<span>The astronaut then measures the abundance of magnesium on the new planet, obtaining the following results:
Isotope Abundance (%) Mass (amu)
24Mg 78.99 23.99
25Mg 10.00 24.99
26Mg 11.01 25.98
The atomic mass of magnesium for this planet = </span><span>24.31 amu</span>
Lasts are used for photosynthesis .
They have a double membrane around them.
The space inside is called the stroma. The space may contain starch grains and lipid bodies.
In the stroma are structures called thylakoids.
The thylakoids are stacked to form structures called grana.
The grana contain the pigment chlorophyll along with some secondary pigments.
Answer: Tightly wound chromosomes, composed of DNA, must unwind before replication. Cell replication splits a cell into two parts, both of which become new, fully functioning cells. Before this can happen, however, cells require a full complement of DNA for each of the new daughter cells that will form as a result of the split. Because of this, DNA makes a copy of itself in a process known as replication during interphase, a stage that occurs before cells divide.
Cell Phases: Mitosis is the process by which parent cells each divide into two identical daughter cells. However, this majority of the cell's time is spent in interphase, during which it performs normal metabolic functions necessary for the organism, such as manufacturing protein. DNA occurs during the S phase of interphase, sandwiched between the G1 and G2 phases. The cell uses checkpoint signals to ensure at the end of G1 that it is big enough to replicate and at the end of G2 to determine whether or not DNA replication has succeeded. If so, the cell can undergo mitosis, at which point DNA winds up tightly for easy transport during the process.
DNA Replication: Replication begins with DNA unwinding and unzipping, its two strands coming apart. While only one side is the “correct” code, containing the actual genetic information used to build the organism’s proteins, both can be the base for a new strand of complete DNA. The enzyme DNA polymerase matches up each base with the correlating base: adenine with thymine and guanine with cytosine. When each pre-existing base has been matched to a nucleotide, which also contains the sugar and phosphate of the DNA’s backbone, the strand is complete.
It binds lactose which changes its conformation so that is no longer binds to DNA. This allows the lactose operon to be transcribed.
