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linkage and crossing over 145 Linkage and Crossing Over TABLE 11.4 Hypothetical

ID: 211080 • Letter: L

Question

linkage and crossing over

145 Linkage and Crossing Over TABLE 11.4 Hypothetical Data llustrating How Certain Gene Products (Enzymes or Other Proteins) an Be Assoclated with Certain Human Chromosomes in Mouse-Human Hybrid Cell Lines Mouse-Human Hybrld Cell Line Human gene products 8 12 18 21 A plus (+) indicates tlir presence of partic lar humin prevein (entyme) or a particularchnere son and a mirms incicates the obience of the enzyme or choomasome in the hybrid done. 2. Can you determine on which chromosome(s) the linked genes are located? Identify the chromosome(s) by giving its numbers) What evidence supports this conclusion? 3. Is t possible to associate any other gine or gtnes with a particular chromosome IF so, which gene on which chromosome? What is the evidence for this conelusion? 4. Are any of the chromosomes isted in Table 11.4 not associated with any of the gene products A-EP B. Molecular Techniques: In Situ Hybridization ta recent years molecular techniques have been developed for mapping genes and other types of DNA sequences to specific chromasomes, Although it is beyond the scope of this investigation, one of the most valuable techniques used in ihis type of mapping is in situ hybridization. With in situ hybridization, any isolated DNA sequence or gene can be mapped to a specific hu- man chromosome if humans posses that gene or have a very similar type of gene. In Drosophila, for example, homeobox genes, vhich are regulatocy developniental genes (genes that switch on whole

Explanation / Answer

2)

a) Yes

b) The linked genes are located on chromosome 3 and chromosome 18

c) When chromosome 3 is inherited in hybrid cell lines I and III, the gene products B and E are always inherited, indicating they are linked genes

When chromosome 18 is inherited in hybrid cell lines I and II, the gene products A and C are always inherited, indicating they are linked genes

3)

a) Yes

b) Gene B and gene E on chromosome 3

Gene A and gene C on chromosome 18

Gene D on chromosome 12

c) When chromosome 3 is inherited in hybrid cell lines I and III, the gene products B and E are always inherited.

When only chromosome 18 is inherited in hybrid cell line II, the gene products A and C are inherited, indicating A and C are present on chromosome 18

When chromosome 12 is only inherited in hybrid cell lines IV and V, the gene product D is inherited.

4) Yes, the chromosome 21 is not associated with any gene products