Forensic Science Overview

Polygraph

• Polygraph tests measure physiological responses to detect deception
• Physiological responses include heartbeat rate and breathing speed
• Polygraph tests are used to detect if a person is lying or not
• Baselines are established to determine a person's normal range of heartbeat or intervals
• Polygraph tests are not 100% reliable

Experimental Design

• Testable hypothesis: Salt dissolves in hot water faster than sugar
• Independent variable: the variable changed to affect the results
• Dependent variable: the variable being measured in an experiment
• Control variable: A dependent variable that is not affected by the independent variable
• It acts as a baseline

Hair Structure

• Cuticle: Outermost layer of hair, made of overlapping dead cells
• Cortex: Middle layer of hair, thickest layer
• Both these layers play a critical role in protecting and maintaining the structural integrity of the hair shaft.

Fingerprints

• Arch: Ridges flow from one side to the other, least common
• Tented Arch: Similar to arches but with a more pronounced spike
• Loop: Ridges flow in one side, recurve, and exit on the same side (radial or ulnar)
• Whorl: Ridges form circles or spirals, classified as plain, central pocket, double loop, or accidental
• Minutiae: Tiny details in fingerprints that make them unique
• Identical fingerprint matching requires 12 minutiae matches

Blood Components

• Red blood cells (erythrocytes): Carry oxygen
• White blood cells (leukocytes): Fight infection
• Platelets (thrombocytes): Help with blood clotting
• Plasma: Liquid component carrying other blood cells and substances

Blood Types

• Antigens: Molecules on blood cells triggering immune response
• Blood types (A, B, AB, O) are determined by specific antigens present

Blood Spatter Analysis

• Blood droplet size is affected by drop height and angle
• Steeper drop angle creates elongated blood spatters
• 90-degree angle creates circular blood spatters

Nucleotide Structure

• Nucleotide components: Nitrogenous base, pentose sugar, phosphate group

DNA Base Pairing

• A pairs with T
• G pairs with C

DNA Structure and Function

• Deoxyribose sugar
• Nitrogen bases
• Nucleotides
• Phosphate group
• Genes: Specific segments of DNA
• Chromosomes: DNA structures inside the nucleus
• Genes are the functional units of heredity located on chromosomes

Prokaryotic vs Eukaryotic Cells

• Prokaryotic: No Nucleus
• Eukaryotic: Has a Nucleus

DNA Analysis/Profiling

• PCR amplifies small amounts of DNA
• Restriction enzymes cut DNA at specific sites creating unique fragment lengths
• Gel electrophoresis separates fragments by size to visualize a DNA profile

Autopsy

• Cause of death: The specific injury or disease that initiated the death sequence.
• Manner of death: How the death occurred (e.g., homicide, suicide, accidental)
• Mechanism of death: The physiological process that directly caused the body to stop functioning.

Body Systems

• Organs matched with their respective systems (e.g., Heart–Cardiovascular).

Time of Death

• Livor mortis, rigor mortis, algor mortis, insect activity
• These factors can help estimate the time of death

Levels of Organization

• Cell, Tissue, Organ, Organ System (e.g., Muscle tissue, Stomach, respiratory system, etc.) -

Brain Lobes

• Frontal lobe: Planning, decision making
• Parietal lobe: Sensory information (touch, taste)
• Temporal lobe: Auditory information, memory
• Occipital lobe: Visual information

TBI vs CTE

• TBI: Single blow to the head
• CTE: Multiple blows or repeated head trauma
• Effects of CTE generally worse than TBI

Heart Defects

• Valve defects: Valves do not open or close properly
• Septal defects: Hole in the heart wall

This quiz explores various aspects of forensic science, including polygraph testing, experimental design in forensics, hair structure, and fingerprint analysis. Each section provides insights into the techniques and concepts used in forensic investigations. Test your knowledge on these critical topics in forensic science!