DNA Fingerprinting and Short Tandem Repeats

DNA

Long sequence of nucleotides carrying genetic information for building molecules in the body.

Nucleotides

Basic structural unit of DNA; also known as bases.

Complementary DNA

Double-stranded with one side having a sequence and the other side having the paired base.

Genetic Variation

Individuals differ in DNA sequence by 0.1%, resulting in 99.9% identical DNA with about 3 million differences out of 3 billion base pairs.

Non-coding DNA

Part of DNA with the most variation (about 90%), allowing room for mutations and variations; used in DNA fingerprinting for identifying people.

DNA Fingerprinting

Method to identify individuals by observing unique patterns in their DNA, commonly used in solving crimes and paternity testing.

Short Tandem Repeat (STR) Locus

Repeating units in DNA, 4-5 nucleotides long, with varying numbers of repeats; found in the non-coding DNA and used in DNA fingerprinting.

Polymerase Chain Reaction (PCR)

A method to create many DNA fragments by heating up DNA to separate strands and adding bases for new strand development.

Gel Electrophoresis

A technique to separate DNA fragments based on size using an electric current, with smaller fragments moving faster than larger ones.

US Combined DNA Index System

Includes 20 STR loci for DNA identification and comparison.

Genetic Variation (STR Loci vs. Genes)

STR Loci and genes for structural traits both receive 1 allele from each parent, but STR Loci do not code for proteins and have more genetic variation compared to genes for structural traits.

STR Loci and Genes for Structural Traits

STR Loci do not code for proteins, have no impact on phenotype, and have more genetic variation, while genes for structural traits usually code for proteins, impact phenotypes, and have less genetic variation.

Short Tandem Repeats (Practice Question)

Short tandem repeats usually do not code for proteins, have no impact on phenotype, and have more genetic variation compared to genes for structural traits.

DNA Fingerprint Bands (Practice Question)

The bands in a DNA fingerprint represent an STR allele of a given locus.