Lecture 2 Flashcards
(33 cards)
Centromere
Structure in mitotic chromosome that holds together 2 chromatids,
Kinetochore
Protein structure on chromatids where spindle fibers connect to pull the two apart and the centromere is the point of attachment of the kinetochore.
Rep Origin
Particular DNA site within a genome at which replication is initiated
Telomerase
Ribonucleoprotein (protein +RNA) that elongates telomere sequences
Telomere defintion and examples
Repeating minisatellite DNA sequence at both ends of a linear chromosome.
Telemores function by preventing chromosomes from degradation and they also prevent chromosomes from fusing to each other.
Cohesin
Ring shaped, chromosome associated, protein complex that mediates cohesion between replicated sister chromatids
CENP-A
Centromere-specific variant (substitute) of histone H3
TERT
Key enzymatic component of telomerase, has reverse transcriptase
Acrocentric chromosome
Chromosome in which the centromere is located quite near one end of the chromosome (contains very short p arm)
Roberstonian translocations
2 chromosomes (usually accentric) joining at the centromere region
Modification of histone tails directly influences what?
Structure of chromatin
Quickly outline the cell cycle
Interphase> M phase
Quickly outline interphase and M phase
Interphase is G1, S phase (DNA replication) then G2.
M phase is Prophase, Prometaphase, metaphase, anaphase, telophase , cytokinesis division,
What does one linear chromosome contain and what is it made from?
Made from one DNA molecule.
Contains 1 centromere, 2 telomeres and multiple replication origins
The 3 things that the linear chromosome contains, is used for what function?
Telomeres and Rep origins are used in S Phase for DNA replication.
Centromeres are used in M phase for Mitosis
Name 2 functions of centromeres
Essential for segregation of chromosomes and directs formation of kinetochores
What can happen when there is more than one centromere?
Translocation, chromosome breakage, random segregation of chromosome
Give the name for the designations when the centromere is located in
a) Middle
b) Between middle and end
c) Close to end
d) At end
a) Metacentric
b) Submetacentric
c) Acrocentric
d) Telocentric
What is the alpha satellite DNA?
Primary centromeric repeat unit in humans of about 171 bp
What other sequences can be found in centromeric regions and what is the name for this region?
LINEs and SINEs transposable elements. Pericentric region
What is CENP A and H2K4me2
CENP A is a chromatin containing centromere specific histone H3 variant.
H3K4me2 is a chromatin containing normal histone H3 that is dimethylated at lysine 4, also lies in the centromere region on either side of the CENPA
What chromosome is down syndrome caused by?
An extra acrocentric chromosome
Explain the fusion between 13 and 14 chromosomes
Short p arms of the acrocentric 13 and do not contain any essentialgenes but contain tRNA and rRNA loci which are present in multiple copies. Same goes for 15, 21, and 22
Replication Origin sequences are rich in what nucelotide bases?
AT rich as it is easier to melt
