DNA Deoxyribonucleic Acid

Nature vs. Nurture?

DNA We know traits are inherited but how are they inherited?

Chargaff ’ s Rule

X-ray Evidence 1952 Rosalind Franklin took an x-ray diffraction to take picture of DNA shape Picture gave clues to structure of DNA

Watson & Crick Watson & Crick made a model of DNA structureWatson & Crick made a model of DNA structure Won Nobel PrizeWon Nobel Prize

Watson and Crick ’ s model of DNA was a double helix

The Components & Structure of DNA Nucleotide 1. 5-carbon sugar deoxyribose 2. phosphate group group 3. nitrogenous base base i. Adenine ii. Thymine iii. Guanine iv. Cytosine

Nucleotides are monomers! Nucleotides are linked in a strand The sides of the “ladder” are phosphates and the sugar deoxyribose

- Sugar & phosphate form backbone - The bases form the “ steps ” of ladder, held together by Hydrogen bonds C-G = 3 hydrogen bonds A-T = 2 hydrogen bonds

How is DNA Packaged? DNA is wrapped around proteins DNA is wrapped around proteins called histones forming beads called histones forming beads These beads pack together, forming These beads pack together, forming nucleosomes. nucleosomes. These coil to make chromatin These coil to make chromatin When the chromatin (stringy DNA) coils it make a chromosome When the chromatin (stringy DNA) coils it make a chromosome

DNA Replication DNA Replication Think about DNA ’ s structureThink about DNA ’ s structure Perfect for use of replication!Perfect for use of replication! Each original sideEach original side is a Template is a Template

Parent Strand Or Template Daughter strand

Before a cell divides, it duplicates its DNA in a process called replication. This makes sure each cell will have a complete set of DNAThis makes sure each cell will have a complete set of DNA

How is it done?! 1. DNA is unwound 2. DNA helicase enzyme unzips the weak hydrogen bonds between base pairs hydrogen bonds between base pairs 3. DNA polymerase enzyme matches up nucleotides to complement the other side nucleotides to complement the other side 4. Strands checked for error

“ Semi-conservative ” - why?

Replicate your own DNA 1. Take piece of paper and fold is vertically NOW REPLICATE Label 1.Template/ Parent Strand 2.Hydrogen Bonds 3.Complementary Base Pairing 4.DNA Helicase 5.DNA Polymerase 6.Daughter Strands

Central Dogma DNA  RNA  Protein DNA gives the instructions for RNA which gives the instructions to make proteins

Central Dogma

What is a gene? Part of the DNA (letters/bases) that code for a particular protein

Genotype vs. Phenotype Genotype, genetic makeup, is the sequence of bases in the DNA Phenotype, traits, due to proteins

Proteins we learned! Structural Keratin ( hair, skin and nails ) Muscles Reactions Enzymes (lactase) Signal Insulin, human growth hormone Hemoglobin- carriers oxygen in your red blood cells

RNA vs DNA RNA Ribonucleic Acid Ribose Sugar A,C,G,U –U = Uracil Single Stranded

Transcription 1.RNA copies the message from DNA - Called messenger RNA ( mRNA) 2.Complementary base pair ( NO T!! In RNA) 3.Only copies a gene of the DNA 4.mRNA Leaves the Nucleus

Transcription Enzyme that build RNA strand RNA polymerase

RNA Splicing Introns stay in the nucleus Exons join (splice) together and exit – final mRNA

Translation mRNA to Protein 1. mRNA goes to the Ribosome –Each 3 letters of the mRNA is called a codon 2. Each mRNA codon bonds to a tRNA (transfer RNA) anticodon –Complementary Base paring rules 3. tRNA carries the amino acid which builds the polypeptide (protein) 4. Begins with mRNA start codon AUG and ends with mRNA STOP Codon

Introduction Worksheet n/dna/transcribe/ n/dna/transcribe/ Transcribe and Translate a Gene

SHOW REAL TIME Great Simple Video!!

Mutations cell.html

1 base change in 438-base sequence. Change in DNA, change in RNA, change in Amino Acid Hemoglobin protein does not work properly to carry oxygen.

Tay Sachs Cracking the Code:17:00-20:00 Inherited genetic mutation Mutation in a gene that codes for an enzyme protein that breaks down fatty acids in the brain

Mutation Change in the nucleotide Sequence ( letters/bases) of a gene 1.Base Substitution (can be bad or silent) 2. Base Addition/ Deletion- worse - Frameshift mutation= alter group of 3 Affects the function of the PROTEIN

ADDITION THE CAT ATE THE RAT THE ACA TAT ETH ERA T

Mutagens cause Mutations Xray, UV light, smoking chemicals, pesticides Sometimes GOOD? How so?

Example of Inherited DNA Mutations: Diseases

Mutations