1. Chapter 12 DNA

2. 12.2 & 12.3 Vocabulary DNA – page 18 & 48
Nucleotide – building blocks of DNA and RNA; composed of a simple sugar, a phosphate group, and a nitrogen base
Complementary base pairing – page 348
Double helix – two strands of DNA nucleotides that spiral together; resembles a twisted-ladder shape
Chromosome – glossary
Replication
DNA polymerase
Telomere

3. Section 2 & 3 Structure of DNA & DNA Replication
Standards: 2A.1, 4A.1, 4A.2
Objectives:
Diagram and label the basic structure of DNA.
Summarize the role of the enzymes involved in the replication of DNA.
Compare/contrast DNA replication in prokaryotes and eukaryotes.

4. DNA Deoxyribonucleic Acid  type of nucleic acid
Genetic code  instructions for making proteins
Found in nucleus
Building blocks  nucleotide
(G, A, T, C)

5. How Many Nucleotides?

6. Structure of DNA Adenine Covalent bond between nucleotides Guanine
Cytosine
Thymine
Covalent bond
between nucleotides

7. DNA
Watson & Crick discovered DNA is a double helix (two strands of nucleotides spiraled together).
P and Sugar alternate on outside
N bases on inside

8. DNA
Complementary base pairing – adenine bonds with thymine and guanine bonds with cytosine
Hydrogen bond holds bases together

9. DNA
Antiparallel

10. DNA
Nucleotides  Double Helix  Chromatin  Chromosome

11. Complementary DNA Strands

12. DNA Replication Replication – copying process of duplicating DNA
Occurs during S phase of interphase
Each strand of DNA serves as a template for the new strand  produces two identical complete sets of DNA molecules from mitotic cell divisions.
Enzymes involved in DNA replication
Occurs in 3 steps

13. DNA Replication

14. Step 1: Unwind Double Helix
DNA Helicase (an enzyme) unwinds and unzips DNA into two separate strands  H bonds break  leaving single strands of DNA.

15. Step 2: Add New Base Pairs
DNA Polymerase (an enzyme) adds nucleotides to produce new strand of DNA.
New bases added to parental DNA strand
Proofreads  exact copy of original
Follows the base-pair rule: (A-T, G-C)

16. Step 3: Join Base Pairs
At the end of replication  2 new strands of daughter DNA are produced.
Each is made of ½ old DNA and ½ new DNA
replication fork
DNA polymerase
Direction
of replication
Direction
of replication
new nucleotides
being added
DNA Replication

17. Telomere Telomere – tips of eukaryotic chromosomes; protective cap.
Telomerase (enzyme) adds DNA sequences to each end.
Telomere

18. DNA Replication Prokaryotes/Eukaryotes
Circular DNA strand  replicated in one section
2 directions
DNA is shorter
Eukaryotes
Replicated in several sections
DNA is longer

19. Chapter 13 RNA & Protein Synthesis

20. 13.1 Vocabulary
RNA – nucleic acid that directs the production of proteins
Messenger RNA - glossary
Ribosomal RNA - glossary
Transfer RNA - glossary
Transcription
RNA Polymerase - glossary

21. Section 1 RNA Standards: 2A.1, 4B.1 Objectives:
Compare/Contrast DNA and RNA.
Explain the process of transcription.

22. Why Proteins are Important
DNA  “code of life” or “genetic code” because it contains the code for each PROTEIN.
Sequence of DNA nucleotides determines type of protein to be synthesized.
Proteins determine how an organism looks & functions.

23. Why Proteins are Important
Gene – segment of DNA that contains instructions for making a protein.
Specific location on a chromosome
Controls inherited trait expression that is passed on for generations.
Ribosomes make proteins

24. Why Proteins are Important
Each organism has unique nucleotide sequences.
Organisms closely related have more common nucleotide sequences  similar DNA.
Oak Tree
Red Maple Trees
Worm

25. Why Proteins are Important

26. DNA  RNA
Problem: DNA contains instructions for making proteins but DNA can’t leave the nucleus.
Solution: RNA will take DNA’s instructions to the ribosomes for protein synthesis.

27. RNA Ribonucleic Acid  type of nucleic acid
Directs production of proteins
Single stranded
Building blocks  nucleotides
Uracil and NO thymine
(G, A, C, U)

28. RNA – 3 Types
mRNA (messenger RNA) – carries copies of instructions to make proteins; complementary to DNA
rRNA (ribosomal RNA) – form ribosomes
tRNA (transfer RNA) – carries amino acids to ribosome
Messenger RNA
Ribosomal RNA
Transfer RNA

29. RNA

30. Protein Synthesis Part 1: Transcription (template of DNA  mRNA)
occurs in nucleus
gene for a specific protein is turned ON and that gene is copied into mRNA Example: (DNA) T A C G G T A STOP codon
(mRNA) A U G C C A U STOP
RNA Polymerase (an enzyme) – links RNA nucleotides as DNA strand unwinds and unzips.
mRNA detaches and leaves nucleus and enters cytoplasm. TWO DNA strands rejoin.

31. Transcription

32. Transcription

33. Transcription Practice
DNA C G T T A G C A A C T G STOP
mRNA
2. DNA A C G T C A A C G T T A STOP

34. 13.2 Vocabulary Polypeptide – glossary Genetic Code – glossary
Codon – glossary
Translation
Anticodon – glossary
Gene Expression - glossary

35. Section 2 Ribosomes and Protein Synthesis
Standards: 4A.1, 4B.1
Objectives:
Explain the process of translation.
Transcribe & translate DNA  mRNA  proteins.

36. Genetic Code Polypeptides – long chains of amino acids
Amino acids make up proteins
20 amino acids total
Genetic Code  mRNA codons
Codon – 3 base code (N base)
1 codon = 1 amino acid

37. This section of DNA represents a gene.
CODON T A C G
This section of DNA represents a gene.
How many codons do you see in this gene?
How many amino acids total make this protein?

38. Genetic Code

40. Genetic Code

41. Practice Converting mRNA  Amino Acids
AUG =
CUC =
AAG =
GGU =
UAC =
CAC =
CAA =
UGA =

42. Protein Synthesis Part 2: Translation (mRNA  Protein)
Occurs at ribosome in the cytoplasm
Interprets genetic message and builds proteins
mRNA attaches to a ribosome (rRNA) and is read 3 bases (codon) at a time

43. Protein Synthesis Part 2: Translation (mRNA  Protein)
tRNA is activated by enzyme and carries amino acid to the ribosome
20 different types of tRNA molecules
tRNA structure:
Anticodon site – 3 nucleotide base complementary to the codon of mRNA; end of tRNA molecule
Amino acid attached on other end

44. Protein Synthesis Part 2: Translation (mRNA  Protein)
Amino acids joins together in a chain by peptide bonds  forming a protein.
Continues until STOP codon is read on the mRNA  last amino acid is added  protein breaks away from ribosome  protein synthesis ends.

45. Gene Expression
Gene Expression – process by which gene produces its product and the product carries out its functions.

46. Central Dogma of Molecular Biology

47. Central Dogma of Molecular Biology

48. 13.3 Vocabulary Mutagen Mutation – glossary Point Mutation – glossary
Frameshift Mutation – glossary
Mutagen
Polyploidy

49. Section 3 Mutations Standards: 4B.1, 4D.1 Objectives:
Summarize the various types of mutations.

50. Gene Regulation
Ability of an organism to control which genes are transcribed.

51. Mutation Mutation – change (or alteration) in DNA Changes vary from…
Single gene (gene mutations)  large segments of DNA (chromosomal mutations)
Beneficial  harmful
Unnoticeable  disorders or death

52. Examples of Gene Mutations
Affects a single gene  small section of DNA.
Huntington’s Disease
Sickle-Cell Disease
Albinism

53. Examples of Chromosomal Mutations
Affects groups of genes or entire chromosome.
Down Syndrome

54. Examples of Beneficial Mutations
Results in traits that are favored by natural selection  species evolve (CHANGE)  increase population size.
Polyploidy – extra sets of chromosomes

55. Mutation
If mutant cell is a body cell (somatic cell) then daughter cells can be affected but mutation will not be passed to offspring  aging and/or cancer.
If mutant cell is a gamete (sex cell) then mutation will be passed to offspring  genetic disorders.

56. Point Mutations Change in one base pair (or one nucleotide)
Missense Mutation – codes for wrong amino acid
Normal: AUG CAU UAC Mutated: AUG GAU UAC
Nonsense Mutation – change amino acid codon to a stop codon; terminates translation early
Normal: AUG CAU UAC Mutated: AUG UGA
histidine

57. Frameshift Mutations
Shifts the “frame” of the amino acid sequence by adding or deleting nucleotides  changes codons
Deletion Mutation – loss of a nucleotide
Normal: AUG CAU UAC GUA
Mutated: AUG AUU ACG UAU
Insertion Mutation – addition of a nucleotide
Mutated: AUG CCA UUA CGU A

58. Duplication Mutations
Entire codon(s) repeat; increases the number of amino acids
Normal: AUG CAU UAC GUA
Mutated: AUG CAU CAU CAU CAU UAC GUA

59. Review: Types of Mutations
Point, Frameshift, or Duplication Mutation?
Missense, Nonsense, Deletion, or Insertion Mutation?

60. Review: Types of Chromosomal Mutations
Inversion  genes reversed
Duplication  extra copies
Translocation  parts break off and reattach somewhere else
Deletion  loss of genes

61. How Mutations Occur
Errors in genetic processes (DNA replication, Transcription, Translation)
Mutagens – substances which cause mutations; certain chemicals and radiation.
Most mutations repaired  no effect

62. Effects of Mutations The shape of a protein controls how it works.
Shape is determined by amino acids.
Incorrect amino acids change protein’s shape  protein may not work properly.