Nucleotides in DNA

The study of modern genetics depends on an understanding of the physical and chemical characteristics of DNA. Some of the most fundamental properties of DNA emerge from the characteristics of its four basic building blocks, called nucleotides. Knowing the composition of nucleotides and the differences between the four nucleotides that make up DNA is central to understanding DNA’s role in living systems.

Read more

genotype phenotype probabilities

Patterns of genetic inheritance obey the laws of probability. In a monohybrid cross, where the alleles present in both parents are known, each genotype shown in a Punnett Square is equally likely to occur. Since there are four boxes in the square, every offspring produced has a one in four, or 25%, chance of having one of the genotypes shown.

Read More

Punnett Square

During sexual reproduction, a parent is equally likely to pass on to its offspring either of the two alleles it has at each genetic locus. This makes it possible to list and estimate the probability of specific genotypes being produced from the pairing of two individuals. Given two allele from each parent, four allele combinations are possible. These combinations and their probabilities can be readily visualized using a Punnett square.
Read More

Alleles, genotype and phenotype

Genetics is the study of the organization, expression and transfer of heritable information. The ability for information to pass from generation to generation requires a mechanism. Living organisms use DNA. DNA is a chain, or polymer, of nucleic acids. Individual polymers of DNA can contain hundreds of millions of individual nucleic acids molecules. These long DNA strands are called chromosomes. Information is contained in the order of the individual nucleic acids that make up the DNA polymer. The use of DNA as the information molecule is a universal property of all life on Earth. Genetic information is read by our cellular machinery and allows our bodies to synthesize the many enzymes and proteins required for life