Structure and Function of DNA We have come a long way on that old molecule [DNA].

Brief Review: What type of macromolecule is DNA or RNA? What monomer makes up DNA? What are the components of this monomer? What organelle houses DNA? What is the division of this organelle called? What part of the cell cycle is DNA replicated in? Nucleic acid Nucleotides sugar, phosphate, nitrogenous base Nucleus Mitosis Interphase, S phase

What are the differences in DNA and RNA StructureSugarBases DNAdouble stranded deoxyriboseadenine, thymine, guanine, cytosine RNAsingle stranded riboseadenine, uracil, guanine, cytosine

How was DNA discovered? James Watson and Francis Crick won the race to find the structure of DNA, and a Nobel prize in 1962 Maurice Wilkins was later also added to the prize list for his contributions

How was DNA discovered? cont’d Wilkins was also working on the problem Rosalind Franklin worked in Wilkins lab taking X-ray diffraction pictures of DNA Her pictures supported the DNA structure She was never given credit as she died before Wilkins name was added due to X- ray exposure

How is DNA structured? DNA is double stranded Backbone made of alternating phosphates and deoxyribose sugars Contains 4 bases (“rungs of the ladder”) Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Looks like a twisted ladder

How is DNA studied? Genetics –branch of biology that studies heredity Heredity – how traits are passed from parent to offspring Traits – characteristics of an organism ex. body shape, cell shape, proteins produced nucleic acids contain information that determine traits made of?

What are nucleic acids? Macromolecules made of nucleotides nucleotides are made up of a sugar backbone, a phosphate, and a nitrogenous base cells contain 2 types DNA (deoxyribonucleic acid) RNA (ribonucleic acid) Both contain 5 carbon sugars arranged in a ring

What is the function of DNA? Carries genetic information instructions for cellular activity and making necessary proteins What are the different structures of proteins? How do those structures interact?

Where is DNA? Where do you find DNA in prokarotes? What are small circular pieces of DNA in prokaryotes called? Where do you find DNA in eukaryotes? In eukaryotes, DNA is coiled into structures called chromosomes What is DNA normally when it is uncoiled? chromatin

How is DNA structured? made of linked nucleotides nucleotides are all the same except with a different nitrogenous base A C T G shaped like a twisted ladder = double helix strands of alternating deoxyribose sugars and phosphates rungs are one of four bases

How do the bases of DNA work? Chargaff’s rule: A always pairs with T C always pairs with G These are called complementary base pairs Held together by weak hydrogen bonds sequence of bases stores genetic information Build a DNA Molecule

How does DNA determine traits? traits are based on proteins produced in an organism proteins are not made directly by DNA information is copied from DNA to an RNA molecule (transcription) RNA carries information to ribosomes (translation) What do these make? What to they make proteins from?

Why is DNA replicated? Cells are alive so what must they do? During the cell cycle, when is DNA replicated? DNA is replicated so that each daughter cell has identical DNA to the parent cell

How is DNA replicated? Step 1: helicase enzymes break H bonds and unwinds DNA down the middle 2 going in opposite directions Step 2: DNA polymerase enzymes from cytoplasm join complementary base pairs to make a matching strand synthesized from 5’ to 3’

What is the result of DNA replication? 2 strands of identical DNA each strand is half old DNA and half new DNA semiconservative process PRACTICE ON YOUR PAPER

Assignment! DNA replication worksheet Use your notes to help you with the information… IT IS ALL HERE

What are chromosomes? chromosomes – are structures of containing genetic information passed down from parent to offspring DNA is a long molecule, nucleus of a human contains over a meter of DNA! coiled to save space so DNA can fit in the nucleus

How are chromosomes and genes related? Each specie has a specific number of chromosomes segments of chromosomes (or DNA) that code for proteins are called genes many genes on 1 chromosome organisms have many more inherited genes that chromosomes

How is DNA compared between species? Genetic information varies between species DNA of all organisms have some things in common The more common things they share the more closely related they are Similarity determined by how many genes are shared AND how alike those genes are Smaller variations are also present among members of the same species

Assignment! DNA extraction You will need: strawberry ziploc bag DNA extraction buffer cheesecloth funnel test tube stirring rod alcohol