Name: Haemophilia: The Royal Disease
Uploaded: 2019-07-19
Duration: 2 min 3 s
Description: Haemophilia is an inherited genetic disorder that impairs the body's ability to make blood clots, a process needed to stop bleeding. Know more about it.

Question

Draw a suitable cross to show Mendel&rsquo;s first law.

Accepted Answer

Mendel's First Law, also known as the Law of Segregation, states that during gamete formation, the two alleles for each gene segregate and are passed into separate gametes. Each offspring inherits one allele from each parent.

For example: When a pure red flowered and a pure white flowered plants are crossed only red flowered are obtained in F1 generation. A pure breeding pea plant with red flowers (RR) was cross-pollinated with a pure breeding pea plant with white flowers(rr). The resulting plants (F1) bear red flowers only.

(Parents) RR ((Homozygous) rr (Homozygous)

Cross pollination: RR × rr

F1 generation: Rr (red)

Self Pollination: Rr × Rr

R r

R RR Rr

r Rr rr

F2 generation: RR, Rr, Rr, rr

As per Mendel's First Law, the alleles segregate during gamete formation, and the offspring inherit one allele from each parent. In this case, you'll observe the following ratios:

50% of the offspring (F1) will have the genotype Rr (heterozygous for flower colour), which results in red flowers (expressing the dominant trait).

50% of the offspring (F1) will have the genotype rr (homozygous for the recessive allele), resulting in white flowers (expressing the recessive trait).

Draw a suitable cross to show Mendel’s first law.

Point Mutation: A change in a single base pair of DNA, such as a substitution of one base for another. For e.g., changing Adenine (A)&nbsp;to Guanine&nbsp;(G).
Insertion: The addition of one or more extra base pairs into the DNA sequence.
Deletion: The removal of one or more base pairs from the DNA sequence.
Frameshift Mutation: Insertions or deletions that shift the reading frame of the genetic code, potentially altering all subsequent amino acids in a protein.

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