SAS 13 Second Exam Review - Genetic, Non-Human, and Infectious Diseases

Comprehensive vocabulary review flashcards for SAS 13 Exam 2, covering genetic diseases, plant pathology, microbiology, cholera, and tuberculosis.

Single Gene Disorder

A genetic disease caused by an alteration or deletion in one specific gene (with over 4,000 known disorders), exemplified by cystic fibrosis, PKU, and hemophilia.

Chromosome Abnormality

A genetic disease resulting from an excess or loss of an entire chromosome, such as Down syndrome or Turner syndrome.

Multifactorial Disease

A complex disease involving abnormalities across multiple genes along with environmental factors, such as cancer or Alzheimer's disease.

Autosomal Disease

A genetic disease linked to an abnormality on one of the non-sex chromosomes, numbered 1 through 22.

Sex-Linked Disease

A genetic disorder caused by a mutation on the sex chromosomes (the X or Y chromosome).

Phenylketonuria (PKU)

An autosomal recessive metabolic disorder caused by a mutation (such as a codon 408 Arg to Trp switch) leading to a deficiency in liver phenylalanine hydroxylase and toxic build-up of phenylalanine.

Phenylalanine Hydroxylase (PAH)

The liver enzyme responsible for converting the amino acid phenylalanine into tyrosine, which is deficient or defective in patients with PKU.

Asbjørn Følling

The Norwegian physician who first described PKU in 1934 (originally called Følling disease) after detecting phenylpyruvic acid in infants with foul- or mousy-smelling diapers.

Maternal PKU Syndrome

A condition affecting the fetus of a pregnant woman with PKU who does not adhere to a low-phenylalanine diet, exposing the developing baby to toxic levels of phenylalanine.

Kuvan

The first approved drug for PKU, which acts as a 'booster' for defective phenylalanine hydroxylase (PAH) to reduce blood levels of phenylalanine.

Guthrie Test

A newborn bacterial inhibition assay created by Robert Guthrie in 1963 using Bacillus subtilis on agar plates to detect elevated phenylalanine from a heel stick blood sample.

Huntington's Disease

An autosomal dominant, adult-onset neurodegenerative disorder characterized by 'dancing propensities' (chorea), cognitive decline, and psychiatric disturbances.

Charles Davenport

A leader in the American eugenics movement who used Huntington's disease to advocate for state-mandated institutionalization and strict immigration controls.

Nancy Wexler

A geneticist who studied over 18,000 individuals and collected 4,000 blood samples in Lake Maracaibo, Venezuela, over a 20-year period to identify the gene responsible for Huntington's disease.

Huntingtin (HTT) Gene

A gene on chromosome 4 whose mutated form contains excessive CAG repeats producing polyglutamine expansions; when $n > 35$, the resulting sticky protein aggregates and damages brain tissue.

AMT-130

A one-time gene-silencing therapy developed by uniQure that infuses viral particles into the brain to produce complementary mRNA binding, slowing Huntington's disease progression by 75%.

CRISPR-Cas9

A targeted 'genetic surgery' tool featuring a guide RNA and a Cas9 endonuclease that makes precise cuts in specific DNA sequences.

HD140Q-knock-in Mice

Genetically engineered mice carrying 140 CAG repeats in the huntingtin gene, evaluated using rotarod balance tests to investigate motor symptoms and CRISPR therapies.

Ex Vivo Gene Therapy

A technique where cells (such as bone marrow or T-cells) are removed from the body, genetically edited in the laboratory, and subsequently reinfused into the patient.

In Vivo Gene Therapy

A gene therapy procedure where therapeutic payloads (such as CRISPR packaged in disarmed viruses) are injected directly into the patient's body tissues.

Germline Modification

The genetic alteration of embryos or reproductive cells—such as using CRISPR-Cas9 to correct a $\beta$-thalassemia mutation—resulting in edits that pass to future generations.

Hemophilia

An X-linked recessive bleeding disorder caused by a mutation in clotting factor 8 (hemophilia A) or factor 9 (hemophilia B), preventing normal blood clotting.

Contraindication

A medical condition, activity, or drug (such as contact sports or anticoagulants in hemophilia patients) that must be avoided because it may cause harm to the patient.

The Disease Triangle

A foundational plant pathology concept developed by George McNew stating that infectious disease requires the interaction of a susceptible host, a virulent pathogen, and a favorable environment.

Phytophthora infestans

An oomycete (fungus-like microorganism) that causes late blight of potato, responsible for destroying crops during the 7-year Irish potato famine.

Consistent Association

The repeated observation of a specific microorganism in direct association with a specific disease, first highlighted in late blight by M.J. Berkeley.

Koch's Postulates

Four criteria developed by Robert Koch to confirm the causative agent of an infectious disease: association with symptoms, isolation in pure culture, inoculation into a healthy host to reproduce symptoms, and reisolation of the microbe.

Anthrax

A bacterial disease caused by Bacillus anthracis affecting animals and humans, and the first bacterium proven by Robert Koch to cause disease.

Autoclave

A pressurized vessel using moist heat at $121^\circ\text{C}$ to kill resilient bacterial endospores that resist ordinary heating.

Germ Theory of Disease

The principle developed by Louis Pasteur and Robert Koch establishing that specific microscopic pathogens cause infectious diseases.

Cryphonectria parasitica

The airborne fungal pathogen introduced from Asia that causes chestnut blight, killing approximately 3,500,000,000 American chestnut trees through stem girdling.

Hypovirulence

A condition where a pathogenic fungus exhibits reduced virulence and slower growth due to infection with a mycovirus (such as Cryphonectria hypovirus), enabling biological control.

Biocontrol

The management of pests or diseases using other organisms or biological agents based on the principle of 'my enemy's enemy is my friend.'

Vibrio cholerae

The comma-shaped, flagellated bacterium identified by Robert Koch that causes cholera, producing watery 'rice water stool' via fecal-oral transmission.

Cholera Toxin (CT)

An enterotoxin released by Vibrio cholerae in the intestine that causes massive epithelial secretion and loss of $H_2O$, $Na^+$, and $K^+$, leading to severe dehydration and rapid drop in blood pressure.

John Snow

The British physician who mapped London cholera cases to the contaminated Broad Street water pump in 1854, demonstrating waterborne transmission and founding modern epidemiology.

Rita Colwell

A scientist who pioneered satellite-based epidemiology to forecast cholera outbreaks by monitoring ocean temperatures, algal blooms, and copepod populations.

Sari Cloth Filtration

A low-cost water purification method where sari cloth folded at least four times filters out $99\%$ of Vibrio cholerae by capturing the copepod plankton on which the bacteria live.

Tuberculosis (TB)

A chronic airborne bacterial infection caused by Mycobacterium tuberculosis, historically referred to as consumption, phthisis, and the white plague.

Granuloma (Tubercle)

A nodular cellular structure formed by macrophages attempting to wall off Mycobacterium tuberculosis inside lung tissue.

Miliary TB

A widespread, severe form of tuberculosis occurring when bacteria disseminate systemically throughout the body, forming lesions resembling millet seeds.

Mantoux Test

A diagnostic tuberculin skin test where a small intradermal injection of bacterial antigen is given; an induration of $\ge 10\,\text{mm}$ indicates a positive reaction.

BCG Vaccine

Bacillus Calmette-Guérin, an attenuated strain derived from Mycobacterium bovis and the only widely available vaccine used to prevent severe forms of tuberculosis.

Sanatoria

Historical health retreats established in rural settings with clean, fresh air where tuberculosis patients were quarantined and given rest prior to the discovery of antibiotics.

MDR-TB and TDR-TB

Multi-Drug Resistant Tuberculosis (resistant to isoniazid and rifampin) and Totally Drug Resistant Tuberculosis (unresponsive to all available antibiotics, identified in 2011).