REVIEW ______________________ contains all the genetic instructions to create all the cells in your body. What Does DNA stand For? ________ -part of a DNA molecule that determines the inherited trait. ____________ - condensed DNA, acts as a storage unit. DNADNA Deoxyribonucleic Acid GENE Chromosome

REVIEW Where in the cell are chromosomes located?Where in the cell are chromosomes located? How many pairs of chromosomes do we as Humans have?How many pairs of chromosomes do we as Humans have? How many chromosomes do you get from each parent?How many chromosomes do you get from each parent? Nucleus 23 pairs of Chromosomes 23 chromosomes from each parent

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History of Genetics People have known about inheritance for a long time. -children resemble their parents -selective breeding of dogs (for breeds) and cattle (best milk or meat)

IMPORTANT Discoveries Three major events in the mid-1800’s led directly to the development of modern genetics: 1)Charles Darwin 2) Gregor Mendel 3) Friedrich Miescher

IMPORTANT Discoveries Three major events in the mid-1800’s led directly to the development of modern genetics. 1859: Charles Darwin publishes The Origin of Species, which describes the theory of evolution by natural selection. This theory requires heredity to work. 1866: Gregor Mendel publishes Experiments in Plant Hybridization, which lays out the basic theory of genetics. (Law of Inheritance) 1871: Friedrich Miescher isolates “nucleic acid” from bread mold.

Major Events in the 20 th Century 1910: Thomas Hunt Morgan: proved that genes are located on the chromosome 1941: Beadle and Tatum - show how genes direct the synthesis of enzymes that control metabolic processes “1 gene = 1 enzyme” 1952: Hershey and Chase - conducted experiments which helped to confirm that DNA was the genetic material that transported traits. Please Copy

More 20 th Century Events 1953: Watson and Crick - determine the structure of the DNA molecule, which leads directly to knowledge of how it replicates 1966: Marshall Nirenberg solves the genetic code, showing that 3 DNA bases in a row code for one amino acid. 2001: Sequence of the entire human genome is announced. Please Copy

Summarizing What we’ve learnt

HOMEWORK Please copy into your diary: Complete Worksheet for next lesson First ½ is the most important