12 Introduction to genetics Flashcards
what are the two main purposes of medical genetics?
Dx inheritable disorders
Dx risk of non-inheritable disorders w/ genetic component
what are the four types of genetic disorders with two examples each
chromosome disorders -> gross change in nubmers ie. trisomy 21(downs), 45X(turners syndrome)
Single gene -> single unit change ie. CFTR mut (cystic fibrosis), Hemophilia A
Multifactorial -> many genes influences disease to occur ie. diabetes, CHD
mitochondrial -> maternally passed down genes has their own diseases ie. LHON (leber hereditary optic neuropathy), MERRF (Myoclonic epilepsy with Ragged Red Fiber
why has the incidences of genetic disorders risen in the past 50 years even with rapidly improving medical health?
better screening and Dx methods mean more that may have never been Dx is beng dDx early and hence makes a good day
what are the two types of repeated DNA sequences in the human genome?
satellites are repeated units in tandem and near centromeres
- mini satellites are larger (few thousand BP)
- micro satellites are smaller (few hundred BP)
Dispersed repetitive sequences are spread throughout the genome
- LINE are “long” sequences
- SINE are short sequences
- Alu repeats are SINES that code for Alu I and makes up 10% of the genome
What is the difference between reductional and equational division?
in meiosis, reductional division is in the first half of the phase at which the number of chromosomes are split from diploid to haploid which is 46 chro to 23 chro and thus 23 centromeres and 46 chromatids left
in equational division unlike redu. div. the centromeres divide –> 4 unique chro. and resulting in 23 centro. and 23 chro per cell
define chiasmata
point –> 2 chromatids xchange info –> prophase I
how does cell division progress in females?
in utero division halts at prophase I
once ovulation begins it will halt at metaphase II
cycle completes only at fertilization
