Genome evolution & multilgene families (lecture 15) Flashcards
what is reciprocal translocation?
where 2 non-homologous chromosomes break and exchange fragments
what is chromosome fusion?
2 heliocentric chromosomes fuse to generate 1 new chromosome
what is robertsonian translocation?
short arms of 2 acrocentric chromosomes are lost
in humans this generates individuals with 45 chromosomes
why do chromosomes have bands on them?
stain
used to clearly discriminate different chromosomes/regions of them
what is inversion of chromosomes?
may be paracentric (within 1 arm)
may be pericentric (involving both arms)
can be break-join or cross over
how do changes to genome happen?
no specific mechanisms
depends on accidents and mistakes
what errors can occur in DNA replication to chromosomes?
base changes translocations deleteions duplications inversions
what are multigene families?
set of several similar genes, formed by duplication of a single original gene
arise after duplication events
followed by a mutation to generate alterations in expression/function
what are homeotic (hox genes)?
found in clusters on chromosomes
proteins encoded by hox genes are transcription factors that influence expression patterns of many genes during development
these genes contain a characteristic 180 nucleotide segment called the homeobox
this encodes a DNA binding part called the homeodomain
what are globin genes?
genes in haemoglobin
haemoglobin is a tetramer of 2 alpha and 2 beta with different genes being expressed for different stages in development
production of alpha and beta chains is usually tightly regulated to give equal amounts
what is thalassemia?
occur when there is an unbalanced proportion of globins
results in the production of abnormal haemoglobin
severity depends on how many genes affected and how severe the mutations are
