1. DNA Genes were known to…
Carry information from one generation to the next
Genes determined the heritable characteristics (phenotypes) of organisms
Genes had to easily be copied

2. Figure 12–5 DNA Nucleotides
Section 12-1
Nitrogen Bases
20- 23
Purines
Pyrimidines
Adenine
Guanine
Cytosine
Thymine
Nucleotide
Sugar
Phosphate Group
Nitrogen Base
Phosphate group
Deoxyribose Sugar
Go to Section:

3. Figure 12–7 Structure of DNA
Section 12-1
Nucleotide
24. Bases paired A-T…G-C
Hydrogen bonds
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Go to Section:

4. Chargaff’s Rule – Base Pairing Rule
25. Chargaffs rule- Chemical analysis showed that percent of A was
equivalent to T and G was equivalent to C
Source of DNA A T G C
Streptococcus
Yeast
Herring
Human
% of A ≈ % of T
% of G ≈ % of C

5. Rosalind Franklin X Ray diffraction
26. Shaped is helix containing two strands

6. Watson and Crick Model
27-28
1953

7. Section Outline 12–2 Chromosomes and DNA Replication
A. DNA and Chromosomes
1. DNA Length
2. Chromosome Structure
B. DNA Replication
1. Duplicating DNA
2. How Replication Occurs
Go to Section:

8. Prokayrotic vs. Eukaryotic DNA
1-3

9. Prokaryotic Chromosome Structure
Section 12-2 5
Chromosome
E. coli bacterium
Bases on the chromosome
Go to Section:

10. How DNA is packaged
3-4

11. Figure 12-10 Chromosome Structure of Eukaryotes
Section 12-2
Human cells contain over one meter of DNA! How?
Nucleosome
7-10
Chromosome
DNA
double
helix
Coils
Supercoils
Histones
Wrapped around proteins (histones and nucleosomes) – only in this
prior to cell division (mitosis) as a way to package all that material
Go to Section:

12. Figure 12–11 DNA Replication
Section 12-2
Original strand
DNA polymerase
New strand
Growth
DNA polymerase
Growth
Replication fork
Replication fork
Nitrogenous bases
New strand
Original strand
Replication
Go to Section:

13. DNA replication

14. Interest Grabber Information, Please
Section 12-3
Information, Please
DNA contains the information that a cell needs to carry out all of its functions. In a way, DNA is like the cell’s encyclopedia. Suppose that you go to the library to do research for a science project. You find the information in an encyclopedia. You go to the desk to sign out the book, but the librarian informs you that this book is for reference only and may not be taken out.
1. Why do you think the library holds some books for reference only?
2. If you can’t borrow a book, how can you take home the information in it?
3. All of the parts of a cell are controlled by the information in DNA, yet DNA does not leave the nucleus. How do you think the information in DNA might get from the nucleus to the rest of the cell?
Go to Section:

15. Section Outline 12–3 RNA and Protein Synthesis A. The Structure of RNA
B. Types of RNA
C. Transcription
D. RNA Editing
E. The Genetic Code
F. Translation
G. The Roles of RNA and DNA
H. Genes and Proteins
Go to Section:

16. RNA vs. DNA GR 1 Differences between RNA and DNA
DNA contain deoxyribose sugar,
RNA contains ribose
DNA is double stranded and RNA
is single
RNA contain Uracil in place
of Thymine

17. Figure 12–14 Transcription
Section 12-3
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
GR 2
RNA is like disposable copy of DNA
Hundreds of copies of RNA made from
One strand of DNA
RNA polymerase
DNA
RNA
Go to Section:

18. RNA GR 5 tRNA – transfer RNA mRNA – messenger RNA
Carries amino acid to the ribosome
to assemble protein
mRNA – messenger RNA
Carries copy of instruction for proteins from
DNA to the ribosomes

19. Bring amino acids to ribosome
Concept Map
Section 12-3
RNA
can be
Messenger RNA
Transfer RNA
also called
which functions to
also called
which functions to
Bring amino acids to ribosome
mRNA
Carry instructions
tRNA
from to
DNA
Ribosome
Go to Section:

20. Figure 12–14 Transcription
Section 12-3
Transcription – process by which DNA code is changed into mRNA
Mr. Krabbs giving secret formula to Squidward to take to kitchen
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA polymerase
DNA
RNA
Go to Section:

21. protein synthesis

23. Figure 12–17 The Genetic Code
Section 12-3
Go to Section:

24. Figure 12–18 Translation Section 12-3 mRNA Go to Section: Nucleus
Messenger RNA
Messenger RNA is transcribed in the nucleus.
mRNA
Lysine
Phenylalanine
tRNA
Transfer RNA
The mRNA then enters the cytoplasm and attaches to a ribosome. Translation begins at AUG, the start codon. Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds methionine. The ribosome also binds the next codon and its anticodon.
Methionine
Ribosome
mRNA
Start codon
Go to Section:

25. Figure 12–18 Translation (continued)
Section 12-3
The Polypeptide “Assembly Line”
The ribosome joins the two amino acids—methionine and phenylalanine—and breaks the bond between methionine and its tRNA. The tRNA floats away, allowing the ribosome to bind to another tRNA. The ribosome moves along the mRNA, binding new tRNA molecules and amino acids.
Growing polypeptide chain
Ribosome
tRNA
Lysine
tRNA
mRNA
Completing the Polypeptide
The process continues until the ribosome reaches one of the three stop codons. The result is a growing polypeptide chain.
mRNA
Translation direction
Ribosome
Go to Section:

26. Interest Grabber Determining the Sequence of a Gene
Section 12-4
Determining the Sequence of a Gene
DNA contains the code of instructions for cells. Sometimes, an error occurs when the code is copied. Such errors are called mutations.
Go to Section:

27. Interest Grabber continued
Section 12-4
1. Copy the following information about Protein X: Methionine—Phenylalanine—Tryptophan—Asparagine—Isoleucine—STOP.
2. Use Figure 12–17 on page 303 in your textbook to determine one possible sequence of RNA to code for this information. Write this code below the description of Protein X. Below this, write the DNA code that would produce this RNA sequence.
3. Now, cause a mutation in the gene sequence that you just determined by deleting the fourth base in the DNA sequence. Write this new sequence.
4. Write the new RNA sequence that would be produced. Below that, write the amino acid sequence that would result from this mutation in your gene. Call this Protein Y.
5. Did this single deletion cause much change in your protein? Explain your answer.
Go to Section:

28. Section Outline 12–4 Mutations A. Gene Mutations Section 12-4
Go to Section:

29. Mutations – any change in genetic material
Gene mutations
Chromosomal
Changes to bases making up the gene
Point – affect only 1 amino acid
Substitution – a change in one base
Frameshift – affect all amino acids from the mutation
Deletion – removal of base
Insertion – addition of base
Changes to entire chromosome

30. Gene Mutations: Substitution, Insertion, and Deletion
Section 12-4
Frameshift
Point
Deletion
Substitution
Insertion
Notice only 1 amino
acid changed
Less impactful?
Notice all amino acids are affected from the point of the mutation
Go to Section: