DNA THE GENETIC MATERIAL OF LIFE UNIT 5 (CHAPTER 8 IN BOOK)

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1 DNA THE GENETIC MATERIAL OF LIFE UNIT 5 (CHAPTER 8 IN BOOK)

2 What is DNA? Deoxyribonucleic acid Molecule that stores genetic information in all organisms DNA is stored in the nucleus of your cells

3 DNA stands for: D: Deoxyribose N: Nucleic A: Acid DNA is too small to see, but under a microscope it looks like a twisted up ladder! Every living thing has DNA. That means that you have something in common with a zebra, a tree, a mushroom and a beetle!!!!

4 DNA Timeline 1866: Gregor Mendel shows that organisms have 2 copies for each heritable trait 1952: Hershey & Chase proved that DNA is the hereditary material for life 1952: First cloned animal the tadpole 1953: Watson and Crick proposed double helix model of DNA based on work of Rosalind Franklin

5 DNA Timeline Continued 1973: The first recombinant DNA experiments are successful a portion of one organism s DNA is inserted into another organism 1996: First adult mammal is cloned Dolly the sheep in Scotland 2000: First cloned monkey be stem cell separation, 5 piglets cloned using same technique

6 8.2: STRUCTURE OF DNA

7 DNA Structure DNA is a long chain made up of units called nucleotides Each nucleotide has three parts: Phosphate group (one phosphorus/3 oxygens) Deoxyribose (ring-shaped sugar) Nitrogen-containing base There are only four types of nucleotides based on what type of nitrogen base they have

8 Structure of Nucleotides Phosphate group Nitrogen Base: Adenine (A) Guanine (G) Cytosine (C) Thymine (T) Deoxyribose

9 One molecule of DNA contains BILLIONS of nucleotides, even though there are only 4 types of nucleotides: Adenine (A) Guanine (G) Thymine (T) Cytosine(C) The letter refers to the DNA bases as well as the nucleotide

10 Base Pairing DNA is a double helix structure this means that there are two strands of DNA that wind together like a twisted ladder The strands are bonded together at the bases based on base pairing rules: Adenine always bonds to thymine Guanine always bonds to cytosine

11 The bases always pair up in the same way Adenine forms a bond with Thymine Adenine Thymine and Cytosine bonds with Guanine Cytosine Guanine

12 Pairing up

13 THE DOUBLE HELIX bases sugarphosphate chain Remember DNA is like an Oreo Phosphates + sugars = cookies Bases = cream filling

14 The structure of DNA consists of two strands wrapped around each other in a double helix

15 Nucleotides linked together: C G Certain Nitrogen bases always link together: Adenine Thymine Cytosine Guanine Hydrogen Bonds A T Covalent Bonds

16 So if one strand is : A T C G A T A G C T A What is the other strand based on base pairing rules? T A G C T A T C G A T

17 8.3: DNA REPLICATION

18 DNA Replication Before a cell divides, it must make a copy of its DNA so that the new cell will have a full set of DNA

19 The steps of DNA Replication: 1. DNA is unwound a) Done by breaking the Hydrogen bonds that hold the strands together 2. DNA polymerase adds nucleotides, according to base pair rules 3. The strand is proofread as nucleotides are added, and mistakes can be fixed if the wrong base was added a) A mistake is called a mutation 4. DNA polymerase continues adding nucleotides until a STOP signal is reached

20 Parent Strand Parent Complement Parent Complement A T A T C G C G T A C G G C A T A T T A C G G C Stop The strands separate T C G A A T C G Stop + A G C T T A G C Stop Copies are made/attached

21 The strands separate

22 Each strand builds up its partner by adding the appropriate nucleotides

23 DNA Replication in action

24 Review Questions You need your CPS responders for this!

25 Which of the following are a part of nucleotides? A. deoxyribose B. phosphates C. Nitrogen bases D. All of the above [Default] [MC Any] [MC All]

26 Which of the following represent a correct pairing of bases? A. Adenine with thymine B. Adenine with guanine C. Guanine with thymine D. Thymine with cytosine [Default] [MC Any] [MC All]

27 Thymine, guanine, and sertocine are all DNA bases. A. True B. False

28 DNA replication occurs A. During cell division B. Before cell division C. anytime [Default] [MC Any] [MC All]

29 Which is the correct sequence for the complement strand to: A G G C T T A. C T T A G G B. G A A T C C C. T C C G A A D. A G G C T T [Default] [MC Any] [MC All]

30 8.4: TRANSCRIPTION

31 RNA RNA: ribonucleic acid Chain of nucleotides made of: Sugar Phosphate group Nitrogen-containing base It s a temporary copy of DNA that is used and then destroyed

32 DNA vs. RNA Both have a sugar, phosphate, & base DNA Its sugar is deoxyribose Bases are: Adenine, Thymine, Guanine, Cytosine Double strand of nucleotides RNA Its sugar is ribose (has one extra oxygen) Bases are: Adenine, Uracil, Guanine, Cytosine (uracil pairs w/ adenine) Single strand of nucleotides

33 Transcription Copying a sequence of DNA to make a complementary strand of RNA This is catalyzed (allowed to happen) by RNA polymerase

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35 Basic steps of Transcription in Eukaryotic Cells 1. DNA strands unwind 2. RNA polymerase copies one strand of DNA and creates a complementary strand of RNA nucleotides (known as mrna) 3. Once the gene has been copied, mrna detaches from DNA 4. mrna moves out of the nucleus and into the cytoplasm

36 Step 1 start site transcription complex Step 2 RNA copying nucleotides DNA Step 3 RNA

37 Transcipted RNA ACG ATA CCC TGA CGAGCGTTAGCTATCG UGC UAU GGG ACU

38 Types of RNA Three types of RNA are formed during transcription, they will be used in translation: Messenger RNA (mrna) Ribosomal RNA (rrna) Transfer RNA (trna)

39 8.5: TRANSLATION

40 Translation Process that converts (translates) mrna into a protein aka protein synthesis mrna is a message that codes for a protein when it attaches to a ribosome in the cytoplasm of the cell Each combination of 3 nucleotides (known as a codon) on the mrna codes for an amino acid groups of amino acids become proteins in the cell

41 Transcription and Translation DNA RNA Protein Transcription Translation

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43 Steps of Translation 1. mrna moves out of nucleus and to cytoplasm 2. mrna attaches to ribosome 3. Transfer RNA (trna) decodes the mrna into amino acids, which link together into proteins 4. Protein (chain of amino acids) detaches from ribosome and goes off to work in the cell

44 Genetic Code Code that matches codons in mrna to amino acids on trnas : The mrna is read 3 letters at a time (codon) Each CODON represents one specific Amino acid There are 64 possible 3 letter combinations BUT only 20 amino acids. SO, some Codons code for more than one amino acid

45 mrna codons (3 bases) Amino acids Stop codon codes for the end of the mrna (no amino acid added)

46 Different codons code for different amino acids!!!

47 Transcription Translation DNA RNA Protein Directions to make proteins are safely stored in the nucleus Carries the directions to the cytoplasm Work to keep the cell alive

48 Transcription vs. Translation Review Transcription Process by which genetic information encoded in DNA is copied onto messenger RNA Occurs in the nucleus DNA mrna Translation Process by which information encoded in mrna is used to assemble a protein at a ribosome Occurs on a Ribosome mrna protein

49 8.7: MUTATIONS

50 Mutation Change in an organism s DNA It s a mistake made during replication or transcription Can be: Harmful: diseases, disorders or deformities Helpful: help the organism to survive Neutral: organism is unaffected

51 Passing on Mutations If a mutation occurs in a sperm or egg cell, the mutation is passed on to offspring If a mutation occurs in a body cell, it only affects the organism and is not passed on to offspring

52 Causes of Mutations 1. During DNA Replication: Base-pairing mistakes can happen but most are fixed 2. Exposure to powerful Chemicals: Cigarette smoke, smokeless tobacco, exhaust from burning petroleum fuels, pesticides, herbicides, alcohol, sawdust from CCA lumber, paints, mineral spirits & oils, asbestos, etc. 3. Exposure to powerful radiation: Gamma Rays (nuclear fuel & bombs) X rays (at hospitals & dental offices) UV rays (from sunlight and tanning beds)