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This article explores the concepts of cell replication, cell division, and inheritance in biology. Topics covered include cell replication in sea urchins, prokaryote and eukaryote genomes, somatic cells vs gametes, the cell cycle, cancer development, and the cellular basis of inheritance.
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Concepts of BIOLOGY Chapter 6 REPRODUCTION AT THE CELLULAR LEVEL
CELL REPLICATION • A sea urchin begins life as a single cell that (a) divides to form two cells, visible by scanning electron microscopy. After four rounds of cell division, (b) there are 16 cells, as seen in this SEM image. After many rounds of cell division, the individual develops into a complex, multicellular organism, as seen in this (c) mature sea urchin.
EUKARYOTE GENOME • karyotype of the genome of a human female
Figure 6.7 • The cell cycle is controlled at three checkpoints. Integrity of the DNA is assessed at the G1 checkpoint. Proper chromosome duplication is assessed at the G2 checkpoint. Attachment of each kinetochore to a spindle fiber is assessed at the M checkpoint.
Concepts of BIOLOGY Chapter 7 THE CELLULAR BASIS OF INHERITANCE
Each of us, like these other large multicellular organisms, begins life as a fertilized egg. After trillions of cell divisions, each of us develops into a complex, multicellular organism.
MEIOSIS & CROSSING OVER - a simple overview VIDEO (1:48) MEIOSIS & CROSSING OVER – a more detailed explanation VIDEO (2:57)
Figure 7.9 • The incidence of having a fetus with trisomy 21 increases dramatically with maternal age.
Figure 7.10 • Tortoiseshell cats
Figure 7.11 • cri-du-chat