Unit 1- Key Area 1.5 & 1.6 Flashcards
What is a genome?
The genome of an organism is the total genetic information encoded into the base sequence of it’s DNA.
What does the genome contain?
The genome contains those sequences that code for protein (genes) and those that do not. The non-coding sequences include those that regulate transcription, those that are transcribed into RNA but not translated and some non-coding DNA sequences that have no function.
What is the coding sequences (genes) function in the genome?
Code for amino acid sequences in proteins.
What is the non-coding sequences function in the genome?
Regulate transcription by turning genes on or off.
Transcribed but not translated (eg rRNA, tRNA)
What are mutations?
Mutations are rare, random DNA changes to the DNA sequences.
What is the effect of single gene mutations?
Changes the amino acid sequence of the protein coded for.
What is the effect of regulatory sequences mutation?
alters the way in which genes are expressed in the phenotype.
What is the affect of splice sites mutations?
Can cause introns to be left in mature mRNA, leading to an altered protein.
What is the affect of a chromosome mutation?
Affects structure or number of chromosomes present in cells.
What is a single gene mutation?
Single gene mutations occur within genes and involve alternations of a DNA nucleotide sequence. Gene mutations result in no protein or an altered protein being expressed.
What do mutations provide?
Mutation provides the only source of new variation for the living organisms and so has held vital importance in evolution.
What do some mutations affect?
The structure or numbber of chromosomes present in the cells of living organisms. Those affecting the structure arise when pieces of one chromosome break off and are lost or join back into the chromosome complement in a different way.
What is non-disjunction?
Non-disjunction is the failure of the spindle to separate the chromosomes properly during cell division. It results in daughter cells with more or less than the correct chromosome number and can even produce cells with the complete genome duplication.
