1A5+6- Structure of the genome and mutations

What is the genome?

an organism's entire hereditary information encoded in DNA

What is the genome made up of?

genes

What are genes?

DNA sequences that code for protein, and other DNA sequences that don't code for proteins

Is the genome in eukaryotes mostly coding sequences or non-coding sequences?

non-coding sequences

What are non-coding sequences involved in?

some regulate transcription, and others are transcribed into RNA but not translated

Name two non-translated forms of RNA

tRNA and rRNA

What are mutations?

changes in the DNA that can result in no protein or an altered protein being synthesised

Name the three types of single gene mutation

insertion, deletion and substitution

Name the three types of substitution mutations

missense, nonsense and splice-site

What is a missense mutation?

where one amino acid is changed for another

What does a missense mutation result in?

a non-functional protein or have little effect on the protein

What is a nonsense mutation?

mutation where a premature stop codon is produced

What does a nonsense mutation result in?

a shorter protein

What is a splice-site mutation?

mutation where some introns are retained and/ or some exons are not included in the mature transcript

What does a splice-site mutation result in?

a non-functional protein being produced

What do insertion and deletion mutations result in?

a frame-shift mutation

What does a frame-shift mutation result in?

causes all codons and amino acids after the mutation to be changed, having a major effect on the structure of the protein produced

Name the four types of chromosome structure mutations

deletion, duplication, inversion and translocation

What is a deletion mutation?

a sequence of genes is lost from a chromsome

What is an inversion mutation?

a set of genes in a chromosome rotates 180°

What is a duplication mutation?

a set of genes from one chromosome becomes attached to its homologous partner

What is a translocation mutation?

detached genes become attached to a non-homologous chromosome

Why are single gene mutations important in evolution?

they provide the only source of new variation for living organisms

Why are duplication mutations important in evolution?

allows potential beneficial mutations to occur in duplicated gene, whilst the original gene can still be expressed to produce its protein