Figure 4.1 The reactions catalysed by the two different kinds of nuclease. (a) An exonuclease, which removes nucleotides from the end of a DNA molecule. (b) An endonuclease, which breaks internal phosphodiester bonds.

Figure 16.1 Genetic fingerprinting. (a) The

positions of polymorphic repeats, such as

hypervariable dispersed repetitive sequences,

in the genomes of two individuals. In the

chromosome segments shown, the second

person has an additional repeat sequence. (b)

An autoradiograph showing the genetic

fingerprints of two individuals.

Gene Cloning and DNA Analysis by T.A. Brown. © 2006 T.A.
Brown.

Figure 16.2 DNA profiling. (a) DNA profiling

makes use of STRs which have variable repeat

units. (b) A gel obtained after DNA profiling. In

lanes 2 and 3 the same STR has been examined in

two individuals. These two people have different

profiles, but have a band in common. Lane 4 shows

the result of a multiplex PCR in which three STRs

have been typed in a single PCR. (c) An automated

DNA sequencer can be used to determine the sizes

of the PCR products.

Gene Cloning and DNA Analysis by T.A. Brown. © 2006 T.A.
Brown.

Figure 16.4 Short tandem repeat analysis of the Romanov

bones. (a) The Romanov family tree. (b) The results of STR

analysis. THO1 and VWA/31 are the names of two STR loci. The

numbers in the columns (8, 10; etc.) are the repeat numbers for

the alleles typed in each individual. The THO1 data show that

female adult 2 cannot be the mother of the children because she

only possesses allele 6, which none of the children have. Female
adult 1, however, has allele 8, which all three children have, and

so is identified as the Tsarina. The THO1 data exclude male adult

4 as a possible father of the children, but do not allow the other

three male adults to be distinguished – each could be the father

of at least two of the children. However, the VWA/31 results

exclude male adults 1 and 2, so male adult 3 is identified as the

Tsar.

Gene Cloning and DNA Analysis by T.A. Brown. © 2006 T.A.
Brown.

Figure 16.5 Sex identification by PCR of a Y-

specific DNA sequence. Male DNA gives a PCR

product (lane 2), but female DNA does not

(lane 3). The problem is that a failed PCR

(lane 4) gives the same result as female DNA.

Gene Cloning and DNA Analysis by T.A. Brown. © 2006 T.A.
Brown.

Figure 16.6 Sex identification by PCR of part

of the amelogenin gene. (a) An indel in the

amelogenin gene. (b) The results of PCRs

spanning the indel. Male DNA gives two PCR

products, of 106 and 112bp in the standard

system used in forensics and biomolecular

archaeology. Female DNA gives just the

smaller product. A failed PCR gives no

products and so is clearly distinguishable

from the two types of positive result.

Figure 16.7 Two hypotheses for the origins

of modern humans: (a) multiregional

evolution; (b) the Out of Africa hypothesis.

Figure 16.8 Phylogenetic analysis of ancient

DNA suggests that Neanderthals are not

directly related to modern humans.

Figure 16.9 Principal component analysis

reveals a southeast to northwest gradient of

human allele frequencies across Europe.

Figure 16.10 The deduced times of arrival in

Europe of the 11 major mitochondrial DNA

haplotypes found in modern populations.

Those haplotypes whose arrivals coincide

with the spread of agriculture are shown in

red.

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