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.

DNA

Deoxyribonucleic AcidGENE

Chromosome

REVIEW• Where in the cell are Where in the cell are

chromosomes located?chromosomes located?

• How many How many pairspairs of chromosomes of chromosomes do we as Humans have?do we as Humans have?

• How many chromosomes do you How many chromosomes do you get from each parent?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 DiscoveriesThree 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 20th 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.

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More 20th 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.

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Summarizing What we’ve learnt

HOMEWORK

• Please copy into your diary:

• Complete Worksheet for next lesson

First ½ is the most important