Chromosomes And Cell Division Flashcards
Describe the structure of a chromosome?
The tip of the arms are telomeres.
Centromere at the centre.
Euchromatin is an open accessible structure (active)
Heterochromatin is a condensed structure (inactive)
Chromosomes are most easily seen at duplicated state.
What are telomeres and what do they do?
5’-TTAGGG-3’ repeats
They help with the end replication problem when the RNA primer is removed so a gap is made. Solved by reverse transcriptase enzyme called telomerase.
They also protect the ends from damage recognition machinery.
What happens in prophase?
The chromosomes condense and the nuclear membranes disappear.
Spindle fibres form the centriole.
What happens in metaphase?
Chromosomes align at the equator of the cell.
Attached by fibre to the centriole.
Condensed even more.
What happens in anaphase?
Sister chromatids separate at centromeres.
Separate longitudinally.
Move to opposite ends of the cell.
What happens in telophase?
A new nuclear membrane forms.
What is the centromere?
Constricted region joining two sister chromatids together. Repetitive DNA sequence.
Site of kinetochore which is a large complex of proteins for microtubules to attach.
What are four types of extragenic DNA sequences?
Tandemly repeated sequences like satellite and mini satellite DNA.
Highly repeated interspersed DNA sequences like SINE and LINE.
What are four levels of chromosome condensing?
1-Nucleosome 2-chromatin fibre 3-fibre scaffold complex 4-chromosome A solenoid is a lot of nucleosomes.
What are three types of chromosome?
Meta centric Sub metacentric (off to one side) Acrocentric (p arm doesn’t contain any coding DNA)
What is FISH?
Fluorescent in situ hybridisation
Probe base pairs with DNA of chromosome to see particular sequence of location.
What are three types of FISH probes and what are they used for?
Centromeric probes determine chromosome number.
Telomeric probes detect subtelomeric rearrangements.
Whole chromosome probes are a cocktail of probes labelled differently to highlight different parts and translocation.
What are egg formation and spleen formation called?
Oogenesis
Spermatogenesis
