Download Slide 1 - KREISELMANBIOLOGY

Mistakes can occur in any
process. When do mistakes
have stronger effects – When
making a DNA? Making mRNA?
Making a protein? Explain why.
(Same as saying - in the
encyclopedia, in the transcript,
in the student’s homework)
Journal 2 11.16.11
All of the cells in our body
contain exactly the same DNA
set. So, how is it possible that
cells of the liver differ from
muscle cells (or other)?
Explain according to what you
know so far about gene
expression.
Journal 1
11.16.11
1) When reading the genetic
code, all the way to the
‘protein’, what kind of
mistakes did you make, or
could have made?
2) What would be the effect of
such mistakes on the resulting
protein (or word)?
•Central Dogma Song
•“DNA Damage”
DNA is under constant attack from reactive
chemicals and natural background radiation. Free
radicals are the byproducts of normal metabolism in
human cells. Seen here as bright particles they
sometimes react with DNA and cause chemical
changes. Radiation can also affect DNA. For
example ultraviolet light from the sun can cause
harmful chemical changes in the DNA of skin. These
changes can lead to kinks in the DNA that prevent
genes from being correctly read or deletions that
alter the type of proteins produced. Thanks to
constant biochemical repair work most mutations
are corrected before that have any effect. But in rare
cases mutations can accumulate and this can give
rise to diseases such as cancer.
1) What is a mutation? Answer as
best you can.
2) Watch the video “DNA
damage”. - What are conditions
that can damage the DNA and
lead to errors in the nucleotide
sequence?
3) Write one more important fact,
or question, based on this
videoclip.
What will be the effect of a
substitution on the resulting
protein?
Let’s examine and see!
(Materials needed:
Genetic Code Table)
If the normal Gene is:
TACTTACCTTATACGATC.
What would happen to the new
protein if the following point
mutations occurred?
1. 2nd T substituted with G.
2. Last G Substituted with T
3. 4th T substituted with G
4. 2nd C was deleted
5. One C inserted after 3rd T.
Mutation
Number:
Amino acid
Sequence:
Mutation
Effect:
normal
M-A-G-I-C
---------
In conclusion: Mutations
1. Mutations are random damages
to the DNA, that can be induced
by chemicals and radiation.
2. Mutations can have a small, or
large, or no effect on the protein.
3. Mutations can have a negative,
positive or no effect on the
organism.
4. Mutations may or may not be
inherited!
Point Mutations - When one
nucleotide is changed.
1. Substitution (replacement)
2. Deletion
(one nucleotide missing)
3. Insertion
(one nucleotide added)
Notes
Substitutions might:
1) Change one amino acid
(which may or may not affect
the protein’s function)
2) Cause an EARLY STOP,
canceling the entire protein.
3) Have NO EFFECT! (3rd base)
Notes
Deletion and Insertions
cause a SHIFT in the
READING FRAME:
All the amino acids further
from the mutation are
changed.
Where in the body
are mutations more
effective?
Germ Cells versus body Cells
Normal cell:
Mutated Cell:
Body Cells:
Germ Cells:
Possible
Local Effect
Does not
pass on to
the
offspring
or
Mutation is
Inherited!
Fertilized
egg
Entire
Offspring
Might be
Affected
A mutation is meaningful if:
1) It affects the amino acid
sequence, which….
2) affected the function of the
protein, which…
3) is important for the organism.
4) The mutation occurred in a
germ cell (except for cancer),
which….
5) participated in fertilization.
Mutation:
Notes
A Random change in the DNA
sequence, usually during DNA
Replication.
Chromosomal
In a single
gene
Point Mutations
(Single Nucleotide)
Animation of Various Mutations!!!
Mutations tutorial
Are all
mutations
Harmful?
No!
Mutations can be
Harmful
Silent
(with no
effect)
Of
Advantage
1. Which mutation (mistakes) in a
gene might have a greater effect
on the resulting protein –
a missing nucleotide (deletion) or
a replaced (substitution)
nucleotide? Explain.
2. How might mutations affect the
entire organism?
Answer: Mistakes in DNA
replication have the highest
potential to cause damage.
a.These errors might cause
mistakes in the mRNA and
sometimes in the protein.
b. Errors in DNA can be
inherited, while errors in mRNA
or in the protein are not
inherited.
1.The DNA is identical in all of
your body cells. How come,
then, do cells differ from one
organ to another?
2. Mutations are said to affect
the entire body only if they
occur during the making of
sperm and egg.
Why is that so?
Reflect on our unit of DNA and
Gene Expression:
1.What did you find most
interesting/important?
2. What would you want to
know more about?
In the Protein Synthesis Lab,
Which parts of the process were
represented by:
1. The Service Table?
2. The space around the table?
3. The walls of the classroom?
4. The group’s table?
5. The letter on the cards?
6. The instructions on the cards?
7. The final product?