This document discusses various models of chromatin packing and organization within chromosomes. It describes how DNA is wrapped around histone proteins to form nucleosomes, which can further coil to form higher-order structures like the solenoid model. Chromatin looping is discussed, where distant genomic sites can be positioned close together in the nucleus. Different staining techniques can reveal characteristic banding patterns in chromosomes.

1. Chapter 9
Molecular Structure of Genes
and Chromosomes
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2. 9.5 The solenoid model of condensed chromatin
Figure 9-31
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3. 9.2 Simple-sequence DNAs are concentrated
in specific chromosomal locations
Figure 9-6
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4. 9.6 A model for chromatin packing in
metaphase chromosomes
Figure 9-35
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5. Copyright (c) by W. H. Freeman and Company

6. 9.6 Experimental demonstration of chromatin
loops in interphase chromosomes
Sites A-F are separated by millions of bp of linear sequence
but are physically close to each other in interphase nuclei Figure 9-36
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8. 9.6 Heterochromatin consists of chromosome
regions that do not uncoil
Figure 9-39
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9. 9.6 Chromosome painting distinguishes each
homologous pair by color
Figure 9-0
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10. 9.6 Stained chromosomes have characteristic
banding patterns
Figure 9-38
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11. DEFINICION MOLECULAR DE GEN
Un gen es una secuencia completa de ADN que es
necesaria para la sintesis de uno o má polipé ptido
s
funcional en un momento determinado.
Regiones de ADN que codifican para moleculas de ARN
como ARNt y ARNr tambien son consideradas genes.
En eucariotes, los genes permanecen en medio de
segmentos no codificantes, no funcionales de ADN.
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15. 9.1 Simple and complex transcription units are
found in eukaryotic genomes
Figure 9-2
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16. 9.2 Genomes of higher eukaryotes
contain much nonfunctional DNA
Amongst eukaryotes, cellular DNA content does not correlate with phylogeny.
Figure 9-3
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18. Copyright (c) by W. H. Freeman and Company

19. 9.3 The two classes of mobile elements
Figure 9-10
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20. Los elementos moviles probablemente tienen
influencia significativa en la evolució n
Mutaciones espontaneas pueden resultar de la
inserció n de un elemento movil dentro o cerca de una
unidad de un gen.
Recombinació n homologa entre elementos mó viles
pueden contribuir a la duplicació n u otros re arreglos,
incluyendo duplicacion de intrones , recombinació n de
intrones para creas nuevos genes y control de
expresió n de genes.
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21. 9.5 Nucleosomes are complexes of histones
Figure 9-30
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22. 9.7 Human mtDNA
Figure 9-44
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