2.1.6 cell division, diversity, organisation Flashcards
cell cycle 4 stages
G1 (growth 1)
Synthesis
G2 (growth 2)
Mitosis (cytokineses)
what triggers going from one phase to enouther
cyclins
3 parts of interphase
g1
s
g2
what happes in G1
- growth
- PROTEIN SYNTHESIS, cells make enzymes, proteins for growth
- CHECKPOINT: dna damage etc, approve going to the next
what happens in g2
- more growing
- DNA is error checked and repaired
does the cell grow during mitosis
no
in whcih part of cell cycle is there the most mRNA produced
- G1
- protein syntehsis and production of mRNA in transcription
product of mitosis
2 genetically identical daughter cells
4 stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
how many chromosomes in human nucleus
46 (23 pairs)
Prophase
- chromosomes SUPERCOIL and become visible
- nuclear envelope disintegrate
- nucleolus disappears
- centrioles move to opposite poles
metaphase
- chromosomes line up at equator of cell
- SF attach to centromeres
anaphase
- sister chromatides pulled apart at centromre
- SF shorten
- separated chromatids pulled to opposite poles by microtubule spindle fibres
telophase
- nuclear enevlope reforms
- SF breaks down
- new nucleoluses formed
cytokineses
cytoplasm and organelles divides into 2
structure of chromosome (post DNA rep)
2 identical chromatids joined together at CENTROMERE
centrosome
pair of centrioles
what in plants can you use to study mitosis
meristem tissue (root tip)
purpose of mitosis
- growth
- replace cells, repair tissues
- asexual reproduction eg ameoba
what type of cells does mitosis produce
diploid
what type of cells does meiosis produce
haploid gametes
meoisis 1
PMATC (1)
P1
- nuclear envelope breaks down into vesicles
- nucleolus disintegrates
- chromosomes condense and become visible
- CROSSING OVER occurs
crossing over is