Mitosis/Meiosis Flashcards
Stages of Interphase
G1 (growth)
S (Growth and duplication of DNA)
G2 (growth and prep for division)
Formation of Mitotic Spindle
Prophase I
Centrosomes move to opposite poles
Microtubules in centrosome develop and increase in length (connect at kinetochore of centromere)
MTOC
Microtubule organizing centers
Centosomes
Metaphase
Micortubules pull apart chromosomes into 2 chromatids
Once seperated, each chromosome is considered a full chromosome (has a centromere of its own)
Anaphase
Microtubules pull on split chromosome
Cell Plate
In plants, vesicels from golgi form together at the plane of dividing cell
Vesicles fuse, forming cell plate, becomes PM
Cleavage Furrow
In animals, microfilaments form a ring inside between dividng cells
Shortening of microfilaments causes cleavage furrow, results in cell dividing
Synapsis
Pairing of homologous chromosomes
Formes tetra/bivalents
Chiasma
Where cross over occurs
Synaptonemal Complex
Tetra with chiasmata and crossing over
Telophase I
In some species, some cells undergo cytokinesis
In others, cytokinesis is delayed until after meiosis II
Mutations
Mutations in proto-oncogenes and tumor suppressor genes can cause a cell to become cancerous
Spores
Haploid cells that divide by mitosis to become a muticellular haploid structure (gametophyte)
Meiosis in Ferns
Games are produced by the gametophyte becuase it is already haploid
2 gametes fuse togetehr to form a diploid sporophyte
Cells in sporophyte divide by meiosis to make haploid spores
Sources of Genetic Variation
Cross Over
Independent Assortment
Random joining of Gametes
Regulation of Cell Cycle
Surface to volume ratio Genome to volume ratio Checkpoints CDKs GFs Density-Dependent Inhibition Anchorage Dependence
Genome to volume ratio
As cell grows, volume increases but genome size is constant
Cells size will exceed ability of its genome to produce sufficient amounts of materials for regulating cellular activities
G1 Checkpoint
Are conditions appropriate to undergo division?
Is cell programmed to divide (if not, enters G0)
G2 Checkpoint
Was DNA replication sufficiently accurate to proceed
M Checkpoint
Metaphase
Did microtubules connect to kinetochores properly
CDKs
Enzymes that phosphorylate and activate proteins that regulate cell cycle
Activated when bound to cyclin
Growth Factors
When a cell is damage, it releases GF that can bind to a membrane receptor of another cell, causing it to divide
Density Dependent Inhibition
When cell density becomes too high, cells stop dividing
Anchorage Dependence
Cells need to be anchored to a surface (such as another cell) to divide
