travel to the eye, with Wolbachia in them which triggers immune response

How is river blindness transmitted?

black fly injects larvae during blood meal

How are hookworms transmitted?

penetration of skin by larvae found in the soil; get to lungs, coughed up, go down to small intestine

What are some symptoms of hookworms?

worm burden can cause anemia and iron deficiency, stunting growth in children

What is the transmission of ascaris? What is it similar to?

orally ingested; similar to hookworms

What is the species name for the parasite that causes malaria?

Plasmodium spp.

What is the envelope and capsid shape of picornaviridae?

naked, polyhedral

What is the envelope and capsid shape of togaviridae?

enveloped, polyhedral

What is the envelope and capsid shape of retroviridae?

enveloped, spherical

What is the envelope and capsid shape of coronaviridae?

enveloped

What's a disease associated with picornaviridae?

Enterovirus; Polio

What's a disease associated with togaviridae?

Rubella virus

What's a disease associated with flaviviridae?

flavivirus; yellow fever

What's a disease associated with retroviridae?

HIV; AIDS

What is the envelope and capsid shape of paramyxoviridae?

enveloped, helical

What is the envelope and capsid shape of rhabdoviridae?

enveloped, helical

What is the envelope and capsid shape of orthomyxoviridae?

enveloped, helical

What is the envelope and capsid shape of filoviridae?

enveloped, filamentous

What is the envelope and capsid shape of bunyaviridae?

enveloped, spherical

What is the envelope and capsid shape of reoviridae?

naked, polyhedral

What's a disease associated with paramyxoviridae?

morbillivirus; measles

What's a disease associated with rhabdoviridae?

lyssavirus; rabies

What's a disease associated with orthomyxoviridae?

influenza