DZI Biology and Health Education cheat sheet

Central dogma: DNA is transcribed to mRNA, which is translated to protein by ribosomes; transcription occurs in the nucleus in eukaryotes, translation in the cytoplasm.

Membrane transport decision rule: simple diffusion moves small nonpolar molecules down a gradient without energy; facilitated diffusion uses channels or carriers down a gradient; active transport uses ATP or a gradient to move solute against its gradient.

Mitochondria generate ATP by oxidative phosphorylation: the electron transport chain builds a proton gradient that drives ATP synthase; this yields roughly 30-32 ATP per glucose in aerobic respiration.

Osmosis rule: water moves toward the compartment with higher solute concentration; a hypertonic solution causes cells to shrink, a hypotonic solution causes them to swell.

Enzymes lower activation energy without changing reaction equilibrium; Michaelis-Menten kinetics describe rate as Vmax times [S] divided by Km plus [S].

Cell cycle checkpoints: G1/S checks cell size and DNA integrity, G2/M checks replication completion, and the spindle checkpoint verifies chromosome attachment before anaphase.

Apoptosis is programmed, ATP-dependent, and non-inflammatory, driven by caspases; necrosis is passive, causes swelling and lysis, and triggers inflammation.

DNA replication is semiconservative and bidirectional from origins; DNA polymerase synthesizes 5' to 3', so the lagging strand forms Okazaki fragments.

Mendel's law of segregation: two alleles separate during meiosis so each gamete carries one allele; the law of independent assortment applies to genes on different chromosomes.

Hardy-Weinberg equilibrium requires no mutation, no migration, random mating, infinite population size, and no selection; deviations indicate evolution is occurring.

Hardy-Weinberg formulas: allele frequencies p + q = 1; genotype frequencies p squared + 2pq + q squared = 1.

Autosomal recessive inheritance: affected individuals usually have two carrier parents, the trait can skip generations, and the recurrence risk for carrier parents is 25 percent per child.

X-linked recessive traits appear far more often in males, who are hemizygous; affected fathers pass the allele to all daughters, who become carriers.

Natural selection requires heritable variation in traits that affect fitness; it acts on phenotypes and changes allele frequencies across generations.

Genetic drift is random change in allele frequency, strongest in small populations; the founder effect and bottleneck effect are its main forms.

Mutation is the ultimate source of new alleles; gene flow (migration) and recombination redistribute existing variation among populations.

Cardiac output equals heart rate times stroke volume; average resting output is about 5 L per minute, and it rises with demand during exercise.

Blood flows through the heart in this order: vena cava, right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein, left atrium, left ventricle, aorta.

Nephron sequence: glomerular filtration, tubular reabsorption in the proximal tubule, secretion, and concentration in the loop of Henle and collecting duct under ADH control.

Gas exchange rule: oxygen binds hemoglobin best at high pH and low CO2 (Bohr effect shifts right with acidosis, heat, and high CO2); CO2 is carried mainly as bicarbonate.

Homeostasis uses negative feedback: a sensor detects deviation, an integrating center compares it to a set point, and an effector reverses the change; oxytocin and childbirth are classic positive feedback.

Action potential phases: depolarization from sodium influx, repolarization from potassium efflux, and refractory periods that prevent backward conduction.

The autonomic nervous system: sympathetic activity raises heart rate, dilates airways and pupils, and diverts blood to muscle; parasympathetic activity slows heart rate and promotes digestion.

Hormone feedback loops: the hypothalamus releases releasing hormones, the anterior pituitary releases tropic hormones, and the target gland secretes its hormone, which feeds back negatively.

Chain of infection links: pathogen, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host; breaking any link interrupts transmission.

Bacteria are prokaryotes lacking a nucleus; viruses are obligate intracellular parasites with either DNA or RNA genomes and no independent metabolism.

Gram staining decision rule: gram-positive cells retain crystal violet and appear purple due to thick peptidoglycan; gram-negative cells appear pink and have an outer membrane.

Koch's postulates link a microbe to disease: the organism is found in all cases, can be isolated and cultured, causes disease when inoculated, and is recovered again.

Antibiotic resistance mechanisms include enzymatic inactivation (beta-lactamase), efflux pumps, target modification, and reduced membrane permeability.

Herd immunity threshold approximates 1 minus 1/R0; for measles (R0 about 12-18) the threshold exceeds 90 percent, requiring very high vaccine coverage.

Sterilization kills all microorganisms including spores; disinfection reduces pathogens on surfaces; antisepsis applies to living tissue.

Nosocomial infections are acquired in healthcare settings; hand hygiene is the single most effective intervention to reduce transmission.

Energy yield per gram: carbohydrate 4 kcal, protein 4 kcal, fat 9 kcal, alcohol 7 kcal.

Basal metabolic rate is measured at rest; total energy expenditure equals BMR plus thermic effect of food plus physical activity.

Glycolysis converts glucose to pyruvate yielding net 2 ATP and 2 NADH; anaerobic conditions convert pyruvate to lactate in humans.

The Krebs cycle and oxidative phosphorylation complete aerobic oxidation of acetyl-CoA, producing most of the ATP from glucose and fatty acids.

Essential nutrients cannot be synthesized in adequate amounts and must come from diet, including nine amino acids, two fatty acids (linoleic and alpha-linolenic), vitamins, and minerals.

Body mass index equals weight in kilograms divided by height in meters squared; a BMI of 25 or above is overweight and 30 or above is obese.

Protein-energy malnutrition presents as marasmus (severe wasting) or kwashiorkor (edema with adequate energy but deficient protein).

Fat-soluble vitamins A, D, E, and K require bile for absorption and are stored in the liver; water-soluble vitamins are excreted more readily.

Incidence measures new cases over a period at risk; prevalence measures all existing cases at a point in time; prevalence approximately equals incidence times duration.

Attack rate equals new cases divided by population at risk during an outbreak, often expressed as a percentage.

Relative risk equals incidence in exposed divided by incidence in unexposed; it is used in cohort studies.

Odds ratio approximates relative risk for rare outcomes and is the standard measure from case-control studies.

Sensitivity equals true positives divided by all with disease; specificity equals true negatives divided by all without disease; predictive values depend on prevalence.

Levels of prevention: primary prevents onset (vaccination), secondary detects early (screening), tertiary limits disability and complications (rehabilitation).

Mortality rate equals deaths in a period divided by population, usually per 100,000; infant mortality rate is a sensitive indicator of population health.

Confounding occurs when a third variable is associated with both exposure and outcome; randomization, restriction, and stratification control it.

Health Belief Model constructs: perceived susceptibility, perceived severity, perceived benefits, perceived barriers, cues to action, and self-efficacy.

Transtheoretical Model stages: precontemplation, contemplation, preparation, action, maintenance, and termination; interventions should match the stage.

Social Cognitive Theory: behavior is shaped by reciprocal determinism among personal, behavioral, and environmental factors; self-efficacy and observational learning are central.

Theory of Planned Behavior: attitudes, subjective norms, and perceived behavioral control predict intention, which predicts behavior.

Diffusion of Innovations categories: innovators, early adopters, early majority, late majority, and laggards; adoption follows an S-shaped curve.

PRECEDE-PROCEED model phases: social assessment, epidemiological assessment, behavioral and environmental diagnosis, educational and ecological diagnosis, administrative and policy diagnosis, then implementation and evaluation.

Self-efficacy is task-specific confidence in performing a behavior; it is strengthened by mastery experiences, vicarious learning, verbal persuasion, and reduced arousal.

Motivational interviewing uses open questions, affirmations, reflections, and summaries to resolve ambivalence and build intrinsic motivation.

Health literacy is the capacity to obtain, process, and understand basic health information to make decisions; plain language targets about a sixth-grade reading level.

SMART objectives are specific, measurable, achievable, relevant, and time-bound; process objectives track activities, outcome objectives track changes.

Formative evaluation occurs during program design and implementation; summative evaluation assesses outcomes after completion.

Message framing rule: gain-framed messages work better for prevention behaviors, loss-framed messages for detection behaviors in many contexts.

Audience segmentation divides a population by shared characteristics so messages and channels can be tailored to each segment.

The communication process requires a source, message, channel, receiver, and feedback; noise refers to interference at any stage.

Logic models link inputs, activities, outputs, short-term outcomes, and long-term impact, showing the causal chain of a program.

Cultural competence in health communication includes assessing literacy, language, beliefs, and access barriers, then adapting materials and delivery accordingly.

Study design hierarchy for causal inference: randomized controlled trial, cohort, case-control, cross-sectional; randomization balances confounders.

Validity types: internal validity concerns whether the study shows causation; external validity concerns generalizability to other populations.

Threats to internal validity include selection bias, history, maturation, testing effects, instrumentation change, and attrition.

Sampling methods: random, stratified, cluster, and systematic are probability methods; convenience and snowball are non-probability methods.

Reliability means consistency of repeated measurement; validity means the instrument measures what it intends to measure.

Bias types: recall bias in retrospective self-report, selection bias in enrollment, information bias in measurement, and social desirability bias in sensitive questions.

Informed consent requires disclosure, comprehension, voluntariness, and capacity; ethics review boards approve human subjects research.

Qualitative methods (interviews, focus groups, observation) explore meaning and context; quantitative methods test hypotheses with numerical data.

Descriptive statistics: mean is sensitive to outliers, median is robust, and mode is the most frequent value; standard deviation measures spread around the mean.

A 95 percent confidence interval means that repeated sampling would capture the true parameter in 95 percent of samples; a wide interval indicates low precision.

A p-value is the probability of observing data at least as extreme as obtained if the null hypothesis is true; it is not the probability the null is true.

Type I error rejects a true null (alpha, usually 0.05); Type II error fails to reject a false null (beta); power equals 1 minus beta.

Correlation coefficient r ranges from -1 to 1 and measures linear association; correlation does not establish causation.

Sample size increases with desired power and variance and decreases with larger effect size; underpowered studies yield imprecise estimates.

Absolute risk reduction equals control event rate minus treatment event rate; number needed to treat equals 1 divided by absolute risk reduction.

Data literacy checks: verify denominators, distinguish rates from counts, watch for missing data and chart axis distortion, and confirm units before interpretation.

Central dogma: DNA is transcribed to mRNA, which is translated to protein by ribosomes; transcription occurs in the nucleus in eukaryotes, translation in the cytoplasm.

Membrane transport decision rule: simple diffusion moves small nonpolar molecules down a gradient without energy; facilitated diffusion uses channels or carriers down a gradient; active transport uses ATP or a gradient to move solute against its gradient.

Mitochondria generate ATP by oxidative phosphorylation: the electron transport chain builds a proton gradient that drives ATP synthase; this yields roughly 30-32 ATP per glucose in aerobic respiration.

Osmosis rule: water moves toward the compartment with higher solute concentration; a hypertonic solution causes cells to shrink, a hypotonic solution causes cells to swell.

Enzymes lower activation energy without changing reaction equilibrium; Michaelis-Menten kinetics describe rate as Vmax times [S] divided by Km plus [S].

Cell cycle checkpoints: G1/S checks cell size and DNA integrity, G2/M checks replication completion, and the spindle checkpoint verifies chromosome attachment before anaphase.

Apoptosis is programmed, ATP-dependent, and non-inflammatory, driven by caspases; necrosis is passive, causes swelling and lysis, and triggers inflammation.

DNA replication is semiconservative and bidirectional from origins; DNA polymerase synthesizes 5' to 3', so the lagging strand forms Okazaki fragments.

Mendel's law of segregation: two alleles separate during meiosis so each gamete carries one allele; the law of independent assortment applies to genes on different chromosomes.

Hardy-Weinberg equilibrium requires no mutation, no migration, random mating, infinite population size, and no selection; deviations indicate evolution is occurring.

Hardy-Weinberg formulas: allele frequencies p + q = 1; genotype frequencies p squared + 2pq + q squared = 1.

Autosomal recessive inheritance: affected individuals usually have two carrier parents, the trait can skip generations, and the recurrence risk for carrier parents is 25 percent per child.

X-linked recessive traits appear far more often in males, who are hemizygous; affected fathers pass the allele to all daughters, who become carriers.

Natural selection requires heritable variation in traits that affect fitness; it acts on phenotypes and changes allele frequencies across generations.

Genetic drift is random change in allele frequency, strongest in small populations; the founder effect and bottleneck effect are its main forms.

Mutation is the ultimate source of new alleles; gene flow (migration) and recombination redistribute existing variation among populations.

Cardiac output equals heart rate times stroke volume; average resting output is about 5 L per minute, and it rises with demand during exercise.

Blood flows through the heart in this order: vena cava, right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein, left atrium, left ventricle, aorta.

Nephron sequence: glomerular filtration, tubular reabsorption in the proximal tubule, secretion, and concentration in the loop of Henle and collecting duct under ADH control.

Gas exchange rule: oxygen binds hemoglobin best at high pH and low CO2 (Bohr effect shifts right with acidosis, heat, and high CO2); CO2 is carried mainly as bicarbonate.

Homeostasis uses negative feedback: a sensor detects deviation, an integrating center compares it to a set point, and an effector reverses the change; oxytocin and childbirth are classic positive feedback.

Action potential phases: depolarization from sodium influx, repolarization from potassium efflux, and refractory periods that prevent backward conduction.

The autonomic nervous system: sympathetic activity raises heart rate, dilates airways and pupils, and diverts blood to muscle; parasympathetic activity slows heart rate and promotes digestion.

Hormone feedback loops: the hypothalamus releases releasing hormones, the anterior pituitary releases tropic hormones, and the target gland secretes its hormone, which feeds back negatively.

Chain of infection links: pathogen, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host; breaking any link interrupts transmission.

Bacteria are prokaryotes lacking a nucleus; viruses are obligate intracellular parasites with either DNA or RNA genomes and no independent metabolism.

Gram staining decision rule: gram-positive cells retain crystal violet and appear purple due to thick peptidoglycan; gram-negative cells appear pink and have an outer membrane.

Koch's postulates link a microbe to disease: the organism is found in all cases, can be isolated and cultured, causes disease when inoculated, and is recovered again.

Antibiotic resistance mechanisms include enzymatic inactivation (beta-lactamase), efflux pumps, target modification, and reduced membrane permeability.

Herd immunity threshold approximates 1 minus 1/R0; for measles (R0 about 12-18) the threshold exceeds 90 percent, requiring very high vaccine coverage.

Sterilization kills all microorganisms including spores; disinfection reduces pathogens on surfaces; antisepsis applies to living tissue.

Nosocomial infections are acquired in healthcare settings; hand hygiene is the single most effective intervention to reduce transmission.

Energy yield per gram: carbohydrate 4 kcal, protein 4 kcal, fat 9 kcal, alcohol 7 kcal.

Basal metabolic rate is measured at rest; total energy expenditure equals BMR plus thermic effect of food plus physical activity.

Glycolysis converts glucose to pyruvate yielding net 2 ATP and 2 NADH; anaerobic conditions convert pyruvate to lactate in humans.

The Krebs cycle and oxidative phosphorylation complete aerobic oxidation of acetyl-CoA, producing most of the ATP from glucose and fatty acids.

Essential nutrients cannot be synthesized in adequate amounts and must come from diet, including nine amino acids, two fatty acids (linoleic and alpha-linolenic), vitamins, and minerals.

Body mass index equals weight in kilograms divided by height in meters squared; a BMI of 25 or above is overweight and 30 or above is obese.

Protein-energy malnutrition presents as marasmus (severe wasting) or kwashiorkor (edema with adequate energy but deficient protein).

Fat-soluble vitamins A, D, E, and K require bile for absorption and are stored in the liver; water-soluble vitamins are excreted more readily.

Incidence measures new cases over a period at risk; prevalence measures all existing cases at a point in time; prevalence approximately equals incidence times duration.

Attack rate equals new cases divided by population at risk during an outbreak, often expressed as a percentage.

Relative risk equals incidence in exposed divided by incidence in unexposed; it is used in cohort studies.

Odds ratio approximates relative risk for rare outcomes and is the standard measure from case-control studies.

Sensitivity equals true positives divided by all with disease; specificity equals true negatives divided by all without disease; predictive values depend on prevalence.

Levels of prevention: primary prevents onset (vaccination), secondary detects early (screening), tertiary limits disability and complications (rehabilitation).

Mortality rate equals deaths in a period divided by population, usually per 100,000; infant mortality rate is a sensitive indicator of population health.

Confounding occurs when a third variable is associated with both exposure and outcome; randomization, restriction, and stratification control it.

Health Belief Model constructs: perceived susceptibility, perceived severity, perceived benefits, perceived barriers, cues to action, and self-efficacy.

Transtheoretical Model stages: precontemplation, contemplation, preparation, action, maintenance, and termination; interventions should match the stage.

Social Cognitive Theory: behavior is shaped by reciprocal determinism among personal, behavioral, and environmental factors; self-efficacy and observational learning are central.

Theory of Planned Behavior: attitudes, subjective norms, and perceived behavioral control predict intention, which predicts behavior.

Diffusion of Innovations categories: innovators, early adopters, early majority, late majority, and laggards; adoption follows an S-shaped curve.

PRECEDE-PROCEED model phases: social assessment, epidemiological assessment, behavioral and environmental diagnosis, educational and ecological diagnosis, administrative and policy diagnosis, then implementation and evaluation.

Self-efficacy is task-specific confidence in performing a behavior; it is strengthened by mastery experiences, vicarious learning, verbal persuasion, and reduced arousal.

Motivational interviewing uses open questions, affirmations, reflections, and summaries to resolve ambivalence and build intrinsic motivation.

Health literacy is the capacity to obtain, process, and understand basic health information to make decisions; plain language targets about a sixth-grade reading level.

SMART objectives are specific, measurable, achievable, relevant, and time-bound; process objectives track activities, outcome objectives track changes.

Formative evaluation occurs during program design and implementation; summative evaluation assesses outcomes after completion.

Message framing rule: gain-framed messages work better for prevention behaviors, loss-framed messages for detection behaviors in many contexts.

Audience segmentation divides a population by shared characteristics so messages and channels can be tailored to each segment.

The communication process requires a source, message, channel, receiver, and feedback; noise refers to interference at any stage.

Logic models link inputs, activities, outputs, short-term outcomes, and long-term impact, showing the causal chain of a program.

Cultural competence in health communication includes assessing literacy, language, beliefs, and access barriers, then adapting materials and delivery accordingly.

Study design hierarchy for causal inference: randomized controlled trial, cohort, case-control, cross-sectional; randomization balances confounders.

Validity types: internal validity concerns whether the study shows causation; external validity concerns generalizability to other populations.

Threats to internal validity include selection bias, history, maturation, testing effects, instrumentation change, and attrition.

Sampling methods: random, stratified, cluster, and systematic are probability methods; convenience and snowball are non-probability methods.

Reliability means consistency of repeated measurement; validity means the instrument measures what it intends to measure.

Bias types: recall bias in retrospective self-report, selection bias in enrollment, information bias in measurement, and social desirability bias in sensitive questions.

Informed consent requires disclosure, comprehension, voluntariness, and capacity; ethics review boards approve human subjects research.

Qualitative methods (interviews, focus groups, observation) explore meaning and context; quantitative methods test hypotheses with numerical data.

Descriptive statistics: mean is sensitive to outliers, median is robust, and mode is the most frequent value; standard deviation measures spread around the mean.

A 95 percent confidence interval means that repeated sampling would capture the true parameter in 95 percent of samples; a wide interval indicates low precision.

A p-value is the probability of observing data at least as extreme as obtained if the null hypothesis is true; it is not the probability the null is true.

Type I error rejects a true null (alpha, usually 0.05); Type II error fails to reject a false null (beta); power equals 1 minus beta.

Correlation coefficient r ranges from -1 to 1 and measures linear association; correlation does not establish causation.

Sample size increases with desired power and variance and decreases with larger effect size; underpowered studies yield imprecise estimates.

Absolute risk reduction equals control event rate minus treatment event rate; number needed to treat equals 1 divided by absolute risk reduction.

Data literacy checks: verify denominators, distinguish rates from counts, watch for missing data and chart axis distortion, and confirm units before interpretation.