Investigating the Scene
Name five types of physical or digital evidence that might be collected at a crime scene to help solve a case.
hair; fingerprints; blood spatter patterns; saliva (or other bodily fluids); digital evidence (e.g., phones, cameras) — DNA is also valid.
Write the complementary DNA strand for GAATACGAT.
Complementary strand: CTTATGCTA.
Name the three presumptive blood tests commonly used in forensic analysis.
Leukocrystal violet (LCV), Luminol, Kastle-Meyer (phenolphthalein) tests.
Name two key differences between Type 1 and Type 2 diabetes (cause and typical treatment).
Type 1 cause = autoimmune destruction of pancreatic beta cells → little/no insulin; treatment = insulin injections or pump. Type 2 cause = insulin resistance/fewer functional receptors (often linked to obesity) → treatment = lifestyle change, oral meds, sometimes insulin
Explain what Hemoglobin A1C measures and why it is useful for diagnosing diabetes.
Normal resting heart rate: 60–100 beats per minute (bpm). Blood pressure units: millimeters of mercury (mmHg).
What three determinations does a medical examiner try to make when performing an autopsy?
Manner of death, cause of death, and mechanism of death.
Which base is in DNA but not in RNA? Which base replaces it in RNA?
Thymine is in DNA but not RNA; Uracil replaces thymine in RNA.
What are the four major components of blood and one function of each?
Major blood components: red blood cells (erythrocytes) — carry O2/CO2; white blood cells (leukocytes) — immune defense; platelets (thrombocytes) — clotting; plasma — liquid transport medium for nutrients/hormones/waste.
Define osmosis and explain why a person with high blood glucose becomes dehydrated and urinates frequently.
Osmosis = movement of water from lower solute (higher water) concentration to higher solute (lower water) concentration across a semipermeable membrane. High blood glucose draws water out of cells into bloodstream → kidneys filter more fluid → increased urination and dehydration.
Trace the path of blood from the body (vena cavae) through the heart to the lungs and back to the body (name major chambers and vessels in order).
Pathway: body → superior/inferior vena cava → right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery → lungs → pulmonary veins → left atrium → mitral (bicuspid) valve → left ventricle → aortic valve → aorta → body.
Define manner of death, cause of death, and mechanism of death — give one example of each for a gunshot victim.
Manner = homicide (overarching reason). Cause = gunshot wound (specific injury). Mechanism = exsanguination (physiologic way the body dies)
What are purines and pyrimidines? Name the bases in each group.
Purines = adenine (A) and guanine (G) (double-ring). Pyrimidines = cytosine (C) and thymine (T) (single-ring).
If a blood sample shows no agglutination with anti-A or anti-B serum, what is the blood type? Explain.
Type O (no agglutination with anti-A or anti-B indicates no A or B antigens).
Label whether these are negative or positive feedback: (a) sweating when hot, (b) blood clot formation, (c) increased respiration when oxygen is low.
(a) Sweating when hot = negative feedback. (b) Blood clot formation attracting more clotting factors = positive feedback. (c) Increased respiration when oxygen low = negative feedback.
What is the role of heart valves? Define mitral valve prolapse and how it can lead to left ventricular hypertrophy.
Valves prevent backflow and ensure one-way blood flow. Mitral valve prolapse = mitral valve leaflets bulge into left atrium during systole causing regurgitation; chronic regurgitation forces the left ventricle to pump harder → can cause left ventricular hypertrophy (thickening).
Using the Glaister equation hours since death=98.4−rectal temperature (F)1.5hours since death=1.598.4−rectal temperature (F), estimate time of death for a body found at 8:00 AM with rectal temp 95.2°F.
Hours since death = (98.4 − 95.2) / 1.5 = 3.2 / 1.5 = 2.13 hours → ~2 hours 8 minutes before 8:00 AM → ~5:52 AM (approx. 6:00 AM)
What do restriction enzymes do? Give an example with the recognition sequence for HaeIII (GGCC).
Restriction enzymes recognize specific short DNA sequences and cut DNA at or near those sites. Example: HaeIII recognizes GGCC and cuts between GG and CC
Explain the difference between the body’s first, second, and third lines of defense; give one example of each.
First line (non-specific): skin, mucous membranes, physical barriers. Second line (non-specific): phagocytes (macrophages, neutrophils), inflammation, fever. Third line (specific): B cells (antibodies) and T cells (cell-mediated immunity)
Describe how insulin and glucagon work together to regulate blood glucose; include which organ produces them.
Insulin (from pancreatic beta cells) lowers blood glucose by promoting uptake into cells and glycogen storage. Glucagon (from pancreatic alpha cells) raises blood glucose by promoting glycogen breakdown and gluconeogenesis in the liver. They act antagonistically to maintain homeostasis
On an EKG, what does the QRS complex represent? Why is it usually larger than the P wave?
QRS complex represents ventricular depolarization (ventricular contraction). It is larger than the P wave because the ventricles have more muscle mass and thus generate a larger electrical signal.
List the main parts of a nucleotide and explain which part gives DNA its overall negative charge.
Nucleotide parts: phosphate group (gives negative charge), deoxyribose sugar, nitrogenous base (A, T, G, C).
Describe the four main steps of creating a DNA profile (start with DNA extraction) and explain how RFLPs are visualized.
DNA profiling steps: (1) DNA extraction, (2) PCR amplification of target regions, (3) restriction enzyme digestion (if using RFLP) or fragment sizing (STR analysis), (4) separation/visualization (gel electrophoresis or capillary electrophoresis). RFLPs are visualized as bands of different fragment lengths on a gel.
Describe gram staining steps and explain why Gram-positive bacteria appear purple while Gram-negative appear pink.
Gram stain steps: heat-fix → crystal violet (primary stain) → rinse → iodine (mordant) → rinse → alcohol decolorizer → rinse → safranin (counterstain) → rinse. Gram-positive retain crystal violet–iodine complex because thick peptidoglycan traps it → appear purple. Gram-negative lose the complex during decolorization and take up safranin → appear pink.
Explain what Hemoglobin A1C measures and why it is useful for diagnosing diabetes.
Hemoglobin A1C measures percent of hemoglobin glycosylated by circulating glucose, reflecting average blood glucose over ~3 months; useful for diagnosing and monitoring long-term glucose control.
Name three procedures to treat coronary artery blockage, identify which is most invasive, and briefly describe each.
Procedures: angioplasty (balloon to widen artery; often with stent) — minimally invasive; stent placement (keeps artery open) — minimally invasive; coronary artery bypass graft (CABG) — most invasive, open-heart surgery that uses grafts to bypass blocked arteries.