10/29 Daily Catalyst

1. 10/29 Daily Catalyst • 1. Use the word “staggering” properly in a sentence. • 2. True or false, only eukaryotic cells contain DNA. • 3. When was the structure of DNA first discovered? (guesses anyone?!)

2. 10/29 Daily Catalyst Answer • 1. Use the word “staggering” properly in a sentence. • Amazed • “I was staggered to find out that the class average on the Biology II exam was 95%.” • 2. True or false, only eukaryotic cells contain DNA. • False, both eukaryotic and prokaryotic cells contain DNA. • 3. When was the structure of DNA first discovered? (guesses anyone?!) • In the 1950’s.

3. 10/2 Class Business • Class Fee • $5 • Pay your class fee to me!! • Evolution Exam #3: • Top Scorers: Andrea Arguello and LeyanGranda • 1st Average: 2.49 • 2nd Average: 2.85

4. 10/29 Agenda • Daily Catalyst • Class Business • Objective • Molecular genetics (DNA) • Exit Ticket #7

5. Daily Objective • Explain how the structure of DNA relates to its function.

6. DNA • Key Point #1: • DNA stands for Deoxyribonucleic Acid

7. DNA History • Early in the 1800’s, Darwin proposed there was a similarity between organisms, but he did not know what that was (DNA). • Mendel in 1859 observed characteristics of pea plants and wanted to know why a red flower and a white flower produced a pink flower.

8. DNA- How its structure was discovered.

9. History of the DNA 1869- Friedrich Miescher-Swiss chemist showed that when pepsin (an enzyme that digested) proteins was used on the nucleus of cells a strange phosphorous-containing material remained. The question arose are genes composed of DNA or proteins. 1914-Robert Feulgen German chemist found a staining technique that stains more or less strongly based in the amount of DNA present. He found that all cells in an organism had the same amount of DNA except gametes, which had half the normal amount.

10. 1928-Fred Griffith performed an experiment with 2 different strains of Pneumococcus. One was virulent and the other was not. The virulent strain had a smooth polysaccharide capsule which protected from the immune system. This allowed to caused pneumonia in mice and killed them. The other strain did not have the capsule and was "rough". This strain could not cause pneumonia in mice. When Griffith injected the rough strain of bacteria in mice they lived, and when the smooth strain of bacteria was injected into the mice they died. He killed some of the smooth bacteria by heating them and then injecting them into the mice. The mice lived. He then took some of the killed smooth bacteria and some of the rough bacteria and mixed them together. This bacteria then had the ability to kill mice. This is because the rough bacteria had been "transformed" by taking up some of the DNA from the smooth bacteria.

11. The conclusion was that the bacteria had incorporated heredity from source and in doing so expressed a new smooth trait. 1944-Avery, McLeod and McCarty tried mixing the rough strain with different chemical from the S strain and it was found the DNA extracted from the smooth-strain and transform the rough strain.

12. In his work with pneumonia-causing bacteria and mice, Griffith found that A)the protein coat from pathogenic cells was able to transform nonpathogenic cells. B)heat-killed pathogenic cells caused pneumonia. C)some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic. D)the polysaccharide coat of bacteria caused pneumonia. E)bacteriophages injected DNA into bacteria.

13. C The above diagram outlines Griffith’s experiment. In his work with pneumonia-causing bacteria and mice, Griffith found that some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic.

14. Alfred Hershey and Martha Chase demonstrated the genetic material is DNA by using viruses that infect bacteria. These viruses only stay on the outside of the cell when infecting. Also viruses are made of protein and DNA.

15. Which of the following scientists developed a stain for DNA and found that gametes had half the amount of DNA found in somatic cells? A)Feulgen B)Griffith C)Miescher D)Avery, McCleod, and McCarty

16. A Robert Feulgen was a German scientist that developed a stain for DNA. The DNA in the cell, the more strongly it stained. It was found that all somatic cells in a particular organism has stains the same amount except for the gametes. They stain half as strongly.

17. If we know the structure, then we can determine the function! • **Structure tells us function** • We will revisit the structure of DNA, but first let’s talk about the function of DNA.

18. DNA as a code • Key Point #2: • DNA is the ________ information. • This information tells the __________ what Amino Acids need to be made. • Why Amino Acids? GENETIC BODY

19. DNA is the blueprint of the cell. What does this mean? • DNA is our genetic information. It tells our body what traits we will have. • For example: eye color and hair color

20. Heritable • A special part of DNA is its ability to be passed on from one generation to the next.

21. Key Point #3: • Since DNA is SOOO important and give us our traits, we store it in a very special place. • We store DNA in the organelle, the nucleus. • The DNA NEVER leaves the nucleus.

22. We know the function of DNA, let’s talk about the structure.

23. More importantly, the structure of DNA was discovered by the scientists Watson, Crick, and Franklin in 1952 at Cambridge. • They used the technique x-ray crystallography to uncover the structure of DNA. • Watson and Crick were awarded the Nobel prize in 1962.

24. Wilkens and Franklin used x-ray crystallography to determine that DNA was double stranded, a helix, phosphates were on the outside and three distances, 2.0 nm, .34 nm, and 3.4 nm showed up in a pattern over and over again

25. Watson and Crick determined that 2.0 nm was the distance from one strand to the other. .34 nm was the distance from one base pair to another and finally 3.4 nm determined that there were 10 bases to a complete twist in the helix. So with 2.0 nm from one strand to the other, it was determined that the a purine had had to be base paired with a pyrimidine. Then looking at the hydrogen bonding, adenine base paired with thyamine because they could form two hydrogen bonds and guanine base paired with cytosine because they could form three hydrogen bonds. Watson, Crick, and Wilkens received the Nobel Prize in 1962. Unfortunately, Franklin died of cancer at the age 38.

26. KEY POINT #4: The Structure of DNA DNA The structure of DNA is a double helix.

27. The building blocks of DNA are Nucleotides • KEY POINT #5: • 1 sugar • 1 phosphate • 1 base

28. The sugar group: The sugar is called “deoxyribose” (DEOXYRIBO NUCLEIC ACID) Why?

29. Deoxyribose • What does this mean?! • Oxy: • De:

30. The Phosphate group • We just need to know the phosphate group as the phosphate group • The phosphate is the “acid” part • Easy, right?!

31. Bases • Each nucleotide contains 1 base. • There are 4 bases: • Thymine (T) • Cytosine (C) • Adenine (A) • Guanine (G)

32. PurAs Gold

33. Let’s put it all together: • DNA is made of nucleotides • Nucleotides have 3 parts: • 1 sugar • 1 phosphate • 1 base • A C G T

34. 10/30 Daily Catalyst • 1. What is the function of DNA? • 2. Which bases are considered purines? • 3. Why is DNA stored in the nucleus?

35. 10/30 Daily Catalyst Answers • 1. What is the function of DNA? • To hold our genetic information • 2. Which bases are considered purines? • Adenines and guanines • 3. Why is DNA stored in the nucleus? • To protect the DNA

36. 10/30 Class Business • $5 Class Fee • Please pay this to me ASAP! • First class to 100% earns a treat! • Buy a “Boo-Gram” today • Cost $1 and you can write a message to your boo!

37. 10/30 Agenda • Daily Catalyst • Notes on DNA structure • Practice m.c. questions • Replication reading 37

38. Recap… • What does DNA stand for? • Deoxyribonucleic Acid • Explain the structure of DNA? • A double helix • What is the building block of DNA? • A nucleotide (phosphate, sugar, and oxygen) 38

39. DNA Recap… • The building block of DNA is a nucleotide. • 1 Phosphate group • 1 Base • 1 Sugar group • The sugar group is called deoxyribose • What does “deoxy” mean? • Without oxygen • The sugar group is missing an oxygen! 39

41. BACKBONE • Key Point #6: • The sides are the ___________: made of sugar & phosphate • The _____ are the bases- A,T,G,C RUNGS

42. Sugar-phosphate backbone

43. The sides of the DNA molecule is composed of A)alternating nitrogenous bases and deoxyribose B)alternating amino acids and phosphate groups C)alternating deoxyribose and amino acids D)alternating phosphate groups and nitrogenous bases E)alternating deoxyribose and phosphate groups

44. E The sides of the DNA molecule is composed of alternating deoxyribose and phosphate groups.

45. Bases Pairing • Key Point #7: • Each base has a specific partner. • A- • C— • Held together by a _____________ bond. T G HYDROGEN

46. To understand the DNA molecule better scientists were trying to make a model to understand how it works and what it does. In the 1940’s another scientist named Erwin Chargaff noticed a pattern in the amounts of the four bases: adenine, guanine, cytosine, and thymine. He took samples of DNA of different cells and found that the amount of adenine was almost equal to the amount of thymine, and that the amount of guanine was almost equal to the amount of cytosine. Thus you could say: A=T, and G=C. This discovery later became Chargaff’s Rule.

47. Two purines are too wide and would overlap. Two pyrimidines are too far apart to form the hydrogen bonds. A purine and a pyrimidines however, are just right!

48. The nitrogenous bases form the rungs of the ladder. Thyamine will base pair with adenine on the opposite side. This is a pyrimidine base paired with a purine. This will form 2 hydrogen bonds. Hydrogen bonds are weak but millions of them together will keep the two strands together.

49. Adenine must base pair with thyamine because A)they both are purines forming two hydrogen bonds B)they are both purines forming three hydrogen bonds C)they are both pyrimidines forming two hydrogen bonds D)they are both pyrimidines forming three hydrogen bonds. E)one is a purine and one is pyrimidine and they from two hydrogen bonds

50. E Adenine must base pair with thyamine because one is a purine and one is pyrimidine and they form two hydrogen bonds.