Download A population is a group of the same species living together in the

Year 12 ATAR Human Biology
Unit 6 – Inheritance
Week 18 2016 - Solutions
Chapter 12 – Mutations & Gene Pools
Review Questions:
1.
a.
Population Definition
A population is a group of the same species living together in the same place at the
same time.
b.
What’s a gene pool?
The total of all the alleles in a given population.
2.
a.
Mutation definition
Mutations are the change in the structure of a gene or allele.
b.
Difference between somatic and germline mutation
Somatic mutations occur in general body cells and can’t be passed on and germline
mutations occur in the gametes and can be passed onto their offspring.
3.
a.
Difference between gene and chromosome mutation
Gene mutations are changes in a single gene whereas a chromosomal mutation involves
changes to a part or the whole chromosome.
b.
Example of a congenital disorder caused by chromosomal mutation
Cystic fibrosis is a mutation occurs on a single gene chromosome number 7
Down’s syndrome occurs when there are three number 21 chromosomes.
4.
Four different types of chromosomal mutations
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5.
a.
Deletion – part of a chromosome is lost
Duplication – section of a chromosome occurs twice
Inversion – Breaks occur in a chromosome and the broken piece joins back in but the wrong
way round.
Translocation – where part of a chromosome breaks off and rejoins to the wrong chromosome.
Non-disjunction – during meiosis an even split of the chromosomes do not occur meaning that
there is one more or one less in a gamete.
What are mutagens?
Mutagens increase the chance of mutations occurring.
b.
5 examples of mutagenic agents
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c.
Ionising radiation
Mustard gas (as used in WW1)
Sulfur dioxide
Formaldehyde
Pesticides and insecticides
Sulfur dioxide
Why pregnant women need to be careful with x-rays.
As x-rays can cause mutations in the developing child.
6.
What is a lethal recessive?
Most gene mutations produce recessive alleles as they prevent the gene from producing a
protein that will be able to function in the body.
7.
Pattern of inheritance in genetic disorders such as Duchenne’s muscular dystrophy.
This condition occurs through a mutation from the mother which will then be inherited by her
sons through x-linked inheritance.
8.
a.
Trisomy v monosomy
Trisomy means an extra chromosome such as with Down’s where monosomy is where a
chromosome is missing.
b.
Example of each condition
Trisomy – Down’s syndrome, Patau syndrome
Monosomy – Cri-du-chat
9.
Klinefelter’s syndrome & Turner’s syndrome
Klinefelters syndrome is also known as XXY syndrome. An extra X chromosome is in the
gamete. Turner’s syndrome is where the Y chromosome is missing.
10.
How mutations could change the proportion of certain alleles in a gene pool.
If the individual dies before reproduction then that particular gene is lost. However the recessive
allele could increase in number if it advantageous in a heterozygote format.
Apply Your Knowledge
1.
Why mutations in reproductive cells are more important than in somatic cells.
Mutations in somatic cells can’t be inherited so they are lost with the individual where in gametes
these can be passed on so hence, more important.
4.
Why can some viruses be considered mutagenic?
The viruses can enter and attach themselves to the cell altering the genetic makeup causing a
mutation.
6.
Lethal recessive alleles and the composition in the gene pool.
Natural selection would remove alleles however if they are advantageous if the allele would increase
in number, altering the composition in the gene pool.