The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Assuming each protein species present in 10 copies
100
6.6
74.5
18.4
0.5
206
200
6.5
74.5
18.4
0.6
238
300
6.4
74.5
18.5
0.6
262
450
6.3
74.5
18.5
0.7
292
950
6.3
74.5
18.5
0.7
359
Assuming each protein species present in 1,000 copies
100
4.4
49.9
12.4
33.3
231
200
4.1
46.8
11.6
37.5
272
300
3.9
45.7
11.3
39.1
303
450
3.8
44.8
11.1
40.3
340
950
3.7
43.8
10.9
41.6
422
As Dr. de Duve commented in opening the workshop, the results given in Tables 1 and 2 above must be regarded as unrealistically low. Referring to the values for cell composition listed In Table 2, he pointed out that In a cell with only 10 copies of each protein species, the ribosomes and the other RNA components of the protein-synthesizing machinery represent more than 90% of the dry weight. Even when 1,000 copies are present, a cell's protein-synthesizing machinery still accounts for more than 50% of its dry weight. Barring the unlikely event that the same ribosome actually serves in the synthesis of several distinct protein species, sizes significantly below the calculated values are possible only if a less bulky machinery makes proteins. Even a single ribosome surrounded by a membrane and a wall would occupy a sphere of 57 nm In diameter.
