Gene Mutations Flashcards
1
Q
What is a mutation?
A
- a sudden change in the genetic makeup (DNA) of an organism
2
Q
How does a gene mutation occur?
A
- from a change in the sequence of nucleotides in a DNA molecule
- causing a change in the information the gene gives to the cell
- i.e. the codons will be altered which will result in a faulty protein or no protein at all being made
3
Q
What are mutagens?
A
- factors that increase the rate of mutations
4
Q
What are some examples of environmental mutagens?
A
- ionising radiation (ultraviolet light and X-rays)
- mutagenic chemicals
- viruses
- micro-organisms
5
Q
What are the different types of cell mutations?
A
- somatic mutations
- gametic mutations
6
Q
What are the characteristics of somatic mutations?
A
- occur in body cells
- not transmitted to the next generation
- can cause cells to become malignant, resulting in cancer
7
Q
What are the characteristics of gametic mutations?
A
- occur in the reproductive organs (ovaries, testes, anthers, embryo sacs)
- produce changes to the genes in the gametes
- these germ-line mutations may lead to variation in the offspring
- eventually by accumulating these changes, a new species may evolve, a process called speciation
- may lead to hereditary diseases
8
Q
What are the 3 kinds of mutations?
A
- neutral mutations
- beneficial mutations
- harmful mutations
9
Q
What are the effects of neutral mutations?
A
- they do not affect the life of the organism
10
Q
When do beneficial mutations occur most often and why?
A
- amongst viruses and bacteria
- due to their rapid reproduction rate
- e.g. new multi-resistant bacteria that have mutated to become resistant to antibiotics
11
Q
How does natural selection occur as a result of beneficial mutations?
A
- when a mutation leads to a change in the phenotype
- resulting in organisms adapting better to new or unfavourable conditions
- allowing them to survive and breed more successfully than the rest of the population
12
Q
What happens as a result of natural selection and beneficial mutations?
A
- in time the whole population will have the new genotype and a new species will have been formed
- i.e. speciation has occurred
13
Q
How are harmful mutations usually inherited?
A
- as autosomal recessive traits
14
Q
What does autosomal mean?
A
- relates to chromosomes that are not sex chromosomes
- i.e. numbers 1 to 22
15
Q
How do harmful mutations occur?
A
- the heterozygous parents each have one normal copy of the gene and one mutated, non-functional copy
- the homozygous recessive individuals exhibit the disorder because both gene copies are non-functional and the correct gene product, a protein, is missing
