Images Dated 6th August 2003

Nucleotide base matrix

Nucleotide base matrix. Computer artwork depicting a matrix of nucleotide bases: adenine (A), cytosine (C), guanine (G) and thymine (T). The sequence of these four molecules on a strand of deoxyribonucleic acid (DNA) is known as the genetic code. Groups of three adjacent bases code for amino acids, which are the basic building blocks of proteins. The genetic code is unique for every individual

© PASIEKA/SCIENCE PHOTO LIBRARY

Thunberg spirea, SEM

Thunberg spirea (Spiraea thunbergii). Coloured scanning electron micrograph (SEM) of a flower of Thunberg spirea, a member of the rose family, found in China and Japan. The small (8 millimetre diameter) flowers have five petals. They appear on the branches in late winter to early spring before the new leaves appear. The flower contains the reproductive parts of the plant. The stamens, comprising filaments topped by pollen grain (male sex cell) producing anthers (pale green), surround the stigmas (orange). The stigma is the top of the carpel in which the ovules (female sex cells) are located. Magnification unknown

© SUSUMU NISHINAGA/SCIENCE PHOTO LIBRARY