1. Gene Expression Eukaryotic versus Prokaryotic
Structure dictates function

2. Prokaryotic transcription is simpler
DNA exists in one chromosome
Less non-coding sequence
RNA polymerase binds the promoter directly
Genes are clustered into functional groups called operons

3. Lac Operon

4. Eukaryotic transcription is far more complex
Transcription factors are required to articulate between RNA polymerase and promoter
Enhancers and Silencers (DNA sequences that affect gene expression) “Positionally free”
Genes include introns
Genes can be methylated on Cs
More methylation less expression
Less methylation more expression

5. Eukaryotic Transcription

6. Post-transcriptional control
mRNA processing
polyA tail
5’ cap
Alternate splicing
Remember Spatial and Temporal Seperation
RNA silencing

7. Epigenetics Chromatin
Epigenetic factors (methyl groups, acetyl groups, phosphate groups)
Chromosome
DNA methylation Methyl group can tag DNA and activate or repress genes.
Histone tails
Methyl group
Histone modification The binding of epigenetic factors to histone “tails” alters the extent to which DNA is wrapped around histones and the accessibility of genes in
the DNA.
DNA
Gene
Histones are proteins around which DNA can wind for compaction and gene regulation
DNA accessible, gene active
Histone
DNA inaccessible, gene inactive

8. Video

9. Wrap up
Was that video happening in a eukaryotic cell or prokaryotic cell?
Make a T chart of structural differences between prokaryotic and eukaryotic cells that effect their gene expression
Short sheets with review questions

10. What is a gene mutation?
Mutations are changes in genetic material – changes in DNA code – thus a change in a gene(s)
In gene mutations, the DNA code will have a base (or more) missing, added, or exchanged in a codon.
General introduction (definition) about mutation

11. How common are mutations?
Humans:Mutations occurs at a frequency of about 1 in every 1 billion base pairs
Everybody has about 6 mutations in each cell in their body!
What do you think the rate of mutation in bacterial cells are?
A fun fact about how common mutations are. Explain that everyone has mutations, although they are not always seen because the mutation may have occurred in a section of DNA that doesn’t make a protein.

12. If I have that many mutations, why don’t I look weird?
Mutations are not always seen. The affected gene may still function.
Mutations may be harmful.
Mutations may be beneficial.
Mutations may have no effect on the organism.
Explain that everyone has mutations, although they are not always seen because the mutation may have occurred in a section of DNA that doesn’t make a protein or the mutation may cause a cell to die (while not affecting the function of the organ).

13. How do mutations affect a population?
Mutations are a major source of genetic variation in a population increasing biodiversity.
Some variations may help them to survive better.
Clip Art

14. How are mutations inherited?
Only mutations in gametes (egg & sperm) are passed onto offspring.
Mutations in body cells only affect the organism in which they occur and are not passed onto offspring.

15. Types of Gene Mutations
There are 4 types:
Substitution
Also called frameshift mutations
Deletion
Insertion
Translocations
General information about the three most common types of mutations to transition into the examples

16. 3 types of Substitution Mutations
Sense
Creates a new amino acid codon
Nonsense
Creates a new stop codon
Missense
Creates a change in 1 amino acid
4. Silent
Creates no change in amino acid sequence

17. Substitution Mutations Sense mutations
Normal DNA: CGA – TGC – ATC
Alanine – Threonine - stop
Mutated DNA: CGA – TGC – TTC
Alanine – Threonine - Lysine
Ask students if they can figure out what is happening in this mutation.
Answer is on the next slide.
What has happened to the protein? Elongated until next stop codon
This is a substitution

18. Substitution Mutations Nonsense mutations
Normal DNA: CGA – TGC – TTC
Alanine – Threonine - Lysine
Mutated DNA: CGA – TGC – ATC
Alanine – Threonine - Stop
Ask students if they can figure out what is happening in this mutation.
Answer is on the next slide.
What has happened to the protein? Shorter

19. Substitution Mutations Missense mutations
Normal DNA: CGA – TGC – TTC
Alanine – Threonine - Lysine
Mutated DNA: CGA – TGC – GTC
Alanine – Threonine - Leucine
Ask students if they can figure out what is happening in this mutation.
Answer is on the next slide.
What has happened to the protein? Changed by one amino acid same length

20. Gene Mutations
An example of a substitution mutation is sickle cell anemia.
Only one amino acid changes in the hemoglobin.
The hemoglobin still functions but it folds differently changing the shape of the rbc.
Normal Red Blood Cells
The hemoglobin ends up with a differently charged amino acid that caused the RBC to stick to itself. This is the sickle part. This affects the way hemoglobin can carry oxygen.
Sickle Shaped Red Blood Cells

21. Frameshift Mutations Change the reading frame of the sequence.
Insertions
Deletions

22. Insertion Mutations What has happened to the DNA?
Normal DNA: CGA – TGC – ATC
Alanine – Threonine – stop
Mutated DNA: CGA – TAG – CAT – C
Alanine – Isoleucine – Valine
Ask students if they can figure out what is happening in this mutation.
Answer is on the next slide.
What has happened to the DNA?
What will happen to the amino acids?
This is an insertion mutation, also a type of frameshift mutation.
An adenine was inserted thereby pushing all the other bases over a frame.

23. Insertion Mutations This is an insertion mutation.
A nitrogen base is inserted/added to the sequence.
It causes the triplet “frames” to shift.
It always affects the amino acids and, consequently, the protein.
Ask students if they can figure out what is happening in this mutation.
Answer is on the next slide.
Normal DNA: CGA – TGC – ATC
Alanine – Threonine - stop
Mutated DNA: CGA – TAG – CAT – C
Alanine – Leucine - Valine

24. Analogy Insertion The cat ate the rat. The cca tat eth era t.
Inserting the c causes a
FRAMESHIFT
THE SENTENCE NO LONGER MAKES SENSE!! Insertions may have huge effects.

25. Deletion Mutations
Normal DNA: CGA – TGC – ATC
Alanine – Threonine – stop
Mutated DNA: CGA – TCA- TC
Alanine – Serine
Ask students if they can figure out what is happening in this mutation.
Answer is on the next slide.
This is called a deletion mutation, also a type of frameshift mutation.

26. Deletion Mutations This is a deletion mutation.
A nitrogen base is deleted/removed from the sequence.
It causes the triplet “frames” to shift.
It always affects the amino acids and, consequently, the protein.
Ask students if they can figure out what is happening in this mutation.
Answer is on the next slide.
Normal DNA: CGA – TGC – ATC
Alanine – Threonine – stop
Mutated DNA: CGA – TCA- TC
Alanine – Serine

27. Analogy Thc ata tet her at FRAMESHIFT
DELETION
The cat ate the rat.
Thc ata tet her at
FRAMESHIFT
The sentence no longer makes sense!! Deletions can have huge effects.

28. Don’t put an oncogene in front of a promoter: Translocations

29. Translocations

30. Gene Mutations
When does a gene mutation have the greatest affect on an organism?
Egg being fertilized
When it occurs in the gamete (egg or sperm) or early in embryonic development (in stem cells or first few days).
Stem cells have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.
Four cell Zygote
Embryo

31. Age is a Leading Risk Factor for Cancer
10,000
1,000
100
Cancer deaths (per 100,000)
KEY 10
Male
Female 1
<1 4 1–
5–9
–14
–24 44 64
85+
15–19
25–34
45–54
65–74
75–84 10 20
35–
55–
Age groups in years

32. Radiation Radiation is a mutagen
From L. J. Kleinsmith, Principles of Cancer Biology. Copyright (c) 2006 Pearson Benjamin Cummings.