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When printing slides, please use the
print handout option and select
black and white option.
That way, you will not print black
backgrounds and thus save ink!
12.1
Chapter 12
The Cell Cycle
12.1 Mitotic cell division results in genetically identical
daughter cells
12.2. Mitosis alternates with Interphase in the cell cycle
12.3. Not for exam
Note the logarithmic scale
6.2
But first some
sections of Ch. 6
Some paradigms in Biology
1. All organisms are
composed of cells
2. There is a universal
genetic code shared by
all organisms and this
code transmits
information between
generations.
Capturing
sharp images
at many
different
planes  3D
Variations in
density
Variations in
density ~3D
Electron
microscopy
dyes
LightAdding
to label
molecules
microscopy
6.3
6.4. Research Methods:
Cell fractionation
The disruption of a cell and
separation of its parts by
centrifugation at
successively higher speeds.
Bacteria, Archaea
6.5. A prokaryotic cell – lacking a true nucleus
and other membrane-enclosed organelles
6.8.
Animal cell
Eukaryotic
cell
6.8.
A plant cell
Eukaryotic
cell
DNA: Deoxyribonucleic acid
Chromosomes (DNA + proteins)
Nucleic Acid
Nucleotide
Nucleosome
2 nm
slinky
Outline
• What are cell division and eukaryotic
chromosomes?
• What is the cell cycle?
• What is mitosis?
• What is meiosis (Ch. 13)?
• What are some meiotic errors
(Ch. 13)?
Functions of cell division:
1. Reproduction (single-celled organism)
2. Growth and development (multi-cellular organisms)
3. Renewal and repair.
12.2
Cells divide with most components equally shared among the daughter cells;
but the DNA on chromosomes divides with exceptional precision!
Mitosis
12.4, 12.5
Chromosome
duplication and
distribution during
cell division
12.6. The cell cycle
12.7a. The mitotic division of an animal cell
12.7b. The mitotic division of an animal cell
12.10. Cytokinesis in animal and plant cells
12.11. Mitosis in a plant cell. Light micrographs
showing mitosis in an onion root cell.
Example Question
• A cell containing 92 chromatids at the start
of mitosis would, at its completion, produce
cells containing how many chromosomes?
–
–
–
–
–
A)
B)
C)
D)
E)
12
23
92
16
46
12.19. Densitydependent inhibition
and anchorage
dependence of cell
division.
Cancer cells do not follow normal signals that regulate the cell
cycle. They lack density-dependent inhibition (crowded cells stop
dividing) and anchorage-dependence (must be attached to substrate
in order to divide) and continue to divide and invade other tissues.
Diving cells near the tip of an onion root. Identify a nucleus in each of the
major stages of mitosis and describe major events occurring at each stage.
Stages in Mitosis
Fig 12.12.
Bacterial cell division
(binary fission)
Look at Chapter 12 Review
(book p. 244)
• 12.1 Mitotic cell
division results in
genetically identical
daughter cells
• 12.2. Mitosis
alternates with
Interphase in the cell
cycle
• 12.3. Not for exam