Energy Types, Infectious Diseases, and Exponential Growth

hydrocarbon

An organic molecule made of hydrogen and carbon atoms; stores energy in chemical bonds.

conventional energy storage

In molecular bonds.

nuclear energy storage

In nuclear bonds.

chemical energy reaction

Atoms rearrange.

nuclear energy reaction

Nucleons (protons and neutrons) rearrange.

newly formed in conventional reactions

Molecules.

newly formed in nuclear reactions

Atoms.

nuclear fission

The splitting of a heavy nucleus into smaller fragments.

isotopes

Atoms of the same element with different numbers of neutrons.

ionizing radiation

Radiation that can remove electrons from atoms, damaging tissue.

types of ionizing radiation

Alpha: heavy, low penetration (stopped by paper); Beta: medium penetration (stopped by foil); Gamma: highly penetrating (stopped by lead/concrete).

ionizing radiation damage to cells

It creates free radicals or directly damages DNA, possibly causing cancer or cell death.

radiometric dating using carbon-14

A method for dating formerly living things by measuring the decay of C-14 after death.

germ theory of disease

Microorganisms (germs) cause disease, not bad air.

John Snow

He linked cholera to contaminated water, founding epidemiology.

Koch's postulates

Steps to prove a microbe causes disease: Found in all sick individuals; Isolated and grown in pure culture; Causes disease in a healthy subject; Re-isolated from the new host.

difference between bacteria and viruses

Bacteria are cells that reproduce independently; viruses hijack host cells.

virulence factors

Proteins produced by pathogens to cause disease (e.g., cholera toxin).

opportunistic infection

Disease caused by normally harmless microbes in a weakened host (e.g., HIV patients).

microbiota shift disease

Disease caused by disruption of healthy microbes (e.g., after antibiotic use).

protists

Single-celled parasites like Giardia and Cryptosporidium.

mycosis

A fungal infection, e.g., athlete's foot.

difference between lytic and lysogenic virus cycles

Lytic: virus destroys cell to release new viruses (e.g., rabies); Lysogenic: virus DNA hides in host genome, activates later (e.g., herpes).

continuous compoudning

A=Pe^{rt}.

variables in A=Pe^{rt}

A = final amount; P = initial amount; r = rate (positive = growth, negative = decay); t = time; e = Euler's number (~2.718).

half-life of an isotope

Time it takes for half the radioactive atoms to decay.

decay of a sample

Around 10 half-lives.

remaining amount after time t with half-life h

Use: A=P⋅(1/2)^{t/h}.