Lesson 1 DNA u2013 The Molecule of Life.pdf - UNIT 3...

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UNIT 3: Lesson 9-- DNA - The Molecule of LifeOverviewIn this unit, you will look at molecular genetics. You will learn about the most important molecule in genetics, which isDNA. You will study DNA structure and learn how DNA is replicated before mitosis. You will also learn about scientistswho contributed to our understanding of DNA. You will also have the opportunity to extract DNA for yourself.DNA - The Molecule of LifeLessonIn Unit 1, you studied the macromolecules that living things are composed of. Now let’s look at one type ofmacromolecule - nucleic acids. Nucleic acids store genetic information and enable protein production. The include DNAand RNA and are made up ofnucleotides.DNA StructureIn the last 20 years DNA has become a common term. It is in the news, on television and very important in solvingcrimes. Most people recognize the word and know that DNA is in our cells. DNA stands fordeoxyribonucleic acid. DNAcarries hereditary information that is passed on from one generation to the next. It is found in all living organisms – frombacteria to plants to mammals. It holds the chemical message for producing every part of the organism. It regulates lifeby carrying the directions for growth, repair, and replacement of cells and their parts. Let’s look at DNA structure inmore detail.DNA is the genetic material that carries all the instructions to makean individual and it carries the instructions to make every detailabout you – your proteins, hair colour, eye colour, etc.It is found in the nucleus of every cell in the body. It is also found inprokaryotic cells that have no nucleus.There are a lot of instructions, so in order for all the information tofit, DNA is packaged tightly in the cell in the form ofchromatin.When it is unwound and stretched out, it looks like a ladder that hasbeen twisted. This structure is called theDNA double helix. It isdouble because it is made of two strands of DNA that connect andlook like a ladder. It is a helix because it has a natural twist to itthat causes the molecule to spiral.DNA Double HelixA Twisted LadderDid you know?You are made up of trillions of cells. Each of those cells contains your DNA. That is a lot of DNA, and if stretchedout end to end, it could reach from the earth to the moon.The structure of DNA was first determined by James Watson and Francis Crick. They were awarded the Nobel prize formedicine in 1962 for making one of the most prominent discoveries of the 20th century.NucleotidesDNA is a macromolecule. The monomer that makes up DNA is called anucleotide.A nucleotide consists of 3 parts:
1.5 carbon pentose sugardeoxyribose in DNA/ ribose in RNA2.1 to 3 phosphate groups3.nitrogenous basePurines: Adenine (A) and Guanine (G)Pyrimidines: Cytosine (C) and Thymine (T)In DNA, there are 4 nitrogenous bases:AdenineGuanineCytosineThymine(uracil in RNA)The nitrogen bases are found facing the middle ofthe double helix and form the rungs of the DNAladder.

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