Structure of the Genome and Mutation Flashcards
What is the genome of an organism?
The total genetic information encoded into the base sequence of its DNA
What types of sequences does the genome contain?
Those that code for protein (genes) and those that do not
What genetic sequences that are contained in the genome, do not code for proteins?
Introns, regulators of transcription and those that are transcribed into RNA but not translated
What is the function of: coding sequences (genes)?
To code for amino acid sequences in proteins
What is the function of: non-coding sequences?
Regulate transcription via turning genes on and off, others are unknown
What are mutations?
Mutations are rare, random changes to DNA sequences
What is the effect of single gene mutation?
No protein, or an altered protein is produced
What is the effect of mutations at splice sites?
Can cause introns to be left in mature mRNA, leading to an altered protein
What is the effect of chromosome mutation?
Affects structure of chromosomes present in cells
Where does single gene mutation occur?
Within genes
What do single gene mutations involve?
The alteration of a DNA nucleotide sequence
What do gene mutations result in?
No protein, or an altered protein being expressed
What are the three types of gene mutation?
Substitution - A single nucleotide is removed and replaced by another with a different base, Insertion - Additional nucleotide added into a DNA sequence, Deletion - Nucleotide removed from a DNA sequence with no replacement
What is the impact of Substitution on protein structure?
Substitution results in a minor impact since there is a maximum of one amino acid changed in the protein structure this is called missense, thought a Major impact could occur if mutation results in the production of a premature stop codon, this is called nonsense
What is the impact of Insertion and Deletion?
Major effect on protein structure likely since all amino acids codded for after the mutation could be affected, sometimes called frame-shift mutation
What is the effect of a single gene mutation at a splice site?
May result in an intron being left in the mature mRNA or an exon being left out, this could result in a protein that would not function normally
What is the significance of gene mutation in evolution?
Mutation provides the only source of new variation for living organism and so has vital importance in evolution
How do chromosome mutations occur?
When pieces of the chromosome break off and are lost or join back into the chromosome complement in a different way
What are the 4 types of chromosome mutations?
Deletion - Detached genes are lost completely, Inversion - Chromosome breaks in two place and a set of genes rotates through 180 degrees, Translocation - Detached genes become attached to a non-homologous chromosome in the complement, Duplication - A set of genes from one chromosome becomes attached to its homologous partner, leading to repeated genes
Discuss chromosome mutations and evolution
It is thought that duplicated genes can undergo single gene mutations without affecting the function of the original gene
