Mendel's principle?

Question

explain mendel's principle of independent assortment. when might this principle no apply?

Answer 1

and this holds true unless you have alleles for two traits that are on the same chromosome. Then they are linked (how often they are inherited together is based on the distance apart on the chromosome). Mendel just happened to pick all traits that were on different chromosomes! Or selected his data very carefully...

Answer 2

Ok, im not going to copy this of websites and all that, but ill try to do my best, which i learnt it

mendel's law of independant assortment was that each pair of alleles separates into gammetes by themselves. If you kno what the 9:3:3:1 ratio is, it is the genotype possibilities ratio
heres an example.

Say you have the gene to be bald as ressevie, and hairy? to be dominant, and blakc hair color is dominant...whcih it is, and blonde is recessive...

So
Hairy=H
Bald=h

Black Hair=B
Blonde=b

So the parents should have two characters for each gene, like HHBB HhBb HHbb hhBB hhbb

They will produce gametes like this, take HhBb for example

HhBb---- HB, Hb, hB, hb,

Then you jsut draw your bigger punnet square...and solve.

Answer 3

? above me ^^ indexed all of them :) i merely wanted to function polymorphic characteristics (the place there are various alleles for one gene) e.g. drosophila have 7 alleles for eye shade (wild form, white eosin, white apricot, white, vermillion, purple and sepia) *yet undergo in ideas somebody basically has 2 alleles - one on each homologous chromosome! additionally, the atmosphere performs an substantial section in the expression of genes!! e.g nutrients and top, some plant lifestyles (like hydrangea) are purple in alkaline soils and blue in acidic soils

Answer 4

The principles that govern heredity were discovered by a monk named Gregor Mendel in the 1860's. One of these principles, now called Mendel's law of segregation, states that the alleles for a trait separate when gametes are formed. These allele pairs are then randomly united at fertilization. Mendel arrived at this conclusion by performing monohybrid crosses. These were cross-pollination experiments with pea plants that differed in one trait, for example pod color.

Mendel began to wonder what would happen if he studied plants that differed in two traits. Would both traits be transmitted to the offspring together or would one trait be transmitted independently of the other? From his experiments Mendel developed the principle now known as Mendel's law of independent assortment.

Mendel's Law of Independent Assortment

Mendel performed dihybrid crosses (mating of parent plants that differ in two traits) in plants that were true-breeding for two traits. For example, a plant that had green pod color and yellow seed color was cross-pollinated with a plant that had yellow pod color and green seeds. In this cross, the traits for green pod color (GG) and yellow seed color (YY) are dominant. Yellow pod color (gg) and green seed color (yy) are recessive.

The resulting offspring or F1 generation were all heterozygous for green pod color and yellow seeds (GgYy).


(Figure A) Image Credit: Steve Berg, used with permission.

Mendel then allowed all of the F1 plants to self-pollinate. He referred to these offspring as the F2 generation. Mendel noticed a 9:3:3:1 ratio. About 9 of the F2 plants had green pods and yellow seeds, 3 had green pods and green seeds, 3 had yellow pods and yellow seeds and 1 had a yellow pod and green seeds.


(Figure B) Image Credit: Steve Berg, used with permission.

Mendel performed similar experiments focusing on several other traits like seed color and seed shape, pod color and pod shape, and flower position and stem length. He noticed the same ratios in each case. From these experiments Mendel formulated what is now known as Mendel's law of independent assortment. This law states that allele pairs separate independently during the formation of gametes. Therefore, traits are transmitted to offspring independently of one another.

Genotype and Phenotype

In Mendel's experiment with pod color and seed color (Figure A) we see that the genotype or genetic makeup of the F1 plants is GgYy. The phenotypes or expressed physical traits are green pod color and yellow seed color. Both of these traits are dominant.

The F2 generation pea plants (Figure B) show two different phenotypes for each trait. Pod color is either green or yellow and seed color is either yellow or green. There are nine different genotypes:

F2 Genotypes F2 Phenotypes
GGYY, GGYy, GgYY, GgYy Green pod, Yellow seeds
GGyy, Ggyy Green pod, Green seeds
ggYY, ggYy Yellow pod, Yellow seeds
ggyy Yellow pod, Green seeds
By looking at dihybrid crosses, Mendel established his law of independent assortment. This law states that one gene's inheritance is not affected by that of another.

The most important principle of Mendel's law of independent assortment is that the emergence of one trait will not affect the emergence of another. While his experiments with mixing one trait always resulted in a 3:1 ratio (Fig. 1) between dominant and recessive phenotypes, his experiments with mixing two traits (dihybrid cross) showed 9:3:3:1 ratios (Fig. 2). Mendel concluded that each organism carries two sets of information about its phenotype. If the two sets differ on the same phenotype, one of them dominates the other. That way, information can be passed on through the generations, even if the phenotype is not expressed (F1 generations, figures 1 and 2).

Mendel's findings allowed other scientists to simplify the emergence of traits to mathematical probability. A large portion of Mendel's findings can be traced to his choice to start his experiments only with true breeding plants. He also only measured absolute characteristics such as color, shape, and position of the offspring. His data was expressed numerically and subjected to statistical analysis. This method of data reporting and the large sampling size he used gave credibility to his data. He also had the foresight to look through several successive generations of his pea plants and record their variations. Without his careful attention to procedure and detail, Mendel's work could not have had the impact it made on the world of genetics.