Chapter 10
Life Science
Name ___________________________________
Growth and Cell Reproduction
1. Cell Division – The process of one cell dividing into two daughter cells is called cell division.
Each daughter cell has an exact copy of the DNA found in the parent cell. (196)
2. Chromosomes – The structures made up of protein & DNA found inside the nucleus of a eukaryotic
cell are called chromosomes. Different organisms have different numbers of chromosomes. (197)
3. Cell Cycle – The period of time from the beginning of one cell division to the beginning of the
next is called the cell cycle. It consists of 3 stages: interphase, mitosis, and cytokinesis. (198)
4. Interphase – The period of time between cell divisions where a cell is just growing,
developing, and performing normal functions is called interphase. It is the longest stage of the
cell cycle. At the end of interphase the DNA (chromosomes) have doubled. Organelles like the
mitochondria also double in number. (198)
5. Mitosis – When the nucleus divides in eukaryotic cells to form two new nuclei this is the second
stage of the cell cycle called mitosis. Each new nucleus will have the same amount of identical
DNA as the original. There are four phases to mitosis: prophase, metaphase anaphase, and
telophase. The first clue that mitosis has started is the appearance of the chromosomes. (198)
6. Prophase – The first phase of mitosis is called prophase. In this phase the chromosomes are fully
visible, the nuclear membrane has disappeared, and the nucleolus has disappeared. (199)
7. Metaphase – The second phase of mitosis is called metaphase. In this phase the chromosomes
line up across the center and spindle fibers attach to each chromosome. (199)
8. Anaphase – The third phase of mitosis is called anaphase. In this phase the chromosomes split
and each half is pulled to opposite sides of the cell. (199)
9. Telophase – The last phase of mitosis is called telophase. In this phase the chromosomes cluster in
the center & a new nuclear membrane begins to form. The cell then begins to separate. In animal
cells they pinch in two, in plant cells a cell plate forms & grows outward forming a new cell wall.
10. Cytokinesis – The shortest stage of the cell cycle is called cytokineses. In this stage the cell
divides into two daughter cells each having an identical set of chromosomes in its nucleus. (198)
11. Reproduction – The formation of new organisms by the same species is called reproduction.
There are two types of reproduction: asexual reproduction, and sexual reproduction. (202)
12. Asexual Reproduction – Asexual reproduction is reproduction that requires only one parent.
Most single-celled organisms reproduce this way. Cell division (fission or cytokinesis) is asexual
reproduction. In asexual reproduction the DNA and cell structures are copied and the new
cells/organisms have the exact same DNA as the parent. There are two other forms of asexual
reproduction. One is called budding. In budding a new organism grows from a small bud on the
parent organism. The other form of asexual reproduction is called regeneration. In regeneration a
piece of a new organism grows from a piece of the parent. These will be explained in class. (202)
13. Sexual Reproduction – In sexual reproduction the DNA that is passed on comes from two
parents. Special types of cells called sex cells are involved (sperm & egg). The sex cells have
half the number of chromosomes that the normal body cells do. Human body cells have 46
chromosomes. Human sex cells have 23 chromosomes. (202)
14. Homologous Chromosomes – In body cells the chromosomes exist in equivalent (equal) pairs.
This is called homologous. The pairs of chromosomes match each other, one from each parent.
Sex cells are not homologous. They contain only a single chromosome from each of the
homologous pairs. (202)
15. Meiosis – Meiosis is cell division that produces sex cells with only half the number of
chromosomes. During meiosis there are two divisions of the cell producing 4 sex cells. (203)
1st division ----The homologous pairs of chromosomes separate in the following steps:
- Chromosomes double the nuclear membrane disappears.
- Homologous chromosomes line up in the center and spindle fibers attach.
- Homologous pairs of chromosomes separate moving to opposite ends.
- Nuclear membrane reforms forming two new cells.
2nd division ---- The doubled chromosomes in the 2 new cells split in the following steps:
- The two new cells do not double their chromosomes.
- Chromosomes line up in the center (genes are exchanged).
- Chromosomes split in the center and are pulled to opposite sides.
- Nuclear membranes reform and four new cells are created.
- Each with half number of chromosomes as the original cell.
- Each with slightly different DNA.
16. Diploid & Haploid – When cells have a double set of chromosomes they are called diploid. All
of your body cells are diploid. When cells have only half a set of chromosomes, or only one set
from each homologous pair, they are called haploid. Sex cells are haploid. (205)
17. Fertilization and Zygotes – When a sperm cell combines with an egg cell (fertilization) the two
haploid cells create a fertilized egg cell called a zygote. The zygote is now a diploid cell with
two sets of chromosomes (homologous pairs), one set from each parent. (205)
18. Embryo – After fertilization the zygote rapidly divides by mitosis and becomes an embryo. An
embryo is an organism in its earliest stages of development. (206)
19. Cell differentiation - Cell differentiation is the process that cells go through as they begin to
specialize in different functions. Some become brain cells, some muscle cells, some skin
cells, etc. This forms tissues, then organs, and then organ systems. (206)
20. DNA – Chromosomes consist of molecules of DNA. These are arranged in sections we call Genes.
Genes determine traits. (238)
21. Double Helix - DNA is shaped like a twisted ladder. This is called a double helix. The sides of the
ladder consist of alternating sugar and phosphate molecules. The rungs of the ladder are composed of
molecules called bases. There are 4 of them: Adenine (A), Thymine (T), Cytosine (C), & Guanine (G).
22. DNA Replication – When DNA molecules make an exact copy of themselves this is called DNA
replication. During replication adenine (A) combines only with thymine (T), & cytosine (C) combines
only with guanine (G). This way the DNA makes 2 exact copies of itself (daughter molecules). We
will go over this in class. (239)
23. Mutation – A change in the hereditary material of an organism is called a mutation. (242)
21. Genetic Disorder – An abnormal condition that an organism inherits from its parents is called
a genetic disorder (cystic fibrosis, hemophilia, sickle cell anemia, downs syndrome). (243)