Genetics is the science of heredity and variation in living organisms.

Why the observable trait the organism has is called it's "phenotype".When organisms are heterozygous, often one allele is caled "dominant" asit's qualities"dominate" the "phenotype" of the orginism,while the other one is called "recessive"as it's qualities "recede"and are not observed. Dominate alleles are often abbreviated with a capital letter, while recessive alleles are given a lower case version of the same letter. Some alleles do not have complete dominance and insed have incomplete dominance by expressing an intermediate phenotype, or codominance by expreaaing both alleles at once.

In mammals the sex chromosomes are called X and Y with the X chromosomes being much larger then the Y chromosome. Females have two X chromosomes and males have X chromosomes and one Y chromosome. All other chromosomes other than sex chromosomes are called autosomal chromosomes.pigs.jpgAfter collection of semen, it is necessary to evaluate the ejaculate to determine how many doses can be made. First, the volume and sperm concentration need to be determined. The number of doses is influenced by the number of doses actually needed and the number of sperm cells contained in the ejaculate. Other factors to be considered include conception data on the boar and physical appearance (morphology) of the sperm cells.If a pigs cromosomes or a persons cromosomes are missing than it will be deformed like the picture on the right.

The pictures on the left show a sow and a boar which you would take and breed together and get a cross litter. Because you see two different kinda this means that thier will be a pig that looks like the one below the two pigs on the right

york_sow.jpg hamp.jpg


This chart at the right is a punnett chart A Punnett chart is a chart which shows/predicts all possible gene combinations in a cross of parents (whose genes are known). Punnett squares are named for an English geneticist, Reginald Punnett. He discovered some basic principles of genetics, including sex linkage anpunnett_chart.jpgd sex determination. We can use this to determinewhat kind of litter your sow will have. Here are the steps in making a punnett chart. And this is a sample problem!

*In pea plants (which Gregor Mendel studied), tall pea plants are dominant over short pea plants. Using Punnett Squares, you can predict the genotypes and phenotypes of the offspring of a cross between a homozygous (purebred) tall pea plant and a homozygous (purebred) short pea plant.

Step 1.

Designate letters which will represent the genes/traits. Capital letters represent dominant traits, and lowercase letters represent recessive traits. T

tall t

short Step 2.

Write down the genotypes (genes) of each parent. These are often given to you or are possible to determine.

TT X tt

(tall) (short) - both homozygous (same) or purebred

Step 3.

List the genes that each parent can contribute.

Parent 1 Parent 2 external image square1.gif

Step 4.

Draw a Punnett square - 4 small squares in the shape of a window. Write the possible gene(s) of one parent across the top and the gene(s) of the other parent along the side of the Punnett square.

external image square2.gif

Step 5.

Fill in each box of the Punnett square by transferring the letter above and in front of each box into each appropriate box. As a general rule, the capital letter goes first and a lowercase letter follows.

external image square3.gif

Step 6.

List the possible genotypes and phenotypes of the offspring for this cross.

The letters inside the boxes indicate probable genotypes (genetic makeup) of offspring resulting from the cross of these particular parents. There are 4 boxes, and the genotypic results can be written either as fractions or percents. In this case, all 4 boxes out of the 4 are showing the Tt genotype. Therefore, each of the offspring has a 4/4 or 100% chance of showing the Tt genotype.

We have also written the phenotype (physical appearance) in each box under the genotype.