Transcript Ch 13 RNA and Protein Synthesis

1 Explain What is a frameshift mutation and give an
example
Infer The effects of a mutation are not always
visible. Choose a species and explain how a
biologist might determine whether a mutation has
occurred and, if so, what type of mutation it is
2 Review List four effect mutations can have on genes
Apply Concepts What is the significance of
mutations to living things
CH 13 RNA AND PROTEIN SYNTHESIS
13.4 Mutations
Mutations

Heritable changes in genetic information

Cells make mistakes in copying their own DNA,
inserting the wrong base or even skipping a base
as a strand is put together.

Gene mutations
 Produce

changes in a single gene
Chromosomal mutations
 Produce
changes in whole chromosomes.
Gene mutations

Point mutations
 Changes
in one or a few nucleotides
 Occur at a single point
 Include substitutions, insertions, and deletions.
Substitutions


One base is changed to a different base
Affect one amino acid or none.
Insertions and Deletions




One base is inserted or removed from the DNA
sequence
Results in codons being shifted
Changes all amino acids after that point
Frame shift mutation.
Chromosomal Mutations


Changes gene location on chromosomes and can
even change the number of copies of some genes
Includes deletion, duplication, inversion, and
translocation.
Deletion

Involves the loss of all or part of a chromosome.
Inversion

Reverses the direction of parts of a chromosome.
Translocation

Occurs when part of one chromosome breaks off
and attaches to another.
Duplication

Produces an extra copy of all or part of a
chromosome.
Mutations

Genetic material can be altered by natural events
or by artificial means
 DNA
inserts an incorrect base roughly once in every 10
million bases
 Mutagen: chemical or physical agent in environment
such as pesticides, cigarette smoke, and radiation

DNA does repair some damage.
Effects of Mutations

Most people think they are harmful
Some are harmful
Some are helpful
Most have no effect
A few are lethal

Mutations are needed at the species level.




Polyploidy


Condition in which an organism has extra sets of
chromosomes
Polyploid plants are often larger and stronger than
diploid plants.
Small mutations in DNA can cause huge changes in
the proteins that are synthesized. Similarly, small
changes in a word can dramatically alter its
meaning
Milk Mile Wile Wise Wisp Wasp
Notice that each word differs from the previous word
by just one letter and none of the words is
meaningless. Think of these changes as “point
mutations.”
Analyze and Conclude
1.
2.
3.
Apply Concepts Start with the word gene, and
change it letter by letter to make new words. Make
sure each new word is an actual word (not proper
noun). Write at least 4 “point mutations” of the
word gene
Apply Concepts Show how you could use words to
model a frameshift mutation (hint: use a sentence)
Use Models Use the words in this sentence to
model a substitution mutation.