Chapter 3 Science Study Guide
Terms to Know:
 Cell Division: the process that causes multicellular (or many-celled)
organisms to grow by increasing the number of cells
 Cell Cycle: process of formation, growth, development, and death that cells
go through
 Mitosis: process when the nucleus divides to form 2 identical nuclei (also
known as cell division)
 Daughter Cells: the two new cells formed from the process of mitosis
 Centromere: the center of the chromosome that holds chromatids together
 Chromosome: structure in the nucleus that contains genetic material
 Chromatid: identical strands that make up a chromosome
 Chromatin: relaxed DNA in the nucleus before mitosis begins (“spaghetti”)
 Asexual Reproduction: a new organism is produced from one parent
organism that goes through cell division (mitosis)
 Rapid rate of reproduction
 Offspring is identical to parent
 Sexual Reproduction: a new organism is produced from two parents that go
through cell division (mitosis) and other processes
 Rate of reproduction is slower than rate of asexual
reproduction
 Offspring have genetic information from both parents
 Nuclei: more than one nucleus (which controls the cell and is where the
DNA and chromosomes are located)

Centrioles: two small organelles found in animal cells that help the cell
divide; they move to opposite ends of the cell during prophase
Stages of Mitosis:

Interphase
stage when the cell
duplicates it’s
chromosomes
and prepares for cell
division; cells spend most of
their life in this phase

Prophase
Stage when nuclear
Membrane disappears,
Centrioles move to opposite
ends of the cell, and spindle
fibers stretch across the cell

Metaphase
Stage when pairs of chromatids
Line up across the center of the cell
 Anaphase
Stage when centromeres
Divide, and chromatid pairs
Separate and move to opposite
Ends of the cell

Telophase
Cytokinesis:
Think chromatIN for
INterphase; looks like
spaghetti
Chromatin pairs off into
chromosomes; think P
for Pair and Prophase
Chromosomes line up in
the middle; think M for
Metaphase and Middle
Chromosomes break apart
into Chromatids and spread to
opposite sides of cell; think A
for Apart and Anaphase
Chromatids relax and
become chromatin again;
two daughter cells are
formed. Think T for Two or
Twin and Telophase
The cytoplasm
divides and the
two new cells
separate; think
CYTO for
Cytoplasm and
Cytokinesis
Results of Mitosis:

Each new cell except for sex cells have 46 chromosomes

Allows for growth and replaces worn out or damaged cells
Types of Mitosis:
1. Binary Fission: an organism with no nucleus divides into two
identical organisms
 Example: bacteria (think B for Bacteria and Binary fission)
2. Budding: a small, exact copy of the adult grows from the body of the
parent
 Example: hydras reproduce by pinching off buds
3. Regeneration: a whole new organism grows from each piece of the
parent
 Example: earthworms and starfish
Functions of Cell Division:
~Cell division occurs in all organisms, but performs different functions
*Unicellular (single-celled) organisms reproduce through cell division
* Multicellular (multi-celled) organisms also reproduce through cell
division, but cell division for them is involved in growth, development,
repair, and reproduction
 Growth: your cells are the same size, but as you grow older, you grow
physically so your cells need to divide into more cells
 Development: cells need to become specialized to perform different jobs and
functions, so they take on different shapes and structures as they develop or
mature; some might become skin cells while others become nerve cells
 Repair: your body needs to repair itself when injuries occur, so your cells
divide and make new cells to heal wounds (like broken bones or cuts); also, your
cells age and die and are constantly being replaced by new cells