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In humans, the gene for red blood corpus...

In humans, the gene for red blood corpuscle shape (alleles elliptical E and normal e) is linked to the gene for Rhesus blood (alleles Rhesus positive R and Rhesus negative r). If crossing over occurs between these two genes, then the two additional types of gametes that could result are

A

RE and re.

B

EE and rr.

C

Er and eR.

D

ee and RR.

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To solve the problem, we need to analyze the genetic linkage between the two genes: the gene for red blood corpuscle shape (alleles E for elliptical and e for normal) and the gene for Rhesus blood type (alleles R for Rhesus positive and r for Rhesus negative). ### Step-by-Step Solution: 1. **Identify the Alleles**: - For red blood corpuscle shape: - E = elliptical shape - e = normal shape - For Rhesus blood type: - R = Rhesus positive - r = Rhesus negative 2. **Determine the Parental Genotypes**: - Assume we have a parent with genotype EERr (elliptical shape and Rhesus positive) and another parent with genotype ee rr (normal shape and Rhesus negative). 3. **Gamete Formation without Crossing Over**: - The parent EERr can produce two types of gametes without crossing over: ER and er. - The parent ee rr can only produce one type of gamete: er. 4. **Crossing Over**: - When crossing over occurs between the two linked genes, it can result in new combinations of alleles. - The two additional types of gametes that can result from crossing over between the genes are: - Er (elliptical shape and Rhesus negative) - eR (normal shape and Rhesus positive) 5. **Summary of All Possible Gametes**: - From the EERr parent: ER, er, Er, eR - From the ee rr parent: er (only one type) 6. **Conclusion**: - The two additional types of gametes resulting from crossing over are Er and eR.
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