Bio 103 Fall 2020 Genetics Assignment Please Answer The Foll ✓ Solved

Bio103 Fall 2020genetics Assignmentplease Answer The Following Genetic

Bio103 Fall 2020genetics Assignmentplease Answer The Following Genetic

BIO103-Fall 2020 Genetics Assignment Please answer the following genetic problems and show how your worked out your answers. Both typed and hand-written assignments are accepted.

1. A man who is a carrier of sickle cell anemia, a recessive genetic disorder, marries a woman who is not a carrier. What proportion of their children is expected to have sickle-cell anemia? (use the letter s for sickle cell anemia allele and the letter S for the healthy allele)

2. Hemophilia is an X-linked recessive disease that prevents blood clotting. If a woman who is a carrier for hemophilia marries a man who is not a carrier. What proportion of their sons are expected to have hemophilia? (use Xh to denote hemophilia allele)

3. Color-blindness is an X-linked disease. A woman who has a colorblind mother and a father with normal color vision marries a man with normal vision. This couple has a son. What is the chance that this son is colorblind? (use Xa for colorblindness allele, and X for healthy)

4. If a heterozygote blood type A marries a homozygote blood type B. What are the possibilities of blood types for their children?

5. If a heterozygous purple flower pea plant is crossed with a homozygous white flower plant, what proportion of the offspring will be white flowered?

Sample Paper For Above instruction

Introduction

Genetics is a fundamental branch of biology that explores how traits are inherited from one generation to the next. Understanding genetic inheritance patterns involves analyzing Mendelian principles, including dominant and recessive traits, as well as sex-linked inheritance. This paper systematically addresses five genetic problems, applying core genetic principles to solve real-world inheritance questions.

Question 1: Sickle Cell Anemia Inheritance

The man is a carrier of sickle cell anemia, with the genotype Ss, and the woman is not a carrier, with genotype SS. To determine the proportion of children expected to have sickle cell anemia, we can use a Punnett square.

Possible gametes from the father: S, s

Possible gametes from the mother: S, S

Punnett square:

| | S (Mother) | S (Mother) |

|-----|------------|------------|

| S (Father) | SS | SS |

| s (Father) | Ss | Ss |

The genotypic ratio: 2 SS : 2 Ss

The phenotypic ratio (affected vs. unaffected): 0 affected (SS is healthy; Ss are carriers without symptoms)

However, since the question asks about children with sickle-cell anemia, which is recessive, children must have genotype ss. Because the mother is Ss (not SS), and the father is Ss, the possible offspring are:

| | S | s |

|-----|---|---|

| S | SS | Ss |

| s | Ss | ss |

Here, the probability of ss (affected) is 1 out of 4, or 25%. Therefore, 25% of their children are expected to have sickle-cell anemia.

Question 2: Hemophilia X-linked Recessive Inheritance

The woman is a carrier (XhX), and the man is unaffected (XY).

Gametes:

- Mother: X, Xh

- Father: X, Y

Possible offspring:

| | X | Xh |

|-----|---|----|

| X (Father) | XX | XhX |

| Y (Father) | XY | XhY |

- Sons: X from mother and Y from father: XY (healthy) or XhY (hemophilia)

- Daughters: X from father and X or Xh from mother.

Probability for sons:

- 50% XhY (hemophilia)

- 50% XY (healthy)

Therefore, 50% of their sons are expected to have hemophilia.

Question 3: Color-blindness X-linked Inheritance

A woman with a colorblind mother (XcXc) and a normal father (XY):

- Mother’s genotype: XcXc

- Father’s genotype: XY

They marry a man with normal vision: XY

Possible offspring:

- Daughters:

- From Xc from mother and X from father: XcX (carrier, normal vision)

- From Xc from mother and Y: XcY (male, colorblind)

- Sons:

- From Xc from mother and Y: XcY (male, colorblind)

- From X from mother and Y: XY (male, normal)

Focusing on their son:

- Since the son inherits the Y chromosome from the father and an X from his mother:

- Probability the son is colorblind depends on whether he inherits Xc from his mother.

Given she’s XcXc, all her X chromosomes are Xc:

- The son has a 100% chance to inherit Xc from his mother, and Y from his father.

Thus, the chance that their son is colorblind is 100%.

Question 4: Blood Type Heterozygote × Homozygote

A heterozygous blood type A (AO) mates with homozygous blood type B (BO).

Gametes:

- Heterozygote A: A, O

- Homozygote B: B, O

Possible offspring:

| | B | O |

|-----|---|---|

| A | AB | AO |

| O | O B | O O |

Blood types:

- AB (from A and B)

- A (from A and O)

- B (from O and B)

- O (from O and O)

So, possible blood types for offspring:

- AB, A, B, and O, with equal probabilities.

Specifically, 25% each for AB, A, B, and O blood types.

Question 5: Cross of Purple and White Flowered Pea Plants

A heterozygous purple flower plant (Pp) crossed with a homozygous white flowered plant (pp):

Gametes:

- Pp: P, p

- pp: p, p

Possible offspring:

| | p | p |

|-----|---|---|

| P | Pp | Pp |

| p | pp | pp |

Offspring genotypes:

- 2 Pp (purple)

- 2 pp (white)

Proportion:

- 50% purple

- 50% white

Therefore, 50% of the offspring will have white flowers.

Conclusion

This analysis demonstrates how Mendelian principles apply to various inheritance patterns, including autosomal dominant and recessive traits, sex-linked traits, and codominance. Understanding these patterns is vital in fields such as genetics counseling and medical genetics, helping predict trait inheritance and disease risk across generations.

References

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