mitosis Sequence of steps in which a nucleus is divided into two daughter nuclei, each with
an identical set of chromosomes.
prophase Initial phase of mitosis where chromosomes condense, the nuclear envelope dis-
solves and the spindle begins to form.
spindle Fibers that move chromosomes during mitosis and meiosis.
telophase Final phase of mitosis where a nuclear envelop forms around each of the two
sets of chromosomes.
Points to Consider
- How might a cell without a nucleus divide?
- How are new cells made that incorporate the DNA of two parents?
5.2 Lesson 5.2: Reproduction
Lesson Objectives
- Name the types of asexual reproduction.
- Explain the advantage of sexual reproduction.
- List the stages of meiosis and explain what happens in each stage.
Check Your Understanding
- Can something that does not reproduce still be considered living?
- What stores the genetic information that is passed on to offspring?
- How many chromosomes are in the human nucleus?
Introduction
Can an organism be considered alive if it cannot make the next generation? For a species
to survive,reproduction,the ability to make the next generation, is absolutely necessary.
For a species to be successful, it not only needs to be well adapted to its environment, but
also needs to be successful at reproduction. Reproduction allows a population of organisms
to pass on their genetic information to the next generation. There are many different ways
that organisms reproduce, and these methods are categorized as either sexual or asexual
reproduction. There are advantages and disadvantages to each method, but the result is
always the same: a new life begins.