DNA. Function: Carry genetic material. located in the nucleus. Many People contributed to the discovery of DNA.

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Ashley Bates
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1 DNA CLIP 1

2 DNA located in the nucleus Function: Carry genetic material Many People contributed to the discovery of DNA. 2

3 People Who Discovered DNA 1928 Frederick Griffith - DNA = carrier of genetic info 1944 Avery Genes = composed of DNA 1952 Hershey and Chase genetic material = DNA, not protein 3

4 People Who Discovered DNA 1952 Rosalind Franklin DNA = twisted 1952 Edwin Chargraff - #A = #T; #C = #G; Chargraff s Rule 1953 Watson and Crick Discovered structure of DNA we know today 4

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6 Shape of DNA 1.Double Helix. -Twisted ladder or spiral staircase 2.Two stranded 3.Held together by hydrogen bonds 4.Made of four Nucleotides 6

7 Structure of DNA Remember: DNA is a nucleic acid. Nucleic acids are made of nucleotides 7

8 8 Nucleotides DNA = long chain of nucleotides 4 that make up DNA Have 3 parts: a sugar molecule (deoxyribose), a phosphate group, and a nitrogenous base

9 4 Nitrogenous Bases Adenine Guanine Cytosine Thymine 9

10 Sides of the Ladder are made up of sugar and phosphate. 10

11 Adenine always pairs with Thymine Cytosine always pairs with Guanine 11

12 Would Thymine be able to pair up with Guanine? 12

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15 DNA Replication Before mitosis, the DNA must be replicated (Copied) exactly. Each strand can be used to make the other strand. Many enzymes are involved. 15

16 Chromosome Structure DNA is packed very tightly as chromosomes in the nucleus. Human nucleus has 1 meter of DNA! Smallest human chromosome has 30 million base pairs. 16

17 Chromosome Structure A chromosome has DNA and proteinchromatin. Tiny sections of DNA are called genes 17

18 Steps: Semi-conservative replication parent/original strands are unwound with the help of DNA helicases (enzymes). Replication Bubble

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20 Steps: DNA polymerase attached new nucleotides to the parent strands

21 DNA replication website 21

22 22 How a protein is made Transcription Translation

23 DNA codes for all of the cell proteins. 23

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25 Overview: DNA is located in the Nucleus Proteins are made on the ribosomes. DNA makes a copy (send a message) called mrna 25

26 Two Steps of Protein Synthesis 1. Transcription 2. Translation 26

27 Transcription a copy of the DNA is made the copy is called messenger RNA or mrna. The mrna takes the code to the ribosome. 27

28 DNA vs. RNA Double Stranded AGTC Deoxyribose NEVER! Single Stranded AGUC Ribose YES! 28

29 DNA Transcription During transcription the DNA unzipped and RNA nucleotide are paired up with the DNA bases. Website 29

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32 Once the mrna copy is made, it can go to the ribosome to be translated. 32

33 Remember.Proteins are made out of amino acids. There are 20 different amino acids. 3 bases code for each amino acid = codon. 33

34 How you figure out which codon is coding for which amino acid 34

35 Once the mrna gets to the ribosome, the protein can be assembled. Transfer RNA brings the amino acids to the ribosome. Website 35

36 The three letter code on the mrna is called a codon. The three letter code on the trna that is matched up with the mrna is called an anticodon. 36

37 Review Clip 37

38 Mutations 38

39 Mutations A sudden change in the genetic code is called a mutation. Most mutations have little or no effect on the organism. Mutations can be spontaneous or may be caused by environmental factors called mutagens. 39

40 Mutations in DNA usually occur through one of three processes: 1- DNA damage from environmental agents such as ultraviolet light (sunshine) or nuclear radiation Certain chemicals called mutagens 2- Errors that occur when a cell replicates its DNA in preparation for cell division. 40

41 41 Types of Mutations

42 Point mutation -a simple change in a single base of the gene sequence - 3 Types: 1. Point 2. Insertion 3. Deletion 42

43 Frame-shift Mutations In a frame-shift mutation, one or more bases are deleted or inserted, the equivalent of adding or removing letters in a sentence. Original: THE CAT ATE THE RAT Deletion: THE CAT ATE THE RAT THE CTA TET HER AT Insertion THE CAT ATE THE RAT THE CAT ATT ETH ERA T 43

44 Chromosomal Mutations Mutations can occur that involve whole or partial chromosomes Non-disjunction homologous chromosomes don t separate during meiosis a gamete ends up with an extra chromosome (ex. Down s syndrome) Crossing Over parts of homologous chromosomes are swapped during meiosis 43A

45 Results of DNA Mutations The results of mutations can be Helpful They can result in a helpful trait such as better camoflage Neutral CLIP If the mutation does not cause a change in amino acid sequence, or the replaces 1 amino acid with one that is similar, the protein will still function the same. Harmful A large change in the amino acid sequence 51 can make a protein that does not function at all. 44

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47 Which of the following is the correct basepairing rule for DNA? A A-U; C-G B A-G; T-C C A-T; G-C D A-C; T-G 46

48 47 DNA TECHNOLOGY genetic recombination.

49 DNA Fingerprinting Determining the sequence of bases in DNA for comparisons How they identify criminals and do paternity tests (i.e. Who is my Baby s Daddy? ) 48

50 How DNA Fingerprinting works: Scientist cut up DNA into pieces using enzymes Then load the pieces into a gel. Electricity is run through the gel. The pieces of DNA move to the other end of the gel. Smaller pieces move farther. 49

51 Who doesn t belong? 50

or another type of cell that rapidly replicates and divides.

52 Recombinant DNA is a form of artificial DNA where DNA combined that would not normally be combined. They cut, splice together, and insert the modified DNA molecules from different species into bacteria or another type of cell that rapidly replicates and divides. The cells copy the foreign DNA right along with their own DNA. Example: goldfish have genes for fluorescent proteins that have been inserted 51

Sheep are used in the production of alpha-1 antitrypsin, which is used in the treatment of

53 Genetic Engineering the manipulation of an organisms genes applications in medicine and the environment, industry, and agriculture. Sheep are used in the production of alpha-1 antitrypsin, which is used in the treatment of emphysema. Goats are also producing the CFTR protein used in the treatment of cystic fibrosis. Crops are being devised that have natural insect repellants 60 52

54 Genetic Engineering Example: In the plant world, the buds of cotton plants are vulnerable to worm attacks. The buds of a modified cotton plant resist these worms, resulting in increased cotton production. These gene insertions are ecologically safer than pesticides. They affect only the targeted pest. 53

55 54 Clip Scientists today have developed genetically altered bacteria. Among them are strains of bacteria that eat up oil spills manufacture alcohol and other chemicals process minerals. There is concern about possible risks to the environment and the general population as genetically engineered bacteria are introduced.

Cloning Occurs when the DNA from an adult is inserted

Results in an offspring that is genetically identical

The DNA in the egg must be removed before the new DNA

56 Cloning Occurs when the DNA from an adult is inserted into the fertilized egg of the organism. Results in an offspring that is genetically identical to the parent. The DNA in the egg must be removed before the new DNA is inserted. Has been used in animals and plants, hopes for the future to allow for the cloning of organs. 55

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How do we know what the structure and function of DNA is? - Double helix, base pairs, sugar, and phosphate - Stores genetic information

DNA: CH 13 How do we know what the structure and function of DNA is? - Double helix, base pairs, sugar, and phosphate - Stores genetic information Discovering DNA s Function 1928: Frederick Griffith studied