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DNA Contents of the Nucleus DNA vocab  Deoxyribonucleic acid  Chromosomes  Chromatin  Genes  Genome.

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Presentation on theme: "DNA Contents of the Nucleus DNA vocab  Deoxyribonucleic acid  Chromosomes  Chromatin  Genes  Genome."— Presentation transcript:



3 Contents of the Nucleus

4 DNA vocab  Deoxyribonucleic acid  Chromosomes  Chromatin  Genes  Genome

5 DNA Structure  What is the structure called?  Who received the Nobel Prize for working out the molecular structure?

6 Building blocks of DNA  What are the building blocks of DNA? (4 types)  What are the building blocks made of? (3 parts)

7 Polymerization of Nucleotides :

8  How do they fit together?  POLYMERIZATION…  “rungs of the ladder”  “sides”

9 Try “replicating” this single strand of DNA

10 DNA Replication: 3 Stages: - Figure 10-9 - page 187   1. Unwinding DNA helicase unwinds and separates the two strands of the molecule, exposing the bases. This is called the “Replication Fork” DNA replication animation- v. realistic but hard to follow replication - it does have primerase and polymerase 1

11 2. Formation of the Complementary Strand   - the parental DNA strands act as a template   - DNA polymerase attaches to the opened strands (one on each side)

12   - it “reads” the parental DNA strand and attaches the appropriate nucleotide to the template; A to T, G to C (and vise versa) DNA polymerase

13   - it also connects the sugars and phosphate sides of the new strand using dehydration synthesis reactions.

14   - DNA polymerase can only travel in one direction - from 3 ’ to 5’, therefore, the 2 polymerases will travel in opposite directions in the replication forks


16 The pieces are joined together by DNA ligase   As the two DNA polymerases move along the DNA molecule, ONE will be following the DNA helicase, while the other one will be going in the opposite direction.

17   - the DNA polymerase that follows the helicase is on the “LEADING STRAND”   - the other polymerase is going to run into the “end” of the replication fork (where the helicase started to open the DNA helix)   - it must detach at that point.

18   - a new polymerase will attach further up the “LAGGING STRAND” and synthesis a new daughter strand up to the point were the first polymerase began, and then IT will detach

19   - this process continues in steps until all of the lagging strand is replicated

20   - every time the polymerases detach, they leave a gap in the sugar-phosphate back-bone   - DNA ligase will travel along the newly synthesized strands, locate the gaps, and make the necessary connections to fill them.

21   Finally, both the leading strand and the lagging strands are “proof-read” by specific enzymes to ensure that the replication was accurate. ( if it wasn’t corrected, it would be called a MUTATION.)

22  What is the significance of the order of the nitrogenous bases?

23 Protein Synthesis  DNA - a ____________ for making proteins. BLUEPRINT

24 A 2 Step Process:   1. Transcription: the information is copied form the DNA molecule to a mRNA molecule

25 Try Transcribing this piece of DNA into mRNA

26   2. Translation: the information in the mRNA is “read” in the ribosome and “translated” by a tRNA to make a protein.

27 Breaking “THE CODE”: DNA Molecules can be thought of as a type of “sentence”. - the bases, (A,T,G,C) make up the “letters” - these ‘letters” are arranged into “words” of three letters -called “triplets” - the triplets each have a specific “meaning” - they code of a specific amino acid THE CAT ATE THE RAT AUG CCG GCA AAG UAG Met pro ala lys stop

28 The Code:  How do you follow the mRNA code?

29   o&mode=related&search= o&mode=related&search Protein synthesis video Youtube videos - protein synthesis

30   Therefore, the DNA molecule simply tells the cell the order of amino acids necessary to make proteins.

31 Nucleic Acids: Material: DNA vs RNA - compare and contrast.

32   RNA: an intermediate between DNA and ribosomes   The same as DNA except:   the sugar is RIBOSE instead of DEOXYRIBOSE   RNA is SINGLE-stranded   the base “THYMINE” is replaced by URACIL.

33 The 3types of RNA are all created the same way: by TRANSCRIPTION o The 3types of RNA are all created the same way: by TRANSCRIPTION of the DNA molecule. 3 types of RNA: 1. RiBOSOMAL: together with some proteins, they make up the structure of RIBOSOMES

34   2. MESSENGER: used to deliver the instructions from the DNA to the RIBOSOMES for protein synthesis

35   3. TRANSFER: ”reads” the instructions and deliver the appropriate AMINO ACID to the ribosome.

36  Why doesn’t the mRNA just stay inside the nucleus?

37  DNA in the nucleus is safe   DNA in the cytoplasm can be destroyed




41 Try “DECODING” this piece of DNA Code DNATACGGACAGTAAATT mRNA Amino acids DNATACGGACAGTAAATTmRNAAUGCCUGUCAUUUAA Methi- onine prolinevaline isoleuc ine stop

42  Great video on a cell’s life functions:   0.html 0.html  Here is the explanation of what is happening:   ml ml  Protein Production

43 Protein Structure


45 Recap: Genes -WHAT are they? -WHERE are they? -How many genes do we have? -WHY are we storing the information for PROTEINS???

46 Preview: Enzymes  WHAT are they?  What do they do?  Why do our DNA molecules store the instructions to make them?

47 One Gene = One Protein?  Human genome = approximately 25,000 genes  Number of proteins humans make is approximately 90,000.  NOT SURE HOW THIS CAN BE!

48 Mutations - Define

49 Types of Mutations  Deletion  Addition  Substitution  Positive  Neutral  Negative  Mutagens Example: Deletion The result can be a completely non- functional protein…doesn’t make sense. i.e. --- THE CAT ATE THE RAT--- If you delete a base (letter) ‘C’ ---THE ATA TET HER AT-----

50 Another example: Original message: THE BIG DOG BIT TED AND RAN OFF --- --- ADDITION/FRAMESHIFT THE BIG FDO GBI TTE DAN DRA NOF F--  Changing the sequence

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