Unit 11- Chromo Structure and Organelle DNA Flashcards
pos supercoiling
overroatated DNA (top coil going down right)
*neg supercoiling
underrotated DNA
topoisomerase
enzyme responsible for adding and removing turns in the coil
euchromatin
- less condensed
- on chromo arms
- unique seq
- many genes
- replicated in S phase
- transcribes often
- crossing over is common
heterochromatin
- more condensed
- at centromeres, telomeres, etc
- repeated seq
- few genes
- replicated late in S phase
- transcribes infrequently
- crossing over is uncommon
linker DNA
DNA between chromososmes
polytene chromos
created by repeating rounds of DNA replication w/ no cell division
dnase I sensitivity
correlates w/ gene activity
epigenetic changes
Stable alterations of chromatin structure that may be passed on
- methylation; capable of being reversed and altered due to environ factors
centromere structure
constricted region where spindle fibers attatch
telomere structure
ends of chromos
c value
amount orgs differ in amount of DNA per cell
gene family
similar but not identical copies of unique DNA seq that arose through duplication of an existing gene
moderately repetitive DNA
150~300 bp long
- tatem
- interspersed
(short: SINEs: Alu ele
long: LINEs)
highly repetitive DNA
less than 10 bp long
- microsatellite DNA
endosymbiotic theory
mito and chloro were once free-livin bacteria
human genome length
16,295 bp
human mtDNA
circular; 16,569 bp; encodes 2 rRNA, 22 tRNA, and 13 proteins
yeast mtDNA
5 times human; encodes 2 rRNA, 25 tRNAs, and 16 polypeptides
flowering plant mtDNA
extensive size variation
transposable elements
sequences that can move about in the genome
genomic imprinting
an allele is expressed differently based on
whether it is inherited from the mom or dad
- caused by methylation
hybridization
DNA from different sources will renature if they are complementary (don’t have to be all bases)
replicative transposition
a new copy of the
transposable element is introduced at a new site while the
old copy remains behind at the original site
nonreplicative transposition
the transposable ele-
ment excises from the old site and inserts at a new site with-
out any increase in the number of its copies.
