Evolutionary Medicine

Question 1

Alexander Bivelich: Example of Coevolution

Answer 1

Alexander Bivelich exemplifies a victim of coevolution, showing how organisms adapt in response to one another, often creating an evolutionary arms race between host defenses and parasite offenses

Question 2

Percentage of Parasitic Species

Answer 2

Approximately 40% of species are parasitic, illustrating how parasitism is a common survival strategy that drives complex evolutionary relationships

Question 3

Behavioral Response of Chimpanzees to Intestinal Worms

Answer 3

Chimpanzees infected with intestinal worms eat rough leaves to help physically dislodge and expel the parasites, demonstrating a self-medicating behavior to reduce parasite load

Question 4

Behavioral Response of Male Fruit Flies to Mite Infection

Answer 4

Male fruit flies infected by bloodsucking mites increase their mating frequency, potentially as a last-ditch effort to pass on genes before the infection impacts their survival

Question 5

Alexander Fleming’s Contribution and Warning (1928)

Answer 5

In 1928, Fleming discovered penicillin, the first effective antibiotic, revolutionizing infection treatment. He cautioned doctors about the risk of resistance from overuse and misuse of antibiotics

Question 6

Reasons Bacteria Coevolve Faster than Insects

Answer 6

Bacteria have an edge in coevolution due to: (1) rapid reproduction–short generation times lead to quick evolutionary changes, (2) high mutation rate–frequent mutations increase genetic diversity, (3) haploid nature–single gene copies mean mutations have immediate effects, and (4) gene transfer–bacteria can acquire beneficial genes from other bacteria through conjugation and transformation

Question 7

Conditions in Russian Prisons Favoring Microbial Evolution

Answer 7

Russian prisons encourage microbial evolution due to: (1) overcrowding–close quarters increase disease transmission, (2) inadequate medical resources–limited treatment fosters resistance, and (3) high immunocompromised population–diseases easily spread and adapt

Question 8

Remarkable London Enterococcus Strain

Answer 8

A strain of Enterococcus identified in London shows resistance to all standard antibiotics, highlighting the challenge posed by superbugs in modern medicine

Question 9

Methods to Reduce Bacterial Resistance Selective Pressure

Answer 9

Strategies include: (1) antibiotic stewardship–restrict and carefully manage antibiotic use, (2) targeted therapy–use narrow-spectrum antibiotics when possible, (3) infection control–strict hygiene in healthcare settings, (4) alternative treatments–explore non-antibiotic therapies, and (5) enhanced hygiene–reduce infection spread to prevent overuse of antibiotics

Question 10

Virus Characteristics and Living Status

Answer 10

Viruses are non-living particles that contain DNA or RNA within a protein shell. They cannot reproduce or carry out metabolic functions independently, requiring a host cell for survival and replication

Question 11

Reasons HIV Evolves Easily in Hosts

Answer 11

HIV evolves rapidly within human hosts due to: (1) high replication rate–frequent reproduction generates numerous variants and (2) mutation frequency–reverse transcriptase introduces errors, adding diversity

Question 12

Common HIV Infection Routes

Answer 12

HIV primarily spreads through: (1) blood transfusion or contact, (2) sexual contact, and (3) mother-to-child transmission during childbirth or breastfeeding

Question 13

Origin Hypothesis of HIV-1

Answer 13

HIV-1 likely originated from cross-species transmission, particularly from Pan troglodytes (chimpanzees) to humans, through the consumption of bushmeat

Question 14

Primary Strain Causing Global AIDS Epidemic

Answer 14

The global AIDS epidemic is largely caused by the HIV-1 strain, known for its high transmissibility and virulence

Question 15

Significance of Protecting Pan t. troglodytes (Chimpanzees)

Answer 15

Conservation of Pan t. troglodytes is crucial to prevent further zoonotic diseases from transferring between species, especially strains that could affect human populations

Question 16

CCR5 Receptor and Its Role in HIV

Answer 16

The CCR5 receptor is essential for HIV entry into T-cells. HIV binds to CD4 and CCR5 receptors on T-cells to infect them, leading to immune system weakening

Question 17

Genotype and Phenotype of HIV-Resistant Individuals

Answer 17

Individuals homozygous for a CCR5 mutation (lacking CCR5 receptors) are resistant to HIV. This mutation prevents HIV from binding to and entering T-cells

Question 18

1347 Selective Pressure Linked to HIV Resistance

Answer 18

The Black Death in 1347 may have selectively increased the frequency of CCR5 mutations in European populations, potentially conferring resistance to diseases like HIV

Question 19

Potential Effects of a CCR5-Blocking Drug

Answer 19

Blocking CCR5 receptors with a drug could prevent HIV from entering cells, offering a therapeutic strategy but possibly affecting immune response regulation

Question 20

Relationship Between Parasite Transmission Mode and Toxicity

Answer 20

Parasites relying on direct human contact for transmission are typically less toxic to keep hosts mobile. In contrast, vector-borne or waterborne parasites (e.g., malaria, cholera) can afford higher toxicity as host movement is not essential for spread

Question 21

HIV Mechanisms Leading to AIDS

Answer 21

HIV targets helper T-cells, using reverse transcriptase to integrate its RNA into the host genome, where high replication and mutation rates undermine immune defenses, leading to AIDS