Cell Cyle Genetics

Cell cycle composed of

interphase and mitosis

22 chromosomes which are

autosomal

23 chromosomes which are

seggs chromosomes

interphase

prep for division, takes the longest

miotic phase consist of

prophase prometaphase metaphase anaphase telophase

karyokinesis is

the division of DNA

cytokinesis is

division of the cytoplasm

chromosome

dna containing structure with a centromere

sister chromatids are

1 chromosome

Centromeres are

specialized sequences where sister chromatids are joined

Kinetochores are

protein complexes which bind to centromeres

centrosomes are

made of a pair of centrioles

centrioles are

microtubule organising centres

microtubles are

key players in cell division which are negative at the ends of centrosomes and positive at the ends which grow away from centrosomes

kinetochore mts

attach to kinetochores at centromeres key for chromosome movement during cell division

polar mts

extend from centrosome of one pole to the other key to cell shape and stability

astral mts

grow toward and attach to the membrane key for cell stability

first during G1

transcription/translation in prep for S

second during S

DNA replication and formation of sister chromatids

third during G2

chromosomes and centrosomes duplicate, Mts begin to extend, intact nuclear envelope

prophase

chromosome condensation starts, centrosomes migrate to opposite poles, nucleolus disappears

prometaphase

chromosomes move to the middle of the cell due to Mts attaching to kinetochores, polar and astral Mts stabilise the cell, nuclear envelope breaks down, cohesin binds chromosomes

sister chromatid cohesion

protein cohesin binds b/w sister chromatids to prevent early separation as kinetochrome Mts re moving to align them in the middle of the cell

during metaphase cohesin is

degraded by separase in anaphase to separate sister chromatids

during metaphase

chromosomes are completely condensed , sister chromatids align at metaphase plate by pulling forces of kinetochore Mts, miotic spindle is in place

during anaphase

sister chromatids separate, separase breaks cohesin (chromosome disjunction) kinetochore Mts depolymerise pulling towards opposite poles

during telophase

polar Mts keep extending pushing poles apart, nuclear envelope reforms, chromosomes decondense, cytokinesis, nucleolus reforms

G1 checkpoint

checks for cell size nutrients and growth factors present

S checkpoint

checks if DNA replication is complete and mismatch or any other errors have been removed

G2 checkpoint

cell size check, chromosome replication is successfully completed

metaphase checkpoint

check that all chromosomes re attached to each other spindle