1.6 Mutations Flashcards
Define a ‘Mutation’
A random irreversible change to an organism’s DNA sequence resulting in no protein or an altered protein be produced
What are the two possible results of a mutation?
No protein
Altered Protein
How can a mutation affect the phenotype?
Mutation will result in a change to amino acid sequence meaning altered protein/ no protein produced. The proteins produced determines the phenotype. This means the phenotype is altered.
What are the three types of single gene mutations?
Substitution
Insertion
Deletion
What are three types of substitution mutations?
Missense
Nonsense
Splice Site
What is a missense substitution mutation?
Missense - causes the change to one amino acid
What is a splice site substitution mutation?
A mutation which changes the boundaries between exons and introns, resulting in introns staying in mature transcript
What is a nonsense substitution?
A mutation when one triplet is changed to form a stop codon
What kind of substitution can result in a change to the mature mRNA transcript?
Splice site - results in introns being left in and alters final protein produced
What is a frame shift mutations?
Mutation resulting in an unnatural reading position of the amino acids
What type of single gene mutations result in a frame shift mutations?
Insertion
Deletion
What are the four types of chromosome mutations?
Duplication
Deletion
Inversion
Translocation
Describe an inversion chromosome mutation
An inversion mutation is where a segment of the chromosome breaks off, is inverted 180 degrees and attaches back onto the same chromosome
Describe a duplication chromosome mutation
A section of the chromosome is duplicated, and genes are repeated
What type of chromosome mutation decreases the length of the chromosome?
Deletion
What is a translocation chromosome mutation?
Segment of chromosome breaks off and attaches to its non homologous chromosome partner
Which type of chromosome mutation is most important in terms of evolutionary terms and why?
Duplication
- provides extra genetic material
- can undergo mutation
- increases chance of a new gene being created
What is the main difference between a gene mutation and a chromosome mutation?
Gene mutation - change to a single triplet of bases in a gene
Chromosome mutation - change to the gene sequence in a chromosome (structure of chromosome)
What is a Polyploid?
When the organism contains extra sets of chromosomes within the genome
How many sets of chromosomes does a tetraploid have?
4n
How many sets of chromosomes does a triploid contain?
3n
What is Polyploidy?
The failure of spindle fibres to separate during cell division resulting in extra sets of genetic material
Why are polyploid organisms important in evolutionary terms?
Provide extra sets of chromosomes which increase the chance of mutations
Mutations may lead to advantageous change in genotype
Describe why polyploid crops important for human food production
Produce more turgid crops/ larger fruits or seeds which grow fasts
Help food security
Give an example of a polyploid food
Banana - triploid
Potato - tetraploid
What is a regulatory sequence mutation and what can it effect?
Regulatory Sequence Mutation - mutation that occurs at non coding regions
Effect: Gene expression
