1. DNA Processes: Replication, Transcription, & Translation

2. DNA Replication Replication – the process of making a copy of DNA
Takes place in the nucleus of cells
Takes place during the S-phase of the cell cycle
More than a dozen enzymes involved
Enzymes can be identified b/c they usually end is –ase
Ex. Phosphofructokinase

3. Enzymes review What type or organic compound are enzymes?
Which are the monomers that make up enzymes?
What is a polypeptide?
What is the function of an enzyme?
How do enzymes affect activation energy?
List three factors that affect how enzymes work.
How are structure and function related? Use the terms enzyme, substrate, active site, reactant, product.

4. Replication Process Step 1:
Helicase splits the two DNA strands beginning with an A=T bond, breaking weak H bonds. (Think of unzipping a sweatshirt.)

5. Replication Process cont.
Step 2:
DNA polymerase binds complementary free-floating nucleotides to each strand. (Each original strand, now unzipped, serves as a template for complementary nucleotides to attach.)

6. Step 2

7. Replication Process cont.
Step 3:
DNA polymerase proofreads, or checks to make sure there are no errors and that each new DNA is identical

9. Replication End Product
Semi-conservative replication
Each of the 2 new DNA molecules have one new strand and one old strand from the original (parent) DNA molecule.

10. Replication Animation

11. Practice creating a complementary strand:

12. https://www. pearsonsuccessnet. com/snpapp/learn/navigateIDP. do
Practice replication at

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19. DNA Codes For Traits
Genes – units of inherited information found in DNA.
Code for inherited traits
The codes are written in the sequence of bases.
Different sequence of bases = different trait
~Different letters = different words (ant vs tan)
DNA  RNA  PROTEINS

20. DNA  RNA  PROTEINS RNA Ribonucleic acid Always single stranded
Has ribose as sugar instead of deoxyribose
Always single stranded
Uracil (U) instead of Thymine (T)
C=G
A=U

21. DNA  RNA  PROTEINS Three types of RNA
mRNA – messenger RNA (carries copies of instructions from DNA)
tRNA – transfer RNA (carries amino acids during protein synthesis)
rRNA – ribosomal RNA (combines with proteins to form ribosomes)

22. DNA  RNA  PROTEINS Proteins
Do the work in our bodies (chemical reactions)
Contribute to our characteristics

23. DNA  RNA Transcription – the process of making mRNA from DNA
A.K.A. RNA synthesis (build)
Takes place in the nucleus of cells
Allows coded instructions from DNA to get out of the nucleus

24. Transcription (RNA synthesis)

25. DNA  RNA (transcription)
Step 1:
RNA polymerase unwinds and unzips the DNA double helix and scans DNA to find a starting point.
Step 2:
One strand of DNA is used as a pattern or template as RNA polymerase joins complementary RNA nucleotides (1000’s of mRNA copies can be made)
Step 3:
mRNA is released into the cytoplasm of the cell. (How does it get out of the nucleus?)
DNA “zips” back together

26. TRANSCRIPTION ANIMATION

27. Transcription Animation

28. Practice
DNA = TAC - CCG - TAA - CTA - GCT - TTA
RNA =

29. Practice DNA = TAC - CCG - TAA - CTA - GCT - TTA
RNA = AUG - GGC - AUU - GAU - CGA - AAU

30. Codons Every 3 bases of mRNA codes for a specific amino acid
Amino acids (building blocks or subunits of proteins) are bonded together to make proteins (polypeptides)

31. RNA= UCG 

32. RNA= UCG  Serine

34. RNA= AUG  Methionine - START

35. RNA= UGA 

36. RNA= UGA  STOP

37. Practice DNA = TAC - CCG - TAA - CTA - GCT - TTA
RNA = AUG - GGC - AUU - GAU - CGA - AAU
A.A. = MET - GLY - ISO - ASP - ARG - ASG

38. RNA  PROTEINS
Translation -making proteins from the nucleic acid code found in mRNA—like translating a code.
tRNA – transfer RNA – translates the 3 letter codons into proteins
tRNA has an anti-codon – a 3 letter sequence complementary to the mRNA codons that corresponds to a certain amino acid

39. Translation Takes place at the ribosomes of the cell
Each ribosome is made of 2 subunits
Each subunit is made of proteins and ribosomal RNA (rRNA)
Ribosomes are the tiny organelles known as protein factories

40. Translation Process Step 1: Step 2:
the ribosome and strand of mRNA attach in the cytoplasm (NOT in the nucleus)
Step 2:
tRNA arrives with the correct amino acid.
Amino acids bond together.
As new tRNA molecules arrive older ones depart.
Amino acids continue to bond together forming growing polypeptide chains (peptide bonds stick the amino acids together)

42. Translation Process Step 3: Termination “END” codon is reached
All parts are disassembled

43. After translation… Protein is released Can travel through ER
Be modified, packaged, sorted in the Golgi Apparatus
Contained in a vesicle for transport within or out of the cell
Active and passive transport…

45. DNA TRANSLATION ANIMATION http://www.youtube.com/watch?v=_6Rrymt6XwI

46. Review of the 3 Processes
Replication: DNA copied into DNA
Transcription: DNA copied into mRNA
Translation: message turned into protein

47. Practice at www.classzone.com

48. Mutations

50. Genetic Mutations
Mutation – any change in the nucleotide sequence of DNA.
Chromosomal--Can involve an entire chromosome or portion of chromosome
Gene--Can involve large regions of DNA or a single base
2 Categories of Gene Mutations
Substitutions
Deletions / Insertions (Frameshift)

51. Substitutions can be harmless as long as they are not in a region that codes for a gene

52. A frameshift mutation inserts or deletes a nucleotide in the DNA sequence. All subsequent amino acids may be affected (typically more severe than substitution).

53. Deletions / Insertions throw the entire sequence off. VERY VERY BAD!!!

54. What causes mutations? Errors during DNA replication
Errors during crossing over (Meiosis I)
Mutagens
Physical or chemical agents that cause DNA mutations
Examples:
High-energy radiation  X-rays & UV light
Virus
Drugs
***THINK--ARE ALL MUTATIONS BAD?

55. Sex cells vs Body cells
Mutations in sex cells (sperm or egg) are inheritable
Mutations in body cells are not passed on

57. Mutations practice
1. Write a DNA code 24 letters long. Label it DNA template.
Transcribe it into mRNA.
Translate it into a protein.
2. Copy the original DNA showing an example of ONE point mutation (substitution).
Label it DNA with point mutation.
Transcribe it into mRNA.
Translate it into a protein.

58. 3. Follow the same instructions as in step 2, except create a frameshift mutation instead of a substitution.
Are there any differences in the protein? How many? Which type of mutation had a more severe effect?

59. Gene Expression—how you “show” the gene

60. Gene Expression All of our cells have the exact same copy of DNA
Cells look and function differently (skin and white blood cell)—why?
Different genes are turned on and off, like light switches, at different times during our development (causing cell differentiation)
Environmental factors can influence gene regulation and expression
Ex. Temperature can affect moth development

61. Phenotype Expression of gene Examples: height, color, blood type
*Controlled by genes; can be affected by environment.
You may have a gene that makes you more likely to get skin cancer, but if you rarely go out in the sun, you will decrease your chance of getting cancer. The UV rays from the sun may be more likely to turn “on” your switch for skin cancer.

65. Practice--mutations
Practice at