Chapter 25: Evaluation of the Strength of Forensic DNA Profiling Results

Mendel’s first law

The principle of segregation of alleles. Each pair of alleles segregates from others in the formation of gametes.

Mendel’s second law

The principle of independent assortment of alleles. The segregation of each pair of alleles is independent of the segregation of other pairs during the formation of gametes.

meiosis

Gametes are formed during a process known as ________, in which cells with haploid chromosome numbers (23 in humans) are produced by the division of cells with diploid chromosome numbers (46 in humans).

Linked Genes

Genes residing very closely together on the same chromosome are usually inherited together.

probabilities

The Mendelian inheritances of genes can often be measured using _____.

Probability

A ratio of the number of actual occurrences of an event to the number of possible occurrences.

Allele Frequency

It can be calculated directly by counting the number of alleles of one type at a given locus and dividing it by the total number of alleles at that locus in a sampled population.

Genotype Frequency

It can be calculated by dividing the number of individuals with one genotype by the total number of individuals in a sampled population. Each genotype at the locus can be calculated separately.

Heterozygosity

The proportion of alleles, at a given locus, that are heterozygous.

Hardy–Weinberg Principle

It allows predictions of genotype frequencies to be made based on allelic frequencies.

Observed Genotype Frequencies

Are calculated by dividing the number of individuals with one genotype by the total number of individuals in the population sampled.

Population Match Probability

The probability of having a matching genotype between two randomly chosen individuals.

Likelihood Ratio

This method is an alternative for evaluating the strength of a match.

Hypothesis 1

The evidence and suspect profiles originated from the same source.

Hypothesis 2

The evidence and suspect profiles did not originate from the same source.

haplotype

The term _____ was first used to describe very closely linked polymorphic loci.

Linkage Disequilibrium

Where recombination is very rare, certain allelic combinations occur in populations much more frequently than would be expected.