These studies are now being done by GWAS in 2 patient groups, examining both baseline HbF and the HbF response to hydroxyurea. Genetic modulation of sickle cell disease: Homozygosity for a single Î²-globin gene mutation (HBB; glu6val) causes sickle cell anemia.hese studies are now being done by GWAS in 2 patient groups, examining both baseline HbF and the HbF response to hydroxyurea. Genetic modulation of sickle cell disease: Homozygosity for a single Î²-globin gene mutation (HBB; glu6val) causes sickle cell anemia.
Spiral Galaxies. Spiral galaxy M100. Spiral galaxies have three main components: a bulge, disk, and halo (see right). The bulge is a spherical structure found in the center of the galaxy. This feature mostly contains older stars. The disk is made up of dust, gas, and younger stars. The disk forms arm structures.
How do astronomers know the shape of our galaxy (the Milky Way), even though it is not possible to take a photograph of it because to do that we would have to go away from it? The clues we have to the shape of the Milky Way are: 1) When you look toward the Galactic Center with your eye, you see a long, thin strip. This suggests a disk seen edge-on, rather than a ellipsoid or another shape. We can also detect the bulge at the center. Since we see spiral galaxies which are disks with central bulges, this is a bit of a tipoff. 2) When we measure velocities of stars and gas in our galaxy, we see an overall rotational motion that differs from random motions. This is another characteristic of a spiral galaxy. 3) The gas fraction, color, and dust content of our Galaxy are like other spiral galaxies.