Lecture 14: Specialized Chromosome Structure Sequences Flashcards
Human telomere sequence is.. and how many repeats at birth
TTAGGG -2500
Centromere is essential for
Chromosome separation
T or F: G strand sequence is longer than C strand on telomere sequence
True - G strand is longer
Which strand of the telomere folds over to from T loop
G rich strand
Shortened telomere sequences are linked to
Shorter life span and increased disease. Specifically restricted cell proliferation/tissue degeneration - CARDIOVASCULAR DISEASE
Lead and telomeres
Lead exposure leads to shortened telomeres
Longer telomeres effect
Increase risk related to increased PROLIFERATVE growth, including major CANCERS
Centriole
Small cylindrical organelle, located near nucleus, divides in perpendicular fashion during mitosis
What is the primary sequence at human centromeres
Alpha satellite DNA in tandem head-tail fashion
What is the predominate form of alpha satellite DNA
Complex high order sequences (HORs)
What is crucial for centromere/kinetochore assembly/function during cell division
Transcription of Alpha satellite DNA
What is at the core of the kinetochore/centromere and it is surrounded by what
Centromere-specific histone H3 variant CENP-A
Surrounded by heterochromatin
What links together centromeric chromatin
Cohesin
What happens if a chromosome break occurs near centromere and one fragment does not get a centromere
That piece of DNA is usually lost from the nucleus
Histones are ___ charged
Positively
Nucleosome core of histone is comprised of
Two H2A-H2B dimers
H3-H4 Tetramer
Nucleosome
Basic unit of DNA packaging
Segment of DNA wound in sequence around 8 core histone proteins (DNA wraps around each 1.65 times)
Chromatosome
A histone octamer, one molecule of linker histone, and 166BP of DNA.
Linker DNA
Double stranded DNA b/w two nucleosome cores, that, in association with Histone H1, holds the cores together
High order chromatin structure
30nm fiber
300nm loops
250nm wide fiber
What is the fundamental repeating unit of chromatin
Nucleosome
Polytene chromosome created by
Repeated rounds of DNA replication w/o cell division
Chromosomal puffs
Regions of relaxed chromatin where active transcription is taking place
Does chromatin structure change during the course of transcription? How would we know?
Yes it does. Shown but the fact that DNA’s sensitivity to be degraded by DNAse I is correlated with gene expression
Epigenetics
A heritable alteration of phenotype because of altered chromatin structure (histone modification, acetylation)
Unique sequence DNA
Similar but not identical copies of unique DNA sequences that arose through duplication of an existing gene
Repetitive DNA
Stretches of DNA that repeat themselves throughout a genome, in tandem or interspersed along the genome.
Alu element
Short interspersed elements: SINEs
Moderately repetitive DNA length
150-300bp long
Highly repetitive DNA length
Less than 10bp
Microsatellite DNA
(Short Tandem Repeats)
Tract of tandemly repeated (adjacent) DNA motifs thtat range in length from 2-5 nucleotides, and are typically repeated 5-50 times. TATATATA is an example of a dinucleotide microsatellite
What can microsatellite DNA be used for
Mapping locations within the genome
STR sequencing project
Initiated to facilitate the description of sequence based alleles at the STR loci
