Medical Genetics Flashcards
Importance of medical genetics
Genetic disorders are widespread, many common problems have genetic components: cancer, diabetes, disease susceptibility
Types of genetic disorders
Chromosome disorders, single-gene disorders, multifactorial disorders, mitochondrial disorders
Examples of chromosome disorders
Down syndrome, Turner syndrome
Examples of single-gene disorders
Hemophilia, cystic fibrosis
Examples of multifactorial disorders
Diabetes, heart disease
Examples of mitochondrial disorders
LHON, MERRF
Organization of genetic material
Genome organized into chromosomes, 23 pairs, 46 total (1 pair of sex chromosomes), chromosomes have specific genes, genes have specific position
Repetitive DNA sequences
Dispersed repetitive, satellite DNA
Dispersed repetitive
45% of genome, LINEs (up to 7000 bp), SINEs (90-500 bp), Alu repeats (300 bp SINEs with Alu site)
Satellite DNA
10% of the genome, classified as alpha (171 bp repeat), minisatellite (few thousand total, 14-500 bp repeat), microsatellite (1-13 bp repeat, few hundred total)
Meiotic recombination
Meiosis produces haploid gametes, maternal and paternal chromosomes mixed, recombination by “crossing over”, increases genetic variation
Chiasma
Point of crossing over/recombination between homologous chromosomes
Bivalent
Pair of homologous chromosomes
Tetrad
Four chromatids
Rate of recombination between genes
Depends on the distance of genes from each other, closer genes are less likely to be separated, measured in centimorgans (cM)- represents 1% chance of recombination
