Module 2 - cell division Flashcards
what is the G1 phase ?
proteins required for organelles are synthesised
what is the s phase?
Dna replication takes place, resulting in the double mass of DNA in the cell
what is the G2 phase?
organelles grow and divide, energy reserves and increases
what three steps is the interphase composed of?
- G1 phase
- S phase
G2 phase
what is mitosis ?
when the nucleus divides into two
what is cytokinesis?
- the cytoplasm divides to form two genetically identical daughter cells
where do the checkpoints occur?
- the end of G1 - before DNA replication occurs
- end of the G2 stage before mitosis begins
- spindle assembly to esnure chromosomes are aligned on the spindle
what happens in prophase ?
- chromsomes comprimise of two genetically identical threads called sister chromatids joined by a centromere
- nuclear envelope disappears
- the centrioles move to the poles of the cells, producing a network of spindle fibres between them
what happens in metaphase ?
- the chromosomes move to the equator of the cell
- each one becomes attached to a spindle fibre by its centromere
what happens in anaphase ?
- the spindle fibres contract, which separates the sister chromatids
- spindle fibres pull the chromatids towards opposite poles of the cell centromere
what is telophase ?
- nuclear envelope forms around each pole to form two new nuclei
- chromosomes start to uncoil
- spindle fibres breakdown
- two new daughter cells are formed
what is the significant of mitosis?
- asexual reproduction
- growth
- tissue repair
what is prophase 1 in meiosis?
chromatids condense, homologous chromosomes form bivalents,crossing over occurs
what is metaphase 1 in meiosis?
bivalents line up at the equator, independent assortment occurs
what is anaphase 1 in meiosis?
- spindle fibres pull homologous chromosomes opposite poles of the cell