Presentation on theme: "Ch. 5: DNA and Modern Genetics!!"— Presentation transcript:
1Ch. 5: DNA and Modern Genetics!! “The Molecule of Life”
2Do Now!! What is DNA? Why is it important? List three places in the body where you can find DNA.
3Objectives To explain the structure of DNA To identify the different types of bases how they pair upTo list the scientists involved in discovering DNA
4So what is DNA? A molecule that stores information What do the letters stand for?DEOXYRIBONUCLEIC ACIDWhere is it found?In the nucleus (or nuclear region in prokaryotes)What is it used for?Blueprints of your genes/traitsTo make proteins!
5What is DNA Made of? Repeating units of nucleotides Nucleotides are made of 3 components:5 carbon sugar (Deoxyribose)Phosphate GroupNitrogenous base
6Nitrogenous Bases Purines Have 2 rings (double ring structure) Adenine (A)Guanine (G)PyrimidinesHave 1 ring (single ring structure)Thymine (T)Cytosine (C)Uracil (U) instead of Thymine in RNA
8Chargaff’s Rule Erwin Chargaff Discovered that A pairs with T and C pairs with G.Chargaff’s rule:A=T, C=GAmounts vary between species
9What is the complimentary sequence?? ATGCTAATTCGCATCG
10Do Now! TGACCAGTTTAGCTAGGGC What makes up a nucleotide? What is the difference between a purine and a pyrimidine? Identify the purines and pyrimidines we talked about!Please write the complementary sequence:TGACCAGTTTAGCTAGGGC
11ObjectivesTo identify the scientists who contributed to the discovery of DNATo define the structure of DNATo complete a DNA structure worksheet
12Rosalind Franklin Used X-ray diffraction to determine shape of DNA X-rays aimed at molecule, bounce off electronsDetermines the molecule’s shape
13Rosalind Franklin Took now famous photo 51 Data indicated that DNA was a double helix shapeHelped Watson and Crick solve the structure of DNA
14Watson and Crick Built a model of the double helix DNA molecule: two outside strands consist of alternating sugar and phosphate moleculesthymine and adenine bases pair to each other by two hydrogen bondscytosine and guanine bases pair to each other by three hydrogen bonds*Go back to your DNA sequence!
15DNA Structure DNA looks like a twisted ladder! Rails: alternating deoxyribose sugars and phosphatesRungs (steps): base pairs (C-G, A-T) bonded by hydrogen bonds
17Objectives To review DNA structure To define DNA replication To identify the steps of DNA replication
18DNA Replication Allows cells to get an exact copy of DNA. Replication: Parent strands separate, serve as templatesDaughter DNA produced (have one DNA strand from parent and one new strand)
19Steps to Replication 1- The two DNA strands unwind and separate: Helicase- enzyme that separates the DNA molecule
20Steps to Replication2- Nucleotides match up base by base with the nucleotides on each TEMPLATE DNA strand:All of the C’s pair with the G’s and all of the A’s pair with the T’s.DNA Polymerase: enzyme that creates new DNA by assembling nucleotides
21Steps to Replication3- Each new daughter DNA molecule has one strand of new DNA and one from the original parent strand.
26We need to make RNA to make proteins!! What is RNA?Ribonucleic AcidHow is it different from DNA?Single strandedIndefinite shapeUses “uracil”Contains Ribose
27Types of RNA 1. Messenger RNA (mRNA): Linear Located in both the nucleus and the cytoplasmBrings genetic code from DNA to the ribosome to make protein (in cytoplasm)Contains codons (every 3 letters, ex. AUG is 1 codon)
28Types of RNA 2. Ribosomal (rRNA): Located within the ribosome Helps make the structure of the ribosome
29Types of RNA 3. Transfer (tRNA) Located in the cytoplasm Clover-like loop structureBrings amino acids (attached to top of tRNA) to ribosome to help build proteinsContains anticodon (3 letter sequence at bottom of tRNA, complements codon)
30The Central Dogma! DNA RNA Protein Transcription: Occurs in nucleus Create (transcribe) mRNA from DNA templateTranslation:Occurs in cytoplasmTakes mRNA and makes proteins with the help of tRNA and ribosomes.
31Do Now!! Please take out your worksheet from last class and finish!
32Objectives To identify the steps of transcription. To understand the process of transcription and how mRNA is made.
33Transcription Gene: a distinct sequence of nucleotides Determines your traitsOnly individual genes are transcribed, not a whole DNA moleculeOccurs in the nucleusProduces mRNA
34TranscriptionStep 1: DNA molecule unwinds and separates just like in replication:RNA polymerase: enzyme that unwinds the DNA and assembles new nucleotides (makes RNA strand).
35TranscriptionStep 2: RNA nucleotides match up with their complimentary bases on the DNA template strand:RNA polymerase assembles these nucleotidesCreates a single stranded mRNA moleculePractice: Write the complimentary mRNA strand from this DNAATCGATGGCAAGCTA
36TranscriptionStep 3: mRNA detaches once entire gene is done and DNA rewinds:mRNA strand leaves nucleus through poresGoes to cytoplasm to help ribosomes make proteins*Delivers directions from DNA for how to make proteins*Many copies of RNA can be made from the same gene in a short period of time.
38Do Now!! With a partner, please complete the worksheet in front of you!
39Do Now!! What is the “Central Dogma”? What is transcription? Please transcribe the DNA sequence below:T A C C G A A T C G T A C G G A C T
40Objectives To define translation To identify the steps of translation To practice building amino acid sequences to form proteins
41Translation What happens in the steps before translation? What happens in translation?Where does this happen?
42TranslationStep 1: Translation begins when a ribosome attaches to the beginning of an mRNA molecule.*Translation MUST START AT THE LETTERS “AUG”:This is the START codon* Every 3 letters on the mRNA is called a “Codon” that codes for a specific amino acid.
44Do Now!! A U G C G G C U A A U U What is translation? Where does translation take place?Write the amino acid sequence this mRNA strand would form:A U G C G G C U A A U U
45Objectives To identify the steps of translation To practice the process of protein synthesis
46TranslationStep 2: A tRNA molecule carrying an amino acid matches up to a complementary codon in the mRNA on the ribosome:*tRNA molecules contain “Anticodons” which are 3 bases on bottom of tRNAAnticodons compliment codons on mRNA
47TranslationStep 3: The ribosome attaches one amino acid to another as it moves along the mRNA molecule.Amino acids are attached by PEPTIDE BONDS.
48TranslationStep 4: The tRNA molecules are released after the amino acids they carry are attached to the growing chain of amino acids.Return to cytoplasm to pick up another amino acid
49TranslationStep 5: The ribosome completes the translation when it reaches a stop codon:The newly made protein is then released.
50Do Now!! Please complete the worksheet in front of you!
51Objectives To define genetic mutation To identify the different types of genetic mutations
52What is a mutation? Mutation: a permanent change in a cell’s DNA Errors can occur when DNA is copiedUV light, X-rays, chemicals, etc. can cause mutations in DNA
53Types of mutations Substitution – Exchanges one base for another. Normal: ACAGAGMutated: ACAGGGInsertion – Extra base pairs are inserted.Normal: AATGAGMutated: AATGTGGAG
54Types of mutations (cont.) Deletion- Section of DNA is lost or deleted.Normal: CTGGAGMutated: CT___AGFrameshift- Message is no longer read correctly.Normal: THE FAT CAT ATE THE BIG RATMutated: HEF ATC ATA TET HEB IGR AT
55What happens when there is a mutation? Cells have different ways to repair mistakes:Proofreading enzymes can correct mismatched base pairsEX: DNA polymerase, exonuclease
56Do Now!! What are the three kinds of mutations? What is a frameshift?Are all mutations bad?
57ObjectivesTo discuss the effects of genetic mutations on protein synthesisTo complete a review protein synthesis worksheetTo simulate genetic mutations in a lab activity
58Mutations can have different effects The mutation has no effect:Amino acids have more than 1 codeThe effect of a mutation is minor:Could affect skin/eye/hair pigmentationThe effect of a mutation is great:Genetic disorder/disease
59Genetic disorders Sometimes passed from parents to offspring: Sickle Cell AnemiaCystic Fibrosis (CF)HemophiliaTay- Sachs DiseaseHuntington’s Disease (HD)Cancer
60Sickle cell anemia Mutation occurs on gene that codes for hemoglobin: Hemoglobin – a protein that carries oxygen in red blood cellsSubstitution mutation causes 1 amino acid to be replaced with another