Chapter 14: Sec. 1 – Mutation & Genetic Change p. 319 – 324
I. Mutation: Basis of Genetic Change
A. Introduction
1. Define the following terms:
a. MUTATION –
b. MUTANT –
2. Where do genetic differences/mutations come from?
B. Causes of Mutations
1. After reading this section, identify 3 ways mutations can occur.
a.
b.
c.
2. What environmental factors are likely to cause mutations?
3. What does the term MUTAGEN mean?
C. Effects of Mutations – after reading this section answer the following
question.
Are all mutations harmful? Explain your answer.
II. Several Kinds of Mutations
A. Mutations as Changes in DNA – sometimes when DNA replicates the wrong
nucleotide may be paired or placed in the sequence.
1. _______________ Mutation – a change of a single nucleotide in a DNA
sequence from one nitrogen base to another.
Example: Correct DNA sequence ATGCCATCG
Point Mutation
ATGCCTCG
2. _______________ Mutation – occurs when an extra nitrogen base is
added to the DNA sequence.
Example: Correct DNA sequence ATGCCATCG
Insertion Mutation
ATGGCCATCG
The cat ate the rat becomes The Gca tat eth era t
3. _______________ Mutation – occurs when a nitrogen base in the DNA
sequence is omitted.
Example: Correct DNA sequence ATGCCATCG
Insertion Mutation
ATCCATCG Which nucleotide is missing?
The cat ate the rat becomes Thc ata tet her at
B. Mutations as Changes in Results of Genes
1. ______________ Mutation – the mutation has no effect on a gene’s
function. ______________ mutations can be an example of a silent
mutation. See Figure 2 @ bottom of page 320
2. ______________ Mutation – results when a ____________ is changed
so that the new codon codes for a different ____________ _________.
Also known as a _________________________ mutation. See Figure 2.
3. ______________ Mutation – occurs when there has been an insertion
or deletion in the DNA & the 3-letter codons are read incorrectly,
causing the wrong ___________ ___________ to be used in the making
of the protein. This protein will not function/work properly. See Figure 2.
Example: The cat ate the rat becomes The Gca tat eth era t OR
The cat ate the rat becomes Thc ata tet her at
4. __________________ Mutation – results when a codon is changed to a
“stop” codon. The chain of amino acids is shorter than it should be &
therefore the protein will not function.
C. Chromosome Mutations – there are several types
1. _______________ - occurs when a piece of a _____________________
is lost; the chromosome will be missing genes. Such a mutation is
usually ___________________.
EXAMPLE: Normal Chromosome: Genes A-B-C-D-E
Deleted Chromosome: Genes A-B-D-E
2. _________________ - occurs when a piece of DNA remains attached to
its homologous chromosome after _____________.
That one
chromosome will carry EXTRA copies of the gene or genes & a mutation
can occur.
EXAMPLE: Normal Chromosome: Genes A-B-C-D-E
Duplicated Chromosome: Genes A-B-A-B-C-D-E
3. ________________ - occurs when a piece of the DNA on the
chromosome breaks off & reattaches to the chromosome, but in the
reverse direction or order.
EXAMPLE: Normal Chromosome: Genes A-B-C-D-E
Inversion Chromosome: Genes A-B-E-D-C
4. ___________________ - occurs when a piece of a chromosome breaks
off & reattaches to an entirely different chromosome.
EXAMPLE: Normal Chromosome: Genes A-B-C-D-E
Translocation Chromosome: Genes A-B-I-J-K-C-D-E
III. Effects of Genetic Change
A. Introduction
1. What are gametes?
2. What are somatic cells?
3. Does every mutation cause a change in the appearance or function of an
organism?
4. Does every mutation get passed on to the offspring?
5. Mutations that occur in _______________/sex cells/sperm or egg cells
CAN be passed on to offspring; mutations in ________ ______/somatic
cells CANNOT be passed on to offspring but can affect the individual or
cell they occur in.
B. Heritable or Not
1. What does the term heritable mean?
2. What type of eukaryotic cells are germ cells?
3. What type of eukaryotic cells are somatic cells?
4. Differentiate between a mutation that occurs in a germ cell/sperm or
egg cell verses a somatic/body cell.
5. A cell in person’s lung cell mutates into a lung cancer cell; will that
mutation be passed on to that person’s children? Explain your answer.
C. Tumors & Cancers
1. What happens if the genes that control normal growth in a cell mutate?
2. What is a tumor?
3. When is a tumor considered to be cancer?
4. How are mutations related to cancer?
D. New Alleles
1. How do new alleles (forms of a gene) develop?
2. Are all mutations harmful? Explain.
E. Genetic Disorders
1. What are genetic disorders?
2. Why are genetic disorders relatively rare?
IV. Large-Scale Genetic Change
A. Define the following terms:
1. Crossover –
2. Nondisjunction –
3. Polyploidy -