Chap6 Cell Division Flashcards
What are the two stages of cell division?
Interphase
Mitotic stage
What happens at G1 of interphase?
Cell growth
Checking for DNA damage and correct size of cell
What happens at G2 of interphase?
Cell growth
Chromosomes checked for replication and no faulty DNA
What happens at checkpoint M in interphase?
Sister chromatids checked for attachment to spindle
What happens at stage S in interphase?
DNA synthesis
INTERPHASE of mitosis
DNA replicated my semi-conservative replication
METAPHASE of mitosis
Chromosomes line up along middle of cell
Attached by centromere
ANAPHASE of mitosis
Chromosomes break into two chromatids
Chromatids separate and spindles contract to pull them to each pole of cell
TELOPHASE of mitosis
Chromatids unravel into chromosomes again
Nuclear envelope forms around chromosomes making two nuclei
Cytoplasm splits forming two daughter cells
Cytokinesis
The division of the cytoplasm bringing about two daughter cells
Centromere
The centre region of chromosome to which spindle attach
Chromatid
Chromosome divides into this during cell division
Each contain double helix of DNA
Centriole
Involved in developing spindle fibres in cell division
Plasmid
Circular double stranded DNA molecule
INTERPHASE of meiosis
Chromosomes replicate to form chromatids
PROPHASE 1 of meiosis
Chromatids condense to form sister chromatid
METAPHASE 1 of meiosis
Chromosomes in diploid organisms found in HOMOLOGOUS PAIRS (identical genes different alleles)
Chromosomes moved by spindle fibres
ANAPHASE 1 of meiosis
Homologous chromosomes pulled to opposite ends of cell by spindle fibres
TELOPHASE 1 of meiosis
Random combinations of chromosomes pulled to each side of cell
Cytokinesis of meiosis 1
One chromosome from pair separated into each cell
2 Genetically different cells produced
PROPHASE 2 of meiosis
Chromatids condense again
Spindles form
METAPHASE 2
Chromosomes line up in centre of cell
Not in pairs
ANAPHASE 2
Sister chromatids pulled by spindle fibres to opposite ends of cell
TELOPHASE 2 + cytokinesis of meiosis
Sister chromatids separated and cell divides into two
4 Genetically different cells produced
How is genetic variation brought about during meiosis?
Independent segregation of homologous chromosomes crossing over
Formation of chiasmata
How does meiosis contribute to genetic diversity?
Mutations can occur during meiosis
Meiosis produces four genetically diverse haploid cells
Random assortment of homologous chromosomes
Exchanging segments of DNA
