| what is a genome of an organism | the organisms entire hereditary information encoded in DNA |
| what is a genome made up of | genes (DNA sequences that code for protein) and
other DNA sequences that do not code for proteins. |
| what does most of the eukaryotic genome consist of? | non-coding sequences. |
| what is the function of other dna sequences that do not code for proteins in our genome | they regulate (control) transcription (production of mRNA)
others are transcribed but never translated (not used for making proteins) |
| name two types of RNA which are transcribed but not translated into proteins | tRNA
rRNA |
| what are mutations | random changes in the DNA that can result in no protein or an altered protein being synthesised |
| what are single gene mutations | involve the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides |
| what is a substitution mutation | occurs when one base is substituted for another.
substitutions result in a change that only affects one codon |
| name the three types of substitution mutations | missense
nonsense
splice site |
| describe a missense substitution mutation | missense mutations result in one amino acid being changed for another.
This may result in a non-functional protein or have little effect on the protein |
| describe a nonsense substitution mutation | nonsense mutations result in a premature stop codon beng produced which results in a shorter protein |
| describe a splice site mutation | when there is a substitution mutation at a splice site and then some introns may be retained and some exons may not be included in the mature transcript |
| describe frame shift mutations | insertions or deletions result in frame shift mutations
frame shift mutations cause all of the codons and all of the amino acids after the mutation to be changed, having a major effect on the structure of the protein |
| describe a deletion mutation | when a deletion mutation occurs, one (or several) bases is deleted from the DNA molecule |
| describe an insertion mutation | when an insertion mutation occurs, one (or several) bases is inserted into the DNA molecule |
| are frameshift mutations more are less dangerous than substitution mutations | they are more detrimental than substitution mutations the whole base sequence after the mutation is changed |
| what are chromosomal structure mutations | involve the number or sequence of genes on a chromosome being altered |
| name the four types of chromosome changes | deletion
duplication
translocation
inversion |
| are chromosomal structure mutations dangerous | the substantial changes in chromosome mutations often make them lethal |
| describe deletion chromosome mutation | where a section of a chromosome is removed |
| describe inversion chromosome mutation | where a section of a chromosome is reversed |
| describe translocation | where a section of a chromosome is added to a chromosome, not its homologous partner |
| describe duplication chromosome mutation | where a section of a chromosome is added from its homologous partner |
| how can gene duplication be beneficial | gene duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce its protein |
