The Nucleus and DNA

Nucleus the most prominent organelle in a cell, housing and protecting its DNA and directs the synthesis of ribosomes and proteins

Deoxyribonucleic Acid (DNA) A molecule that carries genetic instructions used in the development, functioning, and reproduction of all living things The genetic material in DNA determines how traits are passed from one generation to the next DNA is unique to each individual DNA is a practical tool in various fields such as forensics and medicine

Deoxyribonucleic Acid (DNA) The length of DNA in one human cell is estimated to be over 6 ft in length when stretched out. In 1953, Watson and Crick completed a model of the DNA molecule. The Watson-Crick model of the DNA molecule can be compared to a ladder that has been twisted into a continuous spiral, this shape is known as a double helix.

Deoxyribonucleic Acid (DNA) Within the DNA of each cell, human genome is approximately 6500 million base pairs Base pairs (Guanine and Cytosine, Adenine and Thymine) hold the chains together

Chromatin A combination of DNA and proteins and describes the material that makes up chromosomes Chromosomes condense out of chromatin during cell division

Chromosomes DNA is organized into larger structures called chromosomes They are only distinguishable when the cell is ready to divide Humans have a full set of 46 chromosomes (23 pairs) Each chromosome has a different number of genes that code for various traits and variation in genes across a population results in genetic diversity Genes provide the information for our bodies to create proteins, hormones, and sugars

Chromosomes Chromosomes are also organized in two sister chromatids (You get one copy from your mother and one copy from your father) These sister chromatids are exact copies of each other Each pair of chromosomes code for the same genes, but may or may not have the same alleles of each gene.

Karyotype a representation of the number and appearance of chromosomes in the nucleus They are used to determine whether a diagnosed birth defect is due to a chromosomal abnormality or to predict whether a fetus may be at risk for a genetic disorder.

Autosomes and Allosomes Humans have 22 sets of autosomal chromosomes Allosomes are the sex chromosomes; involved in the determination of the sex of the offspring XX = female XY = male

Gregor Mendel Postulated the existence of genes to explain how traits are inherited Alleles are different forms of the same gene and account for the heritable difference among individuals Studied pea plants, analyzing seven of their characteristics: height, pod shape and colour, seed shape and colour, and flower position and colour