Download CHAPTER 8 MUTATIONS PART 8 MUTATIONS – Chromosome

CHAPTER 8
MUTATIONS
PART 8
MUTATIONS – Chromosome (Crossover during meiosis, Deletions,Inversions, TRANSLOCATION,
Duplication ANEUPLOIDY (Non-Disjuction-Trisomy, Klinfelters, Turners) Polyploidy
Gene- Substitution, Inversion, Insertion/deletion, Frameshift, Mutagens, Mutation rates, Somatic or Germ
line
Questions
1. Gene mutations are alterations to the base sequences in genes. Describe the three major types of base
mutations – Substitution, Insertion, Deletion and there effects.
2. Explain why mutations are usually harmful. Which of the 3 above types is the least harmful. Why?
3 Distinguish between germ line and somatic mutations.
4 What sort of mutation can be beneficial to an organisms long term survival?
5. What is Translocation
6. Can genes on different chromosomes become linked? (Think)
7. What is non-disjunction.
8. Make a list of examples of a condition that arises as a result of non-disjunction. Explain what must have
happened during meiosis and at what stage it happens.
9. What is polyploidy. How does it help sterile hybrids?
10. List some causes of mutation.
1. (Question 8)
The origin of new alleles at a gene locus is the result of
A. migration.
B. mutation.
C. recombination.
D. independent assortment.
2.
(Question 13)
Achondroplasia is an autosomal dominant trait in humans that results in a form of dwarfism. In some cases a child
with achondroplasia is born to parents who have normal height.
The most likely reason for the appearance of the child with achondroplasia is that
A. the parents are carriers and the child has inherited the mutant allele from each parent.
B. a mutation has occurred in a gamete of either the mother or the father.
C. a mutation has occurred in a somatic cell of one of the parents.
D. a mutation has occurred in the tissues of the child.
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(Question 6)
Cabbage (Brassica oleracea) and radish (Raphanus sativus) both have a diploid number of 18. However they
do not naturally hybridise with each other.
a. How many chromosomes would be expected in the gametes of the cabbage?
In the laboratory, the two species can be forced to mate and produce offspring. The offspring are sterile.
b. i. What would be the diploid number of the hybrid?
ii. Explain why the hybrid of the cabbage and radish is sterile.
An occasional spontaneous event produces a doubling of each chromosome set in the hybrid. The new plants are able
to grow and produce fertile offspring.
c. What term is used to describe cells with more than two sets of chromosomes?
d. Explain, with reference to the events of meiosis, why the new plants are fertile.
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(3.) Genetic ‘accidents’ can occur to chromosomes. One type of accident is when one chromosome becomes
permanently attached to another. This kind of arrangement is called a translocation.
A scientist observed a translocation involving chromosomes 9 and 18 in somatic cells of a male cat. Figure 8
shows chromosomes 9 and 18 in a normal male cat and their arrangement in the cat carrying the translocation.
Note that the centromere of the translocated number 18 chromosome has been lost.
In some cases translocations lead to abnormalities, but that was not the case here. The cat had a normal phenotype.
b. i. What is meant by the phenotype of an organism?
ii. The cat with the translocation had only 37 chromosomes in each somatic cell. Explain why it still had a normal
phenotype.
The cat’s reproductive tissue also contained the translocation, and investigation showed that he produced four
different kinds of sperm with respect to chromosomes 9 and 18. Two of these four types are shown in Table 2.
c. Complete Table 2 by naming the chromosome
make-up of sperm types 3 and 4 respectively.
One type of sperm produced by the male carrying the
translocation does not survive.
d. i. Explain which type this is most likely to be.
ii. The male cat with the translocation is mated to a
normal female. What is the chance that he will father
a kitten with the same kind of translocation involving
chromosomes 9 and 18, and a normal phenotype?
5. Streptococcus pneumonia is a bacterium which causes pneumonia in humans and may show resistance to
antibiotics.
a. How would antibiotic resistance have first occurred in the Streptococcus pneumonia population?
6. In some Australian insects, new species have arisen through changes that occurred to chromosomes in an ancestral
species. Such changes may involve the joining together of chromosomes, the loss of whole or parts of chromosomes,
and rearrangement of the genetic material within chromosomes.
One ancestral species has the following haploid set of chromosomes.
As the changes in chromosomes accumulate, a number of different species can
result from a single ancestral species.
Three species that have evolved from the ancestral species shown above have
the haploid sets of chromosomes shown below.
6. (Question 25)
The most likely order of evolution of these species is
A. ancestral species, species Z, species G, species M.
B. ancestral species, species G, species M, species Z.
C. ancestral species, species M, species G, species Z.
D. ancestral species, species G, species Z, species M.
Below is the DNA sequence from the beginning of a gene coding for an enzyme involved in photosynthesis. The
upper line of bases (in bold) represents the template strand.
a. Write the mRNA sequence that would be transcribed from this DNA sequence.
7. (b. i. )The 6th base on the template strand of the sequence above is substituted by C.
What type of mutation is this?
ii. Explain the effect this mutation will have on the amino acid sequence of the protein produced
c. The 11th base pair of the sequence is deleted. Explain the effect that this mutation will have on the amino acid
sequence of the protein produced.