2. The Genetic Material DNA/RNA Notes

3.  Bodies are made up of cells  All cells run on a set of instructions spelled out in DNA Bodies  Cells  DNA

4. 1. DNA: What is the role of DNA in heredity? DNA stores genetic information. It tells our eyes which color to be, it tells our cells which proteins to make, and when to make them. DNA copies genetic information. Before a cell divides, it must copy its DNA DNA transmits genetic information from one generation to the next. *** a gene is a part of the DNA that codes for one specific protein.

5. The Structure of DNA: Made of 100s of repeating units called nucleotides. Nucleotides include: a. Deoxyribose (a sugar) b. A Phosphate Group c. One of four possible Nitrogenous Bases…

6. The Four Nucleotides in DNA 1. Adenine 2. Thymine 3. Guanine 4. Cytosine AdenineGuanine Cytosine Thymine Phosphate group Deoxyribose

7. Nucleotide Use Like letters in the alphabet, these four nitrogenous bases are strung together in many different arrangements that code for the genetic information. DNA’s structure is what allows it to code for, copy, and transmit the information need by our cells to function.

8. 2. Structure of DNA 1953 | 1962 Wilkins James Watson and Francis Crick worked out the three- dimensional structure of DNA, based on work by Rosalind Franklin and Maurice Wilkens

9. Rosalind Franklin (1920-1958) Her picture of DNA, taken by x-ray diffraction, helped Watson and Crick tease out the double helix structure of the DNA molecule

10. 2. The Structure of DNA The Double Helix: Adenine always bonds to Thymine A-T Cytosine always bonds to Guanine C-G -This attraction (called Base Pairing) is caused by hydrogen bonds between the bases.

11. Twisted Ladder The double helix looks like a twisted ladder. The rungs of the ladder are the nitrogenous bases (A, T, C, G) The sides of the ladder are the Phosphate and the sugar (sometimes called the backbone of the molecule)

12. More on the double helix Two separate and opposite (called anti-parallel) strands wrap around each other to form a stable twisting molecule called a double helix Nucleotide Sugar- phosphate backbone Hydrogen bonds Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

13. Let’s try building a DNA molecule Build a DNA Molecule Build a DNA Molecule

14. New Strand Original Strand DNA Polymerase

15. 3. DNA Replication Before a cell divides, it duplicates its DNA. This process is called replication and it is controlled by a series of enzymes. 1. Each strand of DNA has all the information to create the other strand by “base pairing.” 2. DNA strands are Complementary (or opposites) if the two strands are separated, they can recreate their own complementary strand.

16. Process of DNA Replication: 1. Enzymes “unzip” a molecule of DNA by breaking the hydrogen bonds between base pairs. (DNA Helicase) 2. The two strands unwind and each becomes a template for the other strand.

17. Process of DNA Replication: 3. Free nucleotides in the nucleus attach to each of the strands, forming two identical sets of DNA! 4. DNA Polymerase- one of the enzymes involved in replication, adds the new bases (nucleotides) and proof- reads each strand so there are very few mistakes.

18. Let’s try Worksheet #3 A Science Odyssey: You Try It: DNA Workshop

19. 4. RNA The main role of RNA is to aid in Protein Synthesis RNA is similar to DNA in that both are made of nucleotides

20. What is RNA?

21. RNA is different than DNA: Sugar backbone in RNA is Ribose (not Deoxyribose) RNA is single stranded while DNA is double stranded RNA contains Uracil in place of Thymine. (U in place of T) DNA always stays in the nucleus, while RNA can be found in the nucleus and cytoplasm.

22. Types of RNA Messenger RNA (mRNA) The role of mRNA is to carry instructions for making proteins from DNA to Ribosomes. Ribosomal RNA (rRNA) One of the building blocks of Ribosomes Transfer RNA (tRNA) Transfers amino acids to ribosomes in the specific order that mRNA states in order to make a specific protein.

23. Process of Protein Synthesis Cells store a huge amount of coded information in their genes. Much of this information is used to make 1000s of proteins that each cell requires for its functions and the structures it contains. The cell’s proteins are made at the ribosomes according to the directions stored in the cell’s DNA code. RNA carries the DNA code from the Nucleus to the ribosomes in the cytoplasm. Protein synthesis is divided into two parts: Transcription Translation

24. 5. Transcription- before we can make a protein, we need a copy of the code that can leave the nucleus Transcription is the process of making strands of RNA from DNA. Transcription requires the enzyme RNA Polymerase.

25. A Look at Transcription Synthesis of a protein starts in the nucleus DNA molecule unzips (just like in DNA replication) RNA polymerase adds nucleotides in groups of three Adenine pairs with Uracil instead of Thymine Cytosine pairs to Guanine

26. Let’s try it A Science Odyssey: You Try It: DNA Workshop DNA Transcription - YouTube

27. 6. The Genetic Code & Protein Synthesis 1. Proteins are made by joining long chains of amino acids together to form polypeptides. a. There are a total of 20 different amino acids. b. Different proteins are made by different combinations and numbers of these amino acids. c. These amino acids are assembled using the Genetic code. Cells store this code in their DNA.

28. More on Protein Synthesis RNA contains 4 different bases A, U, C, and G. The order of these subunits is the Genetic code. a. The genetic code is read three letters at a time, this is called a “Codon.” b. Each codon instructs for one amino acid to be built into a chain.

29. Example: RNA: UCGCACGGU is read as a series of three codons: UCG-CAC-GGU These different codons represent three different amino acids. UCGCACGGU Serine - Histadine - Glycine

30. The codons for the specific amino acids are listed using this table:

31. 7. Translation The process of a cell using mRNA and ribosomes to make proteins is translation

32. How translation takes place

33. mRNA carries the codons to the ribosome. A tRNA that has a complementary codon binds to the mRNA by base pairing. The tRNA carries on its other end an amino acid that corresponds to the codon. As each tRNA binds to the mRNA, the amino acids bond together to form polypeptide chains.

34. A Science Odyssey: You Try It: DNA Workshop

35. Putting it all together DNA  RNA  Proteins  Traits Transcription Translation This simple phrase links all the important genetic components together and is the basis for the science of molecular biology

36. 8. Mutations Mutations are changes in the nucleotide sequence in a DNA molecule that can be inherited. Can have no affect at all Or they can change the amino acid being inserted into a protein and make that protein nonfunctional. Mutations can benefit an organism or harm it.

37. What is Different? DNA sequence 1- GCC-ATC-CGC-ATT-AGA DNA sequence 2- GCC-ATC-CAC-ATT-AGA

38. Mutations –gene mutations The most common type of mutation is a Point Mutation that occur at a single point in the DNA sequence. These generally occur during replication of the DNA.

39. Examples of Point mutations Substitution: CTT -  CAT in the DNA The mRNA switches from GAA to GUA instead of glutamic acid, valine is added to the polypeptide chain. Sickle cell disease affects the shape of red blood cells. It is the result of a point mutation. Evolution: Library: A Mutation Story

40. Point Mutations Types of Point mutations are: Substitutions- one base is changed to a different base Insertions or deletions- one base is inserted or deleted from the DNA sequence

41. Insertions/deletions Insertions and deletions can cause a shift in the reading frame of the mRNA codons during translation. AUG – GCT – ATT - CGA AUG – GAC – TAT – TCG - A This will change the amino acids being inserted from that point of insertion/deletion through the rest of the mRNA code. This is called a frameshift mutation A

42. Types of Chromosomal Mutations Deletion Duplication Inversion Translocation

43. Chromosomal Mutations Changes in the number or structure of the chromosomes themselves Occur when part of a chromosome breaks off and is lost, reattached in reverse order, or attached to a different chromosome.

44. Mutagens Chemical agents that affect the DNA ex: pesticides, tobacco smoke, formeldyhyde Physical agents in the environment ex: UV radiation from the sun, electromagnetic radiation, radon.

45. Repair mechanisms Repair mechanism that fix mutations n cells have evolved. Much like a book editor, enzymes proofread the DNA and replace mistakes with the correct nucleotide. However, the greater the exposure to a mutagen, the more likely a mistake will not be corrected. the problem with tanning booths…….

46. Gene Expression and Environment Both the internal and external environment of the cells can influence which genes are activated in the cell. Some of this influence may occur during the development, leading to the many different types of cells that an organism needs. Although genes are inherited, an organism’s environment can affect the ways some genes are revealed, or expressed.

47. Examples of gene/environment interaction: 1. Effect of light on chlorophyll production. Without light, a yellow pigment is produced With light, a green pigment is produced.

48. 2). Effect of temperature on the hair color in Himalayan rabbits. body fur is - white on the tail, feet, nose, ears the fur is – black This is because the temperature is cooler on these parts of the rabbits body. If Ice is applied to skin of rabbit, black fur will grow.