PBS Test 1

⧠ Activity 1.1.1 – A Sketchy Scene

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⧠ Activity 1.1.2 – Reliable Witnesses

• Polygraph - lie detector test measuring the respiratory and heart rate

• Heart Rate - number of heart beats (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 /conducting experiments in a controlled way to draw conclusions

• Iterative - repeating a process over and over again

• Independent Variable vs. Dependent Variable - IV: the one that you change DV: the one that changes because of the IV

⧠ Activity 1.1.3 – Traces We Leave Behind

• Locard’s Exchange Principle - the perpetrator of a crime will bring something into the crime scene and leave with something from it, and that both can be used as forensic evidence.

• Hair Cuticle / Medulla / Cortex - cuticle is the outmost layer (dead cells) medulla is the middle thick layer and cortex is the center

• Fingerprint Minutiae - where the ridge of the fingerprint line ends

⧠ Activity 1.1.4 – Blood Evidence

• Erythrocytes, Thrombocytes, Leukocytes -

Erythro: red blood cells which carry oxygen through your body.

Thrombo: Platelets, cause your blood to clot

Leuko: white blood cells 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/ doesn’t recognize

• Positive and Negative Controls - positive control group is a group in the experiment that is given a treatment with a known outcome, while a negative control group is given no special treatment

• Kastle-Meyer Blood Test - Most presumptive common test using phenolphthalein which reacts w/ the iron in hemoglobin

Positive control will be pink

Negative will be colorless

• Leucocrystal violet (LCV) - Reacts w/ hemoglobin and turns violet in color. It can be used on porous surfaces like a carpet. Presumptive

• Luminol - glows blue in the dark when in contact w/ blood (but also w/ other substances so it isn’t the best lab test) 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)

• Standard Curve - shows the relationship between the concentration of a substance and its response (graph)

⧠ Activity 1.1.5 – DNA Evidence

• Deoxyribonucleic Acid (DNA) - Negatively charged because of the phosphates

• Nucleotide - (Sugar, Phosphate, Nitrogenous Base)

• Double Helix

• Adenine / Thymine / Guanine / Cytosine

• Purine vs. Pyrimidine - purines A, G and pyrimidines T, C

• Base Pair - A+T and C+G

• Sugar-Phosphate Backbone

• Covalent Bonds - a chemical bond involving electron pairs between atoms.

• Hydrogen Bonds

• Chargaff’s Rules - In any dna sample, the amount of A=T and the amount of G=C

• X-Ray Crystallography - beam of X-rays is shot at a specimen and the scattering of x-rays is recorded to determine the 3d structure of a biological molecule.

• Rosalind Franklin her x-ray diffraction picture helped to determine the structure of DNA

• Watson and Crick - constructed models and pieced bits of info together & published their findings that same year, and were 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 Cells - prokaryotes don’t have a nucleus while eukaryotes

Pro: DNA is circular and floating in the cytoplasm

Eu: DNA in chromosomes

• Chromosome - tightly coiled packages of DNA

• Histone Proteins - toilet paper roll of the chromosome (structural support)

• 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.

⧠ Activity 1.1.6 – DNA Analysis

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

• Micropipette Technique

• 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