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Cell Division Outline (Honors version)
Biology units | Cells links
A. Definitions (from chap 8 and 10)
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Click on the links below for pictures that will help you visualize these definitions,
especially the relationship between genes, chromosomes, and DNA.
Online Biology textbook
1. chromosome
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Explore chromosome structure and the relationship between DNA, genes,
and chromosomes
animation of chromosome structure
2. telomere
3. centromere
4. chromatin
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the 2 meters of DNA in each cell is highly packaged (more detail)
5. gene
6. DNA (p. 184-187)
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explore this site for images of DNA
DNAinteractive is a site covering the history of research and discoveries
about DNA structure and the genetic code. Lot's of good animations
Basics of genetics - includes DNA structure
DNA structure basics
overview of DNA
7. haploid (n)
8. diploid (2n) (humans have 23 pairs of chromosomes)
9. gamete
B. the structure of DNA (p. 184-187) (more details)
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microscope images of DNA
more images, including a gallery of the X-ray diffraction images taken by Franklin and
used by Watson and Crick in their solution to the structure of DNA
1. double helix – discovered by Watson and Crick; image taken by Franklin – p.
186 fig. 10.3
2. other historical discoveries – p. 184-185
3. four bases ("rungs" of the ladder) paired like this (see fig. 10.3, p. 187 and 10.2
p. 185):
A=T
C=G
4. "backbone" or sides of ladder formed of sugar (deoxyribose) and phophate
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fig. 10.2
more details of nucleotide structure
structure is anti-parallel (see fig. 10.3D)
5. DNA can make copies of itself when it needs to divide (p. 188-189, fig. 10.4
and 10.5) watch a video of replication | and explore an animation
C. cell division for growth and repair: mitosis (section 8-6)
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check out animations and diagrams
flash animation comparing mitosis and meiosis
another animation
1. binary fission – reproduction in bacteria – p. 127 fig. 8.3
2. cell cycle p. 129 fig. 8.5
3. stages of mitosis – p. 130-131
4. cytokinesis – p. 132, fig 8.7
5. controls on the cell cycle - fig. 8.9
6. cancer – cell division out of control – p. 135
D. cell division for production of gametes/reproduction: meiosis (p. 136-148)
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compare mitosis and meiosis
animation comparing meiosis and mitosis
check out animations and diagrams
another animation
animation using dragons as model organisms!
1. stages of meiosis – p. 138-39
2. independent assortment – p. 141-142, fig. 8.16, 8.17.
3. variability results from the number of combinations and from crossing over fig. 8.18, p. 143 | more
4. errors in meiosis lead to disorders – p. 145-147, fig. 8.21 and 8.22 and table
8.22
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analysis of errors is done with a karyotype - click here to learn more or to
try it yourself
see the causes of these disorders
more details:
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Turner's syndrome (45, X0) (learn more about the disorder)
Klinefelters syndrome (47, XXY)
Down's syndrome (trisomy 21) (learn more about the
disorder) - p. 145
other abnormalities related to XY and gender: Animations
on sex determination | Gender testing of female athletes |
sex unknown: NOVA website on gender ambiguities
E. DNA replication sometimes makes errors.
1. types of errors (more details showing how errors develop) (p. 148, fig. 8.24)
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An error called a duplication results in alonger
chromosome with a section repeated.
In an insertion a section is copied into the wrong
chromosome
In a translocation, sections of two non-homologous
chromosomes are exchanged.
2. This sort of error could be negative or beneficial
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Philadelphia chromosome is a disorder that can lead to leukemia
Robertsonian transloctions can also lead to disorders
Cri du Chat results from a deletion
F. Stem cells
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extensive overview from NIH
overview with cool animations
learn more by doing the in-class assignment