Chapter 10 – Cell Growth and Division
Why Cells Divide
• When an eukaryotic organism grows what happens to its cells?
– ___________________________________________________________________
• Why do cells divide rather than grow?
– E___________ M____________: _______________________________________
___________________________________________________________________
• Surface to volume ratio
– ___________________________________________________________________
– ___________________________________________________________________
• Town analogy: ___________________________________________________________
________________________________________________________________________
Chromatin, Chromatids, and Chromosomes
Before cell division
• Chromatin: ___________________________________
_____________________________________________
• The DNA is ____________________________________
During Cell Division
• The chromatin coils up into _______________.
• Each chromosome has two _______________
– The chromatids are held together by a _______________
– Each chromatid contains _________________
– The chromatids will split apart and end up in different cells
– When the chromatids split, each chromatid will be considered a ______________
Eukaryotic Cell Cycle: The cell cycle represents the events in the life of a cell.
Interphase: _____________________________
 Interphase occurs in 3 steps
– G1 Phase: ___________________
– S Phase: ____________________
– G2 Phase: ___________________
Cell Division (also known as the M phase)
Cell Division occurs in two steps
– Mitosis: __________________________
– Cytokinesis: _______________________
Mitosis occurs in 4 steps:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
Stages of Mitosis
Prophase
• DNA condenses into ____________________
• 2 centrioles take positions on opposite sides
of the nucleus
– Centrioles: ______________________
________________________________
– Microtubules: ____________________
________________________________
– A spindle begins to form from each
centriole
– Spindle: ________________________
________________________________
– Chromosomes attach to the spindle at
the centromere
• _____________________________________
• _____________________________________
Metaphase
• _____________________________________
_____________________________________
Anaphase
• ______________________________________
______________________________________
______________________________________
• ______________________________________
______________________________________
• The chromatids move away from each other to opposite sides of the cell.
Telophase
• Spindle breaks down
• The nucleus begins to reform in each end of
the cell.
– ________________________________
– ________________________________
________________________________
– ________________________________
________________________________
Cytokinesis
• 2 new nuclei are now in one cytoplasm
• Cytokinesis: _____________________________________________________________
– Animal Cells: _______________________________________________________
– Plant Cells: _________________________________________________________
• Cytokinesis usually occurs the same time as ______________.
Meiosis
Homologous chromosomes: _________ of chromosomes where one comes from the
________ parent and the other from the ___________ parent.
Humans have _____ chromosomes
– _____ from Mom + ______ from Dad = 23 homologous pairs
– Homologous chromosomes are the _____________________
– Homologous chromosomes contain the __________________
– Homologous chromosomes may or may not contain the same alleles
• Diploid: _____________________________________
____________________________________________
– Abbreviated: _____
– In humans, diploid cells have ___ chromosomes.
– Almost all cells in the human body are diploid.
• Haploid: ____________________________________
____________________________________________
– Cells contain only ________________________
_______________________________________
– In humans, haploid cells have ___ chromosomes
– In humans, the only haploid cells are _______
and _______ cells.
• Meiosis: a _______________ process in which
________ and ________ cells are created by cutting the
chromosome number in half.
• Meiosis goes through _______ rounds of division:
– Meiosis I and Meiosis II
– One diploid cell becomes _______ haploid cells
– Produces sperm and egg cells (__________)
Meiosis I
• Interphase: __________________________________
____________________________________________
• Prophase I: each replicated chromosome _______ with
its __________ chromosome.
– Tetrad: a pair of homologous chromosomes
with 4 chromatids.
– Crossing-over: _________________________
_____________________________________
• Metaphase I: ___________ homologous
chromosomes line up in the ______________.
• Anaphase 1: _____________________________________________________________
________________________________________________________________________
• Telophase 1: ___________ ___________ forms around each cluster of ______________
• Cytokinesis: _____________________________________________________________
– The cells are now ________
– Each cell has a different set of _________
Meiosis II
• After meiosis I, chromosomes do not ____________.
• Cells go thru a second round of divisions (Meiosis II)
– Prophase II – ________________________________________________________
– Metaphase II – ______________________________________________________
– Anaphase II – _______________________________________________________
– Telophase II – _______________________________________________________
• Result is _________________________________
• Each cell is _______________________________
Mitosis vs. Meiosis
List the differences between mitosis and meiosis.
Chromosomal Mutations
• Chromosomal mutation: mutation that __________the ___________ or ____________
of chromosomes (happens during the process of
meiosis).
– Deletion: The _______ of all or part of a
___________.
– Duplication: A segment is _________.
– Inversion: part of the chromosome is ________
from its usual direction.
– Translocation: one chromosome _______
_____ and ________ to another ___________.