1. Great Ideas in Science PROV 301-001 (Spring 2017)
Prof. Robert M. Hazen
Office: East 202
Phone: x 32163

2. Great Ideas in Science: Lecture 12
Great Idea: All living things share the same genetic code.
Professor Robert Hazen
PROV 301

3. Key Idea 1. DNA carries the genetic message.
All living things share the same genetic code.
1. DNA carries the genetic message.
2. Messenger RNA copies the DNA.
3. Transfer RNA holds an amino acid.
4. The ribosome assembles a protein.

4. Classical Genetics
Gregor Mendel used pea plants to discover three laws of inheritance.
1. Genes exist.
2. Each parent contributes half.
3. Some traits are dominant and some are recessive traits.

5. Cellular Genetics Chromosomes provide genetic clues.
Humans have 23 pairs of chromosomes.
In mitosis one cell becomes two:
2 daughter cells are the same as the parent.
Most cells divide by mitosis in your body.
In meiosis one cell becomes 4 gametes.
Crossing-over shuffles genes from parents.
Recombination makes every gamete unique.

6. Mitosis Simple cell division: A 3-step process: One cell becomes two.
First copy the chromosomes.
Second, separate chromosomes.
Third, divide the cell into two.

7. Meiosis Chromosome crossover mixes up genes. 1 cell forms 4 gametes:
Gametes are genetically unique. They have ½ normal chromosomes

8. Nucleotides: The Building Blocks of Nucleic Acids
Nucleotides are made from three molecules:
1. Sugar
DNA: deoxyribose
RNA: ribose
2. Phosphate ion
3. Base
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)

9. DNA’s Double Helix

10. DNA Base Pairing
A—T
C—G

11. The Replication of DNA
DNA replication occurs before mitosis & meiosis.
The process is simple:
The DNA double helix splits down the middle.
New bases bond to exposed bases.
This results in two identical DNA strands.

12. The Replication of DNA
DNA replication occurs before mitosis & meiosis.
The process is simple:
The DNA double helix splits down the middle.
New bases bond to exposed bases.
This results in two identical DNA strands.

13. The Replication of DNA
DNA replication occurs before mitosis & meiosis.
The process is simple:
The DNA double helix splits down the middle.
New bases bond to exposed bases.
This results in two identical DNA strands.

14. How Does DNA Make Protein?
Chromosomes (DNA)
Carry the genetic message
Messenger RNA
Copies the genetic message
Transfer RNA
Holds an amino acid
The Ribosome
Assembles a protein

15. Synthesis of Proteins Step 1: Transcription of DNA Messenger RNA (mRNA)

16. Synthesis of Proteins Step 2: Match tRNA to mRNA Transfer RNA (tRNA)

17. The Ribosome

18. The Genetic Code

19. Protein Synthesis Summary

20. DNA & RNA Vocabulary
Nucleotide = one genetic letter – phosphate-sugar-base (A, T, C or G)
Codon = one 3-letter genetic word that defines an amino acid
Gene = the recipe for one protein, typically with >100 genetic words
Chromosome = a genetic cookbook with thousands of protein recipes
Genome = all of the genetic material of an organism (23 volumes for humans)

21. From DNA to Protein Step 1: DNA  mRNA

22. From DNA to Protein mRNA  tRNA  Amino Acid

23. From DNA to Protein Step 2: mRNA locks onto the ribosome

24. From DNA to Protein Step 2: mRNA locks onto the ribosome

25. From DNA to Protein Step 3: tRNA matches mRNA

26. From DNA to Protein Step 4: Amino acids link up

27. From DNA to Protein Step 4: Amino acids link up

28. Genetics – Key Concepts
Human genome project
Viruses
DNA Fingerprinting (PCR)
Genetic Engineering
Microbes
Plants
Animals/People
Cancer
Ethics in genetics

29. Human Genome Project (Our DNA)
We all have 23 pairs of chromosomes with:
~ 25,000 genes (each codes for a protein)
~ 3,000,000,000 base pairs (these are the rungs of the DNA ladder)

30. Human Genome Project Mapping
Mapping = locating the genes

31. Human Genome Project Sequencing
Sequencing = exact sequence of A,T,C, & G

32. Human Genome Project Other Organisms
Mouse, Rat, Rabbit, Cat, Dog
Chimpanzee, Elephant, Whale, Zebrafish
Frog, Fly, Flatworm
Several plants
Yeast
Hundreds of microbes (pathogens)
Thousands of viruses
Mammoth!!!

33. Unanswered Question: Why Are Genes Expressed?
All your cells contain the same genes.
But not all cells have same the function.
Therefore, some process must turn genes on and off.
How and why are certain genes activated?

34. 2. Viruses
Ebola
HIV
SARS
Swine Flu

35. 2. Viruses

36. It “infects” a cell by using the universal genetic code.
2. Viruses What is a Virus?
A virus is a loop of genetic material (DNA or RNA) wrapped in proteins.
It “infects” a cell by using the universal genetic code.

37. 2. Viruses
Viruses are not alive and they cannot reproduce on their own.
The structure is a short piece of DNA or RNA surrounded by a protein coating.
How it works:
It is taken into the cell.
It can takes over the cell to produce more copies.
It may kill the cell, or it may hide in the cell.

38. Viral Epidemics Treatment of Viruses:
Most medications treat the
symptoms, not the virus.
Vaccinations are often
extremely effective.
Viruses evolve rapidly because the DNA/RNA easily mutates (that is, it changes).

39. 3. DNA Fingerprinting (PCR)

40. 3. DNA Fingerprinting
DNA fingerprinting is based on each person’s unique DNA. It can be used to identify victims, criminals, or parents/children.
The process involves analyzing sections of DNA and comparing with a known person of interest.

41. 3. DNA Fingerprinting (PCR)
Step 4: Repeat with 2 strands of DNA.

42. 3. DNA Fingerprinting (PCR)

43. 4. Genetic Engineering

44. 4. Genetic Engineering
Genetic engineering can involve inserting foreign genes or altering existing genes.
The techniques commonly involve cutting and splicing pieces of DNA.
Examples include insulin, agriculture, and security.

45. Stem Cells An embryo’s first cells can be anything.
Later cells differentiate.
As the embryo grows, some
genes are turned on and
other genes are turned off.
A “stem cell” reproduces
without differentiation.

46. Cloning: Engineering an identical individual

47. 4. Gene Therapy

48. 4. Gene Therapy
Gene therapy involves replacing defective genes with healthy one.
“In vivo” therapies use injections.
“In vitro” therapies use testtubes.
Among many problems, the genes are inserted randomly, so often no proteins are made.
Therapeutic viruses offer an important option.

49. 4. Viral Gene Therapy

50. 5. Cancer

51. 5. Cancer-A Different Kind of Genetic Disease
Normal cell division is controlled, but cancer cells reproduce without restraint.
Cancer arises from genetic defects,
usually 3 to 6 damaged genes.
Genetic defects can increase
your lifetime risk of cancer to
more than 80%.
Most cures rely on surgery, radiation, and/or chemotherapy.
For some cancers there are now gene therapies, using viruses.

52. 6. Ethics in Genetics Who should have access to your genetic profile?
Under what circumstances should genetic discrimination be allowed?
If you could alter the genetic makeup of your child, where would you draw the line?
What limits should society place on genetically engineered organisms?