Cell division Flashcards
Mitosis
Nuclear division that created a pair of diploid cells that are identical to the original cell
Prophase
Chromatin consdense into chromosoms
Nucleolous disappears
Mitotic spindle begins to form
Centrosome moves towards opposite ends
Prometaphase
Nucleolus dissasembles
Chromatid is attached to kinetochore
Spindle fibers begin to attach to kinetchoes of chromosomes
Metaphase
Chromosomes line up across center of cell
Karotyping displayed
Anaphase
Sister chromatids pulled apart
Chromosomes pulled to opposite ends of cell
Telophase
Nucleoli redevelop
Chromosomes decondense back into chromatin
cytokinesis occus
Cytokinesis
Divison of the cytoplasm to form two cells
During cell division of mitosis what do animal cells from during cytokinesis?
cleavage furrow
During cell divison of mitosis what do plant cells form during cytokinesis?
cell plate
Result of mitosis
Two identical diploid daughter cells
Meiosis I
Nuclear divison that produces four haploid gametes
Where does meiosis I occur
germ cells
Two stages of meiosis
Meiosis I
Meiosis II
Meiosis I
Genetic recombination occurs and the cell seperates homologous chromosomes
Meiosis II
Sister chromatids seperate to form final gametes
Prophase 1
Same as prophase from mitosis
Synapsis
homologous chromosomes pairing up and aligning
Crossing over
Exchange of chromosomes segments between paired up chromosomes
What is the name for paired up chromosomes
tetrads
What must be formed for genetic recombination to occur
tetrads
Chiasmata
physical points where paired chromosomes swap segments
Metaphase 1
homologous pairs are lined up across the metaphase plate
Anaphase I
Meiotic spindle shortens
Homologous pairs uncouple and are pulled to opposite poles
Telophase 1 and Cytokinesis
Nuclear envelope re-develops
Chromosomes decondense
Each daughter cell has a new nucleus that has half the number of chromosomes
Metaphase II
Chromosomes line up on metaphase plate
Meiotic spindle formed and attached to every chromosomes via kinetochores
Half the # of chromosomes are present
**Sister chromatids are no longer identical due to crossing over in Prophase I
Prophase II
Nucleus and nucleolus disappear
Chromosomes condense
Meiotic spindle develops and attaches to chromosomes
Anaphase II
Microtubules shorten
Sister chromatids are pulled across to opposite ends
** Each sister chromatid is now individual chromosomes
Telophase II and Cytokinesis
Nucleolus reforms
Chromosomes decondense back into chromatin
Cytokinesis splits cell into daughter cells
Final result of meiosis
Four haploid daughter cells, each with half the amount of DNA as the parent cell
Which events does genetic diversity occur
Crossing over, Independent assortment, random joining of gametes
Independent assortment
Which chromosomes gets separated to which end of the cell is random
Random joining of gametes
Different sperm fertilize different eggs
Interphase
Cell is growing and preparing for cell division but not actively dividing
cells spend most of cell cycle here
Phases of Interphase
G1, S, G2, G0, Mitotic
G1 (gap phase 1)
cell grows in size and protein synthesis begins (preparation for cell division)
S (synthesis phase)
DNA and centrosomes are replicated.
Sister chromatids are formed
Which phase of interphase does DNA replication occur
S phase
G2 (gap phase 2)
Final preparation for mitosis
Cell continues to grow and organelles replicate
G0 (resting phase)
Cells are active/functional but are not dividing
Which cells are permanently in G0 phase
nerve and muscle cells
Senescent
permanently in G0 phase
Quiescent
Cell is temporarily in G0 phase
Mitotic phase
Mitosis and cytokinesis
Cell cycle checkpoints
Determine if a cell is prepared to go to the next stage
End of G1 (checkpoint)
Checks cell growth and favorable cellular conditions
End of G2 (checkpoint)
Cell evaluates the accuracy of DNA replication
If healthy goes to M phase
M Checkpoint
During metaphase cells checks if each sister chromatid is attached to a spindle fiber
What happens if a cell fails the checkpoints
Enters G0 phase of apopotosis
p53 gene
tumor suppressor gene that regulates cell division