Genetics

What’s it all about?

Questions: what we will answer. What is genetics? How do chromosomes work? What is the history of genetics? Genetics and probability: What are Punnett Squares? How does the study of genetics affect our lives? What is the future of genetics?

Genetics is the science of heredity. Heredity - the passing of traits from parents to offspring. Traits - characteristics or features of an individual, not always apparent or obvious

Chromosomes: the mechanisms that make it all possible Chromosomes are in pairs, found in the nuclei of cells. A single chromosome is composed of many genes, which determine hereditary traits. Chromosomes are made of a molecule called deoxyribonucleic acid (DNA). Human cells contain 46 (23 pairs) of chromosomes totally about 35,000 genes on them. There are 2 to the 23rd power (or 8,388,608) possible gene combinations. Gametes (sex cells : sperm and eggs) contain only half the number of chromosomes.

Chromosomes are made of DNA. Segments of chromosomes are called genes.

Deoxyribonucleic Acid (DNA) The double helix shape resembles a spiral staircase. The shape was first correctly identified in 1953 by James Watson and Francis Crick, who then won the Nobel prize in The unique shape allows the molecule to “unfold” or “unzip” along a portion of the molecule. When a strand of DNA “unzips”, an exact copy of the “unzipped” portion can be replicated (copied) DNA replication is how cells make proteins, which build new cells, repair cells, and many other functions that keep the cells functioning.

DNA replication (making copies) The unique shape of DNA allows the molecule to “unzip” along a portion of the strand. When a strand of DNA “unzips”, an exact replica of the “unzipped” portion can be replicated (copied) DNA replication is how cells make proteins, which build new cells, repair cells, and countless other functions that keep cells functioning. DNA replication is happening constantly in cells.

DNA vs RNA Double-stranded Longer Master template for all a cell’s information Usually single-stranded Shorter, simpler Made using DNA as the template mRNA, tRNA, snRNA (different forms)

One cell’s DNA unraveled is estimated at 4-12 feet long! Total in one human body? billion miles, or enough to travel from Earth to the Sun 70 times!!

Click here to watch this short video (4:05) on Watson and Crick, and the sad story of another great scientist, Rosalind Franklin