Marshall Nirenberg

Mendel's experiment produced the following results:

1. In all the seven traits, he found that the F1 generation resembled only one of the parents. He obtained same result in reciprocal cross. The trait expressed in F1 generation was called dominant and the one that remained hidden was known as recessive.

2. In F2 generation, both the parental forms reappeared.

3. The ratio of the dominant form to recessive was always 3:1 i.e, the dominant form was three times the number the recessive form.

4. In...

The reason for Mendel's success are;

1. Pre-Mendalian experiments on heredity failed because they concentrated on inheritance of many characters at a time. Mendel focused on inheritance of a single character.

2. He used pure breeding plants which have two contrasting characters .There was no intermediate.

3. Mendel kept accurate records in crosses and even maintained exact number of seeds or plants produced.

4. He used self-pollinated plant in which undesirable cross pollination was totally...

Dominant alleles/characters	Recessive alleles /characters
1. Dominant character is able to express itself even in the presence of its recessive allele.	1. Recessive character is unable to express its effect in presence of dominant allele.
2. It masks the effect of the other recessive allele.	2. The effect of recessive characters is masked by the presence of dominant allele.
3. It can form complete polypeptide or enzyme.	3. It forms incomplete or defective polypeptide or enzyme.

It states that out of two traits of the parents , only one trait appears inF1 generation. The trait which expresses in F1 generation is called dominant trait while hidden trait is called recessive trait.

It states that two alleles of a trait remain together in heterozygote without contamination but they separate or segregate at the time of gamete or spore formation or meiosis.

It states that when two pairs of contrasting alleles present in parents, they inherit to offspring in which, one pair of alleles are independent to another pair, they do not remain linked and assort randomly.

The advantages of pea plant for plant hybridization are;

1.) Its life cycle is short so results can be obtained in shorter period of time.

2.) Large no. of seeds are produced by single plant thus results obtained are more accurate.

3.) Self-pollination occurs and artificial pollination can also be done by emasculation.

4.) When hybrids are mutually crossed, they result in perfectly fertile progeny.

5.) Pea plant shows clear cut contrasting and broad spectrum of characters such as height(tall and...

Homozygous individual	Heterozygous individual
1. It is pure for a trait and breeds true or gives rise to homozygous individuals.	1. It is seldom pure and produces offspring with different phenotype.
2. The alleles are similar.	2. Alleles are dissimilar.
3. It can either carry either dominant or recessive alleles but not both.	3. It has both dominant and recessive alleles.
4. It produces only one type of gametes. Eg; TT,RR ,etc.	4. It produces two types of gametes. Eg; Tt, Rr,etc.

The differences between monohybrid cross and dihybrid cross are;

Monohybrid cross	Dihybrid cross
1. It is a cross between two individuals that differ only in one pair of contrasting characters.	1. It is a cross between two individuals only in two pairs of contrasting characters.
2. It helps to study the inheritance of single trait.	2. It helps to study the inheritance of two traits.
3. The F2 ratio is 3:1.	3. The F2 ratio is 9:3:3:1.