A phenotype is an individual’s observable traits, such as height, eye color, and blood type. The genetic contribution to the phenotype is called the genotype. Some traits are largely determined by the genotype, while other traits are largely determined by environmental factors.

There are four possible combinations of gametes for the AaBb parent. Half of the gametes get a dominant A and a dominant B allele; the other half of the gametes get a recessive a and a recessive b allele. Both parents produce 25% each of AB, Ab, aB, and ab.

Altogether, there are four possible gametes: AB, Ab, aB and ab.

2

four gametes

haploid number

n is the haploid chromosome number, 23 (chromosomes in germ cells) and the diploid (2n = 46, chromosomes in somatic cells (one set from each parent)).

Hence, an organism with cells 2n=6 would be an organism that has only 6 chromosomes, or 3 pairs. Meiosis is a reduction division in that it produces haploid (n) daughter cells, each with half the genetic information of a diploid cell.

dent777. Tetrad = 2 homologous chromosomes (aka 4 chromatids) are paired and appear as one structure in Metaphase of Meiosis I. Humans have 46 chromosomes, but if you pair the homologs together you will have 23 tetrads.

By the end of meiosis, four cells will be created, each with one of the chromatids from the tetrad. Also, don’t forget that there are 23 different tetrads formed during meiosis because each chromosome 1-23 will have a tetrad.

A bivalent is one pair of chromosomes (sister chromatids) in a tetrad. A tetrad is the association of a pair of homologous chromosomes (4 sister chromatids) physically held together by at least one DNA crossover.

Unordered tetrads with four spores The map distance between two linked genes are calculated according to the following formula: cM = 50 * (TT + 6 * NPD) / ( PD + NPD + TT ). Here PD stands for parental ditype, NPD stands for non-parental ditype, and TT stands for tetratype.

In a real cell, chromosomes would not be visible during interphase of the cell cycle. During prophase I and metaphase I of meiosis, a chromosome consists of a tetrad (4 chromatids or 4 DNA molecules) and is reduced to two chromatids (2 DNA molecules) by the time metaphase II occurs.