DNA and DNA Fingerprinting

Flashcards on DNA and DNA Fingerprinting

DNA (Deoxyribonucleic Acid)

The genetic material in our cells. No two people (except identical twins) have the same exact

DNA Fingerprinting

Also known as DNA profiling, it's a technique used to distinguish individuals of the same species using DNA samples.

Alec Jeffreys

English geneticist who invented DNA fingerprinting in 1985 at the University of Leicester.

Trace Evidence

Small amounts of biological evidence left at a crime scene that serve as the DNA source for fingerprinting.

Biological Evidence (for DNA fingerprinting)

Examples include saliva, blood, semen, skin, hair roots, body tissue cells, and urine.

DNA

A nucleic acid located in chromosomes within the nucleus of cells.

23

Most human cells have this many pairs of chromosomes.

Genes

Segments of chromosomes that control different traits.

Four Nitrogenous Bases in DNA

Adenine (A), Thymine (T), Guanine (G), Cytosine (C)

T A G A C G

If one strand of DNA has the genetic code A T C T G C, this would be the complementary strand.

Mitosis

Cell division resulting in two identical daughter cells; allows for body growth and repair.

Meiosis

Special cell division in sexually reproducing organisms that produces sperm and egg cells.

Sides of the DNA helix (backbone)

Alternating sugar and phosphate molecules.

Deoxyribose

The sugar in DNA, from which DNA gets its name.

Rungs of the DNA helix

Paired nitrogenous bases (A-T, C-G).

Exons

Encoded DNA with directions to build molecules; makes up only 1.5% of the entire genome.

Introns

Un-encoded DNA; makes up 98.5% of DNA and may function in gene splicing.

Cutting DNA

Step in DNA fingerprinting when enzymes cut the DNA into restriction fragments (creating RFLPs).

Restriction Fragment Length polymorphism

RFLPs

Amplification

Making many copies of DNA fragments.

Electrophoresis (Gel Electrophoresis)

A process that separates RFLPs according to their length, creating a DNA fingerprint.

DNA Polymerase in PCR

Enzyme used with nucleotides and primers; temperature rises then lowers to add new base polymers.

PCR Steps

Cycles of denaturation, annealing, and extension that amplify the target sequence, producing billions of DNA copies in hours.

Restriction Enzymes

Enzymes that cleave DNA into smaller segments of various sizes.

In addition to crime scene investigations:

• Establish paternity

• Identify victims of war and large scale disasters

• Settle immigration disputes

Follicle

a club-shaped structure in the skin

papilla

At the end of the follicle is the…, a network of blood vessels that supply nutrients to feed the hair and help it grow

Forensic investigators classify hair into five different groups depending on the appearance of the medulla 

continuous: continues in one unbroken line

- interrupted: pigmented line broken at regular intervals

- fragmented or segmented: pigmented line unevenly spaced

- solid: line fills both the medulla and the cortex

- none: no line

A(anagen phase)

period of active growth- Majority where hair is most of the time- when hair is attached to papila

C(catagen phase)

transitional or regressive stage

T(telogen phase)

final resting stage - no growth here (abt 10-15% of our hair is in this phase)

Cheiloscopy

the study of lip prints

Paper Chromatography

method used to separate pigments in a substance