the mongol empire

Essay by huslen2424Junior High, 7th gradeA+, November 2014

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Mastering Concepts


1. Explain the roles of mitotic cell division, meiosis, and fertilization in the human life cycle.

Mitosis allows for growth and repair from the fertilized egg to the adult. In reproductively mature individuals, meiosis creates gametes with half the genetic material. The male gamete then fertilizes the female gamete during sexual reproduction, forming a zygote with a full set of genetic material.

2. Why are both cell division and apoptosis necessary for the development of an organism?

Cell division is needed to produce the large number of cells necessary to form the individual. Combined with apoptosis, the structures in the organism can be carved out and constantly recycled.


1. Why does DNA replicate?

DNA replicates before a cell divides to give a complete set of genetic instructions to each daughter cell.

2. What is semiconservative replication?

Semiconservative replication means that only one strand of a DNA molecule is newly formed.

The other strand is original DNA from the parent cell.

3. What are the steps of DNA replication?

The helicase enzyme unwinds and separates a double-stranded DNA molecule; the primase enzyme forms a short stretch of complementary RNA on each DNA template; starting at the end of the RNA primer, DNA polymerase adds DNA nucleotides that are complementary to the template strand, proofreading and correcting errors as it goes; RNA primers are removed; on the lagging strand, the enzyme ligase joins fragments of DNA.

4. What is the role of RNA primers in DNA replication?

The RNA primer is added to the start of the DNA segment being replicated and acts to attract the DNA polymerase, which can only add nucleotides to an existing strand.

5. What happens if DNA polymerase fails to correct an error?

A mutation occurs.


1. What is the relationship between...