Chromosomes are made of protein & a long, single, tightly-coiled DNA molecule. During the S phase of interphase, the DNA, which makes up the chromosome makes copies of itself. Each half of the chromosome is called a , which is held together by a centromere.

You have just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. what is the significance of this finding? it will be important to include cysteine in the diet of the mice. cysteine residues are required for the formation of α helices and β pleated sheets. cysteine residues are involved in disulfide bridges that form tertiary structure. cysteine causes bends, or angles, to occur in the tertiary structure of proteins.

19. a cell is viewed under a microscope and is found to have two nuclear envelopes and spindles that appear to be breaking apart. which phase of mitosis is the cell most likely in? a. metaphase b. prophase c. telophase d. anaphase

Which contributions did galileo make to the model of the solar system? check all that apply. a mathematical model for the orbits of the planets scientifically accurate data on planetary orbits data that showed that planets reflected sunlight similar to earth's moon up the idea that stars are other suns that do not move u observations of the moons of jupiter rotating around the gas giant