1. Gene expression and regulation & Mutations
Sections 8.6 – 8.7

2. Review What does a gene do? Where is a gene found?
What type of nucleic acid are genes coded in?

3. Genes don’t just code proteins
Protein production has to be regulated somehow
Promoters
Allows a gene to be transcribed
Helps RNA polymerase find where genes start
Operators
These turn genes “on” or “off”
What is happening during transcription?

4. Operons Include the promoter, operator, then protein sequences
Usually only found in prokaryotes/roundworms
Are prokaryotes the big, busy cells or the small, simple cells?

5. Lac operon

6. Regulation in Eukaryotes
Transcription is highly regulated
Why does it have to be?
Transcription factors
Proteins that bind to DNA to control transcription
RNA polymerase wants to do work but doesn’t know where to go
Transcription factors show the way

7. Transcription factors
Consist of…
An enhancer
And a “TATA box” promoter
Seven nucleotide sequence: TATAAAA
Sometimes enhancers can be far away from the start of a gene. How can the system still operate if the promoter and enhancer are nowhere near each other?

8. Transcription factors

9. mRNA processing Like a film that needs editing Introns Exons
Portions of code that are not used to make proteins
No one really knows why they’re present
Exons
These DO get used to make proteins
Get spliced together to form the “final cut” of our film
Addition of a cap and tail
Cap – keeps the mRNA from breaking down quickly/binds to ribosome
Tail – aids the mRNA in leaving the nucleus

11. SoooOOOOoooooOOOooo…..
Which parts of a gene DO get expressed as proteins: introns or exons?
Do promoters and enhancers HAVE to be right next to each other?
What does a promoter do?

12. Mutations!!!
Changes to an organisms genetic code

13. Usually aren’t expressed at all
Mutations can not cause you to be a superhero
Gene mutations
Point mutation – one nucleotide is replaced with another
Frameshift – insertion OR deletion of a nucleotide

16. Chromosomal Mutations
Gene duplication
Causes segments of different size between chromosomes after crossing over
Has happened A LOT
Translocation
Crossing over happens between non-homologous chromosomes

18. Impacts of Mutations Usually nothing happens
Our body is pretty good at fixing catching and fixing mutations
Chromosomal mutations can create hybrid genes with new functions or can cause genes to be more or less active
Gene mutations happen on a smaller scale
Can affect the proper production of proteins if amino acids are improperly assigned
Can cause introns to NOT be removed
Can cause a protein to not be produced at all

19. Silent mutations
This is where nothing bad happens

20. Mutagens Things in the environment that can cause mutations
Can accelerate production of errors or completely break DNA strands