Lecture 11-Genetic Variation, Genes, and Chromosomes Flashcards
What is the difference transcriptionally and histological staining for euchromatin vs heterochromatin
- Euchromatin: high density and is transcriptionally active (darker nucleus on H & E stain)
- Heterochromatin: more folded and pale staining-not as transcriptionally active
Types of DNA variation (4)
- SNP (single nucelotide polymorphism)-single base pair change between individuals (1% population)
- SSR (simple sequence repeat)-tandem repeat of 2,3, or 4 base pairs
- VNTR (variable number of tandem repeats)-longer than SSRs-5,10,100 base pairs
- LCR (low copy repeat)-may be very large
What are SSR’s useful for in practice?
Forensics and paternity testing
-Easy to detect by the PCR method
What is the most common SINE in humuans?
The Alu sequence
SINE=Short interspersed nuclear elements
SNP vs rare variant. What contributes more to human diseases?
Rare variant
What are pseudogenes?
Sequences that look like real genes but have no protein product. The gene is turned off for some reason
Mitochondrial DNA arisen by what? Passed on by whom?
- Endosymbiosis
- Maternal line
What is the long arm in the chromosome? Short?
P=short
Q=long
Hierachical levels of chromatin packaging in a human chromosome.
- Double Helix
- Nucleosome fiber (beads on a string)
- Solenoid
- Interphase nucleus
What stage does X-inactivation take place?
Blastocyst stage in the development of female embryos-turns one X chromosome into a Barr body
It is random-regulated by Xic (X inactivation center)
What is mosaicism? Think Kali the cat
Paternal X/Maternal X are inactivated in different cells so there is reginos of different phenotypes
What is an allele?
Different versions of the SAME gene
What is OMIM?
Online Mendelian Inheritance in Man-each genetic trait has a unique six-digit MIM number
