Activating Strategy
• What will the Amino Acids be?
• A gene whose DNA template strand contains
the sequence:
3’- T A C T T G T C C G A T A T C -5’
mRNA:
A. A.:
Using the following chart, determine the
sequence of amino acids for the gene.
What are mutations?
• Changes to the genetic
information of a cell or
virus
AP Lesson #52
– Responsible for huge
diversity in genes
• Two types of mutations
EQ: What role do mutations play
in transcription and translation?
What are point mutations?
• single base change
• base-pair substitution
Original:
The fat cat ate the wee rat
– Point Mutations
– Frameshift Mutations
What are the types of Point Mutations?
• silent mutation
– no amino acid change
– redundancy in code
• missense
– change amino acid
• nonsense
– change to stop codon
Point Mutation: The fat hat ate the wee rat.
1
What is sickle cell anemia?
• Causes a change in the red blood cell structure and
function
– Sickle shaped cells can block blood vessels and limit the
movement of crucial materials in the blood
• recessive inheritance pattern
• strikes 1 out of 400 African Americans
– 1 in 12 are carriers
How does this mutation occur?
• Missense
– Thymine nucleotide
is changed to an
adenine nucleotide
– Resulting mRNA
codon has changed
– New codon changes
the amino acid
hydrophilic
amino acid
hydrophobic
amino acid
• Amino acid is
changed from
hydrophillic to
hydrophobic
What is a frameshift mutation?
• shift in the reading frame
– changes everything “downstream”
What are types of frameshift mutations?
• insertions
– adding base(s)
• deletions
– losing base(s)
Original:
The fat cat ate the wee rat
Frame Shift:
The fat caa tet hew eer at.
What is Cystic fibrosis?
• Primarily whites of
European descent
– strikes 1 in 2500 births
• 1 in 25 whites is a carrier (Aa)
– normal allele codes for a membrane protein
that transports Cl- across cell membrane
• defective or absent channels limit transport of Cl- (& H2O)
across cell membrane
• thicker & stickier mucus coats around cells
• mucus build-up in the pancreas, lungs, digestive tract &
causes bacterial infections
– without treatment children die before 5;
with treatment can live past their late 20s
• Where would this mutation
cause the most change:
beginning or end of gene?
What is the cause of Cystic fibrosis?
• deletion mutation
– loss of the amino acid phenylalanine located at
position 508 in the protein
– When CFTR protein with the mutation reaches the
ER, it is recognized that the protein is folded
incorrectly and is marked for degradation
delta
F508
loss of one
amino acid
2
How does this effect the Lungs?
• CFTR – (Chloride channel protein) transports chloride
through protein channel out of cell
– Osmotic effects: H2O follows Cl-
Summarizing Strategy
• Create a Graphic Organizer
• ∆ F508 never reaches the cell membrane
– Upsets the Cl- balance = thicken mucus = chronic infections
normal
Cl-
cystic fibrosis
airway
Cl-
H2O
Mutations
H2O
cells lining
lungs
mucus secreting glands
bacteria & mucus build up
thickened mucus
hard to secrete
Assessment
• HW: Complete DNA to Protein Essay
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