1. DNA

2. CA Biology Standard- Genetics
4. Genes are a set of instructions encoded in the DNA sequence of each organism that specify the sequence of amino acids in proteins characteristic of that organism. As a basis for understanding this concept:
a. Students know the general pathway by which ribosomes synthesize proteins, using tRNAs to translate genetic information in mRNA.
b. Students know how to apply the genetic coding rules to predict the sequence of amino acids from a sequence of codons in RNA.
c. Students know how mutations in the DNA sequence of a gene may or may not affect the expression of the gene or the sequence of amino acids in an encoded protein.

3. What is DNA?
DNA (Deoxyribonucleic acid) is the molecule that contains the genes of living things.
It is in chromosomes inside the nucleus of eukaryotic cells. (In prokaryotes, it is free-floating in the cytoplasm.)

4. Animation: Human to DNA

6. DNA Structure

7. What is the structure of DNA?
DNA is a double helix.
The double helix is wound around proteins called histones.
This forms a beadlike structure called a nucleosome.
All packed together, this is chromatin.
Chromatin winds together to form chromosomes.

8. Where is the …. Double helix? Histone? Nucleosome? Chromatin?
Chromosome?

9. What is the structure of DNA?
Double helical ladder
‘Backbone’ of ladder is made of the sugar….
Deoxyribose
And…
Phosphate!

10. What is the structure of DNA?
The ‘rungs’ of the ladder are made of nitrogenous bases …
Pyrimidines (single ring):
Thymine [T] and…
Cytosine [C]
Purines (double ring):
Adenine [A]
Guanine [G]
The purines and pyrimidines are held together by hydrogen bonds.

11. What is the structure of DNA?
A deoxyribose sugar, a phosphate and a base all together make up a…
NUCLEOTIDE!

12. BASE PAIRING RULE! Thymine always pairs with Adenine T-A A-T
Cytosine always pairs with Guanine
C-G
G-C

13. Build a DNA Molecule

14. Why would DNA need to replicate itself?

15. Why would DNA need to replicate itself?
When a cell divides and replicates itself during mitosis, it needs to also replicate its DNA.
During meiosis, the process of gamete formation, DNA needs to be replicated to pass genes onto offspring.

16. DNA Replication Overview
The DNA molecule separates into 2 strands and then produces 2 new complementary daughter strands using the base-pair rule. Each strand of the double helix is a template for the new strand.

17. DNA Replication
The enzyme Helicase ‘unzips’ the double helix by breaking the hydrogen bonds.
The enzyme DNA Polymerase joins individual nucleotides together, making the new strand of DNA.
Period 4 stopped here 10/26/10

18. Modeling Semi-Conservative Replication
10 points Staple into notebook

19. What is the difference between DNA and RNA?

20. DNA RNA Structure Function/Processes Nitrogenous Bases Type of Sugar
Location in Cell
Types

21. DNA RNA 2-stranded double helix Contains genes/instructions for cell
Structure
2-stranded double helix
Function/Processes
Contains genes/instructions for cell
Nitrogenous Bases
Adenine, thymine, cytosine, guanine
Type of Sugar
Deoxyribose
Location in Cell
Nucleus
Types
n/a
Period 2 stopped here 10/19/10

22. What is RNA? Ribonucleic acid
Contains sugar ribose (rather than deoxyribose)
Is single-stranded rather than a double helix
Contains adenine, cytosine, guanine and the base uracil rather than thymine

23. What is the function of RNA?
RNA is involved in protein synthesis  making a gene into a trait!
It takes a copy of DNA out of the nucleus (because DNA is too big to leave the nuclear pores) and functions as a ‘working copy’ of DNA.

24. Types of RNA
Messenger RNA [mRNA]: RNA that makes a copy of DNA and leaves the nucleus
Ribosomal RNA [rRNA]: part of a ribosome, where protein synthesis occurs
Transfer RNA [tRNA]: transfers amino acid to the ribosome as it is needed in the construction of a protein

25. Types of RNA

26. DNA RNA tRNA, mRNA, rRNA Single stranded Involved in protein synthesis
Structure
2-stranded double helix
Single stranded
Function/Processes
Contains genes/instructions for cell
Involved in protein synthesis
Nitrogenous Bases
Adenine, thymine, cytosine, guanine
Adenine, uracil, cytosine, guanine
Type of Sugar
Deoxyribose
Ribose
Location in Cell
Nucleus
Nucleus (mRNA) and cytoplasm (tRNA & rRNA)
Types
n/a
tRNA, mRNA, rRNA
Period 2 stopped here 10/19/10

27. HOW DO GENES BECOME TRAITS?
PROTEIN SYNTHESIS (GENE EXPRESSION)
TRANSCRIPTION
TRANSLATION

29. Transcription
The process where mRNA molecules are produced by copying part of the DNA molecule into a complementary sequence

31. How does transcription work?
RNA polymerase binds to DNA and separates the strands. It then uses one strand of DNA as a template to assemble an RNA strand.
RNA polymerase only binds to regions of DNA called promoters, areas with specific DNA base sequences.

32. RNA Editing Introns: sequences of DNA that do not code for a gene
Exons: sequences of DNA that DO code for a gene
When mRNA is created, the introns are cut out of it and only the exons are kept!

34. Translation
The process where the cell uses mRNA to produce proteins. Occurs in the ribosome of the cell.

35. The Genetic Code
Codon: 3 nucleotide bases that code for a particular amino acid.
AUG is the start codon.
There are 3 stop codons too.
Only 4 bases, but they code for 20 different amino acids (protein sub-units)
HOW?
4x4x4= 64 possibilities

36. How does translation work?
After transcription, mRNA attaches to the ribosome.

37. How does translation work?
2. Starting with the start codon, AUG, the proper amino acid is brought to the ribosome by tRNA. That amino acid is attached to the polypeptide chain. Each tRNA molecule is specific to an amino acid. It has an anticodon that is complementary to the mRNA codon.

39. How does translation work?
Polypeptide bonds are created between amino acids, while bonds between tRNA and the amino acid are broken.
The process continues until tRNA hits a stop codon and the protein is assembled!
2nd period Stopped here 10/21/10

41. Protein Synthesis Wksht
15 points

42. Central Dogma Sing Along!

43. What is a mutation?

44. Mutations = changes in genetic material
Mutations are usually random and spontaneous, but they are sometimes caused by mutagens, chemical or physical agents that cause mutations.
Mutations can be:
Advantageous
Deleterious
Have no effect

45. Mutagens
Mutagens that cause cancer are called carcinogens because they cause unregulated cell growth.
Examples of carcinogens:
Poisons
Smoke in your lungs
Pollution
Radiation

46. What is the difference between these two statements?
My dog bit the cat.
My dog bit the car.
This is a point mutation- a mutation involving changes in one or a few nucleotides.

47. Frameshift mutations are…
When nucleotides are added or deleted, causing the whole reading frame to be shifted so that every amino acid is altered.

48. Gene Action/Mutations
15 points

49. Extra Credit: Translating a DNA Message

50. Make a DNA Keychain Write a Key in your notebook.
Phosphate = big gold bead
Sugar = big green bead
Adenine = silver tube bead
Thymine = red tube bead
Guanine = dark blue tube bead
Cytosine = green tube bead

51. Instructions for DNA Keychains