Chemistry Reference
In-Depth Information
Figure 15.26
Crick and Watson based this model for DNA on X-ray
studies performed by Rosalind Franklin and chemical analysis.
b
Adding dilute sodium hydroxide.
a
Testing for a protein.
Genes are the units of heredity that control the
characteristics of organisms. A gene is made of
DNA. No two individuals have the same DNA
sequence. DNA 'fi ngerprinting' has become a very
powerful forensic science tool in the investigation of
crime (Figure 15.27).
c
Adding 1% copper(ii)
ii
) sulfate.
d
The purple colour shows the
presence of a protein.
Figure 15.25
The Biuret test.
Figure 15.27
Identical patterns shown by DNA fi ngerprinting can
identify the criminal.
DNA
Deoxyribonucleic acid
(DNA)
belongs to a group
of chemicals called the nucleic acids (Figure 15.26).
They are also biopolymers. DNA controls the protein
synthesis within your cells. When you eat a food
containing proteins, such as meat or cheese, your
digestive enzymes break down the proteins present
into individual amino acids. The DNA in your cells
controls the order in which the amino acids are
repolymerised to make the proteins you need!
Questions
1
Which two functional groups do amino acids possess?
2
How many amino acids have to be involved before the
biopolymer is called a protein?
3
Name the process by which the individual amino acids in
a protein are released by reaction with a dilute acid.
4
Explain how DNA fi ngerprinting may be used in
paternity suits.
