Take out paper for notesTake out paper for notesAnswer the following questions Answer the following questions at the beginning of your notesat the beginning of your notes

Don’t look up the answers…make an educated guess!Don’t look up the answers…make an educated guess!

1.1. What do the letters DNA stand for?What do the letters DNA stand for?

2.2. What is DNA made of?What is DNA made of?

3.3. Where can you find DNA?Where can you find DNA?

If your index cards are done, turn them in today for 2pts EC, If your index cards are done, turn them in today for 2pts EC, otherwise they are due tomorrow.otherwise they are due tomorrow.

Turn in your 2 worksheets that were due Mon if you didn’t Turn in your 2 worksheets that were due Mon if you didn’t alreadyalready

Ch. 11 DNA and GenesCh. 11 DNA and Genes History of DNA History of DNA

1800’s Mendel determined that offspring 1800’s Mendel determined that offspring inherited traits from parentsinherited traits from parents

1944 Biomolecule that was involved with 1944 Biomolecule that was involved with heredity was heredity was DNADNA (originally proteins were (originally proteins were thought to pass on traits because DNA thought to pass on traits because DNA was too simple)was too simple)

Rosalind Franklin Rosalind Franklin and and Maurice WilkinsMaurice Wilkins took took diffracted diffracted photographs of DNAphotographs of DNAX-rays were passed X-rays were passed through DNA crystals, through DNA crystals, the X-rays were bent the X-rays were bent by the atoms in the by the atoms in the DNA molecule DNA molecule producing an image producing an image of the shapeof the shape

1953 1953 Watson Watson & & CrickCrick developed a model of developed a model of DNA using the DNA using the diffraction diffraction photographs taken by photographs taken by Rosalind FranklinRosalind Franklin

Double HelixDouble Helix = DNA = DNA comes in 2 long comes in 2 long strands that wrap strands that wrap around each other, around each other, “spiral staircase”“spiral staircase”

Why is DNA so important?Why is DNA so important?

DNA is known as DNA is known as “blueprint of life”“blueprint of life”

DNA contains DNA contains instructions for instructions for making making proteinsproteins within the cellwithin the cell

Genes Genes are on our are on our chromosomeschromosomes, , chromosomes are chromosomes are made of made of DNADNA

Important for all life Important for all life on Earth, makes each on Earth, makes each individual plant or individual plant or animal uniqueanimal unique

Helps us understand Helps us understand diseases better & find diseases better & find potential curespotential cures

Better food cropsBetter food crops

DNA NucleotidesDNA Nucleotides

DNA is a DNA is a nucleic acid nucleic acid made from subunits made from subunits called called nucleotidesnucleotides

NucleotideNucleotide = 3 parts: = 3 parts: 1. 1. five-carbon sugarfive-carbon sugar, , 2. 2. phosphate groupphosphate group, , 3. 3. nitrogenous basenitrogenous base – DeoxyriboseDeoxyribose = the 5-C = the 5-C

sugar in a DNA sugar in a DNA nucleotidenucleotide

How the Double Helix stays How the Double Helix stays togethertogether

Double HelixDouble Helix has two has two strands that twist strands that twist together together

One strand of DNA is One strand of DNA is like one half of a zipperlike one half of a zipper– The backbone of the

molecule is alternating phosphates and deoxyribose sugar

– The teeth are nitrogenous bases

phosphates

deoxyribose

bases

One strand of DNA One strand of DNA (half of a zipper) is (half of a zipper) is a a polymerpolymer of of nucleotidesnucleotides– Remember:Remember:– NucleotideNucleotide = 3 parts: = 3 parts:

1. 1. five-carbon sugarfive-carbon sugar, , 2. 2. phosphate groupphosphate group, , 3. 3. nitrogenous basenitrogenous base

One strand of DNA One strand of DNA has millions of has millions of nucleotidesnucleotides

Do the following:Do the following: Compare/contrast Compare/contrast

the the nitrogenousnitrogenous bases in a space in bases in a space in your notesyour notes

Nitrogenous bases

Nitrogenous (Nitrogen) BasesNitrogenous (Nitrogen) Bases

DNA has four different basesDNA has four different bases

CytosineCytosine CC

ThymineThymine TT

AdenineAdenine AA

GuanineGuanine GG

You will need to memorize these!!You will need to memorize these!!

2 categories of 2 categories of Nitrogenous BasesNitrogenous Bases

PurinesPurines = double = double ring bases, ring bases, A and GA and G

PyrimidinesPyrimidines = single = single ring bases, ring bases, T and CT and C

Complementary BasesComplementary Bases

Nitrogenous bases Nitrogenous bases on the 2 strands of on the 2 strands of DNA pair up with DNA pair up with one anotherone anotherCytosine (C)Cytosine (C) pairs pairs with with Guanine (G)Guanine (G) with with 3 Hydrogen 3 Hydrogen BondsBondsAdenine (A)Adenine (A) pairs pairs with with Thymine (T)Thymine (T) with with 2 Hydrogen 2 Hydrogen BondsBonds

DNA ModelDNA Model