Download Mitosis and Meiosis Study Guide

Mitosis
Interphase
(Technically not part of mitosis, but it is included in the cell cycle)
Cell is in a resting phase, performing cell functions
DNA replicates (copies)
Organelles double in number, to prepare for division
G1 - First growth
S - Synthesis (copy DNA)
G2 - Second growth
Prophase
Spindle forms
Centrioles move to opposite poles
Chromosomes become visible
Nuclear membrane breaks down in prometaphase
Metaphase
Chromosomes line up along the equator
Anaphase
Centromeres divide
Chromatids separate and move to opposite poles
Telophase
Nuclear membrane forms around each group of chromosomes
Chromosomes unwind
Cytokinesis begins - cell pinches inward and forms two daughter cells.
Meiosis
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The process of nuclear division where the number of the chromosomes is halved.
produces four daughter cells
all daughter cells are haploid
chromosomes are shuffled in the process, so that each daughter cell has a unique
combination
used to create gametes (sperm and egg)
Prophase 1
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homologous chromosomes pair up (tetrad)
crossing-over occurs
Crossing Over - chromosomes exchange sections (increases variability)
Independent Assortment
In addition to Crossing-Over, the process of meiosis ensures that chromosomes are
randomly assorted. The following images show three separate possibility for a single cell
that has undergone meiosis. Look at all the different combinations.
Sexual Reproduction
- Involves the fusion of gametes, creates unique offspring
- Eggs are much larger than sperm
Image of egg and sperm
*Polar bodies are nonfunctioning cells
Asexual Reproduction
--Does not involve the fusion of gametes
--Offspring are identical to parents