VCU Exam 2 Flashcards
cell division purpose
growth, maintenance (cell regeneration), repair, reproduction (sexual-meisosis, asexual-mitosis)
binary fission
prokaryote cell division, elongation of plasma membrane until cell walls form. produce 2 identical daughter cells
cell cycle
interphase (G1, S-DNA synthesis, G2), M phase (cell division-mitosis), cytokinesis (actual separation into 2 cells)
somatic cells
all cells in the body except for sperm and egg. 46 chromosomes (23 each from mom and dad)
ploidy
sets of chromosomes.
Somatic-diploid (2n)
Gametes/sex cells- haploid (1n)
Polyploidy- Xn (ex: 28n)
chromatin
loosly unwound and decondensed DNA with associated proteins
sister chromatids
2 identical copies formed by the replication of a single chromosome (either maternal or paternal)
centromere
made of proteins, hold the sister chromatids together
M phase
4 subphases (prophase, metaphase, anaphase, telophase) PMAT
contractile ring
composed of microfilaments-made out of actin. present in at the end of telophase, starting cytokinesis
homologous chromosomes
22 pairs (carrying the same genes), the rest are sex chromosomes
associated proteins of DNA
help the DNA form tight coils and replicate to form sister chromatids
Mitosis
1 cell divides into 2 identical daughter cells. No change in ploidy
Mitosis prophase
most complex and longest, occurs after interphase
DNA is in chromatin form, condenses into chromosomes
spindle apparatus forms each moving towards opposite poles of the cell
Nuclear envelope breaks down, sister chromatids can move freely within the cell
Microtubules from the spindle apparatus extend and attach to chromosomes (fully condensed) at the kinetochore.
Non-kinetochore microtubules extend to expand the cell
Mitosis metaphase
chromosomes line up at the metaphase plate (middle of the cell) while still connected with the microtubules
Mitosis anaphase
sister chromatids pulled apart to opposite sides of the cell by microtubules
Mitosis telophase
the nuclear envelope reforms around both sides of the chromosomes. DNA decondenses into chromatin
Mitosis cytokinesis
starts during telophase, the process of cells splitting in 2. Contractile ring forms until they pinch off into 2 cells
Mitosis in plants
everything is the same except for cytokinesis. The plasma membrane split instead of cleavage furrow forming, and cell wall develops
phragmoplast
overlapping microtubules that guide vesicles containing cell wall components to the middle of the cell
Meiosis
division of germ cells. produce gametes: sperm or egg. Start with 1 cell to produce 4 non-identical daughter cells. Ploidy cut in half.
Meiosis prophase I
chromatin condenses into chromosomes,
sister chromatids join at centromere forming homologs
nuclear envelope breaks down.
spindle apparatus moves towards opposite poles
synapsis and crossing over occurs
microtubules attach at kinetochore, or not to expand cell
synapsis
homologous chromosomes join together forming a bivalent/tetrad
crossing over
occurs at the chiasma, a form of genetic recombination to increase genetic variation
Meiosis metaphase I
homologs line up at the metaphase plate at random orientation (genetic recombination-add to variety)