Transcript Mutations and Gene Regulation

Warm-Up / EOC Prep
1. A segment of a DNA strand has the following bases:
TAC GAT
What is the complementary strand of DNA?
A. UAG CAU
B. TAG CAT
C. ATG CTA
D. AUG CUA
2. Which relationship is most similar to the
relationship below?
tRNA : ribosome
A. book : publisher
B. truck : factory
C. key : lock
D. baker : pie
Agenda
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Warm-up
Notes- Mutations
Mutation Practice WS
BINGO (If we have time)
DNA Quiz
Clean-up
Cool-Down
Mutations and Gene Regulation
• Remember: In Eukaryotes, DNA is found
in the nucleus.
• For the most part, all of the cells in an
organism’s body have the same DNA.
However, we have learned in the past that
cells are specialized for specific tasks and
parts of the body.
• How can they be specialized but have the
exact same DNA, the exact same
instructions?
• Cell differentiation is the way that cells
become different from each other as they
go through mitosis.
• At first, all cells are the same and are not
specialized. These cells are called stem
cells.
• As they grow and divide they become
differentiated and specialized into heart
cells, brain cells, liver cells, etc.
• The differentiation of cells, despite the
fact that all cells have the same DNA,
occurs due to gene regulation. Both
prokaryotic and eukaryotic cells can
regulate which genes are expressed and
which are not, depending on the cell’s
needs.
Cell Organization Review
• Specialized cells have specific jobs.
• A group of similar cells working together to
perform the same function is called a tissue.
• Ex: muscle, epithelial, connective, nervous
• A group of similar tissues working together
to perform the same function is called an
organ
• Ex: heart
• A group of similar organs working together
to perform the same function is called an
organ system.
• Ex: circulatory system
• The four levels of organization:
1.Cell
• 2. Tissue
• Four types: muscle, connective,
epithelial, nervous
• 3. organ
• 4. organ
system
• As different cells respond to the
environment they produce different types
and amounts of proteins by “turning on”
some genes and “turning off” other genes.
• Remember: A gene is a segment of DNA
located on a chromosome that codes for a
specific hereditary trait.
• This protein production is what
specializes different cells for different
jobs.
• Turning on and off genes can be an
advantage or a disadvantage to the cell.
Gene regulation can cause the
overproduction or underproduction of
proteins as well as the production of
proteins at incorrect times.
• An overproduction of proteins can cause
cancer (the uncontrolled growth of cells),
however, overproduction of proteins can
also help the body, such as in injury
repair
• Just like poor gene regulation, mutations
can also cause problems in cells.
• A mutation is a change in the nucleotidebase sequence of a gene or DNA molecule
• When the cell copies its DNA, the enzyme
DNA polymerase is in charge of
proofreading the new DNA strand for
errors. If it makes an error and doesn’t
correct it, a mutation occurs.
• Mutations can disrupt the functions of
proteins.
Examples
• DNA: TAC-GGC-GAG-TAG-CCT
• RNA: AUG-CCG-CUC-AUC-GGA
• AA: Met - Pro -Leu -Iso -Gly
• These amino acids in this order make up a
specific protein that is needed by the body.
Examples
• If one DNA nucleotide is changed, look what
happens to the protein…
• DNA: TAC-GTC-GAG-TAG-CCT
• RNA: AUG-CAG-CUC-AUC-GGA
• AA: Met - Glu -Leu -Iso -Gly
• Now a point mutation has been made, or
perhaps an amino acid sequence that is different
and will do nothing.
Examples
• A different type of mutation can occur called a
frame-shift mutation. What would happen if
DNA Polymerase accidently removed one of the
nucleotides in the original DNA sequence?
X
• DNA: TAC-GGC-GAG-TAG-CCT
• DNA: TAC-GGC-AGT-AGC-CT
• RNA: AUG-CCG-UCA-UCG-GA
• AA: Met - Pro -Ser -Ser - ---
Types of Mutations
• Gene Mutations
▫ Point Mutation (not serious usually)
▫ Frame Shift Mutations (serious)
 Insertion
Deletion
• Chromosome Mutations (all very
serious)
▫ Deletion
▫ Inversion
▫ Translocation
Insertion
Types of Gene Mutations
Types of Chromosome
Mutations
REVIEW
• What is a mutation?
• A change in a nucleotide base sequence
• Name that mutation:
• THE CAT SAT THE TAC SAT
• Inversion
• Name that mutation:
• THE CAT SAT  THE CT SAT
• Deletion
• Name that mutation:
• THE CAT SAT  THE CATTA SAT
• Insertion
• Name that mutation:
• THE CAT SAT  ITH ECA TSA
• Frameshift mutation
Mutation Practice
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If your birthday is..
Jan-Mar: insertion
Apr-June: deletion
July-Sept: inversion
Oct-Dec: point mutation
• Mutate this mRNA strand according to your
birthday.
• ACU CGA ACA
Now..
• Take the original sequence and translate it.
• Also take your mutated sequence and translate
it.
• Did the amino acid chain change because of the
mutation?
Mutation Practice
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If your birthday is..
Jan-Mar: point mutation
Apr-June: insertion
July-Sept: deletion
Oct-Dec: inversion
• Mutate this mRNA strand according to your
birthday.
• CAC UAG AGU
Now..
• Take the original sequence and translate it.
• Also take your mutated sequence and translate
it.
• Did the amino acid chain change because of the
mutation?
Mutation Practice
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If your birthday is..
Jan-Mar: inversion
Apr-June: point mutation
July-Sept: insertion
Oct-Dec: deletion
• Mutate this mRNA strand according to your
birthday.
• UCC GAC GCA
Now..
• Take the original sequence and translate it.
• Also take your mutated sequence and translate
it.
• Did the amino acid chain change because of the
mutation?
Mutation Practice
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If your birthday is..
Jan-Mar: deletion
Apr-June: inversion
July-Sept: point mutation
Oct-Dec: insertion
• Mutate this mRNA strand according to your
birthday.
• ACT CGA UCG
Now..
• Take the original sequence and translate it.
• Also take your mutated sequence and translate
it.
• Did the amino acid chain change because of the
mutation?
• Whiteboards & Markers Away!
• Complete the Mutation Practice worksheet.
Complementary DNA Strand
• TCTAAC
• CTTAAG
• GAGATC
• AGTCAG
• CAGGTT
• AACGUC
• GCTACG
• CGAATT
Transcribe DNA to mRNA
• ATCGAA
• GGCATA
• CTAGCA
• TTCAGG
• AGTCAT
• GTCAGT
• CCAGGT
• AATTGC
Reverse Transcription: mRNA to DNA
• AUGCAA
• UGAACC
• AUGCCA
• GUCACU
• ACUGUA
• CGUCAC
• UCGACC
• ACGUUA
Translate: mRNA to protein chain
• AUGCAA
• UGAACC
• AUGCCA
• GUCACU
• ACUGUA
• CGUCAC
• UCGACC
• ACGUUA
Cool-Down
1- What is the difference between transcription
and translation (consider inputs and outputs)?
2- A mutation changes the original sequence of AT-T-C-G-A to T-T-A-C-G-A. What kind of
mutation was this? Did it shift the reading
frame?
3- Fictional: in the battle between DNA and
protein, who makes the stronger case for
determining who you are as a person?
Mutation Practice
Name the correct mutation!
• Normal Gene: ACA TCA CCG
• Mutation # 1: ACG TCA CCG
• Mutation # 2: ACA ACT CCG
• Mutation # 3: AAT CAC CG
Mutation Practice
Name the correct mutation!
• Normal Gene: TCG CCG ACG
• Mutation # 1: TCT GCC GAC G
• Mutation # 2: TCG CCG CCG ACG
• Mutation # 3: GCC GCT ACG