PBS Test 1

Polygraph

Lie detector test measuring the respiratory and heart rate.

Heart Rate

Number of heartbeats (usually per minute).

Vital Signs

Most crucial medical signs indicating the status of vital body functions.

Pulse

The regular movement of blood through your body, caused by your heartbeat; it can be felt.

Control Group

The variable that stays the same throughout an experiment.

Experimental Design

Planning and conducting experiments in a controlled way to draw conclusions.

Iterative

Repeating a process over and over again.

Independent Variable v Dependent Variable

IV is the one that you change; DV is the one that changes because of the IV.

Locard’s Exchange Principle

The perpetrator of a crime will bring something into the crime scene and leave with something from it, both of which can be used as forensic evidence.

Hair Cuticle / Medulla / Cortex

Cuticle is the outermost layer (dead cells), cortex is the middle thick layer, and medulla is the center.

Fingerprint Minutiae

Where the ridge of the fingerprint line ends.

Erythrocytes

Red blood cells that carry oxygen through your body.

Thrombocytes

Platelets that cause your blood to clot.

Leukocytes

White blood cells that fight infection and injury.

Plasma

Carries nutrients, proteins, and hormones to parts of the body that need it.

Hemoglobin

Red protein that carries oxygen in red blood cells.

Rh Factor

A protein in your blood that can be present (+) or not (-).

Presumptive and Confirmatory Tests

Presumptive confirms it is blood; confirmatory determines what the blood type is.

Antigen

Substance that your body fights off or doesn’t recognize.

Positive and Negative Controls

Positive control group is given a treatment with a known outcome; negative control group is given no special treatment.

Kastle-Meyer Blood Test

Most common presumptive test using phenolphthalein which reacts with the iron in hemoglobin. Turns pink when positive, colorless when negative.

Leucocrystal Violet (LCV)

Reacts with hemoglobin and turns violet in color; can be used on porous surfaces like a carpet. Presumptive

Luminol

Glows blue in the dark when in contact with blood; not the best lab test as it reacts with other substances. Presumptive

Personal Protective Equipment (PPE)

Gloves, apron, goggles.

ABO Blood System

A system of four types (A, AB, B, and O) which human blood is classified into, based on the presence or absence of certain antigens.

Antibody

Counteracts an antigen.

Agglutination

Particles clumping together in response to an antibody.

Drip Stains (Passive), Transfer Stains, Blood Spatter (Low, Med, High Velocity)

Different types of blood evidence based on their origin and movement.

Standard Curve

Shows the relationship between the concentration of a substance and its response (graph).

Deoxyribonucleic Acid (DNA)

Negatively charged because of the phosphates.

Nucleotide

Composed of sugar, phosphate, and nitrogenous base.

Double Helix

The structure of DNA. Twisted ladder

Adenine / Thymine / Guanine / Cytosine

The four nitrogenous bases in DNA.

Purines v Pyrimidines

Purines are A and G; pyrimidines are T and C.

Base Pair

A+T and C+G.

Sugar-Phosphate Backbone

The structural framework of DNA.

Covalent Bonds

A chemical bond involving electron pairs between atoms.

Hydrogen Bonds

Weak bonds that hold the two strands of DNA together.

Chargaff’s Rules

In any DNA sample, the amount of A equals T and the amount of G equals C.

X-Ray Crystallography

A technique to determine the 3D structure of a biological molecule using X-rays.

Rosalind Franklin

Her X-ray diffraction picture helped to determine the structure of DNA.

Watson and Crick

Constructed models of DNA and published their findings, later awarded the Nobel Prize. They used Franklin’s ideas to help propose the double - helix structure

Gene

Hereditary material passed from a parent to offspring.

Genome

Complete set of DNA.

Organelle

A biological structure that performs a certain function inside a cell.

Prokaryotic vs Eukaryotic cell

Prokaryotes don’t have a nucleus; eukaryotes do.

Pro: DNA is circular and floating in the cytoplasm

Eu: DNA in chromosomes

Chromosome

Tightly coiled packages of DNA.

Histone Proteins

Provide structural support to chromosomes.

DNA Extraction Procedure

mix with an extraction buffer of salt/detergent/water, and precipitate with isopropyl alcohol.

Precipitate

an insoluble solid that emerges from a liquid solution

Polymerase Chain Reaction (PCR)

Specific DNA sequences are copied millions of times so they can be analyzed.

Restriction Enzymes

cuts the DNA at a specific sequence, creating a fragment

Recognition Sites

a specific sequence in DNA that is recognized by a restriction enzyme and split there.

Gel Electrophoresis (Agarose, Buffer, Wells, Loading Dye, DNA Marker/Ladder)

used to separate mixtures of DNA, RNA, or proteins according to molecular (fragments) size.

Restriction Fragment Length Polymorphisms (RFLP)

a molecular marker that detects variations in DNA sequences between people;; RFLP can confirm a source of a DNA sample in crime investigations

Sticky ends

short, single-stranded sections of DNA that happen when DNA is cut with a restriction enzyme (non-blunt)

EcoRI

G/AATTC

HaeIII

GG/CC

HindIII

A/AGCTT