Evolutionary Bio: Ch. 18 - Gamble

Natural selection, mutations

Both a population of bacteria and a group of tumor cells may overcome susceptibility to drugs through the process of --- Each cell type acquires random --- during rapid cell proliferation. Some of these changes result in genes that render the carrier cells able to defend themselves against chemical treatment. These cells survive and continue to divide while sensitive cells die off.

Antigenic shift

Dramatic change inf the surface proteins of influenza viruses brought about by reassortment between viral strains leading to a severe drop in immunity to the resulting strain and the potential for a new flu pandemic

Proteins, random mutation, one third

For instance, viruses must interact with host --- to be able to invade a host cell and replicate. When --- occurs in these host macromolecules, a virus may respond to the selective pressure by evolving in kind. One researcher concluded that selective pressures due to viruses have caused --- of the proteins in the hominin lineage to have altered amino acids.

Antibiotics, chemotherapy, resistance

For treatment of bacterial infections and cancer, physicians often use drugs to kill or stop the growth of the disease‑causing cells. The drugs that target bacteria are --- and the drugs that target tumor cells are ---However, both bacteria and tumor cells can become drug --- meaning that they can acquire the ability to defend against the chemicals that target them.

B, C

How can the human body shape the evolution of pathogens? A) Natural selection eventually causes pathogens to be perfectly suited for infecting the human body. B) Natural selection favors mutations that allow pathogens to improve upon use of the host's resources. C) The human immune system exerts pressures that cause pathogens to adapt to evade destruction. D) The immune system of the human body causes pathogens to undergo high mutation rates.

A, B, D

How does the study of bacteria in patients with cystic fibrosis help in understanding pathogen evolution? A) Environmental bacteria re‑evolve similar adaptations in different human hosts. B) In challenging environments, some bacteria evolve a highly increased mutation rate. C) Bacteria evolve to evade the heightened immune systems of patients with cystic fibrosis. D) Environmental bacteria can evolve to become dangerous pathogens after entering a host. E) All the microbes evolve the same traits to thrive in every micro‑environment in the body.

A, B

How does the virulence of a pathogen impact its phylogeny? A) A pathogen with low virulence has a phylogeny with a branching pattern that mirrors that of its host. B) A pathogen with high virulence has a phylogeny with a branching pattern that does not follow one host. C) A pathogen with high virulence has a phylogeny with a branching pattern that mirrors that of its host. D) A pathogen with low virulence has a phylogeny with branching that occurs more frequently than that of its host.

A

How might advances in travel affect future disease outbreaks? A) Mass movement and crowding increase the fitness of highly virulent viruses. B) Mass movement and crowding strengthen the selective constraint on virulence. C) Mass movement and crowding prevent reassortment among different viral strains. D) Mass movement and crowding reduce the probability of viral transmission.

Illness and death, host

Human health has been affected by pathogens and cancer for thousands of years. Both pathogens, such as bacteria and viruses, and cancer weaken the immune system and invade cells and tissue within the human body, resulting in --- There are many similarities in the mechanisms by which both pathogens and cancer work in the body. Both cancer and pathogens continue to evolve after they become established in the body. The cancer cells and pathogens evolve in response to the specific conditions inside their ---

A

Identify the example of antagonistic pleiotropy. A) A gene that increases milk production also increases the risk of cardiovascular disease. B) A mutation in a gene causes sperm to swim slower and be more sensitive to pH changes. C) One gene protects newborns from disease, whereas a similar gene causes early‑onset Alzheimer's. D) A mutation in an allele allows females to be reproductively fertile for a longer period of time.

Antigenic drift

Natural selection on seasonal influenza viruses that alters the structure of surface proteins, allowing them to evade the antibody mediated immunity induced during previous infections or vaccinations

Body fluids, proliferation

Pathogens have an additional requirement for survival. Pathogens must transmit from person to person. Transmission typically occurs through --- Pathogens must replicate and evolve for survival but cannot become too virulent or the host will die before disease transmission can occur. Cancer cells transmitted from person to person, so the survival of cancer cells depends on ---

Protein fragments, attenuation, primate, less

Scientists apply their knowledge of evolution to improve vaccines. Instead of delivering a dead virus or its --- some vaccines induce an immune response by delivering a live virus. Scientists must first weaken the virus using the process of --- so that no serious illness results. To produce a live polio vaccine, for instance, researchers force the virus to evolve in the cells of a ---species in which it does not naturally replicate. The virus manages to survive, mutating as it slowly replicates. As the virus adapts to these cells, it becomes increasingly --- able to infect human cells. However, injected in the human body, it can still elicit a strong immune response.

Universal, one type of antibody, hemagglutinin, base

Scientists are also using their knowledge of evolution to create --- vaccine. Instead of formulating a new vaccine every season, scientists are trying to develop one that stimulates the production of --- that would target all strains of the virus. Standard vaccine antibodies bind to the tip of the --- stalk, which continually mutates. However, the new antibodies would bind to the --- which is nearly identical across all strains and not likely to mutate without causing harm to the virus.

A, C

Select the evidence that refutes the thrifty genotype hypothesis. A) Scientists have not found evidence of natural selection acting on genes that cause metabolic disease. B) Hunter‑gatherers experienced more cyclical patterns of feast and famine than subsistence farmers. C) Hunter‑gatherer populations experienced fewer periods of famine than subsistence farmers. D) Abrupt switches to high‑sugar and high‑fat diets is causing higher rates of metabolic diseases.

Malaria, higher

Specific diseases have also molded the human genome. For example, in geographical areas where mosquitoes commonly carry the pathogen for --- mutations that confer resistance to the disease spread at a high rate through human populations. As a result, these defensive alleles appear at a --- frequency than in areas where the disease is less common.

Selective pressures, genome

The genes of human pathogens are shaped primarily by --- in the environment of the human body. In turn, pathogens shape the human --- This evolutionary arms race has taken place over millions of years.

Pathogens, slower, evolutionary history, fitness, adaptions

There are many maladaptations that have been maintained in human evolution that make us particularly vulnerable to a variety of diseases. Scientists have classified these maladaptations into six categories to explain why humans are vulnerable. 1. --- evolve faster than their hosts. 2. Natural selection is --- than environmental change. 3. Trade-offs make it impossible for evolution to solve certain biological problems. 4. A species' --- puts constraints on future natural selection. 5. Some traits increase --- at the cost of increasing vulnerability to disease. 6. What appear to be diseases may actually be ---

Evolutionary, variation, huntington's, mendelian, some cancers

Today's doctors are taking an ---approach to understanding the genetics behind the various conditions that affect human health. Instead of treating all patients similarly, doctors are considering genetic--- and genetic history to customize the prevention, management, and treatment of disorders. Some inherited conditions, such as --- follow the simple rules of --- genetics. Other genes influence disease in a more complex fashion. For example, certain variants of BRCA1 increase the risk of ---

Frequency, heterozygous, founder, medication, polymorphic

Understanding population genetics can also be helpful in medicine. When individuals succumb to a lethal genetic disease before reproducing, the --- of the defective allele generally decreases in the population. But some harmful alleles can become more common if the --- genotype provides a benefit, such as protection from a different harmful condition. Deleterious alleles can also be amplified with the genetic drift that occurs more readily in small populations, as with the --- effect. Doctors might also use genetics to identify a --- that has optimal efficacy and minimal side effects for a patient. This tool aids in predicting the variability of responses to specific chemicals that occur under the influence of --- genes.

Horizontal gene transfer, cassette

Unlike tumor cells, bacteria are a particular threat because the genes that make them safe from drugs can be amplified by --- which occurs when genes in one lineage jump to a different lineage species. Further, accumulated defensive mutations in one bacterium can be passed to another in one bundle, called a --- that endows instant protection against an entire set of drugs.

B

What bacterial trait allows antibiotic resistance to spread in bacterial populations? A) slow population growth B) high virulence levels C) horizontal gene transfer D) high mutation rate E) control of a host's immune system

D

Which statement describes the outcome of a situation if the thrifty genotype hypothesis holds true? A) Hunter-gatherers responded to food shortages by moving to regions with better resources. B) Obesity decreases in subsistence farmers given sudden access to an excess of calories. C) Scientists find no evidence that natural selection has favored genes contributing to diabetes. D) Diabetes increases in a hunter-gatherer population abruptly exposed to a high‑sugar diet.

B

Why could clean, sterile environments in modern life result in a rise in some genetic diseases such as Alzheimer's? A) In sterile environments, antibiotics only kill the most harmful microbes. B) An increase in life span results in unmasking antagonistic pleiotropy. C) Sterile environments are directly correlated with a high sugar diet and diabetes. D) Excessive cleanliness encourages the evolution of bacteria with new diseases.